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THE CONTINGENT NEGATIVE VARIATION AS

A BIOLOGICAL MARKER IN SCHIZOPHRENIA

Sarah Oke*, Reza Saatchi, Elaine Allen, Banie Jervis, Nigel Hudson, Michael Grimsley

Tone Vale Hospital, Norton Fitzwarren, Taunton, Somerset

UK

The Contingent Negative Variation (CNV) is an evoked poten-

tial which is generated in the frontal and midbrain areas. It re-

flects selective attention, response activation and resolution of

motor activity. It has been found to be abnormal in schizophre-

nia. It is reduced in amplitude and increased in duration in

schizophrenic subjects.

The CNV from 20 medication DSM III R schizophrenic sub-

jects and 20 age and sex matched normal subjects were studied

using three methods of analysis. Using discriminant analysis 19

out of 20 schizophrenic subjects were correctly identified. Neu-

ral networks identified nine out of ten and cluster analysis iden-

tified 18 out of 20 schizophrenic subjects correctly. Both

discriminant analysis and neural networks identified all of the

normal subjects correctly; cluster analysis identified 18 out of 20

normal subjects correctly.

These results suggest the CNV reflects cognitive dysfunction

and could be an important biological marker in schizophrenia. It

is also suggested that these results are further evidence of frontal

and midbrain dysfunction in schizophrenia.

HOW REPRESENTATIONAL GUIDANCE OF

BEHAVIOR MAY AFFECT SMOOTH PURSUIT

EYE MOVEMENT (SPEM) DYSFUNCTION: A

TEST OF GOLDMAN-RAKIC’S FRONTAL LOBE

HYPOTHESIS

Sohee Park*, Philip S. Holzman

Dept. of Psychology, Harvard University, 33 Kirkland St.

Cambridge, MA 02138, USA

About 60% of schizophrenics are unable to track a smoothly

moving target with their eyes. In addition to showing numerous

saccadic events, they seem unable to match their eye velocity to

the target velocity. Goldman-Rakic has proposed that representa-

tional guidance of behavior, mediated by the prefrontal system,

is impaired in schizophrenics. We hypothesized that SPEM

dysfunction may be, in part, due to a inability to represent the

trajectory of the target.

Subjects observed a target, which travelled behind a wall dur-

ing a part of its trajectory. The task was to predict the re-

emergence of the target on the other side of the wall. There were

2 conditions: (1) There was a line on the wall, coinciding with

the trajectory of the target. Subjects were asked to use this line

to imagine the target behind the wall and were asked to ‘anchor’

their eyes on the line (2) In the second condition, there was no

line. We hypothesized that if subjects can form and maintain an

internal representation of the trajectory, they may perform more

accurately and also, that schizophrenics but not normals, would

benefit greatly from this instruction. Normals were accurate in

predicting the trajectory, regardless of speed. Schizophrenics were

worse than normals, especially with slower targets, perhaps

because internal representation must be maintained for longer.

With faster targets, schizophrenics, especially those with impaired

SPEM improved when there was a line.

THE RELATIONSHIP BETWEEN ABNORMAL

SMOOTH PURSUIT EYE MOVEMENTS AND

CLINICAL VARIABLES IN SCHIZOPHRENIC

PATIENTS

D.E. Ross*, G. Thaker, M. Moran, H. Adami, CA. Tamminga

P.O. Bo.r 21247; Maryland Psychiatric Research Center; Univ. of

Maryland at Baltimore, Baltimore, MD 21228, USA

It has been previously reported that abnormal smooth pursuit

eye movements of schizophrenic patients are characterized by two

patterns of defects: (I) low gain with excessive corrective and

intrusive saccades; (2) abnormal 36 Hz oscillations (Ross et al.,

Ghizophrenia Research. 1989 2:9l; Ross et al., 1992, submitted.

Oscillations of similar frequency have been previously reported in

normal subjects (especially during the initiation of pursuit) but not

in schizophrenia. In the present study, a new group of 15

unmedicated schizophrenic patients and I5 normal controls was

examined in an attempt to replicate this finding of abnormal os-

cillations. Sinusoidal and trapezoidal pursuit targets were used, as

well as Rashbass step-ramps. High-resolution infrared oculography

was used to collect the eye movement data, which were then

stored digitally for later quantitative analysis. Oscillations were

quantified by removing saccades, applying a 2-8 hz band-pass fill

ter, and computing the root mean square error. Also, each patient

was administered a Brief Psychiatric Rating Scale (BPRS) and

Schedule for the Deficit Syndrome in order to examine the rela-

tionship between these clinical variables and measures of smooth

pursuit eye movements. The results will be presented and dis-

cussed.

AFFECT RECOGNITION PERFORMANCE

CORRELATES WITH OCULOMOTOR

FUNCTIONING IN SCHIZOPHRENIA

R.B. Rosse, B.L. Schwartz, S.I. Deutsch*

Psychiatry Service 116A, Dept. Veterans Affairs Medical Center,

Washington, DC 20422, USA

Patients with schizophrenia have been reported to have deti-

tits in facial affect recognition and smooth pursuit and antisaccade

perfomurnce. We examined the relation between deficits on these