Cognitive deficits, such as impairments of working memory and attention are associated with reduced social functioning and poor outcome in schizophrenia but it is unknown how they cascade into abnormal social behavior. Schizophrenic patients have a wide range of socio-affective deficits including abnormal emotion recognition, social cue perception, “theory-of-mind” (TOM) and attribution styles but the origins of these deficits and their neural underpinnings are not yet clearly understood. We are studying the relationship between socio-affective and cognitive functions in schizophrenia using behavioral and functional neuroimaging methods. (see Cognitive Neuroscience of Belief ) Successful social interactions depend on fast and accurate interpretation of actions, intentions and emotions of others. We hypothesize that deficits in attentional orienting and working memory may be responsible for abnormal perception and interpretation of social stimuli in schizophrenia. The neural network that supports attention and working memory largely overlap with regions that are heavily implicated in the pathophysiology of schizophrenia, including the prefrontal, the posterior parietal, the anterior cingulate cortices and basal ganglia. Abnormalities of this network also result in social/affective deficits. Cognitive roots of social deficits in schizophrenia may be characterized by: (a) inability to attend to socially or emotionally relevant features, (b) inability to generate internal representation to guide behavior, (c) inability to maintain social/emotional context in working memory. We study perceptual and cognitive abnormalities that may lead to inaccurate interpretation of external events. To better understand possible perceptual origins of ToM problems, we have examined eye gaze perception and biological motion processing in schizophrenic patients. Accurate decoding of social attention in real time is important for grasping the significance of social behavior. In the case of biological motion processing, we find that schizophrenic patients are impaired in the detection and discrimiation of biological motion (i.e., movements generated by living things. Click walking.avi below to see an example or go to Point Light Display Movies ) and that these deficits arise from high 'false alarm' rate in the patients; they tend to see scrambled, nonsense motion as 'living'. In healthy people, biological motion stimuli are clearly associated with increased activation of the superior temporal sulcus whereas in schizophrenic subjects, this association is not observed. An inability to detect and discern socially relevant stimuli (e.g. people) could lead to subtle deficits in social behavior and indeed we observe a correlation between biological motion deficit and social functioning scores in schizophrenic subjects. We are also interested in understanding the relationship between spatial and affective functions. We and other labs have observed the role of affect in attentional orienting, spatial localization and other tasks. It is not surprising that spatial attention and affective arousal should be closely linked. The affective nature of the stimulus determines whether the organism moves towards or away from the stimulus. In addition, neurological data indicate that right hemisphere deficits are associated with emotional and social problems. However, the role of the right parietal cortex in spatial and affective processes is not well understood. We are currently investigating individual differences in empathy in relation to spatial information processing (perspective taking, mental rotation, pseudoneglect). To elucidate generation of internal representation of the social world, we are examining a wide range of imitation abilities in relation to social functioning. Schizophrenic patients seem unable to imitate very simple manual gestures, mouth movements or facial expressions even thought they can correctly identify these acts. Imitation ability is related to simulation of external events is linked to the “mirror neuron” mechanism supported by the left inferior frontal region that includes Broca’s area. We are currently conducting a fMRI study of language and imitation in healthy and schizophrenic subjects to relate behavior, structural findings and functional activation patterns. To summarize, we aim to better understand how cognitive deficits may lead to social deficits and to elucidate functional neuroanatomy of social cognition.
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