P. Trillenberg et al., TARGET ANTICIPATION AND IMPAIRMENT OF SMOOTH-PURSUIT EYE-MOVEMENTS INSCHIZOPHRENIA, Experimental Brain Research, 120(3), 1998, pp. 316-324
A reduced gain of smooth pursuit eye velocity has frequently been repo
rted in schizophrenic patients. With respect to predictable stimuli, t
his could be due to a deficit in predicting the target path. To determ
ine this contribution to smooth pursuit eye movement performance, we a
nalyzed the ocular smooth pursuit response to a sinusoidally moving ta
rget that was suddenly stopped after some cycles of regular movement.
Horizontal eye movements were recorded with infrared reflection oculog
raphy in a group of 17 schizophrenic in-patients and 16 age-matched he
althy subjects for controls. The patients exhibited a reduced gain of
smooth pursuit velocity, but phase lag was not different from the cont
rol group. After the unpredictable stop of target movement, predictive
sinusoidal smooth pursuit was maintained for 150 to 200 ms in both gr
oups. The resulting maximal position and velocity error was larger in
the patient group. In conclusion: schizophrenic patients were able to
generate a normal anticipatory component of smooth pursuit and to swit
ch it off in response to external demands. They showed, however, an in
creased velocity of anticipatory pursuit, which might be used to compe
nsate for the primary deficit of smooth pursuit velocity frequently fo
und in schizophrenics.