20. Eye Movement Physiology MOTION PERCEPTION DEFICITS IN SCHIZOPHRENIC PATIENTS AND THEIR CORRELATION WITH ABNORMAL SMOOTH PURSUIT Vue Chen, Ph.D., Ken Nakayama, Ph.D., Philip S. Holzman , Ph.D., Deborah L. Levy, Ph.D., Steven Matthysse, Ph.D. Department of Psychology, HarvardUniversity, Cambridge, Alassachusetts02138 Abnormal smooth pursuit eye tracking occurs in a majority of schizophrenic patients (SZ) and in about 40% of their biological relatives (Holzman et al., 1973, 1974). The nature of the eye movement disorder remains unsettled. We address this question by studying motion perception of SZ and by examining the link between their performance on motion tasks and on smooth pursuit tasks. We hypothesize a principal role of defective motion perception in the abnormal pursuit of SZ because when motion signals or the cortical regions for process- ing motion signals are not available, smooth pursuit cannot be properly produced (Rashbass, 1961 ; Newsome & Pare, 1988). As an index of motion perception, contrast sensitivity for velocity discrimination was measured for two groups of sub- jects-SZ (n = 15) and normal controls (NC)(n = 19). Contrast sensitivities for detection and for orientation discrimination were also determined as non-motion task controls . We found that, for velocity discrimination at small velocity differences (11 vs. 9 deg/s and 22 vs. 18 deg/s) , the SZ group showed significantly lower contrast sensitivity than the NC (p <0.015) . The contrast sensitivity reduction of a subgroup of SZ (6 out of 15) was severe (about 10 fold). For other tasks-detection, velocity discrimination at large velocity differences (15 vs. 5 deg/s and 30 vs. 10 deg/s) and orientation discrimination, contrast sensitivities of the SZ and the NC groups did not differ from each other (all p's>O.I). These results indicate that a motion perception deficit exists in a subgroup of SZ. Moreover, motion-related contrast sensitivities of all the SZ correlated with initial pursuit acceleration (r = 0.2-0.63) during a step-ramp task (5, 10 or 20 deg/s) but not with pursuit maintenance. In conclusion, motion processing is impaired in a subgroup of SZ and this impairment is associated with a dysfunction in generating, but not in maintain ing, smooth pursuit eye movements. CORRELATES OF NAILFOLD PLEXUS VISIBILITY IN FIRST-EPISODE AND CHRONIC SCHIZOPHRENIA Clayton E. Curtis , William G . Iacono, Morton Beiser Departmentof Psychology. University of Minnesota, N218 Elliott Hall, 75 East River Rd. Minneapolis. MN 55455 241 Although all published studies investigating the association between nailfold plexus visibility and schizophrenia have found the subpapillary plexus (the network of vessels into which capillaries drain) to be unusually visible in many schizophrenia patients , little else is known about this putative marker for schizophrenic liability. To help clarify what the plexus trait may represent in schizophrenia, plexus visibility was rated in 63 chronic schizophrenic, 67 first-episode schizophrenic, 9 schizophreniform, 66 depressed pat ients with psychosis. and 119 normals. In addition, smooth-pursuit eye tracking perfor- mance, clinical features, neuropsychological performance, and ventricle-to-brain ratios (VDR) derived from computed tomog- raphy were assessed in a subset of the subjects. The association between plexus visibility and diagnosis of schizophrenia was confirmed. Approximately 21% of chronic schizophrenic, 22% of first-episode schizophrenic, and 22% of schizophreniform subjects had highly visible plexus compared to only 8% of depressed and 8% of normal subjects. Schizophrenia subjects with visible plexus had poorer oculomotor performance, indexed by root-mean-square error, on a 0.4 Hz sinusoidal task. Additionally, chronic schizophrenic subjects with visible plexus had more negative symptoms, worse course, more severe illness, worse occupational functioning, and poorer neuro- psychological performance . Interestingly, the schizophrenic patients without visible plexus tended to have enlarged lateral ventricles whereas the patients with moderate to highly visible plexus had small to normal size ventricles. This study provides evidence that plexus visibility identifies a subset of schizo- phrenia patients characterized by oculomotor dysfunction, negative symptoms, more severe symptomatology, chronic course, neuropsychological dysfunction, and an absence of enlarged ventricles. 'fb EYELID CONDITIONING-A NON MOTIVATION-DEPENDENT TOOL TO INVESTIGATE TEMPORAL LOBE FUNCTION IN SCHIZOPHRENIA Karl Dantendorfer, Dagmar Maierhofer, Murat Serim, Maria Eberstaller Universitatsklinik fur Psychiatrie Wien Chairman: Professor H. Katschnig Introduction: In schizophrenia (SZ) deficits in different cogni- tive functions such as abstraction, language, memory and learning have been reported. Memory and learning deficits seem to playa stronger role than has been previously accepted and should be considered as more 'specific' to SZ than other cognitive dysfunctions. Conditional discrimination learning based on eyelid condi- tioning is an experimental paradigm that has been shown to be selectively sensitive in testing temporal lobe function and has not yet been used in SZ research. A major advantage of