title: Differential Modification of Cortical and Thalamic Projections to Cat Primary Auditory Cortex Following Early- and Late-Onset Deafness.
abstract: Following sensory deprivation, primary somatosensory and visual cortices undergo crossmodal plasticity, which subserves the remaining modalities. However, controversy remains regarding the neuroplastic potential of primary auditory cortex (A1). To examine this, we identified cortical and thalamic projections to A1 in hearing cats and those with early- and late-onset deafness. Following early deafness, inputs from second auditory cortex (A2) are amplified, whereas the number originating in the dorsal zone (DZ) decreases. In addition, inputs from the dorsal medial geniculate nucleus (dMGN) increase, whereas those from the ventral division (vMGN) are reduced. In late-deaf cats, projections from the anterior auditory field (AAF) are amplified, whereas those from the DZ decrease. Additionally, in a subset of early- and late-deaf cats, area 17 and the lateral posterior nucleus (LP) of the visual thalamus project concurrently to A1. These results demonstrate that patterns of projections to A1 are modified following deafness, with statistically significant changes occurring within the auditory thalamus and some cortical areas. Moreover, we provide anatomical evidence for small-scale crossmodal changes in projections to A1 that differ between early- and late-onset deaf animals, suggesting that potential crossmodal activation of primary auditory cortex differs depending on the age of deafness onset.
authors.affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada, N6A 5C2.|Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada, N6A 5C1.|Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada, N6A 5B7.
authors.forename: Nicole
authors.initials: N
authors.lastname: Chabot
authors.affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada, N6A 5C2.|Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada, N6A 5C1.|Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada, N6A 5B7.
authors.forename: Blake E
authors.initials: BE
authors.lastname: Butler
authors.affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada, N6A 5C2.|Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada, N6A 5C1.|Department of Psychology, University of Western Ontario, London, Ontario, Canada, N6A 5C2.|Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada, N6A 5B7.|National Centre for Audiology, University of Western Ontario, London, Ontario, Canada, N6A 1H1.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Lomber
mesh_terms: D017668:Age of Onset; D000818:Animals; D001303:Auditory Cortex / Q000254:growth & development / Q000473:pathology* / Q000503:physiopathology; D001306:Auditory Pathways / Q000254:growth & development / Q000473:pathology* / Q000503:physiopathology; D002415:Cats; D003638:Deafness / Q000473:pathology* / Q000503:physiopathology; D023421:Models, Animal; D056347:Neuroanatomical Tract-Tracing Techniques; D009473:Neuronal Plasticity; D009474:Neurons / Q000473:pathology* / Q000502:physiology; D010784:Photomicrography; D013788:Thalamus / Q000254:growth & development / Q000473:pathology* / Q000503:physiopathology
keywords: BDA; anatomical connectivity; auditory deprivation; crossmodal plasticity; hearing loss