FRONTAL INTERHEMISPHERIC ASYMMETRY - SELF-REGULATION AND INDIVIDUAL-DIFFERENCES IN HUMANS

Sixteen subjects naive to biofeedback learned lateralised interhemisph eric control of slow cortical potentials (SCPs) across electrode sites F3-F4 during three sessions of visual electroencephalograph (EEG) bio feedback. Subjects were required to generate slow negativity shifts ei ther towards the left or the right hemisphere in sixty pseudorandomly ordered trials per session. Group 1 (n = 8) were told to use emotional strategies in the task (positive emotions for left hemisphere activat ion, negative emotion for right hemisphere activation), group 2 receiv ed no guidance. Both groups received feedback in the form of an on-scr een rocket-skip, initially centrally placed, which rose to indicate an increase in left hemisphere negativity (relative to the right hemisph ere) and fell to indicate an increase in right hemisphere negativity ( relative to the left hemisphere). A 2 x 3 x 3 x 2 ANOVA (group x sessi on x block x trial) showed no performance differences between the stra tegy and no strategy groups. Both groups learned to produce correct di rection shifts in the final third of each session during both trial ty pes (P < 0.001). The no strategy group showed a particularly strong wi thin session learning effect (P < 0.0037) with poor performance in the early part of the sessions, and strong shifts at the end. Subjects hi gh on withdrawal showed stronger rightward shifts in keeping with righ t hemisphere involvement in behavioural withdrawal. This is the first demonstration of self regulation of interhemispheric frontal asymmetry . (C) 1997 Elsevier Science Ireland Ltd.