title: The accessory optic system: basic organization with an update on connectivity, neurochemistry, and function.
abstract: The accessory optic system (AOS) is formed by a series of terminal nuclei receiving direct visual information from the retina via one or more accessory optic tracts. In addition to the retinal input, derived from ganglion cells that characteristically have large receptive fields, are direction-selective, and have a preference for slow moving stimuli, there are now well-characterized afferent connections with a key pretectal nucleus (nucleus of the optic tract) and the ventral lateral geniculate nucleus. The efferent connections of the AOS are robust, targeting brainstem and other structures in support of visual-oculomotor events such as optokinetic nystagmus and visual-vestibular interaction. This chapter reviews the newer experimental findings while including older data concerning the structural and functional organization of the AOS. We then consider the ontogeny and phylogeny of the AOS and include a discussion of similarities and differences in the anatomical organization of the AOS in nonmammalian and mammalian species. This is followed by sections dealing with retinal and cerebral cortical afferents to the AOS nuclei, interneuronal connections of AOS neurons, and the efferents of the AOS nuclei. We conclude with a section on Functional Considerations dealing with the issues of the response properties of AOS neurons, lesion and metabolic studies, and the AOS and spatial cognition.
authors.affiliation: Department of Anatomy and Neurobiology, University of California, College of Medicine, Irvine, CA 92697, USA. ragiolli@uci.edu
authors.forename: Roland A
authors.initials: RA
authors.lastname: Giolli
authors.forename: Robert H I
authors.initials: RH
authors.lastname: Blanks
authors.forename: Fausta
authors.initials: F
authors.lastname: Lui
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology; D010856:Columbidae; D005829:Geniculate Bodies / Q000033:anatomy & histology / Q000502:physiology; D006801:Humans; D008322:Mammals; D008636:Mesencephalon / Q000033:anatomy & histology / Q000502:physiology; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D009474:Neurons / Q000737:chemistry / Q000648:ultrastructure; D018377:Neurotransmitter Agents / Q000032:analysis / Q000502:physiology; D017120:Nystagmus, Optokinetic / Q000502:physiology; D009847:Olivary Nucleus / Q000033:anatomy & histology / Q000502:physiology; D018847:Opioid Peptides / Q000032:analysis / Q000502:physiology; D010802:Phylogeny; D012154:Reticular Formation / Q000033:anatomy & histology / Q000502:physiology; D012160:Retina / Q000033:anatomy & histology / Q000502:physiology; D013037:Spatial Behavior / Q000502:physiology; D013045:Species Specificity; D014714:Vertebrates / Q000033:anatomy & histology* / Q000502:physiology; D014795:Visual Pathways / Q000033:anatomy & histology* / Q000737:chemistry / Q000502:physiology
chemical_list: D018377:Neurotransmitter Agents; D018847:Opioid Peptides