Laboratory for Visual Neuroscience

Research


I. Fundamental Organization of Visual and Auditory Cortex

This branch of research investigates the organization, function and connectivity of human sensory cortex using structural and functional magnetic resonance imaging (MRI, fMRI) and diffusion tensor imaging (DTI).  We have defined multiple visual field maps (VFMs) and examined a general organizing principle of VFMs organized into ‘clover leaf’ clusters across visual cortex. This organization of visuospatial representations is important in understanding higher-order cognition, which relies upon the visuospatial knowledge gained from low-level visual processing. We further use these VFM and cluster definitions in completed and ongoing investigations of the functional properties and connectivity of particular maps. These include measurements of new VFMs involved in color, face, and/or object processing in occipital cortex and in visual working memory in parietal cortex, and have led to an ongoing collaboration of computational retinotopic mapping with Professors Zhong-lin Lu and Yalin Wang.

In collaboration with Professors Greg Hickok and Kourosh Saberi, we have extended these measurements into examinations of human auditory cortex. Our measurements have revealed the first definitions of auditory cortical field maps (AFMs) arising from representations of tonotopic (frequency) and periodotopic (timing) inputs, with a similar organizational pattern of ‘clover leaf’ clusters across visual and auditory cortex. This set of experiments represents the first systematic attempt to map the cortical organization of speech perception from low-level acoustic features to syllables, resulting in our NSF grant ‘Acoustic Foundations of Speech Perception’. These studies are now expanding into investigations of 1) AFM organization throughout higher-order auditory and language-related cortical regions, 2) audiovisual integration across AFMs and VFMS, 3) periodotopic gradients throughout auditory cortex, and 4) the relationship of responses to speech and non-speech stimuli to these AFMs.

Funded grants

9/1/2013 - 8/30/2016

National Science Foundation (NSF).  ‘Acoustic Foundations of Speech Perception.’ #1329255.

Co-PIs: Gregory Hickok, Ph.D.;  Kourosh Saberi, Ph.D.

PI

$475,958

7/2012 - 6/2013

The Academic Senate Council on Research, Computing and Libraries (CORCL) Single Investigator Innovation Grant, University of California, Irvine. ‘Visuospatial Responsivity & Connectivity in the Human Cerebellum.’

PI
$8,550

12/2011

Research and Travel Funds Award, University of California, Irvine. Symposium: ‘Human visual cortex: from receptive fields to maps to clusters to perception.’

PI
$1,000

5/2011

Social Sciences Faculty Desktop Computing Initiative Award, University of California, Irvine.

PI
$1,495

12/2010 - 11/2011

Center for Hearing Research Pilot Award, University of California, Irvine. ‘Mapping tonotopic and periodotopic gradients in human auditory cortex: a traveling wave fMRI study.’
Co-PIs: Gregory Hickok, Ph.D.;  Kourosh Saberi, Ph.D.

Co-PI
$4,000

5/2010 - 4/2011

Social Sciences Assistant Professor Research Award, University of California, Irvine.  ‘Visual working memory in the human dorsal stream.’

PI
$1,500

Peer-Reviewed Publications

21)

A.A. Brewer, B. Barton. (2012) "Visual field map organization in human visual cortex," in Visual Cortex- Current Status and Perspectives, eds. Stephane Molotchnikoff and Jean Rouat. ISBN: 978-953-51-0760-6, InTech, 30-60. Available from: http://www.intechopen.com/books/visual-cortex-current-status-and-perspectives/visual-field-map-organization-in-human-visual-cortex . doi:10.5772/51914.

18)

A.A. Brewer. (2009) Visual Maps: To merge or not to merge. Current Biology. 19(20):R945-7. doi:10.1016/j.cub.2009.09.016.

16)

B.A. Wandell, S.O. Dumoulin*, A.A. Brewer*. {*First and Second authors contributed equally.} (2007) Visual Field Maps in Human Cortex. Neuron. 56(2), 366-83. doi:10.1016/j.neuron.2007.10.012.

15)

B. A. Wandell, S.O. Dumoulin, A.A. Brewer. (2006) Computational Neuroimaging; Color Signals in the Visual Pathways. Neuro-opthalmology Japan. vol. 23, 324-343.

13)

A.A. Brewer, J. Liu, A.R. Wade, B.A. Wandell. (2005) Visual field maps and stimulus selectivity in human ventral occipital cortex. Nature Neuroscience. 8(8), 1102-9. doi:10.1038/nn1507.

11)

R.F. Dougherty, M. Ben-Shacher, R. Bammer, A.A. Brewer, B.A. Wandell. (2005) Functional organization of human occipital-callosal fiber tracts. Proc Natl Acad Sci U S A. 102(20), 7350-5. doi:10.1073/pnas.0500003102.

10)

B.A. Wandell, A.A. Brewer, R.F. Dougherty. (2005) Visual field map clusters in human cortex. Philosophical Transactions of the Royal Society, Series B. (London). Vol: 360, 693-707. (Special theme issue ‘Cerebral cartography 1905–2005’.) doi:10.1098/rstb.2005.1628.

9)

B.A. Wandell, R.F. Dougherty, A. Brewer, M. Ben-Shachar, R. Bammer, G. Deutsch. (2004) Measuring activity and structure in the human brain. Society for Industrial and Applied Mathematics News. Vol: 37 (7).

8)

R. F. Dougherty, V. M. Koch, A.A. Brewer, B. Fischer, J. Modersitzki, B. A. Wandell. (2003) Visual field representations and locations of visual areas V1/2/3 in human visual cortex. Journal of Vision. 3(10), 586-598. doi:10.1167/3.10.1.

6)

A.A. Brewer, W. A. Press, N. K. Logothetis, B. A. Wandell. (2002) Visual areas in macaque cortex measured using functional magnetic resonance imaging. Journal of Neuroscience. 22(23), 10416-10426.

5)

A.R. Wade, A.A. Brewer, B.A. Wandell. (2002) Functional Measurements of Human Ventral Occipital Cortex: Retinotopy and Color. Philosophical Transactions of the Royal Society, Series B. (London). Vol: 357, No.1424, 963- 973. doi:10.1098/rstb.2002.1108.

3)

W.A. Press, A.A. Brewer, R.F. Dougherty, A.R. Wade, B.A. Wandell. (2001) Visual areas and spatial summation in human visual cortex. Vision Research. 41(10-11), 1321-32.

Presentations

33 Conference Presentations: 29 Published; 2 International
15 Invited Talks

Current & Previous Collaborations

Acoustic Foundations of Speech Perception
Gregory Hickok, Ph.D., Department of Cognitive Sciences, University of California, Irvine
Kourosh Saberi, Ph.D., Department of Cognitive Sciences, University of California, Irvine
Status: 1 journal article in revision for PNAS, 2 journal articles in preparation, 4 grants submitted with 1 funded and 1 under review, research in progress

FMRI Measurements of Auditory Attention in Human Cortex
Bruce Berg, Ph.D., Department of Cognitive Sciences, University of California, Irvine
Status: 1 journal article in progress, 1 grant submitted, research in progress

Computational Retinotopic Mapping in Human Visual Cortex
Zhong-lin Lu, Ph.D., Department of Psychology, Ohio State University
Yalin Wang, Ph.D., Departments of Computer Science and Engineering, Arizona State University
Status: research in progress, 1 journal article in progress, 1 grant submission in preparation

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II. Plasticity in Visual, Auditory, and Sensorimotor Cortex

The holy grail of many fields of brain research is to harness the cortex's ability to reorganize. An understanding of how to induce plasticity in cortex could foster the development of treatments of such devastating conditions as paralysis, neurodegenerative disease and stroke. Such conditions typically result in a loss of sensory input, causing many researchers to focus almost exclusively on that. However, it is also imperative to study the brain’s response to changes of sensory input, because changing sensory input is the only way that we will be able to harness the brain’s inherent plasticity to overcome the loss of sensory input. We have been using MRI, fMRI and DTI to investigate plasticity in visual cortex as a result of removing and changing visual input. We have completed work showing 1) large-scale developmental reorganization of human visual cortex, but 2) limited reorganization in adult primate in response to vision loss. Recent work  revealed that prolonged adaptation in healthy, adult humans to an extreme change of visual input (via left-right reversing prism goggles) can produce sustained functional plasticity in parietal cortex. We have also used the removal of visual input under scotopic vision, which produces a reversible scotoma in the central fovea, to 1) show that short-term population receptive field (pRF) dynamics at the edge of a scotoma resemble claims made in several studies of long-term plasticity and 2) to tie perception to cortical activity through perceptual filling-in.

The use of VFM and pRF measurements to track changes in cortex can also be applied to translational clinical studies. In ongoing investigations, we are using neuroimaging measurements of human visual cortex to examine whether there is a systematic change in visual cortex as part of the pathophysiology of neurodegenerative disorders such as Alzheimer’s disease, Dementia with Lewy Bodies, and Posterior Cortical Atrophy. Supported by a pilot grant from UCI’s MIND Institute, these studies explore how these in vivo visual measurements may be used to improve early detection and accurate diagnosis of dementia and complement measurements of the normal aging process in visual cortex. In collaboration with Dr. Steven Cramer at UCI, we are similarly using measurements of VFMs and pRFs in a study of the potential for rehabilitation of damaged human visual cortex in stroke patients. We recently received a pilot grant from UCI’s Institute of Clinical and Translational Sciences for our proposal to encourage the use of spared visual processing of the damaged portion of the visual field through an intensive training program, in which subjects are required to deploy perceptual, attentional, and working memory resources to the damaged portion of the visual field.

Funded grants

2012 -2013

Social Sciences Assistant Professor Research Award, University of California, Irvine.  ‘Visual rehabilitation after stroke through perceptual learning paradigms: harnessing cortical plasticity for therapeutic interventions.’

PI
$5,000

4/2012 - 3/2013

Translational Collaborative Discovery Grant Award, Institute for Clinical and Translational Science, University of California, Irvine. ‘Visual rehabilitation after stroke: harnessing cortical plasticity for therapeutic interventions.
Co-PI: Steven C. Cramer, M.D.

PI
$20,000

2012 - 2013

National Institutes of Health Loan Repayment Program Scholar
Visual rehabilitation after stroke’

Scholar
$7,158.13

2010 - 2012

National Institutes of Health Loan Repayment Program Scholar
‘The dorsal visual stream: Visual field maps and functional plasticity’

Scholar
$27,892.24

3/2010 - 12/2010

The Academic Senate Council on Research, Computing and Libraries (CORCL) Special Research Grant, University of California, Irvine. ‘Functional Plasticity in Human Visual Cortex.’

PI
$3,695

Peer-Reviewed Publications

24)

A.A. Brewer, B. Barton. (under contract)  Cortical Plasticty in the Human Visual System. Springer.

23)

A.A. Brewer, B. Barton. (in press) ”Developmental Plasticity: FMRI Investigations into Human Visual Cortex,” in Functional Magnetic Resonance Imaging / Book 1, eds. T.D. Papageorgiou, George Christopoulos, Stelios Smirnakis. ISBN: 978-953-307-669-0, InTech.

14)

S.M. Smirnakis, M. Schmid, A.A. Brewer, A.S. Tolias, A. Shuz, M. Augath, W. Inhoffen, B.A. Wandell, N.K. Logothetis. (2005) Neuroscience: Rewiring the adult brain (Reply). Nature. 438(7065), E3-E4. doi:10.1038/nature04360.

12)

S.M. Smirnakis,  {A.A. Brewer, M. Schmid}, A.S. Tolias, M. Augath, W. Inhoffen, A. Shuz, B.A. Wandell, N.K. Logothetis, [{}: Authors had equal contribution]. (2005) Lack of long-term cortical reorganization after macaque retinal lesions. Nature. 435(7040), 300-7. doi:10.1038/nature03495.
News and Views by M. I. Sereno (Nature. 435, 288-289).

7)

I. Fine, A.R. Wade, A.A. Brewer, M.G. May, D.F. Goodman, G.M. Boynton, B.A. Wandell, D.I. MacLeod. (2003) Long-term deprivation affects visual perception and cortex. Nature Neuroscience. 6(9), 915-916. doi:10.1038/nn1102.

4)

H.A. Baseler, A.A. Brewer, L.T. Sharpe, A.B. Morland, H. Jägle, B.A. Wandell. (2002) Reorganization of human cortical maps caused by inherited photoreceptor abnormalities. Nature Neuroscience. 5(4), 364-70. doi:10.1038/nn817.

Presentations

25 Conference Presentations: 15 Published; 3 International
6 Invited Talks, 1 International

Current & Previous Collaborations

Visual Rehabilitation after Stroke
Steven C. Cramer, M.D., Departments of Neurology and Anatomy & Neurobiology, University of California, Irvine
Status: 1 funded grant, research in progress

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III. Genetic and Neuromodulatory Effects on Behavior

Finally, we have been complementing my neuroimaging measurements with studies of behavioral genetics to investigate questions ranging from the role of neurotrophic factors in visuomotor adaptation to the effects of neuromodulation on decision-making and social interactions. The first section utilizes polymorphisms in brain-derived neurotrophic factor (BDNF), the most abundant neurotrophin in the brain. BDNF is widely expressed in cortex and influences a broad range of brain events related to developmental neuronal differentiation, synaptic plasticity, and neuronal survival in adulthood.  We have examined the effects of BDNF genetic polymorphisms on visuomotor adaptation and find a paradoxical role of BDNF in the interplay of cortical plasticity and stability that underlies behavioral learning, with more broad implications for the effects of genetic differences on adult cortical recovery and repair. This study forms the foundation for future investigations of individual variation in behavioral adaptation and cortical plasticity.

In the second section, we previously collaborated with Professor Jeffrey Krichmar with funding from the Office of Naval Research to combine economic game theory with measurements of the neuromodulators serotonin and dopamine, which have been shown to modulate social behaviors. We examined the roles of these neuromodulators in human–robot interactions. A major goal of these experiments was to develop a dynamic, yet controlled experimental environment in which socioeconomic decision-making can be probed. Such an environment will be a powerful tool for not only studying decision-making, but also understanding social disorders.

Funded grants

4/2009 - 3/2010

Alzheimer’s Disease Research Center Pilot Grant, University of California, Irvine. ‘Neuroimaging of visual cortex in Alzheimer’s disease and related dementias.’ 

PI
$23,306

3/2009 - 2/2011

Office of Naval Research, Award #N000140910036. ‘The Effects of Neuromodulation on Human-Robot Interaction.’
PI: Jeffrey L. Krichmar, Ph.D.

Co-PI
$299,319

2008 - 2010

National Institutes of Health Loan Repayment Program Scholar
‘Neuroimaging of human visual cortex in Posterior Cortical Atrophy and Alzheimer’s disease’

Scholar
$36,394.48
Scholarship

Peer-Reviewed Publications

22)

A.A. Brewer, B. Barton. (2012) Effects of healthy aging on human primary visual cortex. Health. 4(9A), Special Issue I, 695-702 doi: 10.4236/health.2012.429109.

20)

D. Asher, A. Zaldivar, B. Barton, A.A. Brewer, J.L. Krichmar. (2012) Reciprocity and retaliation in social games with adaptive agents. IEEE Transactions on Autonomous Mental Development. 4(3), 226-238. doi:10.1109/TAMD.2012.2202658.

2)

A.A. Brewer, P. Fisher. (1999) Review of conventional and alternative treatments for glioblastoma multiforme. Donated to AGY Therapeutics and the National Brain Tumor Foundation.

Presentations

8 Conference Presentations: 5 Published

Current & Previous Collaborations

The Effects of Neuromodulation on Human-Robot Interaction
Jeffrey L. Krichmar, Ph.D., Department of Cognitive Sciences, University of California, Irvine
Status: 1 journal article published, 1 conference proceeding published, 2 journal articles in preparation/submitted, 2 conference presentations, 4 grants submitted with 1funded and 1 under revision, research in progress

The Role of BDNF Polymorphisms in Visuomotor Adaptation
Steven C. Cramer, M.D., Departments of Neurology and Anatomy & Neurobiology, University of California, Irvine
Status: Project Completed - Publications: 1 journal article, 1 conference presentation; Grants: 1 UROP/SURP fellowship, 1 AMA Medical Student Fellowship

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