who, on the contrary, are predominantly right-handed. The type of visual asymmetry did not render any significant influence on the size of this illusion. By amount of visual–spatial intelligence two groups of examinees were revealed. For the group of examinees with average and high IQ, an inverse relationship between the size of the distortion and visual–spatial abilities took place. The ERPs were registered by presentation of a set of isomorphic Poggendorff figures in women who were right-handed. It was established that visual P 100 answer for figures causing the illusion was much more in comparison with the control figure. In addition, an occurrence of N 170 wave in symmetric parietal, occipital and parietal areas was revealed. The amplitude of visual N 170 answer to the illusory stimulus was distinctly less. The data received specify that the visual distortion of an arrangement of elements of the Poggendorff figure arises at an earlier stage of information processing than was previously considered to be the case. Supported by the Siberian Federal University and Krasnoyarsk State Pedagogical University. doi:10.1016/j.ijpsycho.2008.05.339 EEG and EYE tracking for visual search task investigation in humans A.V. Latanov a , N.S. Konovalova a , A.A. Yermachenko b a MV Lomonosov State University, Department of Neurobiology, Moscow, Russia b Modern University for the Humanities, Institute of Cognitive Neuroscience, Moscow, Russia Nowadays eye movements (EM) are usually recorded by the video eye tracking (ET) technology. It is widely used for EM pattern analyses during perusal of complex image, but it is seldom done simultaneously with EEG recording. Some electrophysiological parameters (EEG, ECG, GSR) are traditionally considered to indicate processes, related to solving visual tasks. We studied the EEG correlates of finding a relevant stimulus (RS) among irrelevant stimuli (IS) during the visual search task performance. By means of precise EEG and ET synchronization we marked out the short EEG fragments concurrent with the moment of finding the RS and analyzed them. The experiments were held over 15 volunteers without neurological history. 100 images with about fifty nonverbal stimuli were exposed to each subject. The task consisted of finding the RS and fixing the gaze on it for a couple of seconds. There were 45–57 IS on each image and one RS with a pseudorandomly varied position. The difference between two stimuli types was not too hard to detect (all subjects managed to find the proper stimulus on each picture), and at the same time it was not too simple (it seldom took the subjects less than a second to find the key stimulus). The differences among IS were in rotation angle, position and size, but they were always of the same shape. The EEG was recorded over О1, О2, Р3, Р4, С3, С4, F3, F4 leads. We also recorded the EOG, which was used for determining the saccade moving the eyes towards the RS. The gaze fixation on RS was verified by ET. We showed that the RS finding induces an event-related desynchronization (ERD) in alpha band (8–12 Hz). RS finding causes the 1,5–2 times decrease in EEG amplitude in comparison with searching process. ERD was best exposed in occipital and parietal leads. We conclude that solving the visual search task induces changes in human functional condition like top-down attention and recognition, which are partly indicated by ERD. Further research may result in a determining object's visual features, evoking changes in human status. The project is supported by RFBR grant (№ 06-04-48166). doi:10.1016/j.ijpsycho.2008.05.340 Invariant visual-recognition learning in monkey: Effect of hemispheric specialization of the prefrontal cortex K.N. Dudkin, I.V. Chueva, F.N. Makarov Pavlov Institute of Physiology, Russian Academy of Sciences, St Petersburg, Russia Conditioned behavior includes visual recognition as one of the basic stages, its function — the best current interpretation and understanding of visual scenes and objects. Storing of the information necessary for it is realized by means of learning and is connected with two aspects of long-term memory: with forming, storage and reproduction cognitive structures and with selective increase in their biological significance. The prefrontal cortex plays the important role in the visual recognition processing. To understand a possible mechanism of hemispheric specialization of the prefrontal cortex for invariant visual-recognition we studied learning processes involving visual discrimination of stimuli with different visual attributes on three groups of rhesus monkeys. The left and the right prefrontal cortices sulcus principalis were removed in monkeys of the first and of the second groups, accordingly. The remaining intact animals served as control. The monkeys were tested for invariant recognition after complete training to visual discrimination and after stimuli transformations (variation in size, shape, orientation and spatial relation- ships). Monkey's correct decisions, refusals of task decision and motor reaction time were recorded. The results obtained demonstrate “transfer of training” after transformations of conditioned stimuli in monkeys of control group. The invariance of recognition is provided due to the presence of the common sensory properties of visual objects, which are selected during sensory processing and are retained after transformations. It means, that visual discrimination learning processes form in long-term memory certain demarcating features representing cognitive structures providing recognition and classification of visual objects. As compared with control monkeys, after removal of left and right prefrontal cortices sulcus principalis learning processes became unstable for discrimination of all stimuli, and as a result the training periods were significantly lengthened, especially for spatial information. The transforma- tion of stimuli involving nonspatial information: geometrical figures of various shape, size and orientation did not influence correct decisions though refusals of decision and reaction time were increased. The invariance of this discrimination was achieved. However, the invariance for discrimination of stimuli connected with spatial information after transformation was not achieved only in monkeys after removal of left prefrontal cortex sulcus principalis. These results indicate that left (but not right) prefrontal cortex sulcus principalis takes part in invariant visual-recognition by forming demarcating features and providing spatial-information processing. It is clear, that invariance of nonspatial information recognition is provided by other cortical areas, first of all, the inferotemporal cortex. doi:10.1016/j.ijpsycho.2008.05.341 Visual attention modulates the frontal eye field executive functions: Electrophysiological correlates F. Jagla a , M. Jergelova b a Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Laboratory of Cognitive Neuroscience, Bratislava, Slovakia b Laboratory of Cognitive Neuroscience, Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Bratislava, Slovakia Several areas in frontal, temporal and parietal human cortices have been identified as functionally important not only in programming and execution of saccadic eye movements but in attentional control of processing visual information as well. Their functional role in the oculomotor control mechanisms was described in numerous studies. However, how these areas interact to form dynamic attentional networks which control the focusing of visual attention in humans is not yet fully understood. Some insight into the problem, especially for timing, can offer the analysis of evoked potentials time locked to the onset of saccades (SEMRPs) registered simultaneously over the frontal and parietal eye fields. Contrarily to parietal components the frontal ones are not so particularly described in humans. The study presents the electrophysiological data that during the primary encoding the basic space and shape characteristics of new visual stimuli, as revealed by prominent lambda complex over the posterior eye fields, a markedly decreased activity is to be registered over the frontal eye fields. It is reflected as a prominent sharp wave peaking at the time of the lambda response. The hypothesis was proposed that this decreased activity may be assumed as a correlate of blocking the frontal eye field executive functions which protects new visual information encoding from disturbance introduced by triggering new eye movement. Different attenuation of frontal SEMRPs in condition of divided visual attention task, revealed by laterally different attenuation of the frontal sharp wave, correlates with the functional asymmetry of brain hemispheres as well as with their role in programming and generation of saccades. These findings support the proposed hypothesis as also association between programming the direction of saccadic eye movement and shifting the visual attention into the particular region of the visual field. The analysis of the SEMRPs elicited by simple visual targets in selected mental disorders revealed also that the frontal potential changes are more sensitive to various functional 140 Symposium abstracts / International Journal of Psychophysiology 69 (2008) 139–205