RECALL OF SELF-GENERATED ARM MOVEMENTS BY PATIENTS WITH UNILATERAL CORTICAL EXCISIONS

In previous work, Leonard and Milner (Neuropsychologia, 29, 47-58, 199 1) demonstrated that patients with large excisions from the right fron tal lobe have difficulty in reproducing accurately the extent of exami ner-defined arm movements, the displacements being made without the ai d of vision. The impairment in the right frontal-lobe group was not de pendent on recall-condition, being apparent irrespective of the presen ce of a delay, suggesting that the deficit was primarily one of encodi ng. We then went on to show that these same patients have a short-term memory deficit when recalling terminal position of examiner-defined a rm movements (Neuropsychologia 29, 629-640, 1991). From these investig ations we concluded that the right frontal lobe is critically involved in the monitoring of information related to movement. In the present study 58 patients with unilateral temporal- or frontal-lobe excisions were tested on two kinesthetic tasks that required the subjects themse lves to select terminal positions, or movement extents, thereby reduci ng dependence on peripheral feedback. Patients with right frontal-lobe lesions could reproduce these self-generated movements normally, indi cating that when demands on feedback are reduced the frontal-lobe cont ribution is not critical.