Violent behavior has a strong association with schizophrenia. The similarity of brain dysfunction in schizophrenia and violence was notified. The automatic information processing abnormalities were also found in association with schizophrenia and aggressive behavior. However, only single investigations have been provided. The aim of this study was to compare the prepulse inhibition (PPI) of the acoustic startle response (ASR) and P50 evoked potential suppression between violent and non-violent schizophrenic patients and healthy controls. Participants were 171 right-handed males aged 21-53 years. The main group included 62 schizophrenic patients with violent behavior (committed homicides), the comparison group -53 non- violent patients, and the control group - 56 healthy participants. The neurophysiological testing was carried out according to recommendations of Consortium on the genetics of schizophrenia (COGS). Patients’ current symptomatology was assessed with Positive and Negative Symptom Scale (PANSS). The comparison of clinical symptoms revealed that O14 scale (impulsivity) was higher in violent patients compared to non- violent ones (3,03±0,27 vs. 1,82±0,30, p=0,019). Decreased (relative to controls) PPI rate from the right eye at 60 ms lead interval was observed in both groups of patients (pb0,05) but PPI reduction from the left eye (pb0,05) was found in violent patients only. Non-violent patients displayed longer baseline ASR latency and diminished ASR habituation level compared to controls. Analysis of correlations between ASR measures and PANSS scores revealed positive correlations between high rate of ASR habitua- tion and Suspiciousness (P6, r=0,37, p=0,0008) and Hostility (P7, r=0,42, p=0,0001) scales in the group of violent patients; the negative correlation between ASR latency and O14 scale (r=-0,55, p=0,027) was found in non-violent patients group. The sensory gating deficit estimated by P50 suppression was found in both patient groups (pb0,01) compared to healthy subjects. But the increase of amplitude of P50 response to the second (testing) stimulus was found in violent group only compared to controls (pb0,05). Non-violent patients displayed the P50 latency facilitation that manifested as decrease in P50 latency in response to the testing stimulus compared to the conditioning one, and these differences were significant (pb0,01) when compared with both the group of violent patients and healthy controls. The current study revealed the specific disturbances in the early stages of attention and information processing related to the mechanisms of aggressive behavior. The revealed differences be- tween violent and non-violent patients may be used to identify the risk of violence in schizophrenia. Supported by Russian Foundation for Basic Research (grant 16-06-00117). doi:10.1016/j.ijpsycho.2018.07.438 30 Experience differentiation from individual to joint appetitive operant task in female rats O. Svarnik a , Yu. Petrova b , S. Usova c , Yu. Alexandrov a a Institute of Psychology RAS, Moscow, Russian Federation b Moscow State University, Moscow, Russian Federation c Semenov Institute for Chemical Physics, Moscow, Russian Federation Introduction: Social cooperation of subjects is a complex phe- nomenon which has many aspects. One of them is mutual adjustment of subjects’ behavior. This aspect is the basic one because it appears to be important even if a mutual benefit of joint actions is absent. In this study we addressed the issues of how animal behavior is adjusted in a condition of joint appetitive session, and which neuronal groups are involved into such adaptation. Methods: We trained animals (female Wistar rats) an appetitive operant task of lever pressing for two weeks in the experimental cage with one lever and one food-cup. For at least five days animals had to perform this task individually at the level of a plateau. The last session (30 minutes long) was to perform the same behavior, but in a condition, when a home-cage-mate rat (rats were housed in pairs) was also present in the same experimental cage at the same time trying to perform the same behavior. We evaluated peculiarities of their behavioral adjustments by tracking animals’ behavior. Neuronal group involvement was assessed by the means of immunohisto- chemical Fos protein mapping (transcription factor, which specifi- cally marks neurons involved into learning). Results: No conflicts were detected during the joint session. In most cases if one rat pressed the lever, the other rat got the reward. Their roles were frequently switched. From the very beginning of the joint session intensity of rats’ rearings was greatest and significantly reduced from 10,3 (the first five minutes) to 1,3 (during the last five minutes) on average. There were pairs of rats performed the nearly equal number of lever presses, in other pairs one rat pressed the lever more frequently than the other. After the joint session the increased numbers of Fos positive neurons were found in the cingulate cortex, the prelimbic cortex and the retrosplenial cortex, but not in the nucleus accumbens of the rat brain. Intermediate level of Fos induction was found in the basolateral amygdala, central amygdala and the medial amygdala. Conclusions: We found that rats adjusted their behavior into new situation of joint session. In a condition when they had to compete for food and operating the same lever, they choose to cooperate. This cooperation was subserved mostly by the frontal cortical neurons. This study was supported by RSF grant # 14-28-00229. doi:10.1016/j.ijpsycho.2018.07.439 31 Three-stimulus auditory oddball paradigm with environmental sounds K. Tabaru, T. Hirayama, T. Sekiguchi, H. Shoji Ibaraki University, MIto, Ibaraki, Japan Introduction: In three-stimulus oddball task, target stimuli elicit positive potential with a peak latency of approximately 300–600 ms (termed “P3b”), and non-target stimuli also elicit a similar compo- nent with shorter latency (termed “P3a”). Previous studies have reported that the amplitude and latency of P3a is affected by stimulus distinctiveness, stimulus context, and task difficulty. However, many studies have used low-meaning stimulus, such as geometric figures, pure tones, or white noise. Therefore, the present study employed three-stimulus auditory oddball tasks with environ- mental sounds, which have higher meaning than pure tones, leading to stronger features of P3a. Methods: Fifteen student volunteers (20–24 years old) partic- ipated in this study. Three-stimulus auditory oddball paradigm was used under two conditions: (1) similar condition: “dog barking” (standard), “dog barking with pitch frequency decreased by 15 Hz” (target), and “dog pup yelping” (non-target) were used as stimuli; (2) dissimilar condition: the standard and target stimuli were identical to the similar condition, and non- target was changed to “cat meowing”. Participants were asked to respond only to the target, and performed 300 trials for each condition, comprising standard, target, and non-target trials with probabil- ities of .80, .10, and .10, respectively. Electroencephalogram (EEG) signals were recorded from 19 scalp locations with Ag/AgCl Posters / International Journal of Psychophysiology 131S (2018) S69–S184 S166