Responses of Bulboreticular Units To Somatic Stimuli Eliciting Escape Behavior In The Cat

Abstract

Units were recorded from the brainstem of awake, unrestrained cats trained to escape electrical stimulation of a cutaneous nerve; stimuli sufficient to elicit escape were associated with natural pain behavior. Of the 104 units histologically localized, 59, recorded from the bulboreticular area of nucleus gigantocellularis (NGC), show maximal or exclusive response to noxious stimuli (36 units) and/or to nerve stimuli eliciting escape (39 units). Increased inter-stimulus activity commonly precedes escape behavior and is the only stimulus-related response observed from some units not driven by nerve stimulation. However, the pooled data from 39 of 53 units tested with nerve stimulation shows that responsiveness (chi-square, Kolmogorov-Smirnov statistic, and average spikes/ stimulus) increases with stimulus strength, reaching maximum levels at escape-producing intensities. Responses of some units to non-somatic inputs can be altered by repetitive noxious stimulation.

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Notes on contributors

Kenneth L. Casey

Joyce Laing works in the Department of Child and Family Psychiatry, Playfield House, Cupar, Fife, and is a Consultant Art Therapist to Psychiatric Hospitals and Prisons and Chairwoman of the Scottish Society of Art and Psychology.