Joseph Kimm

Reaction-time procedure for measurement of hearing. I. Suprathreshold functions

Reaction time (RT), or response latency, to auditory stimuli has been suggested as a measure of loudness in nonverbal animals as well as in man. In this study RT functions were obtained for human and rhesus monkey subjects under normal conditions and under conditions of hearing impairment. In both humans and monkeys RT varied in a similar manner with changes in intensity and frequency of the stimulus, and in response to experimental manipulation of the receptor organ. The study demonstrated that latency functions are similar to functions derived by loudness−matching procedures in humans: in subjects with normal hearing, equal−latency contours corresponded closely with equal−loudness contours. In subjects with impaired hearing, matched−latency and matched−loudness contours also corresponded closely. Rate of decrease in RT with increasing intensity is discussed and related to rate of growth in loudness. The results suggest that RT is a valuable measure of suprathreshold hearing in human and nonhuman primate...

A rabbit preparation for neuro-behavioral auditory research

Auditory thresholds were determined in rabbits by a classically conditioned nicitating membrane response established with a tone-conditioned stimulus and a shock-unconditioned stimulus. The audiograms obtained were comparable in shape and sensitivity to threshold curves measured for a variety of small mammals by other conditioning techniques. This procedure provides a quick and efficient method for measuring hearing sensitivity in a restrained preparation that permits precise stimulus control as well as providing an ideal situation for a variety of physiological studies of hearing in an awake, behaving animal.

Dynamic analysis of the vestibulo-ocular reflex in the normal and flocculectomized chinchilla.

Abstract The dynamics of the vestibulo-ocular reflex in the chinchilla produce compensatory eye movements which are 180° out of phase with head movements only at frequencies of rotation above 0.2 Hz if no visual fixation point is present. Below 0.2 Hz, eye position leads normalized head position (head position −180°) by as much as 60°. With a visual fixation point present, eye movements are in phase with normalized head movements throughout the entire frequency range tested (0.03 to 1.0 Hz). After bilateral flocculectomy, eye position leads normalized head position by the same amount in the presence and absence of a visual fixation point. In addition, the low frequency phase lead of the vestibulo-ocular reflex is greater in the flocculectomized animal than in the normal animal. A model is developed which accounts for both observed postflocculectomy phenomena.

Fastigial neuronal responses to sinusoidal horizontal rotation.

Abstract The response of single units in the fastigial nucleus of alert monkeys to sinusoidal, horizontal rotation was studied by extracellular recording techniques. Two types of response were found. Type I units increased their firing rates during ipsilateral rotation and decreased their firing rates during contralateral rotation. Type II units increased their activity for contralateral rotation and decreased their activity for ipsilateral rotation. Type I units were located primarily in the caudal portion, while type II units were found predominantly in the rostral portion of the fastigial nucleus. Bode phase and gain plots were derived by comparing the first harmonic determined by the fast Fourier transform of the fastigial neuron responses to the sinusoidal horizontal acceleration input. Gain plots for type I and type II units were similar and were approximately equal to the gain of primary vestibular afferents. Type I and type II units were approximately 180 deg out of phase with each other and both types of response showed a statistically significant increase in phase with increasing frequency.

Foreperiod effects on human single motor unit reaction times

Abstract This study analyzed the effect of foreperiod factors on key release reaction times and single motor unit reaction times. Changes in foreperiod parameters influencing overt reaction times had a similar effect on single motor unit reaction times. Both types of responding decreased in median latency values and increased in variability with the appropriate selection of foreperiod parameters. It is suggested that RT design must be carefully considered in RT studies using single motor unit techniques.

Sensory Neurophysiology and Reaction Time Performance in Nonhuman Primates

It was clear from the conference that information is rapidly accumulating on sensory behavior in animals. Psychophysical relationships between stimulus and response parameters recently derived from animal subjects have been shown to be as reliable and precise as those obtained from man. Moreover, through analysis of these stimulus-response functions we are acquiring a better understanding of the influence of various stimulus parameters on behavior. One of the basic themes of the conference concerned the extension of our understanding of sensory functions to include the role of afferent neural structures in behavior. Contemporary behavioral procedures yielding psychophysical functions in animals provide a vehicle for such an extension. Simply stated, this approach suggests that we begin to study afferent neural activity in behaviorally trained animals from which precise measures of psychophysical relationships may be concurrently obtained.

Auditory sensitivity in the rabbit determined by a conditional nictitating of membrane response

Auditory sensitivity was measured in New Zealand white rabbits trained by means of a behavioral technique utilizing classical conditioning of the nictitating membrane (NM) response. Conditioning trials consisted of the presentation of a 350 msec pure tone stimulus of which the final 100 msec overlapped with the occurrence of a shock to the posterior orbital region. A conditioned NM response was defined as a 0.5 mm deflection with a latency ranging from 130 to 260 msec following tone onset. Threshold and latency‐intensity functions were collected from 500 Hz to 32 kHz using the method of constant stimuli under closed field conditions. Animals were most sensitive to test stimuli between 8 and 16 kHz with maximum sensitivities at sound pressure levels ranging from −1 to 11 dB SPL. For frequencies above 16 kHz and below 3 kHz, sensitivity rapidly decreased. The latency of the NM response was found to be an inverse function of stimulus intensity over a fairly large dynamic range similar to the latency‐intensit...

Chronic gnawing induced by electrolytic lesions dorsolateral and lateral to the lateral hypothalamus

Abstract Electrolytic lesions were placed dorsolateral and lateral to the lateral hypothalamic feeding center in rats. Rats typically showed an initial weight loss followed either by stabilization at reduced weight levels or a gradual return to normal. There was no evidence of hyperphagia. However, these animals showed exaggerated gnawing behavior as measured by the food crumbs accumulating under their cages, averaging 21.3 gm/day, as compared to 5.4 gm/day for normal controls.