According to interpersonal and cognitive theories onset and maintenance of depression is affected by abnormal emotion processing in terms of negative cognitive biases. In particular negative biases in the perception of facial emotion have been identified as enduring vulnerability factor to depression relapse. It has been suggested that the amygdala is critically involved in the processing of facial emotion and in negative judgmental bias. In the present cross-sectional neuroimaging study the effect of brain and especially amygdala reactivity to emotion faces on severity and course of illness as well as on automatic negative judgmental bias was investigated in a sample of unipolar depressed patients. Brain activity was recorded in response to masked displays of angry, sad, and happy facial expressions by means of functional magnetic resonance imaging (fMRI) at 3T in 35 inpatients suffering from major depression. Course of illness was recorded retrospectively. In a separate experiment, the patients performed a masked affective priming task that characterizes automatic emotion processing by investigating the biasing effect of subliminally presented emotional faces on evaluative ratings to subsequently presented neutral stimuli. Subjects were also genotyped for the 5-HTTLPR polymorphism. Significantly activated clusters within the left and right amygdala were detected for masked sad faces and masked angry faces. 5-HTTLPR risk allele carriers manifested stronger amygdala activity in response to emotion faces. Significant associations between amygdala reactivity and automatic negative judgmental bias were observed. As hypothesized, stronger amygdala responses to masked angry and sad faces were associated with more negative bias scores elicited by corresponding negative prime faces in the affective priming task. Automatic negatively biased evaluative processes were associated with a history of chronification and disease severity. Activation of the amygdala in response to negative facial emotion seems to evoke negative judgmental biases even if the patients are not aware of the emotional stimuli. Amygdala hyperresponsiveness appears to be a neural substrate of negatively biased automatic emotion processing and modulated by the 5-HTTLPR polymorphism. Depressed patients displaying automatic evaluative shifts elicited by masked negative faces have a more severe course of disease as indicated by their clinical history. doi:10.1016/j.ijpsycho.2008.05.456 Visual scanning, brain activations and emotional face perception in autism J. Martineau a , N. Hernandez a , F. Andersson b , C. Destrieux a a INSERM U 930, Paedopsychiatry Department, Tours, France b IFR135, Department of Psychology Cognitive Science Unit, Helsinki, Finland Autism is a pervasive neurodevelopmental disorder associated with considerable impairments. Deficits in social interaction, in communicative abilities and unusual, repetitive and stereotyped behaviors are the main characteristics of the autism phenotype. These patients show a particular social and emotional profile. They present a lack of social and emotional reciprocity and a failure to develop pear relationships appropriate to their developmental level. It seems that there is a failure to use information from faces, such as eye gaze, and facial expression to regulate social interaction. Visual scanning and brain activations were used in this study to evidence an abnormality of emotional face perception in autistic pathology (7 adults and 27 children). The faceLab system allows us to determine gaze direction. Facial stimuli were used: 10 neutral, 10 happy, 10 sad, 10 virtual, 10 with a deviated gaze. We analyzed the time spent examining core feature regions (eyes, nose and mouth), the time spent off features and the exploratory strategy. A 1.5 T scanner allows us to record brain activations produced by blocs of 10 images. We presented neutral, happy, sad and virtual faces, mixed with neutral, happy and sad pictures. The activations were linked to the perception of a face, the perception of a facial emotional expression, the perception of a virtual face, and the activations linked to the induction of an emotion. Combined results from the eye-tracking and fMRI study showed, on one hand, a lack of attention to faces, different exploration strategies and involvement of only right occipital structures in face and facial emotion perception, as well as in feeling emotion, in autistic participants, on the other hand, a lack of activation of the Superior Temporal Sulcus. By reference to the Haxby's model, two components of the core system involved in visual analysis of faces show impairments. The STS is inactive and the inferior occipital gyri are only active on the right side. This could underlie abnormal processing by the extended system which could in turn result in impaired social interaction in autistic pathology. doi:10.1016/j.ijpsycho.2008.05.457 SYMPOSIUM 23: Awareness and Self-Awareness in Psychophysiological Measures Symposium Chair: Jan Kaiser (Poland) Correlation dimension of the EEG corresponds with awareness and vigilance A.M.L. Coenen Radboud University Nijmegen, Department of Biological Psychology, Nijmegen, The Netherlands Correlation dimension analysis of the electroencephalogram (EEG) of animals and humans is a relatively new psychophysiological measure that has been customised to estimate the level of awareness and vigilance. The application of a non-linear (fractal) time series provides a measure of complexity reflecting the number of sub-processes contributing in the EEG signal. The small amplitude, high frequency EEG, associated with awareness, is more complex than the large amplitude, low frequency EEG, associated with a subconscious state. Thus high correlation dimension (‘dimensional complexity’) values are related to vigilant states with a high awareness and alertness (more sub-processes are contributing to the EEG), while low values are related to low awareness and low vigilant states, such as sleep and unconsciousness (less sub-processes are contributing to the EEG). These non-linear methods have shown their ability to excel over traditional EEG techniques and these properties have led to the use of correlation dimension analysis in studies of awareness and vigilance, in sleeping and waking, in anaesthesia, in cognitive load, as well as in studies of a subconscious and unconscious brain. Babloyantz et al. (Physical Letters, 111A, 1985) and Pradhan et al. (Computers in Biology and Medicine 25, 1995) studied the correlation dimension during the sleep–wake cycle and showed a strict relationship between brain EEG complexity and the degree of vigilance of humans. Van den Broek et al. (PhD thesis Nijmegen University Press, 2003, and Physica D, 203, 2005) demonstrated in human clinical studies that surgical anaesthesia is associated with a correlation dimension below 60% of base-line (relaxed wakefulness) values, both in humans and rats. This measure was also used by Coenen et al. (Laboratory Animals, 29, 1995 and World's Poultry Science Journal, 56, 2000) to determine the point where animal brains (rats and hens) reach unconsciousness. Finally, Lamberts et al. (Neuropsychobiology, 41, 2000) showed in humans that EEG correlation dimension is positively related to cognitive load. The higher the load, the higher is the correlation dimension value. It is concluded that in all studies in which correlation dimension is measured in relation to the states of awareness and vigilance, the correlation dimension value gives a realistic estimate of the objectively and subjectively experienced levels of awareness and vigilance. doi:10.1016/j.ijpsycho.2008.05.458 Pain and single-trial somatosensory event-related potentials C.M. Van Rijn a , E.N. Van Den Broeke a , O.H.G. Wilder-Smith b , A.M.L. Coenen a , R. Quian Quiroga c , M.L.A. Jongsma a a Department of Biological Psychology, Radboud University Nijmegen, The Netherlands b Pain and Nociception Research Group, Radboud University Nijmegen Medical Centre c Department of Engineering, University of Leicester, Leicester, United Kingdom Pain is an unpleasant sensory and emotional experience, associated with actual or potential tissue-damage or described in terms of such damage (IASP, 1979). It is a clinically highly important but unsolved problem to develop an accurate objective measure for the amount of pain a person experiences. Candidate pain measures might be extracted from Event Related Potentials (ERPs), because ERPs provide a direct measure of stimulus processing in the brain. Conventionally ERPs are obtained by averaging epochs of many stimuli, but the appraisal of pain changes in the course of repetitive stimulation. Single-trial ERPs do enable us to measure temporal changes however. We therefore tried to find correlations between single-trial-ERP components and experienced pain, which was rated on a visual analogue scale (VAS). 175 Symposium abstracts / International Journal of Psychophysiology 69 (2008) 139–205