Cerebral hemisphere memory for manual object handling: an intracarotid Amytal study

The memory capacity of the cerebral hemisphere for manual object handling was studied during preoperative, intracarotid Amytal testing for hemisphere speech and memory in 32 patients with intractable partial epilepsy. The tactile stereognostic memory was tested non-visually before and after amobarbital injection. Two common objects, one in each hand, were given to the patient with the request to identify each by manipulation, but not to name it. Before injection, object handling was carried out correctly by both hands. After injection, while the patient was hemiplegic, the dominant hemisphere executed the object handling correctly; the non-dominant hemisphere, however, did it less properly. Free verbal recall of the object presented before the injection was correct in 85%. The free verbal recall of the postinjection objects was much lower; 22% for the speech-dominant, and only 3% for the non-dominant hemisphere. Tactile, non-visual recognition gave a memory score of 41% for the speech-dominant, and 13% for the opposite hemisphere. An epileptic lesion in the dominant hemisphere impaired the memory performance of that hemisphere compared to the non-lesioned group.