An undergraduate laboratory exercise to study sensory inhibition.

Sensory inhibition was first described by von Békésy as a process in which excitation of a field of sensory neurons leads to the reduction of activity of surrounding neurons and thus promotes contrast enhancement of the excited field. In the context of somatosensory cortex, the cortical neurons excited by touch or vibration will suppress excitation of neurons from surrounding receptive fields. USING TACTILE STIMULATORS BOTH DESIGNED AND FABRICATED AT THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL, WE CONDUCTED TWO SIMPLE EXPERIMENTS IN WHICH SENSORY INHIBITION PLAYS A ROLE IN INFORMATION PROCESSING: a unilateral study in which stimuli are delivered to the digits of one hand, and a bilateral study in which stimuli are delivered to the digits of both hands. In the unilateral study, we demonstrated that threshold detection on the third digit (D3) is impacted by conditioning stimuli delivered to adjacent digits 2 (D2) and digits 4 (D4). In the bilateral study, we delivered different conditions of bilateral stimulation in order to investigate the impact that conditioning stimulation of the right hand had on amplitude discriminative capacity of the left hand. The results demonstrated that conditioning stimulation on the right hand had a significant impact on the discriminative capacity of the left hand, and this alteration in discriminative capacity was consistent with previous animal studies in which somatosensory cortical responses evoked by stimulus conditions of unilateral vs. bilateral stimulation were compared. At the conclusion of this exercise, students will appreciate the fundamentals of sensory inhibition as well as the logistics of obtaining and analyzing data from human subjects. This study is designed to help students prepare for studying other facets of sensory processing by providing a firm foundation in the experimental methods and procedures.