1
|
Manno FAM, Kumar R, An Z, Khan MS, Su J, Liu J, Wu EX, He J, Feng Y, Lau C. Structural and Functional Hippocampal Correlations in Environmental Enrichment During the Adolescent to Adulthood Transition in Mice. Front Syst Neurosci 2022; 15:807297. [PMID: 35242015 PMCID: PMC8886042 DOI: 10.3389/fnsys.2021.807297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 12/14/2021] [Indexed: 01/13/2023] Open
Abstract
Environmental enrichment is known to induce neuronal changes; however, the underlying structural and functional factors involved are not fully known and remain an active area of study. To investigate these factors, we assessed enriched environment (EE) and standard environment (SE) control mice over 30 days using structural and functional MRI methods. Naïve adult male mice (n = 30, ≈20 g, C57BL/B6J, postnatal day 60 initial scan) were divided into SE and EE groups and scanned before and after 30 days. Structural analyses included volumetry based on manual segmentation as well as diffusion tensor imaging (DTI). Functional analyses included seed-based analysis (SBA), independent component analysis (ICA), the amplitude of low-frequency fluctuation (ALFF), and fractional ALFF (fALFF). Structural results indicated that environmental enrichment led to an increase in the volumes of cornu ammonis 1 (CA1) and dentate gyrus. Structural results indicated changes in radial diffusivity and mean diffusivity in the visual cortex and secondary somatosensory cortex after EE. Furthermore, SBA and ICA indicated an increase in resting-state functional MRI (rsfMRI) functional connectivity in the hippocampus. Using parallel structural and functional analyses, we have demonstrated coexistent structural and functional changes in the hippocampal subdivision CA1. Future research should map alterations temporally during environmental enrichment to investigate the initiation of these structural and functional changes.
Collapse
Affiliation(s)
- Francis A M Manno
- Center for Imaging Science, Department of Biomedical Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, United States.,Department of Physics, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Rachit Kumar
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.,Medical Scientist Training Program, University of Pennsylvania, Philadelphia, PA, United States
| | - Ziqi An
- Guangdong Provincial Key Laboratory of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Muhammad Shehzad Khan
- Department of Physics, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Junfeng Su
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Harvard University, Boston, MA, United States
| | - Jiaming Liu
- Guangdong Provincial Key Laboratory of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Ed X Wu
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, Hong Kong SAR, China.,Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Jufang He
- Department of Neuroscience, City University of Hong Kong, Hong Kong, Hong Kong SAR, China.,Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Yanqiu Feng
- Guangdong Provincial Key Laboratory of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Condon Lau
- Department of Physics, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| |
Collapse
|
2
|
Manno FAM, An Z, Kumar R, Wu EX, He J, Feng Y, Lau C. Structural Alterations in a Rat Model of Short-Term Conductive Hearing Loss Are Associated With Reduced Resting State Functional Connectivity. Front Syst Neurosci 2021; 15:655172. [PMID: 34456689 PMCID: PMC8397539 DOI: 10.3389/fnsys.2021.655172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 07/02/2021] [Indexed: 12/14/2022] Open
Abstract
Conductive hearing loss (CHL) results in attenuation of air conducted sound reaching the inner ear. How a change in air conducted sound alters the auditory system resulting in cortical alterations is not well understood. Here, we have assessed structural and functional magnetic resonance imaging (MRI) in an adult (P60) rat model of short-term conductive hearing loss (1 week). Diffusion tensor imaging (DTI) revealed fractional anisotropy (FA) and axial diffusivity alterations after hearing loss that circumscribed the auditory cortex (AC). Tractography found the lateral lemniscus tract leading to the bilateral inferior colliculus (IC) was reduced. For baseline comparison, DTI and tractography alterations were not found for the somatosensory cortex. To determine functional connectivity changes due to hearing loss, seed-based analysis (SBA) and independent component analysis (ICA) were performed. Short term conductive hearing loss altered functional connectivity in the AC and IC, but not the somatosensory cortex. The results present an exploratory neuroimaging assessment of structural alterations coupled to a change in functional connectivity after conductive hearing loss. The results and implications for humans consist of structural-functional brain alterations following short term hearing loss in adults.
Collapse
Affiliation(s)
| | - Ziqi An
- Guangdong Provincial Key Laboratory of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
| | - Rachit Kumar
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Medical Scientist Training Program, University of Pennsylvania, Philadelphia, PA, United States
| | - Ed X. Wu
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, SAR China
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, SAR China
| | - Jufang He
- Department of Neuroscience, City University of Hong Kong, Hong Kong, SAR China
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, SAR China
| | - Yanqiu Feng
- Guangdong Provincial Key Laboratory of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, China
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
| | - Condon Lau
- Department of Physics, City University of Hong Kong, Hong Kong, SAR China
| |
Collapse
|
3
|
Wong E, Radziwon K, Chen GD, Liu X, Manno FA, Manno SH, Auerbach B, Wu EX, Salvi R, Lau C. Functional magnetic resonance imaging of enhanced central auditory gain and electrophysiological correlates in a behavioral model of hyperacusis. Hear Res 2020; 389:107908. [PMID: 32062293 DOI: 10.1016/j.heares.2020.107908] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 12/02/2019] [Accepted: 02/02/2020] [Indexed: 01/24/2023]
Abstract
Hyperacusis is a debilitating hearing condition in which normal everyday sounds are perceived as exceedingly loud, annoying, aversive or even painful. The prevalence of hyperacusis approaches 10%, making it an important, but understudied medical condition. To noninvasively identify the neural correlates of hyperacusis in an animal model, we used sound-evoked functional magnetic resonance imaging (fMRI) to locate regions of abnormal activity in the central nervous system of rats with behavioral evidence of hyperacusis induced with an ototoxic drug (sodium salicylate, 250 mg/kg, i.p.). Reaction time-intensity measures of loudness-growth revealed behavioral evidence of salicylate-induced hyperacusis at high intensities. fMRI revealed significantly enhanced sound-evoked responses in the auditory cortex (AC) to 80 dB SPL tone bursts presented at 8 and 16 kHz. Sound-evoked responses in the inferior colliculus (IC) were also enhanced, but to a lesser extent. To confirm the main results, electrophysiological recordings of spike discharges from multi-unit clusters were obtained from the central auditory pathway. Salicylate significantly enhanced tone-evoked spike-discharges from multi-unit clusters in the AC from 4 to 30 kHz at intensities ≥60 dB SPL; less enhancement occurred in the medial geniculate body (MGB), and even less in the IC. Our results demonstrate for the first time that non-invasive sound-evoked fMRI can be used to identify regions of neural hyperactivity throughout the brain in an animal model of hyperacusis.
Collapse
Affiliation(s)
- Eddie Wong
- Department of Physics, City University of Hong Kong, Hong Kong, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China; Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, China
| | - Kelly Radziwon
- Center for Hearing & Deafness, Department of Communicative Disorders and Sciences, SUNY at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA
| | - Guang-Di Chen
- Center for Hearing & Deafness, Department of Communicative Disorders and Sciences, SUNY at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA
| | - Xiaopeng Liu
- Center for Hearing & Deafness, Department of Communicative Disorders and Sciences, SUNY at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA
| | - Francis Am Manno
- Department of Physics, City University of Hong Kong, Hong Kong, China; School of Biomedical Engineering, University of Sydney, Sydney, New South Wales, Australia
| | - Sinai Hc Manno
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China
| | - Benjamin Auerbach
- Center for Hearing & Deafness, Department of Communicative Disorders and Sciences, SUNY at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA
| | - Ed X Wu
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China; Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, China
| | - Richard Salvi
- Center for Hearing & Deafness, Department of Communicative Disorders and Sciences, SUNY at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA; Department of Audiology and Speech-Language Pathology, Asia University, Taichung, Taiwan, ROC.
| | - Condon Lau
- Department of Physics, City University of Hong Kong, Hong Kong, China.
| |
Collapse
|
4
|
Lau C, Manno FAM, Dong CM, Chan KC, Wu EX. Auditory-visual convergence at the superior colliculus in rat using functional MRI. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2018:5531-5536. [PMID: 30441590 DOI: 10.1109/embc.2018.8513633] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The superior colliculus (SC) of the midbrain has been a model structure for multisensory processing. Many neurons in the intermediate and deep SC layers respond to two or more of auditory, visual, and somatosensory stimuli as assessed by electrophysiology. In contrast, noninvasive and large field of view functional magnetic resonance imaging (fMRI) studies have focused on multisensory processing in the cortex. In this study, we applied blood oxygenation leveldependent (BOLD) fMRI on Sprague-Dawley rats receiving monaural (auditory) and binocular (visual) stimuli to study subcortical multisensory processing. Activation was observed in the left superior olivary complex, lateral lemniscus, and inferior colliculus and both hemispheres of the superior colliculus during auditory stimulation. The SC response was bilateral even though the stimulus was monaural. During visual stimulation, activation was observed in both hemispheres of the SC and lateral geniculate nucleus. In both hemispheres of the SC, the number of voxels in the activation area $( \mathrm {p}<10 -8$) and BOLD signal changes $( \mathrm {p}<0.01)$ were significantly greater during visual than auditory stimulation. These results provide functional imaging evidence that the SC is a site of auditoryvisual convergence due to its involvement in both auditory and visual processing. The auditory and visual fMRI activations likely reflect the firing of unisensory and multisensory neurons in the SC. The present study lays the groundwork for noninvasive functional imaging studies of multisensory convergence and integration in the SC.
Collapse
|
5
|
Manno FAM, Isla AG, Manno SHC, Ahmed I, Cheng SH, Barrios FA, Lau C. Early Stage Alterations in White Matter and Decreased Functional Interhemispheric Hippocampal Connectivity in the 3xTg Mouse Model of Alzheimer's Disease. Front Aging Neurosci 2019; 11:39. [PMID: 30967770 PMCID: PMC6440287 DOI: 10.3389/fnagi.2019.00039] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 02/08/2019] [Indexed: 12/21/2022] Open
Abstract
Alzheimer’s disease (AD) is characterized in the late stages by amyloid-β (Aβ) plaques and neurofibrillary tangles. Nevertheless, recent evidence has indicated that early changes in cerebral connectivity could compromise cognitive functions even before the appearance of the classical neuropathological features. Diffusion tensor imaging (DTI), resting-state functional magnetic resonance imaging (rs-fMRI) and volumetry were performed in the triple transgenic mouse model of AD (3xTg-AD) at 2 months of age, prior to the development of intraneuronal plaque accumulation. We found the 3xTg-AD had significant fractional anisotropy (FA) increase and radial diffusivity (RD) decrease in the cortex compared with wild-type controls, while axial diffusivity (AD) and mean diffusivity (MD) were similar. Interhemispheric hippocampal connectivity was decreased in the 3xTg-AD while connectivity in the caudate putamen (CPu) was similar to controls. Most surprising, ventricular volume in the 3xTg-AD was four times larger than controls. The results obtained in this study characterize the early stage changes in interhemispheric hippocampal connectivity in the 3xTg-AD mouse that could represent a translational biomarker to human models in preclinical stages of the AD.
Collapse
Affiliation(s)
- Francis A M Manno
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong.,Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Arturo G Isla
- Neuronal Oscillations Laboratory, Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Stockholm, Sweden
| | - Sinai H C Manno
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong.,State Key Laboratory of Marine Pollution (SKLMP), City University of Hong Kong, Kowloon, Hong Kong.,Department of Biomedical Sciences, College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
| | - Irfan Ahmed
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong.,Electrical Engineering Department, Sukkur IBA University, Sukkur, Pakistan
| | - Shuk Han Cheng
- State Key Laboratory of Marine Pollution (SKLMP), City University of Hong Kong, Kowloon, Hong Kong.,Department of Biomedical Sciences, College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong.,Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong
| | - Fernando A Barrios
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Condon Lau
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong
| |
Collapse
|
6
|
Leong ATL, Dong CM, Gao PP, Chan RW, To A, Sanes DH, Wu EX. Optogenetic auditory fMRI reveals the effects of visual cortical inputs on auditory midbrain response. Sci Rep 2018; 8:8736. [PMID: 29880842 PMCID: PMC5992211 DOI: 10.1038/s41598-018-26568-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 05/10/2018] [Indexed: 12/20/2022] Open
Abstract
Sensory cortices contain extensive descending (corticofugal) pathways, yet their impact on brainstem processing - particularly across sensory systems - remains poorly understood. In the auditory system, the inferior colliculus (IC) in the midbrain receives cross-modal inputs from the visual cortex (VC). However, the influences from VC on auditory midbrain processing are unclear. To investigate whether and how visual cortical inputs affect IC auditory responses, the present study combines auditory blood-oxygenation-level-dependent (BOLD) functional MRI (fMRI) with cell-type specific optogenetic manipulation of visual cortex. The results show that predominant optogenetic excitation of the excitatory pyramidal neurons in the infragranular layers of the primary VC enhances the noise-evoked BOLD fMRI responses within the IC. This finding reveals that inputs from VC influence and facilitate basic sound processing in the auditory midbrain. Such combined optogenetic and auditory fMRI approach can shed light on the large-scale modulatory effects of corticofugal pathways and guide detailed electrophysiological studies in the future.
Collapse
Affiliation(s)
- Alex T L Leong
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Celia M Dong
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Patrick P Gao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Russell W Chan
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Anthea To
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Dan H Sanes
- Center for Neural Science, New York University, New York, NY, 10003, United States
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China. .,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China. .,School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China. .,Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
| |
Collapse
|
7
|
Yang B, Wong E, Ho WH, Lau C, Chan YS, Wu EX. Reduction of sound-evoked midbrain responses observed by functional magnetic resonance imaging following acute acoustic noise exposure. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:2184. [PMID: 29716239 DOI: 10.1121/1.5030920] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Short duration and high intensity acoustic exposures can lead to temporary hearing loss and auditory nerve degeneration. This study investigates central auditory system function following such acute exposures after hearing loss recedes. Adult rats were exposed to 100 dB sound pressure level noise for 15 min. Auditory brainstem responses (ABRs) were recorded with click sounds to check hearing thresholds. Functional magnetic resonance imaging (fMRI) was performed with tonal stimulation at 12 and 20 kHz to investigate central auditory changes. Measurements were performed before exposure (0D), 7 days after (7D), and 14 days after (14D). ABRs show an ∼6 dB threshold shift shortly after exposure, but no significant threshold differences between 0D, 7D, and 14D. fMRI responses are observed in the lateral lemniscus (LL) and inferior colliculus (IC) of the midbrain. In the IC, responses to 12 kHz are 3.1 ± 0.3% (0D), 1.9 ± 0.3% (7D), and 2.9 ± 0.3% (14D) above the baseline magnetic resonance imaging signal. Responses to 20 kHz are 2.0 ± 0.2% (0D), 1.4 ± 0.2% (7D), and 2.1 ± 0.2% (14D). For both tones, responses at 7D are less than those at 0D (p < 0.01) and 14D (p < 0.05). In the LL, similar trends are observed. Acute exposure leads to functional changes in the auditory midbrain with timescale of weeks.
Collapse
Affiliation(s)
- Bin Yang
- Department of Physics, The City University of Hong Kong, Hong Kong, People's Republic of China
| | - Eddie Wong
- Department of Physics, The City University of Hong Kong, Hong Kong, People's Republic of China
| | - Wai Hong Ho
- Department of Physics, The City University of Hong Kong, Hong Kong, People's Republic of China
| | - Condon Lau
- Department of Physics, The City University of Hong Kong, Hong Kong, People's Republic of China
| | - Ying Shing Chan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, People's Republic of China
| | - Ed X Wu
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, People's Republic of China
| |
Collapse
|
8
|
Blazquez Freches G, Chavarrias C, Shemesh N. BOLD-fMRI in the mouse auditory pathway. Neuroimage 2018; 165:265-277. [DOI: 10.1016/j.neuroimage.2017.10.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/09/2017] [Accepted: 10/13/2017] [Indexed: 01/31/2023] Open
|
9
|
Cao P, Hyder F, Zhou IY, Zhang JW, Xie VB, Tsang A, Wu EX. Simultaneous spin-echo and gradient-echo BOLD measurements by dynamic MRS. NMR IN BIOMEDICINE 2017; 30:e3745. [PMID: 28574615 DOI: 10.1002/nbm.3745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/22/2017] [Accepted: 04/10/2017] [Indexed: 06/07/2023]
Abstract
This study aimed to dissociate the intravascular and extravascular contributions to spin-echo (SE) and gradient-echo (GE) blood oxygenation level-dependent (BOLD) signals at 7 T, using dynamic diffusion-weighted MRS. We simultaneously acquired SE and GE data using a point-resolved spectroscopy sequence with diffusion weightings of 0, 600, and 1200 s/mm2 . The BOLD signals were quantified by fitting the free induction decays starting from the SE center to a mono-exponential decay function. Without diffusion weighting, BOLD signals measured with SE and GE increased by 1.6 ± 0.5% (TESE = 40 ms) and 5.2 ± 1.4% (nominal TEGE = 40 ms) during stimulation, respectively. With diffusion weighting, the BOLD increase during stimulation measured with SE decreased from 1.6 ± 0.5% to 1.3 ± 0.4% (P < 0.001), whereas that measured by GE was unaffected (P > 0.05); the post-stimulation undershoots in the BOLD signal time courses were largely preserved in both SE and GE measurements. These results demonstrated the feasiblity of simultaneous SE and GE measurements of BOLD signals with and without interleaved diffusion weighting. The results also indicated a predominant extravascular contribution to the BOLD signal time courses, including post-stimulation undershoots in both SE and GE measurements at 7 T.
Collapse
Affiliation(s)
- Peng Cao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, USA
| | - Fahmeed Hyder
- Departments of Diagnostic Radiology and Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Iris Y Zhou
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| | - Jevin W Zhang
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| | - Victor B Xie
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| | - Adrian Tsang
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| |
Collapse
|
10
|
Wong E, Yang B, Du L, Ho WH, Lau C, Ke Y, Chan YS, Yung WH, Wu EX. The multi-level impact of chronic intermittent hypoxia on central auditory processing. Neuroimage 2017; 156:232-239. [PMID: 28528846 DOI: 10.1016/j.neuroimage.2017.05.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 04/07/2017] [Accepted: 05/16/2017] [Indexed: 12/21/2022] Open
Abstract
During hypoxia, the tissues do not obtain adequate oxygen. Chronic hypoxia can lead to many health problems. A relatively common cause of chronic hypoxia is sleep apnea. Sleep apnea is a sleep breathing disorder that affects 3-7% of the population. During sleep, the patient's breathing starts and stops. This can lead to hypertension, attention deficits, and hearing disorders. In this study, we apply an established chronic intermittent hypoxemia (CIH) model of sleep apnea to study its impact on auditory processing. Adult rats were reared for seven days during sleeping hours in a gas chamber with oxygen level cycled between 10% and 21% (normal atmosphere) every 90s. During awake hours, the subjects were housed in standard conditions with normal atmosphere. CIH treatment significantly reduces arterial oxygen partial pressure and oxygen saturation during sleeping hours (relative to controls). After treatment, subjects underwent functional magnetic resonance imaging (fMRI) with broadband sound stimulation. Responses are observed in major auditory centers in all subjects, including the auditory cortex (AC) and auditory midbrain. fMRI signals from the AC are statistically significantly increased after CIH by 0.13% in the contralateral hemisphere and 0.10% in the ipsilateral hemisphere. In contrast, signals from the lateral lemniscus of the midbrain are significantly reduced by 0.39%. Signals from the neighboring inferior colliculus of the midbrain are relatively unaffected. Chronic hypoxia affects multiple levels of the auditory system and these changes are likely related to hearing disorders associated with sleep apnea.
Collapse
Affiliation(s)
- Eddie Wong
- Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China; Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Bin Yang
- Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China; Department of Radiology, Children's Hospital of Fudan University, Shanghai, People's Republic of China
| | - Lida Du
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China; Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Wai Hong Ho
- Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Condon Lau
- Department of Physics and Materials Science, The City University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China.
| | - Ya Ke
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China; Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Ying Shing Chan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Wing Ho Yung
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China; Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| |
Collapse
|
11
|
Lau C, Pienkowski M, Zhang JW, McPherson B, Wu EX. Chronic exposure to broadband noise at moderate sound pressure levels spatially shifts tone-evoked responses in the rat auditory midbrain. Neuroimage 2015; 122:44-51. [DOI: 10.1016/j.neuroimage.2015.07.065] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/10/2015] [Accepted: 07/24/2015] [Indexed: 02/09/2023] Open
|
12
|
Pannese A, Grandjean D, Frühholz S. Subcortical processing in auditory communication. Hear Res 2015; 328:67-77. [DOI: 10.1016/j.heares.2015.07.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 06/23/2015] [Accepted: 07/01/2015] [Indexed: 12/21/2022]
|
13
|
Gao PP, Zhang JW, Fan SJ, Sanes DH, Wu EX. Auditory midbrain processing is differentially modulated by auditory and visual cortices: An auditory fMRI study. Neuroimage 2015; 123:22-32. [PMID: 26306991 DOI: 10.1016/j.neuroimage.2015.08.040] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 08/15/2015] [Accepted: 08/18/2015] [Indexed: 11/19/2022] Open
Abstract
The cortex contains extensive descending projections, yet the impact of cortical input on brainstem processing remains poorly understood. In the central auditory system, the auditory cortex contains direct and indirect pathways (via brainstem cholinergic cells) to nuclei of the auditory midbrain, called the inferior colliculus (IC). While these projections modulate auditory processing throughout the IC, single neuron recordings have samples from only a small fraction of cells during stimulation of the corticofugal pathway. Furthermore, assessments of cortical feedback have not been extended to sensory modalities other than audition. To address these issues, we devised blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) paradigms to measure the sound-evoked responses throughout the rat IC and investigated the effects of bilateral ablation of either auditory or visual cortices. Auditory cortex ablation increased the gain of IC responses to noise stimuli (primarily in the central nucleus of the IC) and decreased response selectivity to forward species-specific vocalizations (versus temporally reversed ones, most prominently in the external cortex of the IC). In contrast, visual cortex ablation decreased the gain and induced a much smaller effect on response selectivity. The results suggest that auditory cortical projections normally exert a large-scale and net suppressive influence on specific IC subnuclei, while visual cortical projections provide a facilitatory influence. Meanwhile, auditory cortical projections enhance the midbrain response selectivity to species-specific vocalizations. We also probed the role of the indirect cholinergic projections in the auditory system in the descending modulation process by pharmacologically blocking muscarinic cholinergic receptors. This manipulation did not affect the gain of IC responses but significantly reduced the response selectivity to vocalizations. The results imply that auditory cortical gain modulation is mediated primarily through direct projections and they point to future investigations of the differential roles of the direct and indirect projections in corticofugal modulation. In summary, our imaging findings demonstrate the large-scale descending influences, from both the auditory and visual cortices, on sound processing in different IC subdivisions. They can guide future studies on the coordinated activity across multiple regions of the auditory network, and its dysfunctions.
Collapse
Affiliation(s)
- Patrick P Gao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Jevin W Zhang
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Shu-Juan Fan
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Dan H Sanes
- Center for Neural Science, New York University, New York, NY 10003, United States
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
| |
Collapse
|
14
|
Gao PP, Zhang JW, Chan RW, Leong ATL, Wu EX. BOLD fMRI study of ultrahigh frequency encoding in the inferior colliculus. Neuroimage 2015; 114:427-37. [PMID: 25869860 DOI: 10.1016/j.neuroimage.2015.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/02/2015] [Accepted: 04/02/2015] [Indexed: 01/23/2023] Open
Abstract
Many vertebrates communicate with ultrahigh frequency (UHF) vocalizations to limit auditory detection by predators. The mechanisms underlying the neural encoding of such UHF sounds may provide important insights for understanding neural processing of other complex sounds (e.g. human speeches). In the auditory system, sound frequency is normally encoded topographically as tonotopy, which, however, contains very limited representation of UHFs in many species. Instead, electrophysiological studies suggested that two neural mechanisms, both exploiting the interactions between frequencies, may contribute to UHF processing. Neurons can exhibit excitatory or inhibitory responses to a tone when another UHF tone is presented simultaneously (combination sensitivity). They can also respond to such stimulation if they are tuned to the frequency of the cochlear-generated distortion products of the two tones, e.g. their difference frequency (cochlear distortion). Both mechanisms are present in an early station of the auditory pathway, the midbrain inferior colliculus (IC). Currently, it is unclear how prevalent the two mechanisms are and how they are functionally integrated in encoding UHFs. This study investigated these issues with large-view BOLD fMRI in rat auditory system, particularly the IC. UHF vocalizations (above 40kHz), but not pure tones at similar frequencies (45, 55, 65, 75kHz), evoked robust BOLD responses in multiple auditory nuclei, including the IC, reinforcing the sensitivity of the auditory system to UHFs despite limited representation in tonotopy. Furthermore, BOLD responses were detected in the IC when a pair of UHF pure tones was presented simultaneously (45 & 55kHz, 55 & 65kHz, 45 & 65kHz, 45 & 75kHz). For all four pairs, a cluster of voxels in the ventromedial side always showed the strongest responses, displaying combination sensitivity. Meanwhile, voxels in the dorsolateral side that showed strongest secondary responses to each pair of UHF pure tones also showed the strongest responses to a pure tone at their difference frequency, suggesting that they are sensitive to cochlear distortion. These BOLD fMRI results indicated that combination sensitivity and cochlear distortion are employed by large but spatially distinctive neuron populations in the IC to represent UHFs. Our imaging findings provided insights for understanding sound feature encoding in the early stage of the auditory pathway.
Collapse
Affiliation(s)
- Patrick P Gao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Jevin W Zhang
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Russell W Chan
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Alex T L Leong
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
| |
Collapse
|
15
|
Lau C, Zhang JW, McPherson B, Pienkowski M, Wu EX. Long-term, passive exposure to non-traumatic acoustic noise induces neural adaptation in the adult rat medial geniculate body and auditory cortex. Neuroimage 2015; 107:1-9. [DOI: 10.1016/j.neuroimage.2014.11.048] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 11/12/2014] [Accepted: 11/22/2014] [Indexed: 02/02/2023] Open
|
16
|
So EC, Lu HP, Hsing CH, Wu SN, Chang YK, Poon PWF. Evaluation of microvasculature at the auditory midbrain--the benefits of sectioning at a tangential angle. Microsc Res Tech 2014; 78:105-10. [PMID: 25349128 DOI: 10.1002/jemt.22450] [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: 08/24/2014] [Accepted: 09/30/2014] [Indexed: 11/09/2022]
Abstract
Vascular remodeling in the brain occurs as a plastic change following neural over-activity. The auditory midbrain (or inferior colliculus, IC) is an ideal place to study sound-induced vascular changes because it is the brain's most vascularized structure and it is tonotopically organized. However, its micro-vascular pattern remains poorly understood. Since the IC is a sphere-like structure, the histological assessment of vasculature could depend on the angle of sectioning. Here, we studied the effects of cutting the IC at different angles on microvascular assessment, specifically: micro-vascular density and the shape of microvascular lumen. Photomicrographs were taken from 5 µm toluidine blue-stained histological sections obtained at two angles of sectioning: (a) the conventional coronal sectioning, and (b) a novel "tangential" sectioning (tangential to the dorso-medial surface of the IC). Results showed that the tangential sections, in comparison with the coronal sections, yielded (a) a higher count of micro-vascular density and (b) a higher proportion of round-shaped micro-vascular lumens. This discrepancy in results between two cut angles is likely related to the spatial pattern of blood vessels supplying the IC. We propose that the tangential sectioning should be adopted as standard for the accurate study of microvasculature in the IC.
Collapse
Affiliation(s)
- Edmund Cheung So
- Department of Anesthesia, China Medical University- An Nan Hospital, Tainan, Taiwan; Department of Anesthesia, China Medical University, Taichung, Taiwan; Department of Anesthesia, Taishan Medical University, Taian, Shangdong, People's Republic of China; Department of Anesthesia, Nanshan branch of Qilu Hospital, Shangdong University, People's Republic of China
| | | | | | | | | | | |
Collapse
|
17
|
Cheng JS, Gao PP, Zhou IY, Chan RW, Chan Q, Mak HK, Khong PL, Wu EX. Resting-state fMRI using passband balanced steady-state free precession. PLoS One 2014; 9:e91075. [PMID: 24622278 PMCID: PMC3951283 DOI: 10.1371/journal.pone.0091075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 02/09/2014] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE Resting-state functional MRI (rsfMRI) has been increasingly used for understanding brain functional architecture. To date, most rsfMRI studies have exploited blood oxygenation level-dependent (BOLD) contrast using gradient-echo (GE) echo planar imaging (EPI), which can suffer from image distortion and signal dropout due to magnetic susceptibility and inherent long echo time. In this study, the feasibility of passband balanced steady-state free precession (bSSFP) imaging for distortion-free and high-resolution rsfMRI was investigated. METHODS rsfMRI was performed in humans at 3 T and in rats at 7 T using bSSFP with short repetition time (TR = 4/2.5 ms respectively) in comparison with conventional GE-EPI. Resting-state networks (RSNs) were detected using independent component analysis. RESULTS AND SIGNIFICANCE RSNs derived from bSSFP images were shown to be spatially and spectrally comparable to those derived from GE-EPI images with considerable intra- and inter-subject reproducibility. High-resolution bSSFP images corresponded well to the anatomical images, with RSNs exquisitely co-localized to the gray matter. Furthermore, RSNs at areas of severe susceptibility such as human anterior prefrontal cortex and rat piriform cortex were proved accessible. These findings demonstrated for the first time that passband bSSFP approach can be a promising alternative to GE-EPI for rsfMRI. It offers distortion-free and high-resolution RSNs and is potentially suited for high field studies.
Collapse
Affiliation(s)
- Joe S. Cheng
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Patrick P. Gao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Iris Y. Zhou
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Russell W. Chan
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China
| | | | - Henry K. Mak
- Diagnostic Radiology, The University of Hong Kong, Hong Kong SAR, China
| | - Pek L. Khong
- Diagnostic Radiology, The University of Hong Kong, Hong Kong SAR, China
| | - Ed X. Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China
- Department of Anatomy, The University of Hong Kong, Hong Kong SAR, China
- Department of Medicine, The University of Hong Kong, Hong Kong SAR, China
| |
Collapse
|
18
|
The inferior colliculus is involved in deviant sound detection as revealed by BOLD fMRI. Neuroimage 2014; 91:220-7. [PMID: 24486979 DOI: 10.1016/j.neuroimage.2014.01.043] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 11/24/2022] Open
Abstract
Rapid detection of deviant sounds is a crucial property of the auditory system because it increases the saliency of biologically important, unexpected sounds. The oddball paradigm in which a deviant sound is randomly interspersed among a train of standard sounds has been traditionally used to study this property in mammals. Currently, most human studies have only revealed the involvement of cortical regions in this property. Recently, several animal electrophysiological studies have reported that neurons in the inferior colliculus (IC) exhibit reduced responses to a standard sound but restore their responses at the occurrence of a deviant sound (i.e., stimulus-specific adaptation or SSA), suggesting that the IC may also be involved in deviance detection. However, by adopting an invasive method, these animal studies examined only a limited number of neurons. Although SSA appears to be more prominent in the external cortical nuclei of the IC for frequency deviant, a thorough investigation of this property throughout the IC using other deviants and efficient imaging techniques may provide more comprehensive information on this important phenomenon. In this study, blood-oxygen-level-dependent (BOLD) fMRI with a large field of view was applied to investigate the role of the IC in deviance detection. Two sound tokens that had identical frequency spectrum but temporally inverted profiles were used as the deviant and standard. A control experiment showed that these two sounds evoked the same responses in the IC when they were separately presented. Two oddball experiments showed that the deviant induced higher responses than the standard (by 0.41±0.09% and 0.41±0.10%, respectively). The most activated voxels were in the medial side of the IC in both oddball experiments. The results clearly demonstrated that the IC is involved in deviance detection. BOLD fMRI detection of increased activities in the medial side of the IC to the deviant revealed the highly adaptive nature of a substantial population of neurons in this region, probably those that belong to the rostral or dorsal cortex of the IC. These findings highlighted the complexity of auditory information processing in the IC and may guide future studies of the functional organizations of this subcortical structure.
Collapse
|
19
|
Chandrasekaran B, Skoe E, Kraus N. An integrative model of subcortical auditory plasticity. Brain Topogr 2013; 27:539-52. [PMID: 24150692 DOI: 10.1007/s10548-013-0323-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 10/05/2013] [Indexed: 11/26/2022]
Abstract
In direct conflict with the concept of auditory brainstem nuclei as passive relay stations for behaviorally-relevant signals, recent studies have demonstrated plasticity of the auditory signal in the brainstem. In this paper we provide an overview of the forms of plasticity evidenced in subcortical auditory regions. We posit an integrative model of auditory plasticity, which argues for a continuous, online modulation of bottom-up signals via corticofugal pathways, based on an algorithm that anticipates and updates incoming stimulus regularities. We discuss the negative implications of plasticity in clinical dysfunction and propose novel methods of eliciting brainstem responses that could specify the biological nature of auditory processing deficits.
Collapse
Affiliation(s)
- Bharath Chandrasekaran
- Department of Communication Sciences and Disorders, Center for Perceptual Systems, Institute for Neuroscience, The University of Texas at Austin, Austin, TX, USA,
| | | | | |
Collapse
|
20
|
Zhou IY, Liang YX, Chan RW, Gao PP, Cheng JS, Hu Y, So KF, Wu EX. Brain resting-state functional MRI connectivity: morphological foundation and plasticity. Neuroimage 2013; 84:1-10. [PMID: 23988270 DOI: 10.1016/j.neuroimage.2013.08.037] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/26/2013] [Accepted: 08/16/2013] [Indexed: 01/21/2023] Open
Abstract
Despite the immense ongoing efforts to map brain functional connections and organizations with resting-state functional MRI (rsfMRI), the mechanisms governing the temporally coherent rsfMRI signals remain unclear. In particular, there is a lack of direct evidence regarding the morphological foundation and plasticity of these rsfMRI derived connections. In this study, we investigated the role of axonal projections in rsfMRI connectivity and its plasticity. Well-controlled rodent models of complete and posterior corpus callosotomy were longitudinally examined with rsfMRI at 7T in conjunction with intracortical EEG recording and functional MRI tracing of interhemispheric neuronal pathways by manganese (Mn(2+)). At post-callosotomy day 7, significantly decreased interhemispheric rsfMRI connectivity was observed in both groups in the specific cortical areas whose callosal connections were severed. At day 28, the disrupted connectivity was restored in the partial callosotomy group but not in the complete callosotomy group, likely due to the compensation that occurred through the remaining interhemispheric axonal pathways. This restoration - along with the increased intrahemispheric functional connectivity observed in both groups at day 28 - highlights the remarkable adaptation and plasticity in brain rsfMRI connections. These rsfMRI findings were paralleled by the intracortical EEG recording and Mn(2+) tracing results. Taken together, our experimental results directly demonstrate that axonal connections are the indispensable foundation for rsfMRI connectivity and that such functional connectivity can be plastic and dynamically reorganized atop the morphological connections.
Collapse
Affiliation(s)
- Iris Y Zhou
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Lau C, Zhang JW, Cheng JS, Zhou IY, Cheung MM, Wu EX. Noninvasive fMRI investigation of interaural level difference processing in the rat auditory subcortex. PLoS One 2013; 8:e70706. [PMID: 23940631 PMCID: PMC3733930 DOI: 10.1371/journal.pone.0070706] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 06/21/2013] [Indexed: 12/02/2022] Open
Abstract
Objective Interaural level difference (ILD) is the difference in sound pressure level (SPL) between the two ears and is one of the key physical cues used by the auditory system in sound localization. Our current understanding of ILD encoding has come primarily from invasive studies of individual structures, which have implicated subcortical structures such as the cochlear nucleus (CN), superior olivary complex (SOC), lateral lemniscus (LL), and inferior colliculus (IC). Noninvasive brain imaging enables studying ILD processing in multiple structures simultaneously. Methods In this study, blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is used for the first time to measure changes in the hemodynamic responses in the adult Sprague-Dawley rat subcortex during binaural stimulation with different ILDs. Results and Significance Consistent responses are observed in the CN, SOC, LL, and IC in both hemispheres. Voxel-by-voxel analysis of the change of the response amplitude with ILD indicates statistically significant ILD dependence in dorsal LL, IC, and a region containing parts of the SOC and LL. For all three regions, the larger amplitude response is located in the hemisphere contralateral from the higher SPL stimulus. These findings are supported by region of interest analysis. fMRI shows that ILD dependence occurs in both hemispheres and multiple subcortical levels of the auditory system. This study is the first step towards future studies examining subcortical binaural processing and sound localization in animal models of hearing.
Collapse
Affiliation(s)
- Condon Lau
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China
| | | | | | | | | | | |
Collapse
|
22
|
Saenz M, Langers DRM. Tonotopic mapping of human auditory cortex. Hear Res 2013; 307:42-52. [PMID: 23916753 DOI: 10.1016/j.heares.2013.07.016] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/19/2013] [Accepted: 07/25/2013] [Indexed: 11/26/2022]
Abstract
Since the early days of functional magnetic resonance imaging (fMRI), retinotopic mapping emerged as a powerful and widely-accepted tool, allowing the identification of individual visual cortical fields and furthering the study of visual processing. In contrast, tonotopic mapping in auditory cortex proved more challenging primarily because of the smaller size of auditory cortical fields. The spatial resolution capabilities of fMRI have since advanced, and recent reports from our labs and several others demonstrate the reliability of tonotopic mapping in human auditory cortex. Here we review the wide range of stimulus procedures and analysis methods that have been used to successfully map tonotopy in human auditory cortex. We point out that recent studies provide a remarkably consistent view of human tonotopic organisation, although the interpretation of the maps continues to vary. In particular, there remains controversy over the exact orientation of the primary gradients with respect to Heschl's gyrus, which leads to different predictions about the location of human A1, R, and surrounding fields. We discuss the development of this debate and argue that literature is converging towards an interpretation that core fields A1 and R fold across the rostral and caudal banks of Heschl's gyrus, with tonotopic gradients laid out in a distinctive V-shaped manner. This suggests an organisation that is largely homologous with non-human primates. This article is part of a Special Issue entitled Human Auditory Neuroimaging.
Collapse
Affiliation(s)
- Melissa Saenz
- Laboratoire de Recherche en Neuroimagerie (LREN), CHUV, Department of Clinical Neurosciences, Lausanne University Hospital, Mont Paisible 16, Lausanne 1011, Switzerland; Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
| | | |
Collapse
|
23
|
De Martino F, Moerel M, van de Moortele PF, Ugurbil K, Goebel R, Yacoub E, Formisano E. Spatial organization of frequency preference and selectivity in the human inferior colliculus. Nat Commun 2013; 4:1386. [PMID: 23340426 PMCID: PMC3556928 DOI: 10.1038/ncomms2379] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 12/12/2012] [Indexed: 01/10/2023] Open
Abstract
To date, the functional organization of human auditory sub-cortical structures can only be inferred from animal models. Here we use high-resolution functional MRI at ultra-high magnetic fields (7 Tesla) to map the organization of spectral responses in the human inferior colliculus (hIC), a sub-cortical structure fundamental for sound processing. We reveal a tonotopic map with a spatial gradient of preferred frequencies approximately oriented from dorso-lateral (low frequencies) to ventro-medial (high frequencies) locations. Furthermore, we observe a spatial organization of spectral selectivity (tuning) of fMRI responses in the hIC. Along isofrequency contours, fMRI-tuning is narrowest in central locations and broadest in the surrounding regions. Finally, by comparing sub-cortical and cortical auditory areas we show that fMRI-tuning is narrower in hIC than on the cortical surface. Our findings pave the way to non-invasive investigations of sound processing in human sub-cortical nuclei and to studying the interplay between sub-cortical and cortical neuronal populations.
Collapse
Affiliation(s)
- Federico De Martino
- Faculty of Psychology and Neuroscience, Department of Cognitive Neurosciences, Maastricht University, Universiteitssingel 40, Maastricht 6229ER, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
24
|
Suzuki H, Sumiyoshi A, Kawashima R, Shimokawa H. Different brain activation under left and right ventricular stimulation: an fMRI study in anesthetized rats. PLoS One 2013; 8:e56990. [PMID: 23451129 PMCID: PMC3579932 DOI: 10.1371/journal.pone.0056990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 01/16/2013] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Myocardial ischemia in the anterior wall of the left ventricule (LV) and in the inferior wall and/or right ventricle (RV) shows different manifestations that can be explained by the different innervations of cardiac afferent nerves. However, it remains unclear whether information from different areas of the heart, such as the LV and RV, are differently processed in the brain. In this study, we investigated the brain regions that process information from the LV or RV using cardiac electrical stimulation and functional magnetic resonance imaging (fMRI) in anesthetized rats because the combination of these two approaches cannot be used in humans. METHODOLOGY/PRINCIPAL FINDINGS An electrical stimulation catheter was inserted into the LV or RV (n = 12 each). Brain fMRI scans were recorded during LV or RV stimulation (9 Hz and 0.3 ms width) over 10 blocks consisting of alternating periods of 2 mA for 30 sec followed by 0.2 mA for 60 sec. The validity of fMRI signals was confirmed by first and second-level analyses and temporal profiles. Increases in fMRI signals were observed in the anterior cingulate cortex and the right somatosensory cortex under LV stimulation. In contrast, RV stimulation activated the right somatosensory cortex, which was identified more anteriorly compared with LV stimulation but did not activate the anterior cingulate cortex. CONCLUSION/SIGNIFICANCE This study provides the first evidence for differences in brain activation under LV and RV stimulation. These different brain processes may be associated with different clinical manifestations between anterior wall and inferoposterior wall and/or RV myocardial ischemia.
Collapse
Affiliation(s)
- Hideaki Suzuki
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | | | | | | |
Collapse
|
25
|
Perspective of functional magnetic resonance imaging in middle ear research. Hear Res 2013; 301:183-92. [PMID: 23291496 DOI: 10.1016/j.heares.2012.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 11/26/2012] [Accepted: 12/19/2012] [Indexed: 11/20/2022]
Abstract
Functional magnetic resonance imaging (MRI) studies have frequently been applied to study sensory system such as vision, language, and cognition, but have proceeded at a considerably slower speed in investigating middle ear and central auditory processing. This is due to several factors, including the intrinsic anatomy of the middle ear system and inherent acoustic noise during acquisition of MRI data. However, accumulating evidences have demonstrated that clarification of some fundamental neural underpinnings of audition associated with middle ear mechanics can be achieved using functional MRI methods. This mini review attempted to take a narrow snapshot of the currently available functional MRI procedures and gave examples of what may be learned about hearing from their application. It is hoped that with these technical advancements, many new high impact applications in audition would follow. In particular, because the fMRI can be used in humans and in animals, fMRI may represent a unique tool that should promote translational research by enabling parallel analyses of physiological and pathological processes in the human and animal auditory system. This article is part of a special issue entitled "MEMRO 2012".
Collapse
|
26
|
Functional magnetic resonance imaging of sound pressure level encoding in the rat central auditory system. Neuroimage 2012; 65:119-26. [PMID: 23041525 DOI: 10.1016/j.neuroimage.2012.09.069] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/27/2012] [Accepted: 09/28/2012] [Indexed: 01/23/2023] Open
Abstract
Intensity is an important physical property of a sound wave and is customarily reported as sound pressure level (SPL). Invasive techniques such as electrical recordings, which typically examine one brain region at a time, have been used to study neuronal encoding of SPL throughout the central auditory system. Non-invasive functional magnetic resonance imaging (fMRI) with large field of view can simultaneously examine multiple auditory structures. We applied fMRI to measure the hemodynamic responses in the rat brain during sound stimulation at seven SPLs over a 72 dB range. This study used a sparse temporal sampling paradigm to reduce the adverse effects of scanner noise. Hemodynamic responses were measured from the central nucleus of the inferior colliculus (CIC), external cortex of the inferior colliculus (ECIC), lateral lemniscus (LL), medial geniculate body (MGB), and auditory cortex (AC). BOLD signal changes generally increase significantly (p<0.001) with SPL and the dependence is monotonic in CIC, ECIC, and LL. The ECIC has higher BOLD signal change than CIC and LL at high SPLs. The difference between BOLD signal changes at high and low SPLs is less in the MGB and AC. This suggests that the SPL dependences of the LL and IC are different from those in the MGB and AC and the SPL dependence of the CIC is different from that of the ECIC. These observations are likely related to earlier observations that neurons with firing rates that increase monotonically with SPL are dominant in the CIC, ECIC, and LL while non-monotonic neurons are dominant in the MGB and AC. Further, the IC's SPL dependence measured in this study is very similar to that measured in our earlier study using the continuous imaging method. Therefore, sparse temporal sampling may not be a prerequisite in auditory fMRI studies of the IC.
Collapse
|