title: No ON-OFF maps in supragranular layers of ferret visual cortex.
abstract: Primary visual cortex contains functional maps of a number of stimulus properties including ocular dominance, orientation, direction, color, and spatial frequency. These maps must be organized with respect to each other and to a single continuous retinotopic map of visual space such that each stimulus parameter is represented at each point in space. In the ferret, geniculo-cortical inputs to cortical layer IV are segregated into ON- and OFF-center patches, suggesting the possibility that there might be an additional cortical map in this species. We have used optical imaging of intrinsic signals to search for ON-OFF maps in ferret visual cortical cells and have found none. This suggests that the high degree of ON-OFF segregation seen subcortically in the ferret may play a role in the development of visual cortical receptive fields rather than in adult cortical function.
mesh_terms: D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D001931:Brain Mapping; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D005289:Ferrets / Q000033:anatomy & histology*; D005829:Geniculate Bodies / Q000166:cytology; D010775:Photic Stimulation; D013045:Species Specificity; D014793:Visual Cortex / Q000166:cytology*; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000166:cytology
chemical_list: D000613:Aminobutyrates; D018690:Excitatory Amino Acid Agonists; C012729:2-amino-4-phosphonobutyric acid
keywords: Non-programmatic