Showing papers in "Journal of Neurophysiology in 1963"

Effects of visual deprivation on morphology and physiology of cells in the cat's lateral geniculate body

Abstract: THEIMPORTANCEOFNORMALSENSORYSTIMULATION inthedevelopment and maintenance of the nervous system is now generally recognized. In the visual system this problem has usually been approached by examining the effects of sensory deprivation on structure and behavior (see reviews by Hebb (12) and Riesen (28)). An obvious way of extending this work would be to examine electrophysiologically the functional effects of visual deprivation, but such experiments require some knowledge of normal function. During the last 10 years single-cell responses have been examined and receptive-field arrangements compared at several levels in the cat’s visual pathway: in the retina (Zl), the lateral geniculate body (18), and the visual cortex (17, 19). This information provides the necessary background for a study of the immature and the stimulus-deprived visual system. The results of a physiological and anatomical study of the visual pathways in normal. and visually deprived kittens will be presented in a series of three papers. In the present paper we describe single-unit recordings in the optic tract and lateral geniculate body of kittens in which one eye had been deprived of vision, and an anatomical examination of the visual pathways in these animals. The second paper (20) will describe single-unit recordings in the striate cortex of newborn kittens. The final paper (32) will deal with responses of cells in the visual cortex of visually deprived animals.

Receptive fields of cells in striate cortex of very young, visually inexperienced kittens.

Abstract: IN A SERIES OF STUDIES on the cat over the past 5 years we have recorded from single cells in the striate cortex and mapped receptive fields using patterned retinal stimulation. The results suggest that connections between geniculate and striate cortex, and between cortical cells, must be highly specific (5). Indeed, cells in the striate cortex respond in such a characteristic way that departures from the normal adult physiology should be easily recognizable. In the present study we have made similar experiments in kittens ranging in age from l-3 weeks. Our purpose was to learn the age at which cortical cells have normal, adult-type receptive fields, and to find out whether such fields exist even in animals that have had no patterned visual stimulation.

Gamma-aminobutyric acid and other blocking compounds in crustacea. iii. their relative concentrations in separated motor and inhibitory axons.

Abstract: IN THE TWO PRECEDING PAPERS it was reported that gamma-aminobutyric acid (GABA) was the most active of ten blocking substances extracted from the nervous systems of lobsters and crabs. The concentrations of GABA in several peripheral nerves were measured and found to be highest in a nerve that contained only one motor and one inhibitory axon. It was natural to wonder if GABA was specifically concentrated in the inhibitory axon. In the present study, therefore, we have isolated individual axons and found, within the limits of sensitivity of our enzymic assay, that motor fibers contained no GABA while inhibitory neurons contained surprisingly high concentrations. Other blocking compounds were also extracted from separated motor and inhibitory axons, but in contrast to GABA, these are present in both neuron types, as is the precursor of GABA, glutamic acid. The current studies strongly suggest that GABA has a specific physiological role confined to inhibitory neurons.

Acoustic and nonacoustic factors modifying middle-ear muscle activity in waking cats

Abstract: Author(s): CARMEL, PW; STARR, A | Abstract: MOST STUDIES OF THE MIDDLE-EAR MUSCLES have emphasized their reflex role in protecting the inner ear from damaging loud sounds (8,12, 13, 24, 26, 30, 36). Recent demonstrations of middle-ear muscle activity during lowintensity sounds (29) suggest that these muscles may have a wider role than merely protecting against mechanical damage. The present experiments reveal that in waking cats middle-ear muscle activity may be modified by prior acoustic experience, by nonacoustic factors such as bodily movements, and by changing the significance of the sound for the animal. This paper presents an analysis of some of the mechanisms underlying middle-ear muscle activity and illustrates both sustained and transient contractions which are regulated according to complex central activities, rather than responding as a fixed protective reflex arc.