Projections to the inferior colliculus from layer VI cells of auditory cortex.
A large injection of a retrograde tracer into the inferior colliculus of guinea pigs labeled two bands of cells in the ipsilateral auditory cortex: a dense band of cells in layer V and a second band of cells in layer VI. On the contralateral side, labeled cells were restricted to layer V. The ipsilateral layer VI cells were distributed throughout temporal cortex, suggesting projections from multiple auditory areas. The layer VI cells included pyramidal cells as well as several varieties of non-pyramidal cells. Small tracer injections restricted to the dorsal cortex or external cortex of the inferior colliculus consistently labeled cells in layer VI. Injections restricted to the central nucleus of the inferior colliculus labeled layer VI cells only rarely. Overall, 10% of the cells in temporal cortex that project to the ipsilateral inferior colliculus were located in layer VI, suggesting that layer VI cells make a significant contribution to the corticocollicular pathway.
Schofield
B R
BR
Department of Anatomy and Neurobiology, Northeastern Ohio Universities College of Medicine, 4209 State Route 44, PO Box 95, Rootstown, OH 44272, USA. bschofie@neoucom.edu
D000578:Amidines / Q000378:metabolism; D000818:Animals; D001303:Auditory Cortex / Q000166:cytology* / Q000502:physiology*; D002772:Cholera Toxin / Q000378:metabolism; D004525:Efferent Pathways / Q000502:physiology; D005456:Fluorescent Dyes / Q000378:metabolism; D007839:Functional Laterality; D006168:Guinea Pigs; D007245:Inferior Colliculi / Q000502:physiology*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009474:Neurons / Q000145:classification / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism
D000578:Amidines; D005456:Fluorescent Dyes; C031455:diamidino compound 253-50; D002772:Cholera Toxin; D052248:Nitric Oxide Synthase Type I; D009252:NADPH Dehydrogenase