Differential left hemisphere activation during the voluntary control of skin resistance level.

Sixteen dextral subjects were presented auditory feedback (FBK) in the form of clicks, the frequency of which was inversely proportional to the sum of the skin resistance levels (SRLs) of the two hands. The FBK was presented in a two-ear changeover paradigm: FBK was presented for 10 minutes to one ear while a white noise masking stimulus was presented to the other; the ears of FBK and masking stimulus presentation were then reversed. Subjects were instructed to decrease the frequency of the clicking. An increase in the SRL of each hand was used as a measure of the activation of the contralateral hemisphere. Significant increases in right-hand SRL (on the order of 40% of baseline) were seen following FBK and obtained regardless of the ear to which FBK was presented, the order of FBK presentation, or the sex of the subjects. Also seen were small-magnitude changes in left-hand SRL, which were not statistically significant. These findings indicate that the left hemisphere was differentially active during acquisition of inhibitory control of SRL in dextrals receiving auditory FBK. Clinical implications of this finding are discussed.