title: Amplified somatosensory and visual cortical projections to a core auditory area, the anterior auditory field, following early- and late-onset deafness.
abstract: Cross-modal reorganization following the loss of input from a sensory modality can recruit sensory-deprived cortical areas to process information from the remaining senses. Specifically, in early-deaf cats, the anterior auditory field (AAF) is unresponsive to auditory stimuli but can be activated by somatosensory and visual stimuli. Similarly, AAF neurons respond to tactile input in adult-deafened animals. To examine anatomical changes that may underlie this functional adaptation following early or late deafness, afferent projections to AAF were examined in hearing cats, and cats with early- or adult-onset deafness. Unilateral deposits of biotinylated dextran amine were made in AAF to retrogradely label cortical and thalamic afferents to AAF. In early-deaf cats, ipsilateral neuronal labeling in visual and somatosensory cortices increased by 329% and 101%, respectively. The largest increases arose from the anterior ectosylvian visual area and the anterolateral lateral suprasylvian visual area, as well as somatosensory areas S2 and S4. Consequently, labeling in auditory areas was reduced by 36%. The age of deafness onset appeared to influence afferent connectivity, with less marked differences observed in late-deaf cats. Profound changes to visual and somatosensory afferent connectivity following deafness may reflect corticocortical rewiring affording acoustically deprived AAF with cross-modal functionality.
authors.affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, N6A 5K8, Canada.|Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, N6A 5K8, Canada.
authors.forename: Carmen
authors.initials: C
authors.lastname: Wong
authors.affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, N6A 5K8, Canada.|Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, N6A 5K8, Canada.
authors.forename: Nicole
authors.initials: N
authors.lastname: Chabot
authors.affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, N6A 5K8, Canada.|Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, N6A 5K8, Canada.
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Kok
authors.affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, N6A 5K8, Canada.|Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, N6A 5K8, Canada.|Department of Psychology, University of Western Ontario, London, Ontario, N6A 5K8, Canada.|Brain and Mind Institute, University of Western Ontario, London, Ontario, N6A 5K8, Canada.|National Centre for Audiology, University of Western Ontario, London, Ontario, N6A 5K8, Canada.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Lomber
mesh_terms: D000161:Acoustic Stimulation; D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D002415:Cats; D003638:Deafness / Q000473:pathology* / Q000503:physiopathology; D003911:Dextrans / Q000378:metabolism; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D008297:Male; D016900:Neurofilament Proteins / Q000378:metabolism; D012677:Sensation; D013003:Somatosensory Cortex / Q000473:pathology*; D013997:Time Factors; D014793:Visual Cortex / Q000473:pathology*
chemical_list: D003911:Dextrans; D016900:Neurofilament Proteins; C076397:biotinylated dextran amine; C051774:neurofilament protein H; D001710:Biotin
keywords: anatomical connectivity; anterior auditory field; cat; deafness; plasticity