'Utilization behaviour' and its relation to lesions of the frontal lobes.

A new type of behaviour, termed 'utilization behaviour', was observed among patients affected with left or right unilateral, or bilateral, frontal lesions. It is an extension of bilateral manual grasping behaviour (magnetic apraxia). The tactile, visuotactile and visual presentation of objects compels the patients to grasp and use them. This behaviour was obtained with miscellaneous utilitarian objects. For the patients, the presentation of objects implies the order to grasp and use them. It is proposed that the balance between the subject's dependence on and independence from the outside world is disturbed. With frontal lesions, the inhibitory function of the frontal lobes on the parietal lobes is suppressed. The result is a release of the activities of the parietal lobes so that the subject becomes dependent on visual and tactile stimulation from the outside world. Five cases are reported as examples: one anatomoclinical case with bilateral lesions of the frontal lobe. The role of lesions affecting different parts of the frontal lobes is discussed. The neuropathological observations lead to the suggestion that lesions of the orbital surface of the frontal lobe, and perhaps of the head of the caudate nucleus, are responsible for this behaviour.