STIMULATION IN THE HUMAN SOMATOSENSORY THALAMUS CAN REPRODUCE BOTH THE AFFECTIVE AND SENSORY DIMENSIONS OF PREVIOUSLY EXPERIENCED PAIN

Thalamic structures involved in the unpleasant emotional or affective aspect of pain are poorly understood. We now describe studies of the r egion of the thalamic principal somatosensory nucleus (Vc) performed b efore thalamotomy for tremor in a patient who also had panic disorder. Microstimulation in the region posterior to Vc evoked chest pain, inc luding a strong affective dimension, almost identical to that occurrin g during his panic attacks, as measured using a questionnaire. Results in our other patients indicate that stimulation-associated pain with a strong affective dimension occurred only in those patients who had p reviously experienced spontaneous pain with a strong affective compone nt. These results are consistent with stimulation-evoked activation of limbic structures, which are connected through cortex with the region posterior to Vc and involved in the affective dimension of pain throu gh conditioning by previous experience.