Visual deprivation and blindness famously cause certain brain regions to reorganize in response to environmental constraints and in order to compensate for the loss of a sensory modality. Studies in visually deprived animals and blind humans have long demonstrated the cross-modal recruitment of the visual cortex to process nonvisual information. Yet, little is known about the functional specialization of the reorganized visual cortex (VC), its precise role in the processing of nonvisual information, or the source and routing of its nonvisual inputs. The main aims of the present project are, therefore, to (1) determine the functional organization of the occipital cortex in blind volunteers using a sensory substitution device, (2) to examine whether nonvisual information is processed hierarchically in the VC of the blind, and (3) identify the structural basis of adaptive changes and the source of nonvisual input to VC in the blind. Results from three years of funding by this grant have demonstrated that spatial and nonspatial processing streams do indeed exist for auditory and tactile processing (Renier et al., 2009). Furthermore, spatial auditory and tactile processing in the VC of the early blind occur in the same dorsal-stream regions as visual spatial processing in sighted subjects (Renier et al., 2010). These findings have led us to hypothesize that functionally specialized modules are preserved in the cortex of the early blind. We will pursue this hypothesis further by testing paradigms within the ventral stream. Thus, using functional magnetic resonance imaging, we will examine brain activity in blind subjects while they identify (via the auditory modality) houses, faces and 2-D geometrical shapes coded into sound patterns. These experiments will allow us to determine whether the parahippocampal place area (PPA), the fusiform face area (FFA), and the lateral occipital complex (LOC) retain their designated functional roles in early blindness, while switching their input modality. We will also examine the organization of VC by testing whether nonvisual information is processed in a hierarchical manner, in the same way that normal sensory information is processed in its intact sensory system. Using complexity-varied pitch information, we will determine if early-to-late visual regions of the blind respond to sound in the direction of simple-to-complex levels of pitch processing. Finally, using diffusion tensor imaging (DTI) and analysis of functional connectivity, we will investigate the structural basis of adaptive changes in the cerebral cortex and white matter of blind subjects. Using DTI, we will examine the strength of white-matter fiber tracts projecting to and from VC in both subject groups, thus determining relative changes in the connections between VC and other cortical areas. We will also test how visual and other sensory areas interact during auditory and tactile information processing in blind and sighted volunteers, and whether this interaction depends on the strength of anatomical pathways connecting these areas. Combining the two different methodological approaches will provide us an excellent opportunity to identify the source of nonvisual inputs to VC in the early blind.

Public Health Relevance

A better understanding of the physiological mechanisms underlying brain and cognitive plasticity in blindness will help to develop more adequate rehabilitation strategies and assistive devices for the blind, such as visual prostheses or sensory substitution devices. In a wider perspective, the results expected from this project will provide u with valuable information regarding the contribution of genetic and environmental factors to brain development and about mechanisms of brain plasticity in general, that is, how the brain modifies its own organization in response to environmental constraints. This could lead to the development of better neuropsychological and rehabilitation methods for patients with brain injuries.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
4R01EY018923-06
Application #
9100730
Study Section
Mechanisms of Sensory, Perceptual, and Cognitive Processes Study Section (SPC)
Program Officer
Wiggs, Cheri
Project Start
2009-08-01
Project End
2017-06-30
Budget Start
2016-07-01
Budget End
2017-06-30
Support Year
6
Fiscal Year
2016
Total Cost
$432,876
Indirect Cost
$154,499
Name
Georgetown University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
049515844
City
Washington
State
DC
Country
United States
Zip Code
20057
van der Heijden, Kiki; Rauschecker, Josef P; Formisano, Elia et al. (2018) Active Sound Localization Sharpens Spatial Tuning in Human Primary Auditory Cortex. J Neurosci 38:8574-8587
Rauschecker, Josef P (2018) Where, When, and How: Are they all sensorimotor? Towards a unified view of the dorsal pathway in vision and audition. Cortex 98:262-268
Derey, Kiki; Rauschecker, Josef P; Formisano, Elia et al. (2017) Localization of complex sounds is modulated by behavioral relevance and sound category. J Acoust Soc Am 142:1757
Boucard, Christine C; Rauschecker, Josef P; Neufang, Susanne et al. (2016) Visual imagery and functional connectivity in blindness: a single-case study. Brain Struct Funct 221:2367-74
Rauschecker, Josef P (2015) Auditory and visual cortex of primates: a comparison of two sensory systems. Eur J Neurosci 41:579-85
Anurova, Irina; Renier, Laurent A; De Volder, Anne G et al. (2015) Relationship Between Cortical Thickness and Functional Activation in the Early Blind. Cereb Cortex 25:2035-48
Erickson, Laura C; Heeg, Elizabeth; Rauschecker, Josef P et al. (2014) An ALE meta-analysis on the audiovisual integration of speech signals. Hum Brain Mapp 35:5587-605
Erickson, Laura C; Zielinski, Brandon A; Zielinski, Jennifer E V et al. (2014) Distinct cortical locations for integration of audiovisual speech and the McGurk effect. Front Psychol 5:534
Renier, Laurent; De Volder, Anne G; Rauschecker, Josef P (2014) Cortical plasticity and preserved function in early blindness. Neurosci Biobehav Rev 41:53-63
Rauschecker, Josef P (2011) An expanded role for the dorsal auditory pathway in sensorimotor control and integration. Hear Res 271:16-25

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