Mechanisms of efferent neuronal control of the reflex nictitating membrane response in rabbit (Oryctolagus cuniculus).

Abstract

Efferent mechanisms controlling the nictitating membrane (NM) reflex response to air puff in the albino rabbit were analyzed using stimulation, lesions, and recording techniques. In brief, stimulation of the sixth nerve (abducens) yields short-latency NM extension. Stimulation of the fourth and seventh nerves and the superior cervical ganglion has essentially no effect on the NM. Stimulation of the third nerve causes short-latency retraction of the NM. Lesions and recording data are consistent with this result--the sole efferent neuronal control of NM extension is the sixth cranial nerve and of NM retraction is the third cranial nerve. The NM extension response appears to be mediated by mechanical actions via retraction of the eyeball by the retractor bulbi muscle, and NM retraction appears to result from direct activation of muscle fibers in the NM by the third nerve. The superior cervical ganglion appears to play no role in reflex NM retraction in the rabbit, in contrast to its action in the cat.We have recently adopted classical con-(1962), as an extremely useful system for ditioning of the rabbit nictitating membrane analysis of brain substrates of associative (NM) response, first developed by Gor-learning (Thompson, Cegavske, & Pattermezano, Schneiderman, Deaux, and Fuentes son, 1973). The preparation has many ad-"TheTata were collected primarily in the second vantages for electrophysiological recording author's laboratory at Irvine, with replication of of neuronal activity that develops during several experiments in the third author's labora-the course of learning (see discussion in tory at Kirksville. Portions of the research formed Thompson, Patterson, & Teyler, 1972). portions of the first author's PhD dissertation at Acquisition occurs in a single training ses-Irvme. The research was supported primarily by . ^ ,, . , .

Neural Substrates of Eyeblink Conditioning: Acquisition and Retention

“…Initial studies of motor control of the reflex and conditioned responses focused on NM extension, actually eyeball retraction, controlled mostly (but not entirely) by the retractor bulbus muscle, innervated largely by axons of the sixth nerve originating in the accessory abducens (and to a much lesser extent, abducens) nuclei. However, the other extraocular muscles also contract synergistically with the retractor bulbus or relax in an antagonistic manner in the case of the levator palpebrae motor neurons (Cegavske et al 1976(Cegavske et al , 1979(Cegavske et al , 1987Berthier et al 1987;Disterhoft et al 1987). At the time there was much debate about the details of innervation of the retractor bulbus muscle, which in retrospect was somewhat irrelevant because the most prominent and sensitive component of the response is EMG activity in the orbicularis oculi muscle controlling external eyelid closure ), innervated by the seventh nerve from the facial nucleus.…”

Neural circuitry and plasticity mechanisms underlying delay eyeblink conditioning

“…The accessory abducens nucleus receives sensory relay input from the trigeminal nuclei and reticular brainstem . The activity of abducens motor neurons has an amplitude/time-course profile that closely mirrors the nictitating membrane response in rabbits for the UR and CR (Cegavske and Thompson 1976;Cegavske et al 1979).…”

The learning-related activity that develops in the pontine nuclei during classical eye-blink conditioning is dependent on the interpositus nucleus.

“…As a control, we also cooled the facial nucleus during recording from the pontine nuclei. The facial nucleus is critically involved in the expression of both the eye-blink CR and UR (Cegavske et al 1976), although it is not critical for the formation of the conditioned response (Krupa et al 1996;Clark et al 1997;A.A. Zhang and D.G.…”