Sensory discrimination thresholds with cutaneous nerve volleys in the cat.

Abstract

Cats were trained to bar-press to sensory cues produced by direct electrical stimulation of the superficial radial nerve through implanted electrodes. By varying the stimulus intensity, it was possible to determine sensory discrimination thresholds. These were compared with thresholds for peripheral nerve and cortical evoked potentials. Using stimuli at 4/sec it was found that cats were able to respond at about the same stimulus intensities required to evoke a threshold response in peripheral nerve and cerebral cortex. At 100/sec sensory discrimination thresholds remained essentially unchanged but at suprathreshold stimulus intensities high frequency stimulation appeared to produce more intense subjective sensations than low frequency volleys. The methods used in this study provided a sensitive test for relating sensory discrimination thresholds to physiological criteria; discrimination thresholds were found to occur near minimum theoretical values.