Sensory discriminability comparisons in human and monkey with implications for the study of central nervous...

Psychophysical measurements of sensory discriminability were obtained from rhesus monkeys and humans to suprathreshold electrical cutaneous stimulation by employing a two-choice discrimination task and a signal detection theoretical analysis. Sensory discriminatory capacities were found to be similar for monkeys and humans. Choice-latency data permitted the construction of relative operating characteristic (ROC) functions for both groups. These functions provided similar descriptions of the hypothetical sensory process underlying the discrimination performance of both species. Theoretical predictions were made concerning characteristics of the underlying sensory activity and tested by a joint analysis of behavior and somatosensory evoked potentials obtained from monkeys. Results indicated that the magnitude of an average evoked component with peaks at 40 and 70 msec in one monkey, and 60 and 100 msec in the other, correlated well with behavioral choices and choice latencies. The evidence obtained in these studies was discussed in the context of neural coding of sensation in humans and monkeys.