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

Abstract

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.