Motor control of schizophrenics—I. Oculomotor control of schizophrenics: A deficit in sensory processing, not strictly in motor control

Release of saccades in schizophrenics: Inattention or inefficiency?

“…Schizophrenic and depressive subjects were worse in both tasks than normals (also see Mather and Putchat 1983), and their performance in them was correlated (see Tables 1 and 2). The eye movement stability problems may, in contrast, be attentional.…”

“…He postulated that "saccadic disturbances should be more frequent at the extremes of the pendulum's motion" where attention lapsed. Mialet and Pichot (1981), Mather and Putchat (1983) and Iacono and Koenig (1983) all found that there were more saccades not at the end but at the high-velocity "catch-up" phases of target motion, which suggests a tracking efficiency and not an attentional problem. Mialet and Pichot (1981) and Matsue et al, (1986) looked at saccade production across fixation and tracking, but did not find the significant correlations across tasks which would suggest a common deficit.…”

“…A. Mather This article was presented in part at the Symposium on Eye Movements and Psychopathology, Berlin, 23-24 June 1988 (Holzman et al 1976;Iacono 1982;Mather and Putchat 1983). The source of the disorder has been specified as attentional dysfunction (Inattention) (Holzman et al 1976), or as faulty processing of perceptual information (Inefficiency) (Mather 1986).…”

“…Saccade production was measured during three oculomotor tasks: smooth pursuit tracking, both in normal room illumination and in the dark; looking to a continuous and flashed target; and fixation, by the number of departures from steady gaze and the number of predictive departures before the target moved (Mather and Putchat 1983). The perceptual manipulation of room background should remove the group differences if the problem is attentional, or stimulate parallel changes if the problem is efficiency.…”

Sensory and motor aspects of saccade control

“…Recently, however, there has emerged increasing evidence that the pathophysiology of various psychoses might be linked with abnormalities in eye movements. It has been shown, for instance, that patients suffering from schizophrenia frequently exhibit saccadic dysmetria (Mather and Putchat 1983;Schmid-Burgk et al 1983), impaired smooth pursuit performance (Shagass et al 1974;Holzman et al 1977; and poorer visual search performance . It is unclear, however, whether reduced sensory acquisition of the visual stimulus, attentional deficits or deficits in motor programming may account for these findings.…”