Hemisphere inactivation and mood-state changes.

Mood-state changes were studied during a sodium Amytal testing procedure in epilepsy patients with unilateral temporal lobe foci. The results showed that inactivation of the left hemisphere, but not the right hemisphere, produced a negative mood state. This decline in mood was not specifically related to side of focus or sex. As expected, the inactivation of either hemisphere also lead to an impairment in memory performance. This impairment was somewhat worse during a left than a right hemisphere inactivation. Furthermore, patients with left hemisphere foci showed a lower memory performance than patients with a right-hemisphere lesion. These results suggest (a) a hemispheric specialization for emotion that underlie changes in mood and (b) a discrepancy between mood states at encoding (during inactivation) and retrieval (after inactivation).