title: A quantitative comparison of the hemispheric, areal, and laminar origins of sensory and motor cortical projections to the superior colliculus of the cat.
abstract: The superior colliculus (SC) is a midbrain structure central to orienting behaviors. The organization of descending projections from sensory cortices to the SC has garnered much attention; however, rarely have projections from multiple modalities been quantified and contrasted, allowing for meaningful conclusions within a single species. Here, we examine corticotectal projections from visual, auditory, somatosensory, motor, and limbic cortices via retrograde pathway tracers injected throughout the superficial and deep layers of the cat SC. As anticipated, the majority of cortical inputs to the SC originate in the visual cortex. In fact, each field implicated in visual orienting behavior makes a substantial projection. Conversely, only one area of the auditory orienting system, the auditory field of the anterior ectosylvian sulcus (fAES), and no area involved in somatosensory orienting, shows significant corticotectal inputs. Although small relative to visual inputs, the projection from the fAES is of particular interest, as it represents the only bilateral cortical input to the SC. This detailed, quantitative study allows for comparison across modalities in an animal that serves as a useful model for both auditory and visual perception. Moreover, the differences in patterns of corticotectal projections between modalities inform the ways in which orienting systems are modulated by cortical feedback. J. Comp. Neurol. 524:2623-2642, 2016. © 2016 Wiley Periodicals, Inc.
authors: 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: Blake E
authors: BE
authors: Butler
authors: 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: Nicole
authors: N
authors: Chabot
authors: 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, N6G 1H1.
authors: Stephen G
authors: SG
authors: Lomber
mesh_terms: D000818:Animals; D001303:Auditory Cortex / Q000033:anatomy & histology* / Q000502:physiology; D001306:Auditory Pathways / Q000033:anatomy & histology / Q000502:physiology; D002415:Cats; D005260:Female; D065726:Limbic Lobe / Q000033:anatomy & histology* / Q000502:physiology; D009044:Motor Cortex / Q000033:anatomy & histology* / Q000502:physiology; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D013003:Somatosensory Cortex / Q000033:anatomy & histology* / Q000502:physiology; D013477:Superior Colliculi / Q000033:anatomy & histology* / Q000502:physiology; D014793:Visual Cortex / Q000033:anatomy & histology* / Q000502:physiology
keywords: RRID:SciRes_000161; RRID:nif-0000-1029; auditory cortex; corticotectal projections; somatosensory cortex; visual cortex