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. 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. The present 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.

Roots of a social brain: Developmental models of emerging animacy-detection mechanisms

“…The third retinal projection consists of the accessory optic system (AOS) and pretectum, which are highly conserved in vertebrates (Butler and Hodos, 2005;Fite, 1985;Giolli et al, 2005;McKenna and Wallman, 1985;Simpson, 1984). The origin of this system in the retina gives rise to the so-called displaced retinal ganglion cells, which project to two mesencephalic nuclei, the nucleus of the basal optic root and the nucleus lentiformis mesencephali, which in turn send information to cerebellar regions (Brecha et al, 1980;Gamlin and Cohen, 1988;Lau et al, 1998;Pakan and Wylie, 2006;Wylie, 2001).…”

“…The origin of this system in the retina gives rise to the so-called displaced retinal ganglion cells, which project to two mesencephalic nuclei, the nucleus of the basal optic root and the nucleus lentiformis mesencephali, which in turn send information to cerebellar regions (Brecha et al, 1980;Gamlin and Cohen, 1988;Lau et al, 1998;Pakan and Wylie, 2006;Wylie, 2001). The AOS and pretectum are mainly concerned with displacements of the visual field by self-movement and are important for the analysis of optic flow and the generation of the optokinetic response to control posture and stabilizing eye movements (Giolli et al, 2005;Simpson, 1984;Simpson et al, 1988). However, some pretectal nuclei might also be involved in innate predispositions, which need fast motoric responses.…”

Retinorecipient areas in the diurnal murine rodent Arvicanthis niloticus: A disproportionally large superior colliculus

“…No ipsilateral input was found in the DTN and the INSFp. It is noteworthy that the distribution of the uncrossed AOT projection is inconsistent among rodents (Frost et al, 1979;Lazar, 1983;Wree and Zilles, 1983;Pak et al, 1987;Major et al, 2003;Giolli et al, 2006).…”

Symmetries of the Central Vestibular System: Forming Movements for Gravity and a Three-Dimensional World

“…By actively and circumstantially combining the different sensory and motor information, the CVS facilitates the ability to grasp a motion experience with whatever sensory information is relevant and available. The CVS occupies a confluence of the spinal cord, direct neural connections from the inertial sensory receptors of the inner ear, and the accessory optic system, which carries optic flow [1,2,9,10], and it provides spatially-organized information to the hippocampus, thalamus, and cerebral cortex [11][12][13][14]. Spatially-related symmetry groups have been observed which organize the anatomy and physiology of the CVS [15][16][17].…”

“…Visual information in the accessory optic system is organized into these three planes [9,10]. When the eye rotates in one plane, the visual field flows in the opposite direction without deformation.…”