Purpose

Stimuli & Task

Results

Discussion

Bottom Line

References

Non-Motor Contributions To Motion Deficits In SchizophreniaNestor Matthews1,2 Bruce Luber 3,4 Ning Qian2 Sarah H. Lisanby 3,4

Denison University, Dept. of Psychology1, Granville, OH, USA

Columbia University, Ctr. for Neurobiology & Behavior2, Dept. of Psychiatry3, Dept. of Biological Psychiatry4, New York, NY, USA

Experimental Conditions

MotionStimulus

SpeedTask

MotionStimulusDirection

Task

MotionStimulus

BrightnessTask

ScrambledStimulus

BrightnessTask

StationaryStimulus

BrightnessTask

Patients

Controls

Same Stimulus, Different Task .... Same Task, Different Stimulus

Our findings suggest that eye-movement deficits in patients withschizophrenia are at least partiallydue to impaired perceptual input.

We previously reported evidencethat separate neural events mediate speed and direction discrimination

(Matthews et al 1999, 2001).

Accordingly, a neuro-pathologicalprocess, such as schizophrenia,

could in principle differentially affectspeed and direction discrimination.

However, these data indicate that bothspeed and direction discrimination

are impaired in patients. This is trueeven before eye-movements have begun.

Matthews & Qian (1999). Axis-of-motion affectsspeed discrimination, not direction discrimination.

Vision Research, 39(13), 2205-2211.

Matthews, Luber, Qian & Lisanby (2001). Transcranial magnetic stimulation differentially

affects speed and direction judgments. Experimental Brain Research, 140(4), 397-406.

A trial comprised two random-dot patterns, each presented for a duration (200 ms)

too brief for reliable eye movements.

The task required judging the speed, direction, or brightness of

the second stimulus relative to the first.

Across these three tasks the stimuli(schematized below) were identical.

We also held one of the tasks(i.e., brightness discrimination) constant,

while manipulating the stimuli,as described in the next panel.

It is well known that eye movements are impaired in patients with schizophrenia.

Here we study motion sensitivity in patients before eye movements occur.