The accessory optic system of rabbit. I. Basic visual response properties

Abstract

1. The response properties of accessory optic system (AOS) neurons were assessed using single-unit extracellular recording from each of the three AOS terminal nuclei [medial, lateral, and dorsal terminal nuclei (MTN, LTN, and DTN)] in the anesthetized rabbit. 2. AOS neurons had large, monocular (contralateral) receptive fields (tens of degrees on a side) and exhibited a pronounced selectivity to the speed and direction of movement of large, textured patterns. The greatest responses occurred at slow speeds on the order of 0.5 degrees/s. 3. MTN and LTN neurons responded best to movement in near vertical directions. However, the stimulus directions corresponding to the greatest excitation and the greatest inhibition both had a posterior component and, thus, the preferred excitatory and inhibitory directions were not opposite each other. DTN neurons responded most strongly to horizontal movement and were excited by temporal to nasal movement. 4. AOS neurons were unresponsive to natural vestibular stimulation presented as sinusoidal oscillations of the rabbit about the yaw, pitch, and roll axes. 5. The response properties of AOS neurons are remarkably similar to those of the ON, direction-selective ganglion cells of the rabbit retina, and therefore this class of ganglion cell is most likely the predominant, if not the only, direct retinal input to the AOS. The local direction-selective properties of AOS neurons can be accounted for by combining the tuning curves of ON, direction-selective ganglion cells in a simple manner. 6. The low speed preference of AOS neurons, along with their large receptive fields suggests that they are suited to complement the vestibular system in detecting self-motion.

The accessory optic system: basic organization with an update on connectivity, neurochemistry, and function

“…However, their distribution is complex and appears to be determined by at least two different overlapping mosaics (Cook and Podugolnikova, 2001). The double-mosaic theory appears to be in agreement with the proposed subdivision of the MTN in two separate functional classes (and morphologically indistinguishable) according to their preferred direction Soodak and Simpson, 1988; see also below in this chapter).…”

“…Later it was Walley (1967) who discovered that most neurons in the MTN respond to moving visual stimuli, mainly upward vertical. The seminal works of Simpson and co-workers (also performed on rabbit) elucidated the response features of the AOS nuclei (Simpson et al, 1979;Soodak and Simpson, 1988;Simpson et al, 1988). They were characterized as having very large receptive fields and responding to large moving textured patterns (ideal optokinetic stimuli), with optimal speed ranging between 0.1 and 1.0 °/s.…”

“…These results suggest that the AOS nuclei are the first post-retinal relay station in the pathway mediating the horizontal and vertical optokinetic reflex (OKR), a class of compensatory eye movements that serve the functional purpose of stabilizing images on the retina during self-motion and/or motion of the visual surround. The low optimal speed of AOS neurons, and their preferred directions, which basically overlap with the orientations in space of the vestibular semicircular canals, suggest that this neurons complement the vestibular system in detecting self-motion, and provide the substrate for the coordination of OKR with the vestibulo-ocular response (Soodak and Simpson, 1988;Simpson et al, 1979).…”

Activity-Dependent Expression of Acyl-Coenzyme A-Binding Protein in Retinal Muller Glial Cells Evoked by Optokinetic Stimulation

“…The coupling maintained a head pitch angle of 12°with respect to earth horizontal. This angle corresponds to that maintained by unrestrained rabbits and aligns the visual streak and the horizontal semicircular canals in the horizontal plane (Hughes, 1971;Barmack and Nelson, 1987;Soodak and Simpson, 1988). The head coupling permitted small movements in the sagittal plane but prevented head movements in the horizontal plane.…”

“…The visual streak lies just below and parallel to retinal vessels and myelinated nerve fibers that extend horizontally from the optic nerve head (Hughes, 1971;Choudhury, 1981). DSGCs are sensitive to stimulus velocities of 0.1-10°/sec and respond to light-dark edges (Collewijn, 1975;Oyster et al, 1980;Simpson et al, 1988;Soodak and Simpson, 1988).…”