Disturbances of the rapid eye movements (REMs) of REM sleep in patients with unilateral attentional neglect: clue for the understanding of the functional meaning of REMs.

Horizontal saccades during wakefulness and horizontal rapid eye movements (REMs) during REM sleep were recorded in 6 unilateral brain damaged patients suffering from attentional neglect and 6 unilateral brain damaged control patients. During REM sleep, patients with neglect showed a nearly total suppression of REMs directed away from the side of the lesion; controls had a significantly milder frequency reduction of the same movements. In all patients the frequency reduction of REMs contralateral to the lesion equally affected isolated REMs (i.e., REMs preceded by intervals of oculomotor quiescence longer than 2 sec) and REM bursts (i.e., REMs preceded by intervals shorter than 2 sec). During voluntary inspection in waking, saccades directed ipsilaterally and contralaterally to the lesion were present in both groups of patients, although patients with neglect confined their inspection to the hemispace ipsilateral to the lesion. Results are discussed in terms of their implications for the understanding of the neurophysiological basis of REM sleep oculomotor activity and dream production, as well as for the neurophysiopathological basis of the neglect syndrome. It is proposed that REMs are functionally equivalent to waking reflex orienting saccades generated by a neural network including the relevant modulatory action of the parietal lobes and the superior colliculi