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Lin TF, Busch SE, Hansel C. Intrinsic and synaptic determinants of receptive field plasticity in Purkinje cells of the mouse cerebellum. Nat Commun 2024; 15:4645. [PMID: 38821918 PMCID: PMC11143328 DOI: 10.1038/s41467-024-48373-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 04/28/2024] [Indexed: 06/02/2024] Open
Abstract
Non-synaptic (intrinsic) plasticity of membrane excitability contributes to aspects of memory formation, but it remains unclear whether it merely facilitates synaptic long-term potentiation or plays a permissive role in determining the impact of synaptic weight increase. We use tactile stimulation and electrical activation of parallel fibers to probe intrinsic and synaptic contributions to receptive field plasticity in awake mice during two-photon calcium imaging of cerebellar Purkinje cells. Repetitive activation of both stimuli induced response potentiation that is impaired in mice with selective deficits in either synaptic or intrinsic plasticity. Spatial analysis of calcium signals demonstrated that intrinsic, but not synaptic plasticity, enhances the spread of dendritic parallel fiber response potentiation. Simultaneous dendrite and axon initial segment recordings confirm these dendritic events affect axonal output. Our findings support the hypothesis that intrinsic plasticity provides an amplification mechanism that exerts a permissive control over the impact of long-term potentiation on neuronal responsiveness.
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Affiliation(s)
- Ting-Feng Lin
- Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, IL, USA
| | - Silas E Busch
- Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, IL, USA
| | - Christian Hansel
- Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, IL, USA.
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Wang C, Jiang ZY, Chai JY, Chen HS, Liu LX, Dang T, Meng XM. Mouse auditory cortex sub-fields receive neuronal projections from MGB subdivisions independently. Sci Rep 2024; 14:7078. [PMID: 38528192 DOI: 10.1038/s41598-024-57815-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 03/21/2024] [Indexed: 03/27/2024] Open
Abstract
Mouse auditory cortex is composed of six sub-fields: primary auditory field (AI), secondary auditory field (AII), anterior auditory field (AAF), insular auditory field (IAF), ultrasonic field (UF) and dorsoposterior field (DP). Previous studies have examined thalamo-cortical connections in the mice auditory system and learned that AI, AAF, and IAF receive inputs from the ventral division of the medial geniculate body (MGB). However, the functional and thalamo-cortical connections between nonprimary auditory cortex (AII, UF, and DP) is unclear. In this study, we examined the locations of neurons projecting to these three cortical sub-fields in the MGB, and addressed the question whether these cortical sub-fields receive inputs from different subsets of MGB neurons or common. To examine the distributions of projecting neurons in the MGB, retrograde tracers were injected into the AII, UF, DP, after identifying these areas by the method of Optical Imaging. Our results indicated that neuron cells which in ventral part of dorsal MGB (MGd) and that of ventral MGB (MGv) projecting to UF and AII with less overlap. And DP only received neuron projecting from MGd. Interestingly, these three cortical areas received input from distinct part of MGd and MGv in an independent manner. Based on our foundings these three auditory cortical sub-fields in mice may independently process auditory information.
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Affiliation(s)
- Chi Wang
- Inner Mongolia Institute of Digestive Diseases, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
| | - Zhen-Yu Jiang
- Inner Mongolia Institute of Digestive Diseases, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
| | - Jian-Yuan Chai
- Inner Mongolia Institute of Digestive Diseases, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
| | - Hong-Suo Chen
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
| | - Li-Xia Liu
- Department of Scientific Research, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
| | - Tong Dang
- Inner Mongolia Institute of Digestive Diseases, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Baotou Medical College, Baotou, China
| | - Xian-Mei Meng
- Inner Mongolia Institute of Digestive Diseases, The Second Affiliated Hospital of Baotou Medical College, Baotou, China.
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Baotou Medical College, Baotou, China.
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Lin TF, Busch SE, Hansel C. Intrinsic and synaptic determinants of receptive field plasticity in Purkinje cells of the mouse cerebellum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.19.549760. [PMID: 37502848 PMCID: PMC10370111 DOI: 10.1101/2023.07.19.549760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Non-synaptic ('intrinsic') plasticity of membrane excitability contributes to aspects of memory formation, but it remains unclear whether it merely facilitates synaptic long-term potentiation (LTP), or whether it plays a permissive role in determining the impact of synaptic weight increase. We use tactile stimulation and electrical activation of parallel fibers to probe intrinsic and synaptic contributions to receptive field (RF) plasticity in awake mice during two-photon calcium imaging of cerebellar Purkinje cells. Repetitive activation of both stimuli induced response potentiation that is impaired in mice with selective deficits in either intrinsic plasticity (SK2 KO) or LTP (CaMKII TT305/6VA). Intrinsic, but not synaptic, plasticity expands the local, dendritic RF representation. Simultaneous dendrite and axon initial segment recordings confirm that these dendritic events affect axonal output. Our findings support the hypothesis that intrinsic plasticity provides an amplification mechanism that exerts a permissive control over the impact of LTP on neuronal responsiveness.
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Affiliation(s)
- Ting-Feng Lin
- Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
| | - Silas E Busch
- Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
| | - Christian Hansel
- Department of Neurobiology and Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
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Mitsuhashi D, Hishida R, Oishi M, Hiraishi T, Natsumeda M, Shibuki K, Fujii Y. Visualization of cortical activation in human brain by flavoprotein fluorescence imaging. J Neurosurg 2022; 137:1105-1113. [PMID: 35180697 DOI: 10.3171/2022.1.jns212542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 01/07/2022] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To develop an innovative brain mapping and neuromonitoring method during neurosurgery, the authors set out to establish intraoperative flavoprotein fluorescence imaging (iFFI) to directly visualize cortical activations in human brain. The significance of iFFI was analyzed by comparison with intraoperative perfusion-dependent imaging (iPDI), which is considered the conventional optical imaging, and by performing animal experiments. METHODS Seven patients with intracerebral tumors were examined by iFFI and iPDI following craniotomy, using a single operative microscope equipped with a laser light source for iFFI and xenon lamp for iPDI. Images were captured by the same charge-coupled device camera. Responses to bipolar stimulation at selected points on the cortical surface were analyzed off-line, and relative signal changes were visualized by overlaying pseudocolor intensity maps onto cortical photographs. Signal changes exceeding 3 SDs from baseline were defined as significant. The authors also performed FFI and PDI on 10 mice using similar settings, and then compared signal patterns to intraoperative studies. RESULTS Signals acquired by iFFI exhibited biphasic spatiotemporal changes consisting of an early positive signal peak (F1) and a delayed negative signal peak (F2). In contrast, iPDI signals exhibited only 1 negative peak (P1) that was significantly delayed compared to F1 (p < 0.02) and roughly in phase with F2. Compared to F2 and P1, F1 was of significantly lower amplitude (p < 0.02) and located closer to the bipolar stimulus center (p < 0.03), whereas F2 and P1 were more widespread, irregular, and partially overlapping. In mice, the spatiotemporal characteristics of FFI and PDI resembled those of iFFI and iPDI, but the early positive signal was more robust than F1. CONCLUSIONS This is the first report in humans of successful intraoperative visualization of cortical activations by using iFFI, which showed rapid evoked cortical activity prior to perfusion-dependent signal changes. Further technical improvements can lead to establishment of iFFI as a real-time intraoperative tool.
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Affiliation(s)
| | - Ryuichi Hishida
- 2Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, Japan
| | | | | | | | - Katsuei Shibuki
- 2Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, Japan
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Nakanishi M, Nemoto M, Kawai HD. Cortical nicotinic enhancement of tone-evoked heightened activities and subcortical nicotinic enlargement of activated areas in mouse auditory cortex. Neurosci Res 2022; 181:55-65. [DOI: 10.1016/j.neures.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/19/2022] [Accepted: 04/01/2022] [Indexed: 10/18/2022]
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Zhou DB, Castanos MV, Geyman L, Rich CA, Tantraworasin A, Ritch R, Rosen RB. Mitochondrial Dysfunction in Primary Open-angle Glaucoma Characterized by Flavoprotein Fluorescence at the Optic Nerve Head. Ophthalmol Glaucoma 2021; 5:413-420. [PMID: 34968754 DOI: 10.1016/j.ogla.2021.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 12/18/2021] [Accepted: 12/22/2021] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To investigate the presence of flavoprotein fluorescence (FPF) at the optic nerve head (ONH) rim as a marker of mitochondrial dysfunction in primary open-angle glaucoma (POAG) and control eyes. DESIGN Retrospective cross-sectional study, with patients recruited from the New York Eye and Ear Infirmary of Mount Sinai. SUBJECTS, PARTICIPANTS, AND/OR CONTROLS A total of 86 eyes (50 eyes of 30 POAG patents and 36 eyes of 20 controls) were enrolled. The presence of POAG was defined by circumpapillary retinal nerve fiber layer thickness below the bottom fifth percentile of the normative database, glaucomatous ONH changes, and visual field defects on 24-2 tests. METHODS, INTERVENTION, OR TESTING POAG and control eyes were imaged using the OcuMet Beacon. A 23°x23° infrared scan was obtained, and an FPF scan was performed within a capture field spanning 13 degrees in diameter. The ONH margins on the infrared image were identified by software algorithms. FPF then was measured within an elliptical annulus around the ONH rim, with the inner and outer boundaries corresponding to 0.5 to 1.1 times the ONH rim size. MAIN OUTCOMES MEASURES FPF at the OHN rim in POAG and control eyes. RESULTS Differences in FPF between POAG and control eyes were characterized through mixed-effects logistic regression, adjusted for age and interocular pressure. FPF was significantly higher in POAG versus control eyes, with a mean±SD of 46.4±27.9 versus 28.0±11.7 (P<0.001), respectively. Evaluation of anatomical quadrants revealed greater FPF in POAG versus control eyes at the temporal (P=0.001), superior (P<0.001), nasal (P=0.002), and inferior (P=0.001) quadrants. Among POAG eyes, FPF showed correlation to visual field mean deviation (P<0.001), visual field pattern standard deviation (P=0.003), and circumpapillary retinal nerve fiber thickness (P=0.001) on linear mixed-effects models. CONCLUSIONS Higher FPF in POAG versus control eyes suggests the presence of mitochondrial dysfunction at the ONH rim in eyes with glaucomatous damage. The degree of FPF corresponds to disease severity, as measured by visual field and nerve fiber layer thickness metrics. FPF may thus represent a metabolic indicator of disease status that reveals the extent of injury in glaucoma.
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Affiliation(s)
- Davis B Zhou
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai; Department of Ophthalmology, Icahn School of Medicine at Mount Sinai
| | - Maria V Castanos
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai; Department of Ophthalmology, Icahn School of Medicine at Mount Sinai
| | - Lawrence Geyman
- Einhorn Clinical Research Center, New York Eye and Ear Infirmary of Mount Sinai, New York; Department of Ophthalmology, Illinois Eye and Ear Infirmary, Chicago, Illinois
| | | | - Apichat Tantraworasin
- Clinical Epidemiology and Clinical Statistic Center, and Department of Surgery, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Robert Ritch
- Einhorn Clinical Research Center, New York Eye and Ear Infirmary of Mount Sinai, New York
| | - Richard B Rosen
- Department of Ophthalmology, New York Eye and Ear Infirmary of Mount Sinai; Department of Ophthalmology, Icahn School of Medicine at Mount Sinai.
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Characterization of autofluorescence and quantitative protoporphyrin IX biomarkers for optical spectroscopy-guided glioma surgery. Sci Rep 2021; 11:20009. [PMID: 34625597 PMCID: PMC8501114 DOI: 10.1038/s41598-021-99228-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 09/14/2021] [Indexed: 01/04/2023] Open
Abstract
5-Aminolevulinic acid (5-ALA)-mediated fluorescence does not effectively depict low grade gliomas (LGG) or the infiltrative tumor portion of high-grade gliomas (HGG). While spectroscopy improves sensitivity and precision, this is currently limited by autofluorescence and a second protoporphyrin IX (PpIX) fluorescence state at 620 nm. We investigated the autofluorescence to better characterize the present spectra and thus increase PpIX quantification precision and sensitivity. This study included 128 patients undergoing surgery for malignant glioma. 5-ALA (Gliolan) was administered before anesthesia, and fluorescence was measured using a hyperspectral device. It was found that all 2692 measured spectra consisted of contributions from 620 to 634 nm PpIX, NADH, lipofuscin, and flavins. The basis spectra were characterized and their use in spectral unmixing led to 82.4% lower fitting error for weakly fluorescing areas (p < 0.001), and 92.3% fewer false positive tumor identifications in control measurements (p = 0.0065) compared to previous works. They also decreased the PpIX620 contribution, thus halving the mean Ratio620/634 (p < 0.001). The ratio was approximately 0 for HGGs and increasing for LGGs, as demonstrated previously. Additionally, the Ratio620/634, the MIB-1/Ki-67 proliferation index, and the PpIX peak blue-shift were found to be significantly related to WHO grade, fluorescence visibility, and PpIX contribution (p < 0.001), and the value of these three as quantitative biomarkers is discussed.
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Analyzing Olfactory Neuron Precursors Non-Invasively Isolated through NADH FLIM as a Potential Tool to Study Oxidative Stress in Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms22126311. [PMID: 34204595 PMCID: PMC8231156 DOI: 10.3390/ijms22126311] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/29/2021] [Accepted: 04/29/2021] [Indexed: 12/22/2022] Open
Abstract
Among all the proposed pathogenic mechanisms to understand the etiology of Alzheimer’s disease (AD), increased oxidative stress seems to be a robust and early disease feature where many of those hypotheses converge. However, despite the significant lines of evidence accumulated, an effective diagnosis and treatment of AD are not yet available. This limitation might be partially explained by the use of cellular and animal models that recapitulate partial aspects of the disease and do not account for the particular biology of patients. As such, cultures of patient-derived cells of peripheral origin may provide a convenient solution for this problem. Peripheral cells of neuronal lineage such as olfactory neuronal precursors (ONPs) can be easily cultured through non-invasive isolation, reproducing AD-related oxidative stress. Interestingly, the autofluorescence of key metabolic cofactors such as reduced nicotinamide adenine dinucleotide (NADH) can be highly correlated with the oxidative state and antioxidant capacity of cells in a non-destructive and label-free manner. In particular, imaging NADH through fluorescence lifetime imaging microscopy (FLIM) has greatly improved the sensitivity in detecting oxidative shifts with minimal intervention to cell physiology. Here, we discuss the translational potential of analyzing patient-derived ONPs non-invasively isolated through NADH FLIM to reveal AD-related oxidative stress. We believe this approach may potentially accelerate the discovery of effective antioxidant therapies and contribute to early diagnosis and personalized monitoring of this devastating disease.
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Beykin G, Norcia AM, Srinivasan VJ, Dubra A, Goldberg JL. Discovery and clinical translation of novel glaucoma biomarkers. Prog Retin Eye Res 2020; 80:100875. [PMID: 32659431 DOI: 10.1016/j.preteyeres.2020.100875] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 06/01/2020] [Accepted: 06/04/2020] [Indexed: 12/16/2022]
Abstract
Glaucoma and other optic neuropathies are characterized by progressive dysfunction and loss of retinal ganglion cells and their axons. Given the high prevalence of glaucoma-related blindness and the availability of treatment options, improving the diagnosis and precise monitoring of progression in these conditions is paramount. Here we review recent progress in the development of novel biomarkers for glaucoma in the context of disease pathophysiology and we propose future steps for the field, including integration of exploratory biomarker outcomes into prospective therapeutic trials. We anticipate that, when validated, some of the novel glaucoma biomarkers discussed here will prove useful for clinical diagnosis and prediction of progression, as well as monitoring of clinical responses to standard and investigational therapies.
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Affiliation(s)
- Gala Beykin
- Spencer Center for Vision Research at Stanford University, 2370 Watson Ct, Palo Alto, CA, 94303, USA.
| | - Anthony M Norcia
- Department of Psychology, Stanford University, 290 Jane Stanford Way, Stanford, CA, 94305, USA.
| | - Vivek J Srinivasan
- Department of Biomedical Engineering, University of California, Davis, One Shields Ave, Davis, CA, 95616, USA; Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, 4610 X St, Sacramento, CA, 96817, USA.
| | - Alfredo Dubra
- Spencer Center for Vision Research at Stanford University, 2370 Watson Ct, Palo Alto, CA, 94303, USA.
| | - Jeffrey L Goldberg
- Spencer Center for Vision Research at Stanford University, 2370 Watson Ct, Palo Alto, CA, 94303, USA.
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Flavin Adenine Dinucleotide Fluorescence as an Early Marker of Mitochondrial Impairment During Brain Hypoxia. Int J Mol Sci 2020; 21:ijms21113977. [PMID: 32492921 PMCID: PMC7312830 DOI: 10.3390/ijms21113977] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 05/28/2020] [Accepted: 05/30/2020] [Indexed: 12/31/2022] Open
Abstract
Multimodal continuous bedside monitoring is increasingly recognized as a promising option for early treatment stratification in patients at risk for ischemia during neurocritical care. Modalities used at present are, for example, oxygen availability and subdural electrocorticography. The assessment of mitochondrial function could be an interesting complement to these modalities. For instance, flavin adenine dinucleotide (FAD) fluorescence permits direct insight into the mitochondrial redox state. Therefore, we explored the possibility of using FAD fluorometry to monitor consequences of hypoxia in brain tissue in vitro and in vivo. By combining experimental results with computational modeling, we identified the potential source responsible for the fluorescence signal and gained insight into the hypoxia-associated metabolic changes in neuronal energy metabolism. In vitro, hypoxia was characterized by a reductive shift of FAD, impairment of synaptic transmission and increasing interstitial potassium [K+]o. Computer simulations predicted FAD changes to originate from the citric acid cycle enzyme α-ketoglutarate dehydrogenase and pyruvate dehydrogenase. In vivo, the FAD signal during early hypoxia displayed a reductive shift followed by a short oxidation associated with terminal spreading depolarization. In silico, initial tissue hypoxia followed by a transient re-oxygenation phase due to glucose depletion might explain FAD dynamics in vivo. Our work suggests that FAD fluorescence could be readily used to monitor mitochondrial function during hypoxia and represents a potential diagnostic tool to differentiate underlying metabolic processes for complementation of multimodal brain monitoring.
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Birefringence Changes of Dendrites in Mouse Hippocampal Slices Revealed with Polarizing Microscopy. Biophys J 2020; 118:2366-2384. [PMID: 32294480 DOI: 10.1016/j.bpj.2020.03.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/20/2020] [Accepted: 03/06/2020] [Indexed: 11/23/2022] Open
Abstract
Intrinsic optical signal (IOS) imaging has been widely used to map the patterns of brain activity in vivo in a label-free manner. Traditional IOS refers to changes in light transmission, absorption, reflectance, and scattering of the brain tissue. Here, we use polarized light for IOS imaging to monitor structural changes of cellular and subcellular architectures due to their neuronal activity in isolated brain slices. To reveal fast spatiotemporal changes of subcellular structures associated with neuronal activity, we developed the instantaneous polarized light microscope (PolScope), which allows us to observe birefringence changes in neuronal cells and tissues while stimulating neuronal activity. The instantaneous PolScope records changes in transmission, birefringence, and slow axis orientation in tissue at a high spatial and temporal resolution using a single camera exposure. These capabilities enabled us to correlate polarization-sensitive IOS with traditional IOS on the same preparations. We detected reproducible spatiotemporal changes in both IOSs at the stratum radiatum in mouse hippocampal slices evoked by electrical stimulation at Schaffer collaterals. Upon stimulation, changes in traditional IOS signals were broadly uniform across the area, whereas birefringence imaging revealed local variations not seen in traditional IOS. Locations with high resting birefringence produced larger stimulation-evoked birefringence changes than those produced at low resting birefringence. Local application of glutamate to the synaptic region in CA1 induced an increase in both transmittance and birefringence signals. Blocking synaptic transmission with inhibitors CNQX (for AMPA-type glutamate receptor) and D-APV (for NMDA-type glutamate receptor) reduced the peak amplitude of the optical signals. Changes in both IOSs were enhanced by an inhibitor of the membranous glutamate transporter, DL-TBOA. Our results indicate that the detection of activity-induced structural changes of the subcellular architecture in dendrites is possible in a label-free manner.
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Noninvasive Detection of Mitochondrial Dysfunction in Ocular Hypertension and Primary Open-angle Glaucoma. J Glaucoma 2019; 27:592-599. [PMID: 29750714 DOI: 10.1097/ijg.0000000000000980] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
PURPOSE To assess mitochondrial dysfunction in vivo in ocular hypertension (OHT) and primary open-angle glaucoma (POAG) using retinal metabolic analysis. PATIENTS AND METHODS This was an observational, cross-sectional study performed from November 2015 to October 2016 at the New York Eye and Ear Infirmary of Mount Sinai. Thirty-eight eyes with varying stages of POAG, 16 eyes with OHT, and 32 control eyes were imaged on a custom fundus camera modified to measure full retinal thickness fluorescence at a wavelength optimized to detect flavoprotein fluorescence (FPF). Optical coherence tomography was used to measure the retinal ganglion cell-plus layer (RGC+) thickness. Macular FPF and the ratio of macular FPF to RGC+ thickness were the primary outcome variables and were compared among the three groups using an age-adjusted linear regression model. A mixed-effects model was used to assess correlations between FPF variables and clinical characteristics. RESULTS Both macular FPF and the macular FPF/RGC+ thickness ratio were significantly increased in OHT compared with control eyes (P<0.05 and <0.01, respectively). In POAG eyes, macular FPF was not significantly increased compared with controls (P=0.24). However, the macular FPF/RGC+ thickness ratio in POAG eyes was significantly increased compared with controls (P<0.001). FPF was significantly correlated to age in POAG eyes. CONCLUSIONS Despite lacking clinical evidence of glaucomatous deterioration, OHT eyes displayed significantly elevated macular FPF, suggesting that mitochondrial dysfunction may be detected before structural changes visible on current clinical imaging. Our preliminary results suggest that macular FPF analysis may prove to be a useful tool in assessing and evaluating OHT and POAG eyes.
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Ogi M, Yamagishi T, Tsukano H, Nishio N, Hishida R, Takahashi K, Horii A, Shibuki K. Associative responses to visual shape stimuli in the mouse auditory cortex. PLoS One 2019; 14:e0223242. [PMID: 31581242 PMCID: PMC6776301 DOI: 10.1371/journal.pone.0223242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 09/17/2019] [Indexed: 11/18/2022] Open
Abstract
Humans can recall various aspects of a characteristic sound as a whole when they see a visual shape stimulus that has been intimately associated with the sound. In subjects with audio-visual associative memory, auditory responses that code the associated sound may be induced in the auditory cortex in response to presentation of the associated visual shape stimulus. To test this possibility, mice were pre-exposed to a combination of an artificial sound mimicking a cat’s “meow” and a visual shape stimulus of concentric circles or stars for more than two weeks, since such passive exposure is known to be sufficient for inducing audio-visual associative memory in mice. After the exposure, we anesthetized the mice, and presented them with the associated visual shape stimulus. We found that associative responses in the auditory cortex were induced in response to the visual stimulus. The associative auditory responses were observed when complex sounds such as “meow” were used for formation of audio-visual associative memory, but not when a pure tone was used. These results suggest that associative auditory responses in the auditory cortex represent the characteristics of the complex sound stimulus as a whole.
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Affiliation(s)
- Manabu Ogi
- Department of Neurophysiology, Brain Research Institute, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medical and Dental Sciences, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
| | - Tatsuya Yamagishi
- Department of Neurophysiology, Brain Research Institute, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medical and Dental Sciences, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
| | - Hiroaki Tsukano
- Department of Neurophysiology, Brain Research Institute, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
| | - Nana Nishio
- Department of Neurophysiology, Brain Research Institute, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
| | - Ryuichi Hishida
- Department of Neurophysiology, Brain Research Institute, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
| | - Kuniyuki Takahashi
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medical and Dental Sciences, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
| | - Arata Horii
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medical and Dental Sciences, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
| | - Katsuei Shibuki
- Department of Neurophysiology, Brain Research Institute, Niigata University, Asahi-machi, Chuo-ku, Niigata, Japan
- * E-mail:
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McCarthy ME, Birtwistle MR. Highly Multiplexed, Quantitative Tissue Imaging at Cellular Resolution. CURRENT PATHOBIOLOGY REPORTS 2019. [DOI: 10.1007/s40139-019-00203-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Onishi T, Watanabe T, Sasaki M, Kamiya Y, Horie M, Tsukano H, Hishida R, Kohno T, Takebayashi H, Baba H, Shibuki K. Acute spatial spread of NO-mediated potentiation during hindpaw ischaemia in mice. J Physiol 2019; 597:3441-3455. [PMID: 31087329 PMCID: PMC6851834 DOI: 10.1113/jp277615] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 04/29/2019] [Indexed: 12/31/2022] Open
Abstract
Key points Neuropathic pain spreads spatially beyond the injured sites, and the mechanism underlying the spread has been attributed to inflammation occurring in the spinal cord. However, the spatial spread of spinal/cortical potentiation induced by conduction block of the peripheral nerves can be observed prior to inflammation. In the present study, we found that spreading potentiation and hypersensitivity acutely induced by unilateral hindpaw ischaemia are nitric oxide (NO)‐dependent and that NO is produced by ischaemia and quickly diffuses within the spinal cord. We also found that NO production induced by ischaemia is not observed in the presence of an antagonist for group II metabotropic glutamate receptors (mGluRs) and that neuronal NO synthase‐positive dorsal horn neurons express group II mGluRs. These results suggest strongly that NO‐mediated spreading potentiation in the spinal cord is one of the trigger mechanisms for neuropathic pain.
Abstract Cortical/spinal responses to hindpaw stimulation are bilaterally potentiated by unilateral hindpaw ischaemia in mice. We tested the hypothesis that hindpaw ischaemia produces nitric oxide (NO), which diffuses in the spinal cord to induce spatially spreading potentiation. Using flavoprotein fluorescence imaging, we confirmed that the spreading potentiation in hindpaw responses was induced during ischaemia in the non‐stimulated hindpaw. This spreading potentiation was blocked by spinal application of l‐NAME, an inhibitor of NO synthase (NOS). Furthermore, no spreading potentiation was observed in neural NOS (nNOS) knockout mice. Spinal application of an NO donor was enough to induce cortical potentiation and mechanical hypersensitivity. The spatial distribution of NO during unilateral hindpaw ischaemia was visualized using 4‐amino‐5‐methylamino‐2′,7′‐difluorofluorescein (DAF‐FM). An increase in fluorescence derived from the complex of DAF‐FM with NO was observed on the ischaemic side of the spinal cord. A similar but smaller increase was also observed on the contralateral side. Somatosensory potentiation after hindpaw ischaemia is known to be inhibited by spinal application of LY354740, an agonist of group II metabotropic glutamate receptors (mGluRs). We confirmed that the spinal DAF‐FM fluorescence increases during hindpaw ischaemia were not observed in the presence of LY354740. We also confirmed that approximately half of the nNOS‐positive neurons in the superficial laminae of the dorsal horn expressed mGluR2 mRNA. These results suggest that disinhibition of mGluR2 produces NO which in turn induces a spreading potentiation in a wide area of the spinal cord. Such spreading, along with the consequent non‐specific potentiation in the spinal cord, may trigger neuropathic pain. Neuropathic pain spreads spatially beyond the injured sites, and the mechanism underlying the spread has been attributed to inflammation occurring in the spinal cord. However, the spatial spread of spinal/cortical potentiation induced by conduction block of the peripheral nerves can be observed prior to inflammation. In the present study, we found that spreading potentiation and hypersensitivity acutely induced by unilateral hindpaw ischaemia are nitric oxide (NO)‐dependent and that NO is produced by ischaemia and quickly diffuses within the spinal cord. We also found that NO production induced by ischaemia is not observed in the presence of an antagonist for group II metabotropic glutamate receptors (mGluRs) and that neuronal NO synthase‐positive dorsal horn neurons express group II mGluRs. These results suggest strongly that NO‐mediated spreading potentiation in the spinal cord is one of the trigger mechanisms for neuropathic pain.
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Affiliation(s)
- Takeshi Onishi
- Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan.,Department of Anesthesiology, Faculty of Medicine, Niigata University, Niigata, 951-8510, Japan
| | - Tatsunori Watanabe
- Department of Anesthesiology, Faculty of Medicine, Niigata University, Niigata, 951-8510, Japan
| | - Mika Sasaki
- Department of Anesthesiology, Faculty of Medicine, Niigata University, Niigata, 951-8510, Japan
| | - Yoshinori Kamiya
- Department of Anesthesiology, Faculty of Medicine, Niigata University, Niigata, 951-8510, Japan
| | - Masao Horie
- Department of Morphological Sciences, Faculty of Medicine, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Hiroaki Tsukano
- Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Ryuichi Hishida
- Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Tatsuro Kohno
- Department of Anesthesiology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, 983-8536, Japan
| | - Hirohide Takebayashi
- Department of Neurobiology and Anatomy, Faculty of Medicine, Niigata University, Niigata, 951-8510, Japan
| | - Hiroshi Baba
- Department of Anesthesiology, Faculty of Medicine, Niigata University, Niigata, 951-8510, Japan
| | - Katsuei Shibuki
- Department of Neurophysiology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
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16
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17
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Giannoni L, Lange F, Tachtsidis I. Hyperspectral imaging solutions for brain tissue metabolic and hemodynamic monitoring: past, current and future developments. JOURNAL OF OPTICS (2010) 2018; 20:044009. [PMID: 29854375 PMCID: PMC5964611 DOI: 10.1088/2040-8986/aab3a6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 01/29/2018] [Accepted: 03/02/2018] [Indexed: 05/21/2023]
Abstract
Hyperspectral imaging (HSI) technologies have been used extensively in medical research, targeting various biological phenomena and multiple tissue types. Their high spectral resolution over a wide range of wavelengths enables acquisition of spatial information corresponding to different light-interacting biological compounds. This review focuses on the application of HSI to monitor brain tissue metabolism and hemodynamics in life sciences. Different approaches involving HSI have been investigated to assess and quantify cerebral activity, mainly focusing on: (1) mapping tissue oxygen delivery through measurement of changes in oxygenated (HbO2) and deoxygenated (HHb) hemoglobin; and (2) the assessment of the cerebral metabolic rate of oxygen (CMRO2) to estimate oxygen consumption by brain tissue. Finally, we introduce future perspectives of HSI of brain metabolism, including its potential use for imaging optical signals from molecules directly involved in cellular energy production. HSI solutions can provide remarkable insight in understanding cerebral tissue metabolism and oxygenation, aiding investigation on brain tissue physiological processes.
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Affiliation(s)
- Luca Giannoni
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Frédéric Lange
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
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18
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Hedges VL, Chen G, Yu L, Krentzel AA, Starrett JR, Zhu JN, Suntharalingam P, Remage-Healey L, Wang JJ, Ebner TJ, Mermelstein PG. Local Estrogen Synthesis Regulates Parallel Fiber-Purkinje Cell Neurotransmission Within the Cerebellar Cortex. Endocrinology 2018; 159:1328-1338. [PMID: 29381778 PMCID: PMC5839732 DOI: 10.1210/en.2018-00039] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 01/19/2018] [Indexed: 02/04/2023]
Abstract
Estrogens affect cerebellar activity and cerebellum-based behaviors. Within the adult rodent cerebellum, the best-characterized action of estradiol is to enhance glutamatergic signaling. However, the mechanisms by which estradiol promotes glutamatergic neurotransmission remain unknown. Within the mouse cerebellum, we found that estrogen receptor activation of metabotropic glutamate receptor type 1a strongly enhances neurotransmission at the parallel fiber-Purkinje cell synapse. The blockade of local estrogen synthesis within the cerebellum results in a diminution of glutamatergic neurotransmission. Correspondingly, decreased estrogen availability via gonadectomy or blockade of aromatase activity negatively affects locomotor performance. These data indicate that locally derived, and not just gonad-derived, estrogens affect cerebellar physiology and function. In addition, estrogens were found to facilitate parallel fiber-Purkinje cell synaptic transmission in both sexes. As such, the actions of estradiol to support cerebellar neurotransmission and cerebellum-based behaviors might be fundamental to understanding the normal processing of activity within the cerebellar cortex.
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Affiliation(s)
- Valerie L. Hedges
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
| | - Gang Chen
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
| | - Lei Yu
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Amanda A. Krentzel
- Department of Psychological and Brain Sciences, University of Massachusetts, Amherst, Massachusetts 01003
| | - Joseph R. Starrett
- Department of Psychological and Brain Sciences, University of Massachusetts, Amherst, Massachusetts 01003
| | - Jing-Ning Zhu
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | | | - Luke Remage-Healey
- Department of Psychological and Brain Sciences, University of Massachusetts, Amherst, Massachusetts 01003
| | - Jian-Jun Wang
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Timothy J. Ebner
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
| | - Paul G. Mermelstein
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
- Correspondence: Paul G. Mermelstein, PhD, Department of Neuroscience, University of Minnesota, 6-145 Jackson Hall, 321 Church Street SE, Minneapolis, Minnesota 55455. E-mail:
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19
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Chen G, Carter RE, Cleary JD, Reid TS, Ranum LP, Swanson MS, Ebner TJ. Altered levels of the splicing factor muscleblind modifies cerebral cortical function in mouse models of myotonic dystrophy. Neurobiol Dis 2018; 112:35-48. [PMID: 29331264 PMCID: PMC5859959 DOI: 10.1016/j.nbd.2018.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 12/20/2017] [Accepted: 01/08/2018] [Indexed: 01/18/2023] Open
Abstract
Myotonic dystrophy (DM) is a progressive, multisystem disorder affecting skeletal muscle, heart, and central nervous system. In both DM1 and DM2, microsatellite expansions of CUG and CCUG RNA repeats, respectively, accumulate and disrupt functions of alternative splicing factors, including muscleblind (MBNL) proteins. Grey matter loss and white matter changes, including the corpus callosum, likely underlie cognitive and executive function deficits in DM patients. However, little is known how cerebral cortical circuitry changes in DM. Here, flavoprotein optical imaging was used to assess local and contralateral responses to intracortical motor cortex stimulation in DM-related mouse models. In control mice, brief train stimulation generated ipsilateral and contralateral homotopic fluorescence increases, the latter mediated by the corpus callosum. Single pulse stimulation produced an excitatory response with an inhibitory-like surround response mediated by GABAA receptors. In a mouse model of DM2 (Mbnl2 KO), we observed prolonged and increased responsiveness to train stimulation and loss of the inhibition from single pulse stimulation. Conversely, mice overexpressing human MBNL1 (MBNL1-OE) exhibited decreased contralateral response to train stimulation and reduction of inhibitory-like surround to single pulse stimulation. Therefore, altering levels of two key DM-associated splicing factors modifies functions of local cortical circuits and contralateral responses mediated through the corpus callosum.
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Affiliation(s)
- Gang Chen
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - Russell E Carter
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - John D Cleary
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Tammy S Reid
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Laura P Ranum
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Maurice S Swanson
- Center for NeuroGenetics, Department of Molecular Genetics & Microbiology and Neurology, College of Medicine, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Timothy J Ebner
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA.
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20
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Mahbub SB, Plöschner M, Gosnell ME, Anwer AG, Goldys EM. Statistically strong label-free quantitative identification of native fluorophores in a biological sample. Sci Rep 2017; 7:15792. [PMID: 29150629 PMCID: PMC5693869 DOI: 10.1038/s41598-017-15952-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/03/2017] [Indexed: 11/16/2022] Open
Abstract
Bioimaging using endogenous cell fluorescence, without any external biomarkers makes it possible to explore cells and tissues in their original native state, also in vivo. In order to be informative, this label-free method requires careful multispectral or hyperspectral recording of autofluorescence images followed by unsupervised extraction (unmixing) of biochemical signatures. The unmixing is difficult due to the scarcity of biochemically pure regions in cells and also because autofluorescence is weak compared with signals from labelled cells, typically leading to low signal to noise ratio. Here, we solve the problem of unsupervised hyperspectral unmixing of cellular autofluorescence by introducing the Robust Dependent Component Analysis (RoDECA). This approach provides sophisticated and statistically robust quantitative biochemical analysis of cellular autofluorescence images. We validate our method on artificial images, where the addition of varying known level of noise has allowed us to quantify the accuracy of our RoDECA analysis in a way that can be applied to real biological datasets. The same unsupervised statistical minimisation is then applied to imaging of mouse retinal photoreceptor cells where we establish the identity of key endogenous fluorophores (free NADH, FAD and lipofuscin) and derive the corresponding molecular abundance maps. The pre-processing methodology of image datasets is also presented, which is essential for the spectral unmixing analysis, but mostly overlooked in the previous studies.
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Affiliation(s)
- Saabah B Mahbub
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia.
| | - Martin Plöschner
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia
| | - Martin E Gosnell
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia
- Quantitative Pty Ltd, ABN 17165684186, 116-118 Great Western Highway, Mt. Victoria, NSW, 2786, Australia
| | - Ayad G Anwer
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia
| | - Ewa M Goldys
- ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, 2109, NSW, Australia.
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21
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Wright PW, Brier LM, Bauer AQ, Baxter GA, Kraft AW, Reisman MD, Bice AR, Snyder AZ, Lee JM, Culver JP. Functional connectivity structure of cortical calcium dynamics in anesthetized and awake mice. PLoS One 2017; 12:e0185759. [PMID: 29049297 PMCID: PMC5648115 DOI: 10.1371/journal.pone.0185759] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 09/19/2017] [Indexed: 11/30/2022] Open
Abstract
The interplay between hemodynamic-based markers of cortical activity (e.g. fMRI and optical intrinsic signal imaging), which are an indirect and relatively slow report of neural activity, and underlying synaptic electrical and metabolic activity through neurovascular coupling is a topic of ongoing research and debate. As application of resting state functional connectivity measures is extended further into topics such as brain development, aging and disease, the importance of understanding the fundamental physiological basis for functional connectivity will grow. Here we extend functional connectivity analysis from hemodynamic- to calcium-based imaging. Transgenic mice (n = 7) expressing a fluorescent calcium indicator (GCaMP6) driven by the Thy1 promoter in glutamatergic neurons were imaged transcranially in both anesthetized (using ketamine/xylazine) and awake states. Sequential LED illumination (λ = 454, 523, 595, 640nm) enabled concurrent imaging of both GCaMP6 fluorescence emission (corrected for hemoglobin absorption) and hemodynamics. Functional connectivity network maps were constructed for infraslow (0.009–0.08Hz), intermediate (0.08–0.4Hz), and high (0.4–4.0Hz) frequency bands. At infraslow and intermediate frequencies, commonly used in BOLD fMRI and fcOIS studies of functional connectivity and implicated in neurovascular coupling mechanisms, GCaMP6 and HbO2 functional connectivity structures were in high agreement, both qualitatively and also quantitatively through a measure of spatial similarity. The spontaneous dynamics of both contrasts had the highest correlation when the GCaMP6 signal was delayed with a ~0.6–1.5s temporal offset. Within the higher-frequency delta band, sensitive to slow wave sleep oscillations in non-REM sleep and anesthesia, we evaluate the speed with which the connectivity analysis stabilized and found that the functional connectivity maps captured putative network structure within time window lengths as short as 30 seconds. Homotopic GCaMP6 functional connectivity maps at 0.4–4.0Hz in the anesthetized states show a striking correlated and anti-correlated structure along the anterior to posterior axis. This structure is potentially explained in part by observed propagation of delta-band activity from frontal somatomotor regions to visuoparietal areas. During awake imaging, this spatio-temporal quality is altered, and a more complex and detailed functional connectivity structure is observed. The combined calcium/hemoglobin imaging technique described here will enable the dissociation of changes in ionic and hemodynamic functional structure and neurovascular coupling and provide a framework for subsequent studies of neurological disease such as stroke.
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Affiliation(s)
- Patrick W. Wright
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Lindsey M. Brier
- Department of Neuroscience, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Adam Q. Bauer
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Grant A. Baxter
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Andrew W. Kraft
- Department of Neuroscience, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Matthew D. Reisman
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Physics, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Annie R. Bice
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Abraham Z. Snyder
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jin-Moo Lee
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department Neurology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Joseph P. Culver
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Neuroscience, Washington University in St. Louis, St. Louis, Missouri, United States of America
- * E-mail:
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22
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Effect of temperature on FAD and NADH-derived signals and neurometabolic coupling in the mouse auditory and motor cortex. Pflugers Arch 2017; 469:1631-1649. [PMID: 28785802 DOI: 10.1007/s00424-017-2037-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 07/03/2017] [Accepted: 07/13/2017] [Indexed: 12/13/2022]
Abstract
Tight coupling of neuronal metabolism to synaptic activity is critical to ensure that the supply of metabolic substrates meets the demands of neuronal signaling. Given the impact of temperature on metabolism, and the wide fluctuations of brain temperature observed during clinical hypothermia, we examined the effect of temperature on neurometabolic coupling. Intrinsic fluorescence signals of the oxidized form of flavin adenine dinucleotide (FAD) and the reduced form of nicotinamide adenine dinucleotide (NADH), and their ratios, were measured to assess neural metabolic state and local field potentials were recorded to measure synaptic activity in the mouse brain. Brain slice preparations were used to remove the potential impacts of blood flow. Tight coupling between metabolic signals and local field potential amplitudes was observed at a range of temperatures below 29 °C. However, above 29 °C, the metabolic and synaptic signatures diverged such that FAD signals were diminished, but local field potentials retained their amplitude. It was also observed that the declines in the FAD signals seen at high temperatures (and hence the decoupling between synaptic and metabolic events) are driven by low FAD availability at high temperatures. These data suggest that neurometabolic coupling, thought to be critical for ensuring the metabolic health of the brain, may show temperature dependence, and is related to temperature-dependent changes in FAD supplies.
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Rapid Postnatal Expansion of Neural Networks Occurs in an Environment of Altered Neurovascular and Neurometabolic Coupling. J Neurosci 2017; 36:6704-17. [PMID: 27335402 DOI: 10.1523/jneurosci.2363-15.2016] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 05/10/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED In the adult brain, increases in neural activity lead to increases in local blood flow. However, many prior measurements of functional hemodynamics in the neonatal brain, including functional magnetic resonance imaging (fMRI) in human infants, have noted altered and even inverted hemodynamic responses to stimuli. Here, we demonstrate that localized neural activity in early postnatal mice does not evoke blood flow increases as in the adult brain, and elucidate the neural and metabolic correlates of these altered functional hemodynamics as a function of developmental age. Using wide-field GCaMP imaging, the development of neural responses to somatosensory stimulus is visualized over the entire bilaterally exposed cortex. Neural responses are observed to progress from tightly localized, unilateral maps to bilateral responses as interhemispheric connectivity becomes established. Simultaneous hemodynamic imaging confirms that spatiotemporally coupled functional hyperemia is not present during these early stages of postnatal brain development, and develops gradually as cortical connectivity is established. Exploring the consequences of this lack of functional hyperemia, measurements of oxidative metabolism via flavoprotein fluorescence suggest that neural activity depletes local oxygen to below baseline levels at early developmental stages. Analysis of hemoglobin oxygenation dynamics at the same age confirms oxygen depletion for both stimulus-evoked and resting-state neural activity. This state of unmet metabolic demand during neural network development poses new questions about the mechanisms of neurovascular development and its role in both normal and abnormal brain development. These results also provide important insights for the interpretation of fMRI studies of the developing brain. SIGNIFICANCE STATEMENT This work demonstrates that the postnatal development of neuronal connectivity is accompanied by development of the mechanisms that regulate local blood flow in response to neural activity. Novel in vivo imaging reveals that, in the developing mouse brain, strong and localized GCaMP neural responses to stimulus fail to evoke local blood flow increases, leading to a state in which oxygen levels become locally depleted. These results demonstrate that the development of cortical connectivity occurs in an environment of altered energy availability that itself may play a role in shaping normal brain development. These findings have important implications for understanding the pathophysiology of abnormal developmental trajectories, and for the interpretation of functional magnetic resonance imaging data acquired in the developing brain.
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Afrashteh N, Inayat S, Mohsenvand M, Mohajerani MH. Optical-flow analysis toolbox for characterization of spatiotemporal dynamics in mesoscale optical imaging of brain activity. Neuroimage 2017; 153:58-74. [PMID: 28351691 DOI: 10.1016/j.neuroimage.2017.03.034] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/10/2017] [Accepted: 03/16/2017] [Indexed: 12/15/2022] Open
Abstract
Wide-field optical imaging techniques constitute powerful tools to investigate mesoscale neuronal activity. The sampled data constitutes a sequence of image frames in which one can investigate the flow of brain activity starting and terminating at source and sink locations respectively. Approaches to the analyses of information flow include qualitative assessment to identify sources and sinks of activity as well as their trajectories, and quantitative measurements based on computing the temporal variation of the intensity of pixels. Furthermore, in a few studies estimates of wave motion have been reported using optical-flow techniques from computer vision. However, a comprehensive toolbox for the quantitative analyses of mesoscale brain activity data is still lacking. We present a graphical-user-interface toolbox based in Matlab® for investigating the spatiotemporal dynamics of mesoscale brain activity using optical-flow analyses. The toolbox includes the implementation of three optical-flow methods namely Horn-Schunck, Combined Local-Global, and Temporospatial algorithms for estimating velocity vector fields of flow of mesoscale brain activity. From the velocity vector fields we determined the locations of sources and sinks as well as the trajectories and temporal velocities of flow of activity. Using simulated data as well as experimentally derived sensory-evoked voltage and calcium imaging data from mice, we compared the efficacy of the three optical-flow methods for determining spatiotemporal dynamics. Our results indicate that the combined local-global method we employed, yields the best results for estimating wave motion. The automated approach permits rapid and effective quantification of mesoscale brain dynamics and may facilitate the study of brain function in response to new experiences or pathology.
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Affiliation(s)
- Navvab Afrashteh
- Canadian Center for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada T1K 3M4
| | - Samsoon Inayat
- Canadian Center for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada T1K 3M4
| | - Mostafa Mohsenvand
- Canadian Center for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada T1K 3M4
| | - Majid H Mohajerani
- Canadian Center for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada T1K 3M4.
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25
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Uytingco CR, Puche AC, Munger SD. Using Intrinsic Flavoprotein and NAD(P)H Imaging to Map Functional Circuitry in the Main Olfactory Bulb. PLoS One 2016; 11:e0165342. [PMID: 27902689 PMCID: PMC5130181 DOI: 10.1371/journal.pone.0165342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/10/2016] [Indexed: 12/02/2022] Open
Abstract
Neurons exhibit strong coupling of electrochemical and metabolic activity. Increases in intrinsic fluorescence from either oxidized flavoproteins or reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] in the mitochondria have been used as an indicator of neuronal activity for the functional mapping of neural circuits. However, this technique has not been used to investigate the flow of olfactory information within the circuitry of the main olfactory bulb (MOB). We found that intrinsic flavoprotein fluorescence signals induced by electrical stimulation of single glomeruli displayed biphasic responses within both the glomerular (GL) and external plexiform layers (EPL) of the MOB. Pharmacological blockers of mitochondrial activity, voltage-gated Na+ channels, or ionotropic glutamate receptors abolished stimulus-dependent flavoprotein responses. Blockade of GABAA receptors enhanced the amplitude and spatiotemporal spread of the flavoprotein signals, indicating an important role for inhibitory neurotransmission in shaping the spread of neural activity in the MOB. Stimulus-dependent spread of fluorescence across the GL and EPL displayed a spatial distribution consistent with that of individual glomerular microcircuits mapped by neuroanatomic tract tracing. These findings demonstrated the feasibility of intrinsic fluorescence imaging in the olfactory systems and provided a new tool to examine the functional circuitry of the MOB.
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Affiliation(s)
- Cedric R Uytingco
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.,Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Adam C Puche
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.,Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Steven D Munger
- Center for Smell and Taste, University of Florida, Gainesville, Florida, United States of America.,Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States of America.,Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Florida, Gainesville, Florida, United States of America
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26
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Chisholm KI, Ida KK, Davies AL, Tachtsidis I, Papkovsky DB, Dyson A, Singer M, Duchen MR, Smith KJ. Hypothermia protects brain mitochondrial function from hypoxemia in a murine model of sepsis. J Cereb Blood Flow Metab 2016; 36:1955-1964. [PMID: 26661160 PMCID: PMC5094296 DOI: 10.1177/0271678x15606457] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 07/14/2015] [Indexed: 11/17/2022]
Abstract
Sepsis is commonly associated with brain dysfunction, but the underlying mechanisms remain unclear, although mitochondrial dysfunction and microvascular abnormalities have been implicated. We therefore assessed whether cerebral mitochondrial dysfunction during systemic endotoxemia in mice increased mitochondrial sensitivity to a further bioenergetic insult (hyoxemia), and whether hypothermia could improve outcome. Mice (C57bl/6) were injected intraperitoneally with lipopolysaccharide (LPS) (5 mg/kg; n = 85) or saline (0.01 ml/g; n = 47). Six, 24 and 48 h later, we used confocal imaging in vivo to assess cerebral mitochondrial redox potential and cortical oxygenation in response to changes in inspired oxygen. The fraction of inspired oxygen (FiO2) at which the cortical redox potential changed was compared between groups. In a subset of animals, spontaneous hypothermia was maintained or controlled hypothermia induced during imaging. Decreasing FiO2 resulted in a more reduced cerebral redox state around veins, but preserved oxidation around arteries. This pattern appeared at a higher FiO2 in LPS-injected animals, suggesting an increased sensitivity of cortical mitochondria to hypoxemia. This increased sensitivity was accompanied by a decrease in cortical oxygenation, but was attenuated by hypothermia. These results suggest that systemic endotoxemia influences cortical oxygenation and mitochondrial function, and that therapeutic hypothermia can be protective.
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Affiliation(s)
| | - Keila K Ida
- Institute of Neurology, University College London, UK.,Anaesthesiology LIM-8, Medical School, University of São Paulo, Brazil
| | | | - Ilias Tachtsidis
- Medical Physics and Biomedical Engineering, University College London, UK
| | - Dmitri B Papkovsky
- School of Biochemistry and Cell Biology, University College Cork, Ireland
| | - Alex Dyson
- Bloomsbury Institute of Intensive Care Medicine, University College London, UK
| | - Mervyn Singer
- Bloomsbury Institute of Intensive Care Medicine, University College London, UK
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27
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Rösner J, Liotta A, Angamo EA, Spies C, Heinemann U, Kovács R. Minimizing photodecomposition of flavin adenine dinucleotide fluorescence by the use of pulsed LEDs. J Microsc 2016; 264:215-223. [PMID: 27368071 DOI: 10.1111/jmi.12436] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/27/2016] [Accepted: 05/30/2016] [Indexed: 01/08/2023]
Abstract
Dynamic alterations in flavin adenine dinucleotide (FAD) fluorescence permit insight into energy metabolism-dependent changes of intramitochondrial redox potential. Monitoring FAD fluorescence in living tissue is impeded by photobleaching, restricting the length of microfluorimetric recordings. In addition, photodecomposition of these essential electron carriers negatively interferes with energy metabolism and viability of the biological specimen. Taking advantage of pulsed LED illumination, here we determined the optimal excitation settings giving the largest fluorescence yield with the lowest photobleaching and interference with metabolism in hippocampal brain slices. The effects of FAD bleaching on energy metabolism and viability were studied by monitoring tissue pO2 , field potentials and changes in extracellular potassium concentration ([K+ ]o ). Photobleaching with continuous illumination consisted of an initial exponential decrease followed by a nearly linear decay. The exponential decay was significantly decelerated with pulsed illumination. Pulse length of 5 ms was sufficient to reach a fluorescence output comparable to continuous illumination, whereas further increasing duration increased photobleaching. Similarly, photobleaching increased with shortening of the interpulse interval. Photobleaching was partially reversible indicating the existence of a transient nonfluorescent flavin derivative. Pulsed illumination decreased FAD photodecomposition, improved slice viability and reproducibility of stimulus-induced FAD, field potential, [K+ ]o and pO2 changes as compared to continuous illumination.
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Affiliation(s)
- J Rösner
- Neuroscience Research Center, Charité Universitätsmedizin, Berlin
| | - A Liotta
- Department of Anesthesiology and Intensive Care Medicine, Charité Universitätsmedizin, Berlin
| | - E A Angamo
- Neuroscience Research Center, Charité Universitätsmedizin, Berlin
| | - C Spies
- Department of Anesthesiology and Intensive Care Medicine, Charité Universitätsmedizin, Berlin
| | - U Heinemann
- Neuroscience Research Center, Charité Universitätsmedizin, Berlin
| | - R Kovács
- Institute for Neurophysiology, Charité Universitätsmedizin, Berlin.
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28
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Rapid Postnatal Expansion of Neural Networks Occurs in an Environment of Altered Neurovascular and Neurometabolic Coupling. J Neurosci 2016. [PMID: 27335402 DOI: 10.1523/jneurosci.2363‐15.2016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED In the adult brain, increases in neural activity lead to increases in local blood flow. However, many prior measurements of functional hemodynamics in the neonatal brain, including functional magnetic resonance imaging (fMRI) in human infants, have noted altered and even inverted hemodynamic responses to stimuli. Here, we demonstrate that localized neural activity in early postnatal mice does not evoke blood flow increases as in the adult brain, and elucidate the neural and metabolic correlates of these altered functional hemodynamics as a function of developmental age. Using wide-field GCaMP imaging, the development of neural responses to somatosensory stimulus is visualized over the entire bilaterally exposed cortex. Neural responses are observed to progress from tightly localized, unilateral maps to bilateral responses as interhemispheric connectivity becomes established. Simultaneous hemodynamic imaging confirms that spatiotemporally coupled functional hyperemia is not present during these early stages of postnatal brain development, and develops gradually as cortical connectivity is established. Exploring the consequences of this lack of functional hyperemia, measurements of oxidative metabolism via flavoprotein fluorescence suggest that neural activity depletes local oxygen to below baseline levels at early developmental stages. Analysis of hemoglobin oxygenation dynamics at the same age confirms oxygen depletion for both stimulus-evoked and resting-state neural activity. This state of unmet metabolic demand during neural network development poses new questions about the mechanisms of neurovascular development and its role in both normal and abnormal brain development. These results also provide important insights for the interpretation of fMRI studies of the developing brain. SIGNIFICANCE STATEMENT This work demonstrates that the postnatal development of neuronal connectivity is accompanied by development of the mechanisms that regulate local blood flow in response to neural activity. Novel in vivo imaging reveals that, in the developing mouse brain, strong and localized GCaMP neural responses to stimulus fail to evoke local blood flow increases, leading to a state in which oxygen levels become locally depleted. These results demonstrate that the development of cortical connectivity occurs in an environment of altered energy availability that itself may play a role in shaping normal brain development. These findings have important implications for understanding the pathophysiology of abnormal developmental trajectories, and for the interpretation of functional magnetic resonance imaging data acquired in the developing brain.
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29
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Potter LE, Paylor JW, Suh JS, Tenorio G, Caliaperumal J, Colbourne F, Baker G, Winship I, Kerr BJ. Altered excitatory-inhibitory balance within somatosensory cortex is associated with enhanced plasticity and pain sensitivity in a mouse model of multiple sclerosis. J Neuroinflammation 2016; 13:142. [PMID: 27282914 PMCID: PMC4901403 DOI: 10.1186/s12974-016-0609-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/01/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chronic neuropathic pain is a common symptom of multiple sclerosis (MS). MOG35-55-induced experimental autoimmune encephalomyelitis (EAE) has been used as an animal model to investigate the mechanisms of pain in MS. Previous studies have implicated sensitization of spinal nociceptive networks in the pathogenesis of pain in EAE. However, the involvement of supraspinal sites of nociceptive integration, such as the primary somatosensory cortex (S1), has not been defined. We therefore examined functional, structural, and immunological alterations in S1 during the early stages of EAE, when pain behaviors first appear. We also assessed the effects of the antidepressant phenelzine (PLZ) on S1 alterations and nociceptive (mechanical) sensitivity in early EAE. PLZ has been shown to restore central nervous system (CNS) tissue concentrations of GABA and the monoamines (5-HT, NA) in EAE. We hypothesized that PLZ treatment would also normalize nociceptive sensitivity in EAE by restoring the balance of excitation and inhibition (E-I) in the CNS. METHODS We used in vivo flavoprotein autofluorescence imaging (FAI) to assess neural ensemble responses in S1 to vibrotactile stimulation of the limbs in early EAE. We also used immunohistochemistry (IHC), and Golgi-Cox staining, to examine synaptic changes and neuroinflammation in S1. Mechanical sensitivity was assessed at the clinical onset of EAE with Von Frey hairs. RESULTS Mice with early EAE exhibited significantly intensified and expanded FAI responses in S1 compared to controls. IHC revealed increased vesicular glutamate transporter (VGLUT1) expression and disrupted parvalbumin+ (PV+) interneuron connectivity in S1 of EAE mice. Furthermore, peri-neuronal nets (PNNs) were significantly reduced in S1. Morphological analysis of excitatory neurons in S1 revealed increased dendritic spine densities. Iba-1+ cortical microglia were significantly elevated early in the disease. Chronic PLZ treatment was found to normalize mechanical thresholds in EAE. PLZ also normalized S1 FAI responses, neuronal morphologies, and cortical microglia numbers and attenuated VGLUT1 reactivity-but did not significantly attenuate the loss of PNNs. CONCLUSIONS These findings implicate a pro-excitatory shift in the E-I balance of the somatosensory CNS, arising early in the pathogenesis EAE and leading to large-scale functional and structural plasticity in S1. They also suggest a novel antinociceptive effect of PLZ treatment.
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Affiliation(s)
- Liam E Potter
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Department of Anesthesiology and Pain Medicine, University of Alberta, Clinical Sciences Building, 8-120, Edmonton, AB, T6G 2G3, Canada
| | - John W Paylor
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Department of Psychiatry (NRU), University of Alberta, Edmonton, AB, T6G 2B7, Canada
| | - Jee Su Suh
- Department of Anesthesiology and Pain Medicine, University of Alberta, Clinical Sciences Building, 8-120, Edmonton, AB, T6G 2G3, Canada
| | - Gustavo Tenorio
- Department of Anesthesiology and Pain Medicine, University of Alberta, Clinical Sciences Building, 8-120, Edmonton, AB, T6G 2G3, Canada
| | - Jayalakshmi Caliaperumal
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Department of Psychology, University of Alberta, Edmonton, AB, T6G 2E9, Canada
| | - Fred Colbourne
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Department of Psychology, University of Alberta, Edmonton, AB, T6G 2E9, Canada
| | - Glen Baker
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Department of Psychiatry (NRU), University of Alberta, Edmonton, AB, T6G 2B7, Canada
| | - Ian Winship
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Department of Psychiatry (NRU), University of Alberta, Edmonton, AB, T6G 2B7, Canada
| | - Bradley J Kerr
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2E1, Canada. .,Department of Pharmacology, University of Alberta, Edmonton, AB, T6E 2H7, Canada. .,Department of Anesthesiology and Pain Medicine, University of Alberta, Clinical Sciences Building, 8-120, Edmonton, AB, T6G 2G3, Canada.
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30
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Grinvald A, Sharon D, Omer D, Vanzetta I. Imaging the Neocortex Functional Architecture Using Multiple Intrinsic Signals: Implications for Hemodynamic-Based Functional Imaging. Cold Spring Harb Protoc 2016; 2016:pdb.top089375. [PMID: 26933255 DOI: 10.1101/pdb.top089375] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Optical imaging based on intrinsic signals has provided a new level of understanding of the principles underlying cortical development, organization, and function, providing a spatial resolution of up to 20 µm for mapping cortical columns in vivo. This introduction briefly reviews the development of this technique, the types of applications that have been pursued, and the general implications of some findings for other neuroimaging techniques based on hemodynamic responses (e.g., functional magnetic resonance imaging).
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31
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Fan A, Stebbings KA, Llano DA, Saif T. Stretch induced hyperexcitability of mice callosal pathway. Front Cell Neurosci 2015; 9:292. [PMID: 26300729 PMCID: PMC4525056 DOI: 10.3389/fncel.2015.00292] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/15/2015] [Indexed: 01/09/2023] Open
Abstract
Memory and learning are thought to result from changes in synaptic strength. Previous studies on synaptic physiology in brain slices have traditionally been focused on biochemical processes. Here, we demonstrate with experiments on mouse brain slices that central nervous system plasticity is also sensitive to mechanical stretch. This is important, given the host of clinical conditions involving changes in mechanical tension on the brain, and the normal role that mechanical tension plays in brain development. A novel platform is developed to investigate neural responses to mechanical stretching. Flavoprotein autofluoresence (FA) imaging was employed for measuring neural activity. We observed that synaptic excitability substantially increases after a small (2.5%) stretch was held for 10 min and released. The increase is accumulative, i.e., multiple stretch cycles further increase the excitability. We also developed analytical tools to quantify the spatial spread and response strength. Results show that the spatial spread is less stable in slices undergoing the stretch-unstretch cycle. FA amplitude and activation rate decrease as excitability increases in stretch cases but not in electrically enhanced cases. These results collectively demonstrate that a small stretch in physiological range can modulate neural activities significantly, suggesting that mechanical events can be employed as a novel tool for the modulation of neural plasticity.
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Affiliation(s)
- Anthony Fan
- Department of Mechanical Science and Engineering, University of Illinois Urbana, IL, USA
| | | | - Daniel A Llano
- Neuroscience Program, University of Illinois Urbana, IL, USA ; Department of Molecular and Integrative Physiology, University of Illinois Urbana, IL, USA ; Beckman Institute, University of Illinois Urbana, IL, USA ; College of Medicine, University of Illinois Urbana, IL, USA
| | - Taher Saif
- Department of Mechanical Science and Engineering, University of Illinois Urbana, IL, USA
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32
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Vazquez AL, Murphy MC, Kim SG. Neuronal and physiological correlation to hemodynamic resting-state fluctuations in health and disease. Brain Connect 2015; 4:727-40. [PMID: 25300278 DOI: 10.1089/brain.2014.0276] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Low-frequency, spatially coherent fluctuations present in functional magnetic resonance imaging time series have had a tremendous impact on brain connectomics. This work aims to explore the degree with which hemodynamic connectivity is associated with neuronal, metabolic, and vascular connectivity measures. For this purpose, GCaMP and nontransgenic mice were used to image neuronal activity and oxidative metabolism activity, respectively, along with blood-oxygenation- and cerebral blood volume (CBV)-sensitive hemodynamic changes from the same animals. Although network clusters calculated using either GCaMP (neuronal activity) or optical imaging of intrinsic signal (OIS)-BOLD (blood oxygenation) data did not exhibit strong spatial similarity, the strengths of node-to-node connectivity measured with these modalities were strongly correlated with one another. This finding suggests that hemodynamic connectivity as measured by blood oxygenation measurements, such as functional connectivity magnetic resonance imaging, is a valuable surrogate for the underlying neuronal connectivity. In nontransgenic animals, greater connectivity correlation was observed between tissue oxidative metabolism (flavoprotein autofluorescence imaging [FAI]) and blood oxygenation measurements, suggesting that metabolic contributions to hemodynamic signals are likely responsible for its significant correlation with neuronal connectivity. Lastly, a mouse model of Alzheimer's disease was used to explore the source of decreases in connectivity reported in these mice, a finding that is thought to be associated with amyloid load-driven metabolic decline. The intercluster connectivity measured by metabolic-sensitive measurements (FAI and OIS-BOLD) was maintained while vascular-only signals (OIS-CBV) provided negligible correlation. Therefore, metabolism-sensitive measurements as used in this work are better positioned to capture changes in neuronal connectivity, such that decreases in hemodynamic connectivity likely reflect decreases in oxidative metabolic function.
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Affiliation(s)
- Alberto L Vazquez
- 1 Department of Bioengineering, University of Pittsburgh , Pittsburgh, Pennsylvania
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33
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Chisholm KI, Ida KK, Davies AL, Papkovsky DB, Singer M, Dyson A, Tachtsidis I, Duchen MR, Smith KJ. In Vivo Imaging of Flavoprotein Fluorescence During Hypoxia Reveals the Importance of Direct Arterial Oxygen Supply to Cerebral Cortex Tissue. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 876:233-239. [PMID: 26782217 PMCID: PMC6125806 DOI: 10.1007/978-1-4939-3023-4_29] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Live imaging of mitochondrial function is crucial to understand the important role played by these organelles in a wide range of diseases. The mitochondrial redox potential is a particularly informative measure of mitochondrial function, and can be monitored using the endogenous green fluorescence of oxidized mitochondrial flavoproteins. Here, we have observed flavoprotein fluorescence in the exposed murine cerebral cortex in vivo using confocal imaging; the mitochondrial origin of the signal was confirmed using agents known to manipulate mitochondrial redox potential. The effects of cerebral oxygenation on flavoprotein fluorescence were determined by manipulating the inspired oxygen concentration. We report that flavoprotein fluorescence is sensitive to reductions in cortical oxygenation, such that reductions in inspired oxygen resulted in loss of flavoprotein fluorescence with the exception of a preserved 'halo' of signal in periarterial regions. The findings are consistent with reports that arteries play an important role in supplying oxygen directly to tissue in the cerebral cortex, maintaining mitochondrial function.
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Affiliation(s)
- K. I. Chisholm
- 0000000121901201grid.83440.3bUniversity College London, London, UK
| | - K. K. Ida
- 0000000121901201grid.83440.3bUniversity College London, London, UK ,0000 0004 1937 0722grid.11899.38University of São Paulo, São Paulo, Brazil
| | - A. L. Davies
- 0000000121901201grid.83440.3bUniversity College London, London, UK
| | - D. B. Papkovsky
- 0000000123318773grid.7872.aUniversity College Cork, Cork, Ireland
| | - M. Singer
- 0000000121901201grid.83440.3bUniversity College London, London, UK
| | - A. Dyson
- 0000000121901201grid.83440.3bUniversity College London, London, UK
| | - I. Tachtsidis
- 0000000121901201grid.83440.3bUniversity College London, London, UK
| | - M. R. Duchen
- 0000000121901201grid.83440.3bUniversity College London, London, UK
| | - K. J. Smith
- 0000000121901201grid.83440.3bUniversity College London, London, UK
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Abnormal excitability and episodic low-frequency oscillations in the cerebral cortex of the tottering mouse. J Neurosci 2015; 35:5664-79. [PMID: 25855180 DOI: 10.1523/jneurosci.3107-14.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Ca(2+) channelopathies caused by mutations of the CACNA1A gene that encodes the pore-forming subunit of the human Cav2.1 (P/Q-type) voltage-gated Ca(2+) channel include episodic ataxia type 2 (EA2). Although, in EA2 the emphasis has been on cerebellar dysfunction, patients also exhibit episodic, nonmotoric abnormalities involving the cerebral cortex. This study demonstrates episodic, low-frequency oscillations (LFOs) throughout the cerebral cortex of tottering (tg/tg) mice, a widely used model of EA2. Ranging between 0.035 and 0.11 Hz, the LFOs in tg/tg mice can spontaneously develop very high power, referred to as a high-power state. The LFOs in tg/tg mice are mediated in part by neuronal activity as tetrodotoxin decreases the oscillations and cortical neuron discharge contain the same low frequencies. The high-power state involves compensatory mechanisms because acutely decreasing P/Q-type Ca(2+) channel function in either wild-type (WT) or tg/tg mice does not induce the high-power state. In contrast, blocking l-type Ca(2+) channels, known to be upregulated in tg/tg mice, reduces the high-power state. Intriguingly, basal excitatory glutamatergic neurotransmission constrains the high-power state because blocking ionotropic or metabotropic glutamate receptors results in high-power LFOs in tg/tg but not WT mice. The high-power LFOs are decreased markedly by acetazolamide and 4-aminopyridine, the primary treatments for EA2, suggesting disease relevance. Together, these results demonstrate that the high-power LFOs in the tg/tg cerebral cortex represent a highly abnormal excitability state that may underlie noncerebellar symptoms that characterize CACNA1A mutations.
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35
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36
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Characterization of activity-dependent changes in flavoprotein fluorescence in cerebellar slices from juvenile rats. Neurosci Lett 2014; 584:17-22. [PMID: 25301569 DOI: 10.1016/j.neulet.2014.09.052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/17/2014] [Accepted: 09/29/2014] [Indexed: 01/30/2023]
Abstract
Flavoprotein autofluorescence signals attributed to neuronal metabolism have been used to assess synaptic function. Here, we characterized flavoprotein autofluorescence responses in the molecular layer of rat cerebellar slices. High frequency stimulation elicited a transient fluorescence increase (peak phase) that was followed by a longer-lasting fluorescence decrease (valley phase). The peak phase was restricted to the molecular layer, whereas the valley phase extended into the Purkinje cell layer and a portion of the granule cell layer. Responses were abolished by either the Na(+) channel antagonist, tetrodotoxin, or a combination of the AMPA receptor antagonists, NBQX and GIKI-53655, and were also reduced by a flavoprotein inhibitor (diphenyleneiodonium). These findings are consistent with responses being mediated by an increase in mitochondrial activity triggered by increased energy demands evoked by AMPA receptor-mediated synaptic transmission. The GABAA receptor antagonist picrotoxin did not significantly influence evoked responses. Likewise, exogenous application of ethanol, at concentrations known to increase GABAA receptor-mediated synaptic transmission at Purkinje cells, did not modify peak responses. These observations indicate that flavoprotein autofluorescence imaging could be useful to assess the coupling between glutamatergic synaptic transmission and neuronal metabolism in cerebellar slices.
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37
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Jongen JLM, Smits H, Pederzani T, Bechakra M, Hossaini M, Koekkoek SK, Huygen FJPM, De Zeeuw CI, Holstege JC, Joosten EAJ. Spinal autofluorescent flavoprotein imaging in a rat model of nerve injury-induced pain and the effect of spinal cord stimulation. PLoS One 2014; 9:e109029. [PMID: 25279562 PMCID: PMC4184817 DOI: 10.1371/journal.pone.0109029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 08/27/2014] [Indexed: 11/23/2022] Open
Abstract
Nerve injury may cause neuropathic pain, which involves hyperexcitability of spinal dorsal horn neurons. The mechanisms of action of spinal cord stimulation (SCS), an established treatment for intractable neuropathic pain, are only partially understood. We used Autofluorescent Flavoprotein Imaging (AFI) to study changes in spinal dorsal horn metabolic activity. In the Seltzer model of nerve-injury induced pain, hypersensitivity was confirmed using the von Frey and hotplate test. 14 Days after nerve-injury, rats were anesthetized, a bipolar electrode was placed around the affected sciatic nerve and the spinal cord was exposed by a laminectomy at T13. AFI recordings were obtained in neuropathic rats and a control group of naïve rats following 10 seconds of electrical stimulation of the sciatic nerve at C-fiber strength, or following non-noxious palpation. Neuropathic rats were then treated with 30 minutes of SCS or sham stimulation and AFI recordings were obtained for up to 60 minutes after cessation of SCS/sham. Although AFI responses to noxious electrical stimulation were similar in neuropathic and naïve rats, only neuropathic rats demonstrated an AFI-response to palpation. Secondly, an immediate, short-lasting, but strong reduction in AFI intensity and area of excitation occurred following SCS, but not following sham stimulation. Our data confirm that AFI can be used to directly visualize changes in spinal metabolic activity following nerve injury and they imply that SCS acts through rapid modulation of nociceptive processing at the spinal level.
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Affiliation(s)
| | - Helwin Smits
- Pain Management and Research Center, UMC+, Maastricht, the Netherlands
| | | | - Malik Bechakra
- Dept. of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | - Mehdi Hossaini
- Dept. of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | | | | | - Chris I. De Zeeuw
- Dept. of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
- Netherlands Institute for Neuroscience, Royal Academy for Arts and Sciences, Amsterdam, the Netherlands
| | - Jan C. Holstege
- Dept. of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
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38
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Mutant β-III spectrin causes mGluR1α mislocalization and functional deficits in a mouse model of spinocerebellar ataxia type 5. J Neurosci 2014; 34:9891-904. [PMID: 25057192 DOI: 10.1523/jneurosci.0876-14.2014] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Spinocerebellar ataxia type 5 (SCA5), a dominant neurodegenerative disease characterized by profound Purkinje cell loss, is caused by mutations in SPTBN2, a gene that encodes β-III spectrin. SCA5 is the first neurodegenerative disorder reported to be caused by mutations in a cytoskeletal spectrin gene. We have developed a mouse model to understand the mechanistic basis for this disease and show that expression of mutant but not wild-type β-III spectrin causes progressive motor deficits and cerebellar degeneration. We show that endogenous β-III spectrin interacts with the metabotropic glutamate receptor 1α (mGluR1α) and that mice expressing mutant β-III spectrin have cerebellar dysfunction with altered mGluR1α localization at Purkinje cell dendritic spines, decreased mGluR1-mediated responses, and deficient mGluR1-mediated long-term potentiation. These results indicate that mutant β-III spectrin causes mislocalization and dysfunction of mGluR1α at dendritic spines and connects SCA5 with other disorders involving glutamatergic dysfunction and synaptic plasticity abnormalities.
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39
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Cerebellum involvement in cortical sensorimotor circuits for the control of voluntary movements. Nat Neurosci 2014; 17:1233-9. [PMID: 25064850 DOI: 10.1038/nn.3773] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 07/02/2014] [Indexed: 11/08/2022]
Abstract
Sensorimotor integration is crucial to perception and motor control. How and where this process takes place in the brain is still largely unknown. Here we analyze the cerebellar contribution to sensorimotor integration in the whisker system of mice. We identify an area in the cerebellum where cortical sensory and motor inputs converge at the cellular level. Optogenetic stimulation of this area affects thalamic and motor cortex activity, alters parameters of ongoing movements and thereby modifies qualitatively and quantitatively touch events against surrounding objects. These results shed light on the cerebellum as an active component of sensorimotor circuits and show the importance of sensorimotor cortico-cerebellar loops in the fine control of voluntary movements.
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40
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Reevaluation of the beam and radial hypotheses of parallel fiber action in the cerebellar cortex. J Neurosci 2013; 33:11412-24. [PMID: 23843513 DOI: 10.1523/jneurosci.0711-13.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The role of parallel fibers (PFs) in cerebellar physiology remains controversial. Early studies inspired the "beam" hypothesis whereby granule cell (GC) activation results in PF-driven, postsynaptic excitation of beams of Purkinje cells (PCs). However, the "radial" hypothesis postulates that the ascending limb of the GC axon provides the dominant input to PCs and generates patch-like responses. Using optical imaging and single-cell recordings in the mouse cerebellar cortex in vivo, this study reexamines the beam versus radial controversy. Electrical stimulation of mossy fibers (MFs) as well as microinjection of NMDA in the granular layer generates beam-like responses with a centrally located patch-like response. Remarkably, ipsilateral forepaw stimulation evokes a beam-like response in Crus I. Discrete molecular layer lesions demonstrate that PFs contribute to the peripherally generated responses in Crus I. In contrast, vibrissal stimulation induces patch-like activation of Crus II and GABAA antagonists fail to convert this patch-like activity into a beam-like response, implying that molecular layer inhibition does not prevent beam-like responses. However, blocking excitatory amino acid transporters (EAATs) generates beam-like responses in Crus II. These beam-like responses are suppressed by focal inhibition of MF-GC synaptic transmission. Using EAAT4 reporter transgenic mice, we show that peripherally evoked patch-like responses in Crus II are aligned between parasagittal bands of EAAT4. This is the first study to demonstrate beam-like responses in the cerebellar cortex to peripheral, MF, and GC stimulation in vivo. Furthermore, the spatial pattern of the responses depends on extracellular glutamate and its local regulation by EAATs.
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Purkinje cell ataxin-1 modulates climbing fiber synaptic input in developing and adult mouse cerebellum. J Neurosci 2013; 33:5806-20. [PMID: 23536093 DOI: 10.1523/jneurosci.6311-11.2013] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Previous studies indicate that while transgenic mice with ATXN1[30Q]-D776-induced disease share pathological features caused by ATXN1[82Q] having an expanded polyglutamine tract, they fail to manifest the age-related progressive neurodegeneration seen in spinocerebellar ataxia type 1. The shared features include morphological alterations in climbing fiber (CF) innervation of Purkinje cells (PCs). To further investigate the ability of ataxin-1 (ATXN1) to impact CF/PC innervation, this study used morphological and functional approaches to examine CF/PC innervation during postnatal development in ATXN1[30Q]-D776 and ATXN1[82Q] cerebella. Notably, ATXN1[30Q]-D776 induced morphological alterations consistent with the development of the innervation of PCs by CFs being compromised, including a reduction of CF translocation along the PC dendritic tree, and decreased pruning of CF terminals from the PC soma. As previously shown for ATXN1[82Q], ATXN1[30Q]-D776 must enter the nucleus of PCs to induce these alterations. Experiments using conditional ATXN1[30Q]-D776 mice demonstrate that both the levels and specific timing of mutant ATXN1 expression are critical for alteration of the CF-PC synapse. Together these observations suggest that ATXN1, expressed exclusively in PCs, alters expression of a gene(s) in the postsynaptic PC that are critical for its innervation by CFs. To investigate whether ATXN1[30Q]-D776 curbs the progressive disease in ATXN1[82Q]-S776 mice, we crossed ATXN1[30Q]-D776 and ATXN1[82Q]-S776 mice and found that double transgenic mice developed progressive PC atrophy. Thus, the results also show that to develop progressive cerebellar degeneration requires expressing ATXN1 with an expanded polyglutamine tract.
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Tsytsarev V, Arakawa H, Borisov S, Pumbo E, Erzurumlu RS, Papkovsky DB. In vivo imaging of brain metabolism activity using a phosphorescent oxygen-sensitive probe. J Neurosci Methods 2013; 216:146-51. [PMID: 23624034 DOI: 10.1016/j.jneumeth.2013.04.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 04/09/2013] [Accepted: 04/11/2013] [Indexed: 12/12/2022]
Abstract
Several approaches have been adopted for real-time imaging of neural activity in vivo. We tested a new cell-penetrating phosphorescent oxygen-sensitive probe, NanO2-IR, to monitor temporal and spatial dynamics of oxygen metabolism in the neocortex following peripheral sensory stimulation. Probe solution was applied to the surface of anesthetized mouse brain; optical imaging was performed using a MiCAM-02 system. Trains of whisker stimuli were delivered and associated changes in phosphorescent signal were recorded in the contralateral somatosensory ("barrel") cortex. Sensory stimulation led to changes in oxygenation of activated areas of the barrel cortex. The oxygen imaging results were compared to those produced by the voltage-sensitive dye RH-1691. While the signals emitted by the two probes differed in shape and amplitude, they both faithfully indicated specific whisker evoked cortical activity. Thus, NanO2-IR probe can be used as a tool in visualization and real-time analysis of sensory-evoked neural activity in vivo.
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Affiliation(s)
- Vassiliy Tsytsarev
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, HSF II, 20 Penn Street, Baltimore, MD 21201-1075, USA.
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Quercetin as a fluorescent probe for the ryanodine receptor activity in Jurkat cells. Pflugers Arch 2013; 465:1101-19. [DOI: 10.1007/s00424-013-1235-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 01/29/2013] [Accepted: 01/31/2013] [Indexed: 02/07/2023]
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Small-molecule fluorophores and fluorescent probes for bioimaging. Pflugers Arch 2013; 465:347-59. [DOI: 10.1007/s00424-013-1234-z] [Citation(s) in RCA: 180] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 01/31/2013] [Accepted: 01/31/2013] [Indexed: 12/14/2022]
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Maleki S, Gopalakrishnan S, Ghanian Z, Sepehr R, Schmitt H, Eells J, Ranji M. Optical imaging of mitochondrial redox state in rodent model of retinitis pigmentosa. JOURNAL OF BIOMEDICAL OPTICS 2013; 18:16004. [PMID: 23291617 PMCID: PMC3537487 DOI: 10.1117/1.jbo.18.1.016004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Oxidative stress (OS) and mitochondrial dysfunction contribute to photoreceptor cell loss in retinal degenerative disorders. The metabolic state of the retina in a rodent model of retinitis pigmentosa (RP) was investigated using a cryo-fluorescence imaging technique. The mitochondrial metabolic coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are autofluorescent and can be monitored without exogenous labels using optical techniques. The cryo-fluorescence redox imaging technique provides a quantitative assessment of the metabolism. More specifically, the ratio of the fluorescence intensity of these fluorophores (NADH/FAD), the NADH redox ratio (RR), is a marker of the metabolic state of the tissue. The NADH RR and retinal function were examined in an established rodent model of RP, the P23H rat compared to that of nondystrophic Sprague-Dawley (SD) rats. The NADH RR mean values were 1.11 ± 0.03 in the SD normal and 0.841 ± 0.01 in the P23H retina, indicating increased OS in the P23H retina. Electroretinographic data revealed a significant reduction in photoreceptor function in P23H animals compared to SD nozrmal rats. Thus, cryo-fluorescence redox imaging was used as a quantitative marker of OS in eyes from transgenic rats and demonstrated that alterations in the oxidative state of eyes occur during the early stages of RP.
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Affiliation(s)
- Sepideh Maleki
- University of Wisconsin Milwaukee, Biophotonics Lab, Department of Electrical engineering, 3200 N Cramer Street, Milwaukee, Wisconsin 53211
- Address all correspondence to: Mahsa Ranji, University of Wisconsin Milwaukee, Biophotonics Lab, Department of Electrical engineering, 3200 N Cramer Street, Milwaukee, Wisconsin 53211. Tel: (414) 229-5889; E-mail: or Janis Eells, University of Wisconsin Milwaukee, Photobiomodulation Laboratory, Department of Health Sciences, 2200 E. Kenwood Boulevard, Milwaukee, Wisconsin 53201, E-mail:
| | - Sandeep Gopalakrishnan
- University of Wisconsin Milwaukee, Photobiomodulation Laboratory, Department of Health Sciences, 2200 E. Kenwood Boulevard, Milwaukee, Wisconsin 53201
- Address all correspondence to: Mahsa Ranji, University of Wisconsin Milwaukee, Biophotonics Lab, Department of Electrical engineering, 3200 N Cramer Street, Milwaukee, Wisconsin 53211. Tel: (414) 229-5889; E-mail: or Janis Eells, University of Wisconsin Milwaukee, Photobiomodulation Laboratory, Department of Health Sciences, 2200 E. Kenwood Boulevard, Milwaukee, Wisconsin 53201, E-mail:
| | - Zahra Ghanian
- University of Wisconsin Milwaukee, Biophotonics Lab, Department of Electrical engineering, 3200 N Cramer Street, Milwaukee, Wisconsin 53211
| | - Reyhaneh Sepehr
- University of Wisconsin Milwaukee, Biophotonics Lab, Department of Electrical engineering, 3200 N Cramer Street, Milwaukee, Wisconsin 53211
| | - Heather Schmitt
- University of Wisconsin Milwaukee, Photobiomodulation Laboratory, Department of Health Sciences, 2200 E. Kenwood Boulevard, Milwaukee, Wisconsin 53201
| | - Janis Eells
- University of Wisconsin Milwaukee, Photobiomodulation Laboratory, Department of Health Sciences, 2200 E. Kenwood Boulevard, Milwaukee, Wisconsin 53201
| | - Mahsa Ranji
- University of Wisconsin Milwaukee, Biophotonics Lab, Department of Electrical engineering, 3200 N Cramer Street, Milwaukee, Wisconsin 53211
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Hiraishi T, Kitaura H, Oishi M, Fukuda M, Kameyama S, Takahashi H, Kakita A, Fujii Y. Significance of horizontal propagation of synchronized activities in human epileptic neocortex investigated by optical imaging and immunohistological study. Epilepsy Res 2012. [PMID: 23200433 DOI: 10.1016/j.eplepsyres.2012.09.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To characterize the physiological condition of human epileptic neocortex, we employed flavoprotein fluorescence imaging (FFI), an optical imaging method which detects intrinsic signals accompanying neural activation, and immunohistologically studied human cortical specimens. The experimented materials were cortical tissues surrounding various intracerebral lesions obtained from 5 patients with epilepsy (epileptic patients: EPs) and 5 without epilepsy (non-epileptic patients: NEPs). These tissues were immersed in oxygenated artificial cerebrospinal fluid immediately after removal in the operating room. Signal changes of FFI in the cortical layers subjected to electrical stimulation were observed under bicuculline methiodide perfusion. Immunohistological staining for parvalbumin (PV), calbindin, and calretinin were performed on the same specimens to evaluate expressions of calcium-binding protein positive cells. The FFI study showed the characteristic cortical propagation pattern of elicited activities horizontally along the cortical layers in EPs but not in NEPs. The propagated area with more than 0.5% signal changes was significantly larger in EPs than in NEPs (p=0.008). Only the expression of PV positive neurons was significantly lower in EPs than in NEPs (p=0.006). The propagated area on FFI and the decrease in PV positive neurons correlated significantly (R=-0.78, p=0.04). The present study visualized the unique horizontal propagation of signal changes on FFI and demonstrated a correlation of this propagation with immunohistological decreases in PV positive neurons in human epileptic cortex. Further investigations may elucidate the mechanism of hyper-excitability and hyper-synchronization in epileptic cortical tissue itself.
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Affiliation(s)
- Tetsuya Hiraishi
- Department of Neurosurgery, Brain Research Institute, University of Niigata, Niigata, Japan.
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Hedges VL, Ebner TJ, Meisel RL, Mermelstein PG. The cerebellum as a target for estrogen action. Front Neuroendocrinol 2012; 33:403-11. [PMID: 22975197 PMCID: PMC3496070 DOI: 10.1016/j.yfrne.2012.08.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 08/20/2012] [Accepted: 08/24/2012] [Indexed: 12/22/2022]
Abstract
This review focuses on the effects of estrogens upon the cerebellum, a brain region long ignored as a site of estrogen action. Highlighted are the diverse effects of estradiol within the cerebellum, emphasizing the importance of estradiol signaling in cerebellar development, modulation of synaptic neurotransmission in the adult, and the potential influence of estrogens on various health and disease states. We also provide new data, consistent with previous studies, in which locally synthesized estradiol modulates cerebellar glutamatergic neurotransmission, providing one underlying mechanism by which the actions of estradiol can affect this brain region.
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Affiliation(s)
- Valerie L Hedges
- Department of Neuroscience and Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN 55455, United States
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Evolution of the dynamic changes in functional cerebral oxidative metabolism from tissue mitochondria to blood oxygen. J Cereb Blood Flow Metab 2012; 32:745-58. [PMID: 22293987 PMCID: PMC3318152 DOI: 10.1038/jcbfm.2011.198] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The dynamic properties of the cerebral metabolic rate of oxygen consumption (CMR(O2)) during changes in brain activity remain unclear. Therefore, the spatial and temporal evolution of functional increases in CMR(O2) was investigated in the rat somato-sensory cortex during forelimb stimulation under a suppressed blood flow response condition. Temporally, stimulation elicited a fast increase in tissue mitochondria CMR(O2) described by a time constant of ~1 second measured using flavoprotein autofluorescence imaging. CMR(O2)-driven changes in the tissue oxygen tension measured using an oxygen electrode and blood oxygenation measured using optical imaging of intrinsic signal followed; however, these changes were slow with time constants of ~5 and ~10 seconds, respectively. This slow change in CMR(O2)-driven blood oxygenation partly explains the commonly observed post-stimulus blood oxygen level-dependent (BOLD) undershoot. Spatially, the changes in mitochondria CMR(O2) were similar to the changes in blood oxygenation. Finally, the increases in CMR(O2) were well correlated with the evoked multi-unit spiking activity. These findings show that dynamic CMR(O2) calculations made using only blood oxygenation data (e.g., BOLD functional magnetic resonance imaging (fMRI)) do not directly reflect the temporal changes in the tissue's mitochondria metabolic rate; however, the findings presented can bridge the gap between the changes in cellular oxidative rate and blood oxygenation.
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Abstract
Most neurons fire in bursts, imposing episodic energy demands, but how these demands are coordinated with oxidative phosphorylation is still unknown. Here, using fluorescence imaging techniques on presynaptic termini of Drosophila motor neurons (MNs), we show that mitochondrial matrix pH (pHm), inner membrane potential (Δψm), and NAD(P)H levels ([NAD(P)H]m) increase within seconds of nerve stimulation. The elevations of pHm, Δψm, and [NAD(P)H]m indicate an increased capacity for ATP production. Elevations in pHm were blocked by manipulations that blocked mitochondrial Ca2+ uptake, including replacement of extracellular Ca2+ with Sr2+ and application of either tetraphenylphosphonium chloride or KB-R7943, indicating that it is Ca2+ that stimulates presynaptic mitochondrial energy metabolism. To place this phenomenon within the context of endogenous neuronal activity, the firing rates of a number of individually identified MNs were determined during fictive locomotion. Surprisingly, although endogenous firing rates are significantly different, there was little difference in presynaptic cytosolic Ca2+ levels ([Ca2+]c) between MNs when each fires at its endogenous rate. The average [Ca2+]c level (329±11 nM) was slightly above the average Ca2+ affinity of the mitochondria (281±13 nM). In summary, we show that when MNs fire at endogenous rates, [Ca2+]c is driven into a range where mitochondria rapidly acquire Ca2+. As we also show that Ca2+ stimulates presynaptic mitochondrial energy metabolism, we conclude that [Ca2+]c levels play an integral role in coordinating mitochondrial energy metabolism with presynaptic activity in Drosophila MNs.
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Nakajima A, Kimura H, Sawadsaringkarn Y, Maezawa Y, Kobayashi T, Noda T, Sasagawa K, Tokuda T, Ishikawa Y, Shiosaka S, Ohta J. CMOS image sensor integrated with micro-LED and multielectrode arrays for the patterned photostimulation and multichannel recording of neuronal tissue. OPTICS EXPRESS 2012; 20:6097-108. [PMID: 22418489 DOI: 10.1364/oe.20.006097] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We developed a complementary metal oxide semiconductor (CMOS) integrated device for optogenetic applications. This device can interface via neuronal tissue with three functional modalities: imaging, optical stimulation and electrical recording. The CMOS image sensor was fabricated on 0.35 μm standard CMOS process with built-in control circuits for an on-chip blue light-emitting diode (LED) array. The effective imaging area was 2.0 × 1.8 mm². The pixel array was composed of 7.5 × 7.5 μm² 3-transistor active pixel sensors (APSs). The LED array had 10 × 8 micro-LEDs measuring 192 × 225 μm². We integrated the device with a commercial multichannel recording system to make electrical recordings.
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Affiliation(s)
- Arata Nakajima
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
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