Some properties of conditioned and unconditioned eyelid reflexes in the albino rat

Abstract

GENERAL METHODSSubjects Male albino rats, descendants of the Sprague-Dawley strain and weighing 250-350 g, were Ss. Individual Ss, 40 in all, were sometimes used in more than one experiment. Miller, 1967), the rat has not been used in studies of eyelid responses. The size of this species and its reluctance to accept restraint have made the measurement of eyelid responses difficult. But it seemed that if this difficulty could be overcome, all of those attributes that make the rat such a good laboratory S would make it most valuable to a long-term research program requiring many animals and experiments of many kinds. The difficulties have not been overcome completely, but the results below are encouraging in this respect and bear on several problems in the study of eyelid responses. Eyelid responses in the rat were recorded as electromyographic activity (EMG) or as movements detected by a photoelectric technique. Spontaneous blinks, startle responses to acoustic stimuli, unconditioned responses to air puffs, and conditioned responses based on the corneal reflex were recorded under a variety of conditions. Special attention was given to topographical and temporal characteristics of the responses. Some relationships between the EMG and eyelid movements are described, as well as changes in eyelid responses related to habituation, conditioning, and various stimulus manipulations. In addition to the substantive findings, the study suggests that the rat may yet become a useful S in the study of eyelid conditioning.One attractive feature of eyelid reflexes that has gone almost unnoticed is a relative simplicity that might well recommend them for analysis at the neuronal level. Eyelid responses are accomplished primarily by two small muscles, orbicularis oculi and levator palpebrae superioris, and they are to a considerable degree independent of other behavior. Although clearly influenced by eye and head movements, they seem less entangled in most postural and movement activities than responses of the skeletal musculature mediated by the spinal cord. Woody and his associates (Engle & Woody, 1972;Woody, 1970; Woody & Brozek, 1969a, b, c; Woody, Vassilevsky, & Engel, 1970; Woody & Yarowsky, 1972), with their studies of the glabella reflex in cats, have been the first to recognize these advantages of eyelid reflexes and the possibilities they afford in electrophysiological inquiries into the neural substrate of conditioning. The experiments on the rat described in this paper were undertaken as part of a program initiated with the same intent, to use eyelid reflexes to study neural events underlying conditioned responses.Except for a few early conditioning studies (Biel & Wickens, 1941; Hughes & Schlosberg, 1938) Measurement of EyelidResponsesThe eyelid electromyogram (EMG) was recorded from two stainless steel Teflon-insulated stranded wires, 125 /Jm in diam, implanted subcutaneously in the upper lid. The EMG was filtered to eliminate potential changes below 10 Hz. It was also integrated, following full-wave rectificat...

Bilateral cerebellar lesions disrupt conditioned eyelid responses in unrestrained rats.

“…Robust eyelid conditioning was observed in 16 of the 20 rats: Only one rat did not learn, the other three were excluded due to faulty electrodes. As shown in Figure 1A, the topography of the eyelid responses was consistent with that previously reported for rats (Hall, 1973) and rabbits (Schneiderman, Fuentes, & Gormezano, 1962), except for the presence of an additional response component prior to the CR. This early response appeared to be the eyelid component of a whole-body startle response (Landis & Hunt, 1939): It had a short latency (15–25 ms) and rapid rise time (peak at 40–80 ms).…”

“…rats (Hall, 1973) and restrained rabbits (Schneiderman et al, 1962): Mean trials to criterion was 139.7 ± 24 (SE M ). Figure IB illustrates the gradual acquisition of CRs over the last 3 days before the lesions: The statistical significance of the increase in CR amplitudes was revealed by a multivariate repeated measures analysis of variance (ANOVA), which showed a significant change over days, F(2, 12) = 18.8, p < .001, and a significant linear trend, F( 1, 13) = 39.8, p < .001.…”

“…However, the rat would appear to be also well suited to this approach for two reasons: (a) it is economical to acquire, maintain, and test, and (b) it has an extensively studied neuroanatomy, neurophysiology, and behavioral repertoire. Surprisingly, the rat has rarely been used to study eyelid conditioning (Biel & Wickens, 1941; Ebel, 1966; Hall, 1973; Hughes & Schlosberg, 1938), presumably because of its resistance to restraint. However, recent advances in laboratory instrumentation and microcomputers now make it practical to test eyelid conditioning in rats without restraining.…”

Effect of the interstimulus (CS–UCS) interval on hippocampal unit activity during classical conditioning of the nictitating membrane response of the rabbit (Oryctolagus cuniculus).

“…Perhaps the most intensively studied behavioral aspect of the ISI effect on conditioning is the fact that the peak of the CR tends to occur near the point of US onset, i.e., the control of the response by the CS-UCS interval. This phenomenon has been extensively documented in classical conditioning of the rabbit NM response (S. Coleman & Gormezano, 1971;Gormezano, 1972;Hoehler & Leonard, 1976;Leonard & Theios, 1967;Millenson et al, 1977;Smith, 1968) and the human eyelid response (Ebel & Prokasy, 1963;Martin & Levey, 1969) and has also been reported to occur in classical conditioning of the rat's eyelid response (R. Hall, 1973), human autonomic responding (Kimmel, 1965), and conditioning of cortical evoked potentials in the cat (Adam, Kukorelli, & Markel, 1971). One might claim that the first report of this phenomenon was Pavlov's "inhibition of delay" (1927, p. 89).…”

Presidential Address 2014: The more‐or‐less interrupting effects of the startle response

“…Sternocleidomastoid muscles in the neck and flexors and extensors in the limbs are also activated, although they require more intense stimuli to elicit, and rapidly habituate to being undetectable (Brown et al, ). Generalizability across species is supported by the fact that whole‐body startle is clearly evident in humans (Landis & Hunt, ), and the eyeblink response is also evident in nonhuman animals (Arnfred, Lind, Hansen, & Hemmingsen, ; Hall, ; Landis & Hunt, )…”