Unconscious Processing Of Emotion Information And Abnormal Binocular Rivalry Dynamics In Patients Of Mental Disorders And Brain Damages

Binocular rivalry is a spontaneous alternation of visual perception when conflicting image stimuli are presented to each eye in the corresponding retinal area. Binocular rivalry task provides a powerful tool to investigate the visual awareness and the information process of visual perception. Our research focus on the perceptual switching rate of binocular rivalry from mental disorder patients and brain tumor patients. Also we used the binocular rivalry as a tool to investigate the information processing of facial expression. All of the current studies improve our understanding of the consciousness and visual information process system also can help us find a more effective way of the classification of mental disorders.Study A.There is ample evidence to show that many types of visual information, including emotional information, could be processed in the absence of visual awareness. For example, it has been shown that masked subliminal facial expressions can induce priming and adaptation effects. However, stimulus made invisible in different ways could be processed to different extent and have differential effects. In this study,we adopted a flanker type behavioral method to investigate whether a flanker rendered invisible through Continuous Flash Suppression(CFS) could induce a congruency effect on the discrimination of a visible target. Specifically, during the experiment, participants judged the expression(either happy or fearful) of a visible face in the presence of a nearby invisible face(with happy or fearful expression). Results show that participants were slower and less accurate indiscriminating the expression of the visible face when the expression of the invisible flanker face was incongruent. Thus, facial expression information rendered invisible with CFS and presented a different spatial location could enhance or interfere with consciously processed facial expression information.Study B.When two different images are presented to the two eyes dichoptically, observers usually experience a perceptual alternation between the two images. This phenomenon, known as binocular rivalry, has been used as a powerful tool to investigate mechanisms of visual awareness. It was also found that the rates of perceptual alternation are slower in patients with bipolar disorder than that in normal controls(Pettigrew & Miller, 1998). To investigate the broader clinical relevance of binocular rivalry in mental disorders, we measured the perceptual alternation rates during rivalry in normal controls(n=39) as well as patients with different types of psychiatric disorders, including bipolar disorder type I(n=28),obsessive compulsive disorder(OCD, n=22), major depression(n=50),schizophrenia(n=44), and first-degree relatives of schizophrenics(n=32).Participants viewed competing red-green images on computer monitor through red-green anaglyph glasses and pressed one of two buttons to record their alternating perception. The distribution of rivalry rates was well described by a gamma function in all groups. Critically, the median rate of perceptual alternation was 0.27 Hz for bipolar patients, 0.26 Hz for OCD patients, 0.25 Hz for major depression patients, 0.23 Hz and 0.27 Hz for schizophrenia patients and their first-degree relatives respectively, all significantly slower than the rate of 0.41 Hz obtained from the normal controls. Our results show that binocular rivalry is slower in several groups of patients with mental disorders. It is possible that the abnormal temporal dynamics of binocular rivalry in patient groups may serve as apotential endophenotype for these mental disorders. However, the fact that different types of mental disorders all demonstrated similarly slower rivalry alternation suggest that the mechanism responsible for the slowdown in perceptual switching is not disease-specific. On the other hand, the current results are consistent with the possibility that these different mental disorders may have shared genetic roots. The finding that first-degree relatives of schizophrenics also had slower rivalry alternation provides further support that there might be a common genetic component in schizophrenia and in the mechanism that determines the temporal dynamics of rivalry.Study C.Previous studies have shown the possible involvement in spontaneous alternations of different brain area including prefrontal cortex and super parietal lobe. And grey matter density of several regions showed significant correlations with spontaneous switch rate. In the study we used different area brain tumor damage patients into different groups and measure the binocular rivalry change of each group. The finding have shown that the brain tumor centered in several brain area significantly decreased the binocular rivalry rate which including the temporal-parietal junction area, the frontal-parietal junction and the parietal area.