Temporal Lobe Suppressor Cortex in Man ‡

Dusser de Barenne and McCulloch' demonstrated that activation of certain parts of the cerebral cortex produces a suppressor response characterized by decreased electrical activity of all areas of the cerebral cortex manifested by decrease in the motor responses and evoked potential responses of the appropriate cortex. The first of these areas described was area 4-S. They subsequently demonstrated2 other suppressor areas: 8-S, 19-S, and 2-S. These areas were shown by neuronography to discharge into the caudate nucleus' and to have an inhibitory function on this structure. Dusser de Barenne and McCulloch conjectured a cortico-caudate-thalamocortical circuit which served as a dampening circuit on the activity of other areas of the cortex. In 1944 Garol and Bucy3 demonstrated to their satisfaction that the suppression of motor response could be evoked in man by electrical stimulation of a circumscribed area of the human cerebral cortex. This area was equivalent to area 4-S as had been previously described in infrahuman primates. Some investigators in the neurological field have not been convinced that the suppressor areas exist. Some believe that the response obtained is due to drying of the cortex and is not really a function of the cerebral cortex, holding that it is akin to the spreading depression described by Leao.6 Some neurosurgeons who are also competent neurophysiologists have failed to demonstrate the suppressor area in humans at operation, while other neurosurgeons, in the same category, feel that they may have, from time to time, elicited points of suppression.