Recall of self-generated arm movements by patients with unilateral cortical excisions

In previous work, Leonard and Milner (Neuropsychologia, 29, 47-58, 1991) demonstrated that patients with large excisions from the right frontal lobe have difficulty in reproducing accurately the extent of examiner-defined arm movements, the displacements being made without the aid of vision. The impairment in the right frontal-lobe group was not dependent on recall-condition, being apparent irrespective of the presence of a delay, suggesting that the deficit was primarily one of encoding. We then went on to show that these same patients have a short-term memory deficit when recalling terminal position of examiner-defined arm movements (Neuropsychologia 29, 629-640, 1991). From these investigations 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 themselves to select terminal positions, or movement extents, thereby reducing dependence on peripheral feedback. Patients with right frontal-lobe lesions could reproduce these self-generated movements normally, indicating that when demands on feedback are reduced the frontal-lobe contribution is not critical.