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Paulk AC, Yang JC, Cleary DR, Soper DJ, Halgren M, O’Donnell AR, Lee SH, Ganji M, Ro YG, Oh H, Hossain L, Lee J, Tchoe Y, Rogers N, Kiliç K, Ryu SB, Lee SW, Hermiz J, Gilja V, Ulbert I, Fabó D, Thesen T, Doyle WK, Devinsky O, Madsen JR, Schomer DL, Eskandar EN, Lee JW, Maus D, Devor A, Fried SI, Jones PS, Nahed BV, Ben-Haim S, Bick SK, Richardson RM, Raslan AM, Siler DA, Cahill DP, Williams ZM, Cosgrove GR, Dayeh SA, Cash SS. Microscale Physiological Events on the Human Cortical Surface. Cereb Cortex 2021; 31:3678-3700. [PMID: 33749727 PMCID: PMC8258438 DOI: 10.1093/cercor/bhab040] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 02/05/2021] [Accepted: 02/07/2021] [Indexed: 01/14/2023] Open
Abstract
Despite ongoing advances in our understanding of local single-cellular and network-level activity of neuronal populations in the human brain, extraordinarily little is known about their "intermediate" microscale local circuit dynamics. Here, we utilized ultra-high-density microelectrode arrays and a rare opportunity to perform intracranial recordings across multiple cortical areas in human participants to discover three distinct classes of cortical activity that are not locked to ongoing natural brain rhythmic activity. The first included fast waveforms similar to extracellular single-unit activity. The other two types were discrete events with slower waveform dynamics and were found preferentially in upper cortical layers. These second and third types were also observed in rodents, nonhuman primates, and semi-chronic recordings from humans via laminar and Utah array microelectrodes. The rates of all three events were selectively modulated by auditory and electrical stimuli, pharmacological manipulation, and cold saline application and had small causal co-occurrences. These results suggest that the proper combination of high-resolution microelectrodes and analytic techniques can capture neuronal dynamics that lay between somatic action potentials and aggregate population activity. Understanding intermediate microscale dynamics in relation to single-cell and network dynamics may reveal important details about activity in the full cortical circuit.
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Devor A. Diversity is our Strength. NEUROPHOTONICS 2021; 8:030101. [PMID: 34604438 PMCID: PMC8480322 DOI: 10.1117/1.nph.8.3.030101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Neurophotonics Editor in Chief Anna Devor reflects on need to cherish and cultivate diversity within the global neuroscience and neurophotonics community by creating inclusive environments to welcome young students in sharing the joy of science.
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Mächler P, Broggini T, Mateo C, Thunemann M, Fomin-Thunemann N, Doran PR, Sencan I, Kilic K, Desjardins M, Uhlirova H, Yaseen MA, Boas DA, Linninger AA, Vergassola M, Yu X, Lewis LD, Polimeni JR, Rosen BR, Sakadžić S, Buxton RB, Lauritzen M, Kleinfeld D, Devor A. A Suite of Neurophotonic Tools to Underpin the Contribution of Internal Brain States in fMRI. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2021; 18:100273. [PMID: 33959688 PMCID: PMC8095678 DOI: 10.1016/j.cobme.2021.100273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Recent developments in optical microscopy, applicable for large-scale and longitudinal imaging of cortical activity in behaving animals, open unprecedented opportunities to gain a deeper understanding of neurovascular and neurometabolic coupling during different brain states. Future studies will leverage these tools to deliver foundational knowledge about brain state-dependent regulation of cerebral blood flow and metabolism as well as regulation as a function of brain maturation and aging. This knowledge is of critical importance to interpret hemodynamic signals observed with functional magnetic resonance imaging (fMRI).
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Puppo F, Sadegh S, Trujillo CA, Thunemann M, Campbell EP, Vandenberghe M, Shan X, Akkouh IA, Miller EW, Bloodgood BL, Silva GA, Dale AM, Einevoll GT, Djurovic S, Andreassen OA, Muotri AR, Devor A. All-Optical Electrophysiology in hiPSC-Derived Neurons With Synthetic Voltage Sensors. Front Cell Neurosci 2021; 15:671549. [PMID: 34122014 PMCID: PMC8193062 DOI: 10.3389/fncel.2021.671549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/03/2021] [Indexed: 12/26/2022] Open
Abstract
Voltage imaging and “all-optical electrophysiology” in human induced pluripotent stem cell (hiPSC)-derived neurons have opened unprecedented opportunities for high-throughput phenotyping of activity in neurons possessing unique genetic backgrounds of individual patients. While prior all-optical electrophysiology studies relied on genetically encoded voltage indicators, here, we demonstrate an alternative protocol using a synthetic voltage sensor and genetically encoded optogenetic actuator that generate robust and reproducible results. We demonstrate the functionality of this method by measuring spontaneous and evoked activity in three independent hiPSC-derived neuronal cell lines with distinct genetic backgrounds.
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Devor A. Welcome New Members of the Neurophotonics Editorial Board! NEUROPHOTONICS 2021; 8:020101. [PMID: 34169116 PMCID: PMC8217743 DOI: 10.1117/1.nph.8.2.020101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Neurophotonics Editor in Chief Anna Devor welcomes an expanded editorial board and announces three Special Sections for the coming year.
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Tang J, Cheng X, Kilic K, Devor A, Lee J, Boas DA. Imaging localized fast optical signals of neural activation with optical coherence tomography in awake mice. OPTICS LETTERS 2021; 46:1744-1747. [PMID: 33793533 PMCID: PMC8086197 DOI: 10.1364/ol.411897] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 03/10/2021] [Indexed: 05/05/2023]
Abstract
We report optical coherence tomography (OCT) imaging of localized fast optical signals (FOSs) arising from whisker stimulation in awake mice. The activated voxels were identified by fitting the OCT intensity signal time course with a response function over a time scale of a few hundred milliseconds after the whisker stimulation. The significantly activated voxels were shown to be localized to the expected brain region for whisker stimulation. The ability to detect functional stimulus-evoked, depth-resolved FOS with intrinsic contrast from the cortex provides a new tool for neural activity studies.
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Kılıç K, Desjardins M, Tang J, Thunemann M, Sunil S, Erdener ŞE, Postnov DD, Boas DA, Devor A. Chronic Cranial Windows for Long Term Multimodal Neurovascular Imaging in Mice. Front Physiol 2021; 11:612678. [PMID: 33551837 PMCID: PMC7862556 DOI: 10.3389/fphys.2020.612678] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 12/18/2020] [Indexed: 01/18/2023] Open
Abstract
Chronic cranial windows allow for longitudinal brain imaging experiments in awake, behaving mice. Different imaging technologies have their unique advantages and combining multiple imaging modalities offers measurements of a wide spectrum of neuronal, glial, vascular, and metabolic parameters needed for comprehensive investigation of physiological and pathophysiological mechanisms. Here, we detail a suite of surgical techniques for installation of different cranial windows targeted for specific imaging technologies and their combination. Following these techniques and practices will yield higher experimental success and reproducibility of results.
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Devor A. Editorial: Neurophotonics for you. NEUROPHOTONICS 2021; 8:010101. [PMID: 33693051 PMCID: PMC7937575 DOI: 10.1117/1.nph.8.1.010101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Neurophotonics Editor in Chief Anna Devor outlines a vision for the journal.
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van der Meer D, Frei O, Kaufmann T, Shadrin AA, Devor A, Smeland OB, Thompson WK, Fan CC, Holland D, Westlye LT, Andreassen OA, Dale AM. Author Correction: Understanding the genetic determinants of the brain with MOSTest. Nat Commun 2020; 11:4700. [PMID: 32929091 PMCID: PMC7490377 DOI: 10.1038/s41467-020-18628-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Rogers N, Thunemann M, Devor A, Gilja V. Impact of Brain Surface Boundary Conditions on Electrophysiology and Implications for Electrocorticography. Front Neurosci 2020; 14:763. [PMID: 32903652 PMCID: PMC7438758 DOI: 10.3389/fnins.2020.00763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 06/29/2020] [Indexed: 12/02/2022] Open
Abstract
Volume conduction of electrical potentials in the brain is highly influenced by the material properties and geometry of the tissue and recording devices implanted into the tissue. These effects are very large in EEG due to the volume conduction through the skull and scalp but are often neglected in intracranial electrophysiology. When considering penetrating electrodes deep in the brain, the assumption of an infinite and homogenous medium can be used when the sources are far enough from the brain surface and the electrodes to minimize the boundary effect. When the electrodes are recording from the brain's surface the effect of the boundary cannot be neglected, and the large surface area and commonly used insulating materials in surface electrode arrays may further increase the effect by altering the nature of the boundary in the immediate vicinity of the electrodes. This gives the experimenter some control over the spatial profiles of the potentials by appropriate design of the electrode arrays. We construct a simple three-layer model to describe the effect of material properties and geometry above the brain surface on the electric potentials and conduct empirical experiments to validate this model. A laminar electrode array is used to measure the effect of insulating and relatively conducting layers above the cortical surface by recording evoked potentials alternating between a dried surface and saline covering layer, respectively. Empirically, we find that an insulating boundary amplifies the potentials relative to conductive saline by about a factor of 4, and that the effect is not constrained to potentials that originate near the surface. The model is applied to predict the influence of array design and implantation procedure on the recording amplitude and spatial selectivity of the surface electrode arrays.
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van der Meer D, Frei O, Kaufmann T, Shadrin AA, Devor A, Smeland OB, Thompson WK, Fan CC, Holland D, Westlye LT, Andreassen OA, Dale AM. Understanding the genetic determinants of the brain with MOSTest. Nat Commun 2020; 11:3512. [PMID: 32665545 PMCID: PMC7360598 DOI: 10.1038/s41467-020-17368-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 06/22/2020] [Indexed: 12/11/2022] Open
Abstract
Regional brain morphology has a complex genetic architecture, consisting of many common polymorphisms with small individual effects. This has proven challenging for genome-wide association studies (GWAS). Due to the distributed nature of genetic signal across brain regions, multivariate analysis of regional measures may enhance discovery of genetic variants. Current multivariate approaches to GWAS are ill-suited for complex, large-scale data of this kind. Here, we introduce the Multivariate Omnibus Statistical Test (MOSTest), with an efficient computational design enabling rapid and reliable inference, and apply it to 171 regional brain morphology measures from 26,502 UK Biobank participants. At the conventional genome-wide significance threshold of α = 5 × 10-8, MOSTest identifies 347 genomic loci associated with regional brain morphology, more than any previous study, improving upon the discovery of established GWAS approaches more than threefold. Our findings implicate more than 5% of all protein-coding genes and provide evidence for gene sets involved in neuron development and differentiation.
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Sætra MJ, Solbrå AV, Devor A, Sakadžić S, Dale AM, Einevoll GT. Spatially resolved estimation of metabolic oxygen consumption from optical measurements in cortex. NEUROPHOTONICS 2020; 7:035005. [PMID: 32855994 PMCID: PMC7441469 DOI: 10.1117/1.nph.7.3.035005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 08/04/2020] [Indexed: 06/11/2023]
Abstract
Significance: The cerebral metabolic rate of oxygen (CMRO 2 ) is an important indicator of brain function and pathology. Knowledge about its magnitude is also required for proper interpretation of the blood oxygenation level-dependent (BOLD) signal measured with functional MRI. Despite the need for estimatingCMRO 2 , no gold standard exists. Traditionally, the estimation ofCMRO 2 has been pursued with somewhat indirect approaches combining several different types of measurements with mathematical modeling of the underlying physiological processes. The recent ability to measure the level of oxygen (pO 2 ) in cortex with two-photon resolution in in vivo conditions has provided a more direct way for estimatingCMRO 2 , but has so far only been used to estimate the averageCMRO 2 close to cortical penetrating arterioles in rats. Aim: The aim of this study was to propose a method to provide spatial maps ofCMRO 2 based on two-photonpO 2 measurements. Approach: The method has two key steps. First, thepO 2 maps are spatially smoothed to reduce the effects of noise in the measurements. Next, the Laplace operator (a double spatial derivative) in two spatial dimensions is applied on the smoothedpO 2 maps to obtain spatially resolvedCMRO 2 estimates. Result: The smoothing introduces a bias, and a balance must be found where the effects of the noise are sufficiently reduced without introducing too much bias. In this model-based study, we explored this balance using synthetic model-based data, that is, data where the spatial maps ofCMRO 2 were preset and thus known. The correspondingpO 2 maps were found by solving the Poisson equation, which relatesCMRO 2 andpO 2 . MATLAB code for using the method is provided. Conclusion: Through this model-based study, we propose a method for estimatingCMRO 2 with high spatial resolution based on measurements ofpO 2 in cerebral cortex.
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Todd N, Angolano C, Ferran C, Devor A, Borsook D, McDannold N. Secondary effects on brain physiology caused by focused ultrasound-mediated disruption of the blood-brain barrier. J Control Release 2020; 324:450-459. [PMID: 32470359 DOI: 10.1016/j.jconrel.2020.05.040] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/22/2020] [Accepted: 05/23/2020] [Indexed: 12/12/2022]
Abstract
Focused ultrasound (FUS) combined with microbubbles is a non-invasive method for targeted, reversible disruption of the blood-brain barrier (FUS-BBB opening). This approach holds great promise for improving delivery of therapeutics to the brain. In order to achieve this clinically important goal, the approach necessarily breaks a protective barrier, temporarily, which plays a fundamental role in maintaining a homeostatic environment in the brain. Preclinical and clinical research has identified a set of treatment parameters under which this can be performed safely, whereby the BBB is disrupted to the point of being permeable to normally non-penetrant agents without causing significant acute damage to endothelial or neuronal cells. Much of the early work in this field focused on engineering questions around how to achieve optimal delivery of therapeutics via BBB disruption. However, there is increasing interest in addressing biological questions related to whether and how various aspects of neurophysiology might be affected when this fundamental protective barrier is compromised by the specific mechanisms of FUS-BBB opening. Improving our understanding of these secondary effects is becoming vital now that FUS-BBB opening treatments have entered clinical trials. Such information would help to safely expand FUS-BBB opening protocols into a wider range of drug delivery applications and may even lead to new types of treatments. In this paper, we will critically review our current knowledge of the secondary effects caused by FUS-BBB opening on brain physiology, identify areas that remain understudied, and discuss how a better understanding of these processes can be used to safely advance FUS-BBB opening into a wider range of clinical applications.
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Cheng X, Sadegh S, Zilpelwar S, Devor A, Tian L, Boas DA. Comparing the fundamental imaging depth limit of two-photon, three-photon, and non-degenerate two-photon microscopy. OPTICS LETTERS 2020; 45:2934-2937. [PMID: 32412504 PMCID: PMC8059139 DOI: 10.1364/ol.392724] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 04/17/2020] [Indexed: 05/12/2023]
Abstract
We have systematically characterized the degradation of imaging quality with depth in deep brain multi-photon microscopy, utilizing our recently developed numerical model that computes wave propagation in scattering media. The signal-to-background ratio (SBR) and the resolution determined by the width of the point spread function are obtained as functions of depth. We compare the imaging quality of two-photon (2PM), three-photon (3PM), and non-degenerate two-photon microscopy (ND-2PM) for mouse brain imaging. We show that the imaging depth of 2PM and ND-2PM are fundamentally limited by the SBR, while the SBR remains approximately invariant with imaging depth for 3PM. Instead, the imaging depth of 3PM is limited by the degradation of the resolution, if there is sufficient laser power to maintain the signal level at large depth. The roles of the concentration of dye molecules, the numerical aperture of the input light, the anisotropy factor g, noise level, input laser power, and the effect of temporal broadening are also discussed.
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Li B, Ohtomo R, Thunemann M, Adams SR, Yang J, Fu B, Yaseen MA, Ran C, Polimeni JR, Boas DA, Devor A, Lo EH, Arai K, Sakadžić S. Two-photon microscopic imaging of capillary red blood cell flux in mouse brain reveals vulnerability of cerebral white matter to hypoperfusion. J Cereb Blood Flow Metab 2020; 40:501-512. [PMID: 30829101 PMCID: PMC7026840 DOI: 10.1177/0271678x19831016] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 01/19/2019] [Accepted: 01/21/2019] [Indexed: 01/15/2023]
Abstract
Despite the importance of understanding the regulation of microvascular blood flow in white matter, no data on subcortical capillary blood flow parameters are available, largely due to the lack of appropriate imaging methods. To address this knowledge gap, we employed two-photon microscopy using a far-red fluorophore Alexa680 and photon-counting detection to measure capillary red blood cell (RBC) flux in both cerebral gray and white matter, in isoflurane-anesthetized mice. We have found that in control animals, baseline capillary RBC flux in the white matter was significantly higher than in the adjacent cerebral gray matter. In response to mild hypercapnia, RBC flux in the white matter exhibited significantly smaller fractional increase than in the gray matter. Finally, during global cerebral hypoperfusion, RBC flux in the white matter was reduced significantly in comparison to the controls, while RBC flux in the gray matter was preserved. Our results suggest that blood flow in the white matter may be less efficiently regulated when challenged by physiological perturbations as compared to the gray matter. Importantly, the blood flow in the white matter may be more susceptible to hypoperfusion than in the gray matter, potentially exacerbating the white matter deterioration in brain conditions involving global cerebral hypoperfusion.
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Sadegh S, Yang MH, Ferri C, Thunemann M, Devor A, Fainman Y. Advantages of Non-degenerate Two-photon Microscopy for Deep Tissue Imaging. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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42
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Cheng X, Li Y, Mertz J, SakadŽić S, Devor A, Boas DA, Tian L. Development of a beam propagation method to simulate the point spread function degradation in scattering media. OPTICS LETTERS 2019; 44:4989-4992. [PMID: 31613246 PMCID: PMC6889808 DOI: 10.1364/ol.44.004989] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/12/2019] [Indexed: 05/23/2023]
Abstract
Scattering is one of the main issues that limit the imaging depth in deep tissue optical imaging. To characterize the role of scattering, we have developed a forward model based on the beam propagation method and established the link between the macroscopic optical properties of the media and the statistical parameters of the phase masks applied to the wavefront. Using this model, we have analyzed the degradation of the point-spread function of the illumination beam in the transition regime from ballistic to diffusive light transport. Our method provides a wave-optic simulation toolkit to analyze the effects of scattering on image quality degradation in scanning microscopy. Our open-source implementation is available at https://github.com/BUNPC/Beam-Propagation-Method.
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Trujillo CA, Gao R, Negraes PD, Gu J, Buchanan J, Preissl S, Wang A, Wu W, Haddad GG, Chaim IA, Domissy A, Vandenberghe M, Devor A, Yeo GW, Voytek B, Muotri AR. Complex Oscillatory Waves Emerging from Cortical Organoids Model Early Human Brain Network Development. Cell Stem Cell 2019; 25:558-569.e7. [PMID: 31474560 PMCID: PMC6778040 DOI: 10.1016/j.stem.2019.08.002] [Citation(s) in RCA: 394] [Impact Index Per Article: 78.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 05/03/2019] [Accepted: 08/06/2019] [Indexed: 01/05/2023]
Abstract
Structural and transcriptional changes during early brain maturation follow fixed developmental programs defined by genetics. However, whether this is true for functional network activity remains unknown, primarily due to experimental inaccessibility of the initial stages of the living human brain. Here, we developed human cortical organoids that dynamically change cellular populations during maturation and exhibited consistent increases in electrical activity over the span of several months. The spontaneous network formation displayed periodic and regular oscillatory events that were dependent on glutamatergic and GABAergic signaling. The oscillatory activity transitioned to more spatiotemporally irregular patterns, and synchronous network events resembled features similar to those observed in preterm human electroencephalography. These results show that the development of structured network activity in a human neocortex model may follow stable genetic programming. Our approach provides opportunities for investigating and manipulating the role of network activity in the developing human cortex.
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Sadegh S, Yang MH, Ferri CGL, Thunemann M, Saisan PA, Wei Z, Rodriguez EA, Adams SR, Kiliç K, Boas DA, Sakadžić S, Devor A, Fainman Y. Efficient non-degenerate two-photon excitation for fluorescence microscopy. OPTICS EXPRESS 2019; 27:28022-28035. [PMID: 31684560 PMCID: PMC6825618 DOI: 10.1364/oe.27.028022] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Non-degenerate two-photon excitation (ND-TPE) has been explored in two-photon excitation microscopy. However, a systematic study of the efficiency of ND-TPE to guide the selection of fluorophore excitation wavelengths is missing. We measured the relative non-degenerate two-photon absorption cross-section (ND-TPACS) of several commonly used fluorophores (two fluorescent proteins and three small-molecule dyes) and generated 2-dimensional ND-TPACS spectra. We observed that the shape of a ND-TPACS spectrum follows that of the corresponding degenerate two-photon absorption cross-section (D-TPACS) spectrum, but is higher in magnitude. We found that the observed enhancements are higher than theoretical predictions.
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Mäki-Marttunen T, Devor A, Phillips WA, Dale AM, Andreassen OA, Einevoll GT. Computational Modeling of Genetic Contributions to Excitability and Neural Coding in Layer V Pyramidal Cells: Applications to Schizophrenia Pathology. Front Comput Neurosci 2019; 13:66. [PMID: 31616272 PMCID: PMC6775251 DOI: 10.3389/fncom.2019.00066] [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: 02/15/2019] [Accepted: 09/09/2019] [Indexed: 11/13/2022] Open
Abstract
Pyramidal cells in layer V of the neocortex are one of the most widely studied neuron types in the mammalian brain. Due to their role as integrators of feedforward and cortical feedback inputs, they are well-positioned to contribute to the symptoms and pathology in mental disorders-such as schizophrenia-that are characterized by a mismatch between the internal perception and external inputs. In this modeling study, we analyze the input/output properties of layer V pyramidal cells and their sensitivity to modeled genetic variants in schizophrenia-associated genes. We show that the excitability of layer V pyramidal cells and the way they integrate inputs in space and time are altered by many types of variants in ion-channel and Ca2+ transporter-encoding genes that have been identified as risk genes by recent genome-wide association studies. We also show that the variability in the output patterns of spiking and Ca2+ transients in layer V pyramidal cells is altered by these model variants. Importantly, we show that many of the predicted effects are robust to noise and qualitatively similar across different computational models of layer V pyramidal cells. Our modeling framework reveals several aspects of single-neuron excitability that can be linked to known schizophrenia-related phenotypes and existing hypotheses on disease mechanisms. In particular, our models predict that single-cell steady-state firing rate is positively correlated with the coding capacity of the neuron and negatively correlated with the amplitude of a prepulse-mediated adaptation and sensitivity to coincidence of stimuli in the apical dendrite and the perisomatic region of a layer V pyramidal cell. These results help to uncover the voltage-gated ion-channel and Ca2+ transporter-associated genetic underpinnings of schizophrenia phenotypes and biomarkers.
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Ganji M, Paulk AC, Yang JC, Vahidi NW, Lee SH, Liu R, Hossain L, Arneodo EM, Thunemann M, Shigyo M, Tanaka A, Ryu SB, Lee SW, Tchoe Y, Marsala M, Devor A, Cleary DR, Martin JR, Oh H, Gilja V, Gentner TQ, Fried SI, Halgren E, Cash SS, Dayeh SA. Selective Formation of Porous Pt Nanorods for Highly Electrochemically Efficient Neural Electrode Interfaces. NANO LETTERS 2019; 19:6244-6254. [PMID: 31369283 PMCID: PMC7174248 DOI: 10.1021/acs.nanolett.9b02296] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The enhanced electrochemical activity of nanostructured materials is readily exploited in energy devices, but their utility in scalable and human-compatible implantable neural interfaces can significantly advance the performance of clinical and research electrodes. We utilize low-temperature selective dealloying to develop scalable and biocompatible one-dimensional platinum nanorod (PtNR) arrays that exhibit superb electrochemical properties at various length scales, stability, and biocompatibility for high performance neurotechnologies. PtNR arrays record brain activity with cellular resolution from the cortical surfaces in birds and nonhuman primates. Significantly, strong modulation of surface recorded single unit activity by auditory stimuli is demonstrated in European Starling birds as well as the modulation of local field potentials in the visual cortex by light stimuli in a nonhuman primate and responses to electrical stimulation in mice. PtNRs record behaviorally and physiologically relevant neuronal dynamics from the surface of the brain with high spatiotemporal resolution, which paves the way for less invasive brain-machine interfaces.
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Li B, Esipova TV, Sencan I, Kılıç K, Fu B, Desjardins M, Moeini M, Kura S, Yaseen MA, Lesage F, Østergaard L, Devor A, Boas DA, Vinogradov SA, Sakadžić S. More homogeneous capillary flow and oxygenation in deeper cortical layers correlate with increased oxygen extraction. eLife 2019; 8:42299. [PMID: 31305237 PMCID: PMC6636997 DOI: 10.7554/elife.42299] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 07/01/2019] [Indexed: 01/01/2023] Open
Abstract
Our understanding of how capillary blood flow and oxygen distribute across cortical layers to meet the local metabolic demand is incomplete. We addressed this question by using two-photon imaging of resting-state microvascular oxygen partial pressure (PO2) and flow in the whisker barrel cortex in awake mice. Our measurements in layers I-V show that the capillary red-blood-cell flux and oxygenation heterogeneity, and the intracapillary resistance to oxygen delivery, all decrease with depth, reaching a minimum around layer IV, while the depth-dependent oxygen extraction fraction is increased in layer IV, where oxygen demand is presumably the highest. Our findings suggest that more homogeneous distribution of the physiological observables relevant to oxygen transport to tissue is an important part of the microvascular network adaptation to local brain metabolism. These results will inform the biophysical models of layer-specific cerebral oxygen delivery and consumption and improve our understanding of the diseases that affect cerebral microcirculation.
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Sadegh S, Yang MH, Ferri CGL, Thunemann M, Saisan PA, Devor A, Fainman Y. Measurement of the relative non-degenerate two-photon absorption cross-section for fluorescence microscopy. OPTICS EXPRESS 2019; 27:8335-8347. [PMID: 31052653 PMCID: PMC6825612 DOI: 10.1364/oe.27.008335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In non-degenerate two-photon microscopy (ND-TPM), the required energy for fluorescence excitation occurs via absorption of two photons of different energies derived from two synchronized pulsed laser beams. ND-TPM is a promising imaging technology offering flexibility in the choice of the photon energy for each beam. However, a formalism to quantify the efficiency of two-photon absorption (TPA) under non-degenerate excitation, relative to the resonant degenerate excitation, is missing. Here, we derive this formalism and experimentally validate our prediction for a common fluorophore, fluorescein. An accurate quantification of non-degenerate TPA is important to optimize the choice of photon energies for each fluorophore.
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Mäki-Marttunen T, Krull F, Bettella F, Hagen E, Næss S, Ness TV, Moberget T, Elvsåshagen T, Metzner C, Devor A, Edwards AG, Fyhn M, Djurovic S, Dale AM, Andreassen OA, Einevoll GT. Alterations in Schizophrenia-Associated Genes Can Lead to Increased Power in Delta Oscillations. Cereb Cortex 2019; 29:875-891. [PMID: 30475994 PMCID: PMC6319172 DOI: 10.1093/cercor/bhy291] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/03/2018] [Indexed: 12/13/2022] Open
Abstract
Genome-wide association studies have implicated many ion channels in schizophrenia pathophysiology. Although the functions of these channels are relatively well characterized by single-cell studies, the contributions of common variation in these channels to neurophysiological biomarkers and symptoms of schizophrenia remain elusive. Here, using computational modeling, we show that a common biomarker of schizophrenia, namely, an increase in delta-oscillation power, may be a direct consequence of altered expression or kinetics of voltage-gated ion channels or calcium transporters. Our model of a circuit of layer V pyramidal cells highlights multiple types of schizophrenia-related variants that contribute to altered dynamics in the delta-frequency band. Moreover, our model predicts that the same membrane mechanisms that increase the layer V pyramidal cell network gain and response to delta-frequency oscillations may also cause a deficit in a single-cell correlate of the prepulse inhibition, which is a behavioral biomarker highly associated with schizophrenia.
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Cheng X, Berman AJL, Polimeni JR, Buxton RB, Gagnon L, Devor A, Sakadžić S, Boas DA. Dependence of the MR signal on the magnetic susceptibility of blood studied with models based on real microvascular networks. Magn Reson Med 2019; 81:3865-3874. [PMID: 30659643 DOI: 10.1002/mrm.27660] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 12/05/2018] [Accepted: 12/21/2018] [Indexed: 01/02/2023]
Abstract
PURPOSE The primary goal of this study was to estimate the value of β , the exponent in the power law relating changes of the transverse relaxation rate and intra-extravascular local magnetic susceptibility differences as Δ R 2 ∗ ∝ ( Δ χ ) β . The secondary objective was to evaluate any differences that might exist in the value of β obtained using a deoxyhemoglobin-weighted Δ χ distribution versus a constant Δ χ distribution assumed in earlier computations. The third objective was to estimate the value of β that is relevant for methods based on susceptibility contrast agents with a concentration of Δ χ higher than that used for BOLD fMRI calculations. METHODS Our recently developed model of real microvascular anatomical networks is used to extend the original simplified Monte-Carlo simulations to compute β from the first principles. RESULTS Our results show that β = 1 for most BOLD fMRI measurements of real vascular networks, as opposed to earlier predictions of β = 1 .5 using uniform Δ χ distributions. For perfusion or fMRI methods based on contrast agents, which generate larger values for Δ χ , β = 1 for B 0 ≤ 9.4 T, whereas at 14 T β can drop below 1 and the variation across subjects is large, indicating that a lower concentration of contrast agent with a lower value of Δ χ is desired for experiments at high B0 . CONCLUSION These results improve our understanding of the relationship between R2 * and the underlying microvascular properties. The findings will help to infer the cerebral metabolic rate of oxygen and cerebral blood volume from BOLD and perfusion MRI, respectively.
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