Certain traits that are not necessarily psychotic in appearance are more prevalent in the families of schizophrenic patients than they are in the general population. We have identified and studied several of these traits using them as supplementary phenotypes in linkage analysis and also as guides to the pathophysiology of schizophrenia. Here we propose studies of two of the major traits we have previously, identified as being significantly associated with schizophrenic psychosis and also occurring prominently in the unaffected biological family members of the patients: eye tracking dysfunctions (ETD) and spatial working memory impairments. Our research has shown that a major component of ETD is a defect in motion perception. We propose to follow up this finding to see whether the raised motion discrimination thresholds observed in patients also occur in unaffected relatives. Further, using psychophysical method we will study whether local or global motion processing is involved in the impairments, a result that has consequences for the brain localization of ETD. fMRl scanning of patients and relatives viewing pursuit, saccade, and pure motion targets will be undertaken to supply physiological information about the brain localization of the eye tracking defect and as support or disconfirmation of the psychophysical studies. The second trait, spatial working memory, will be studied along side of two kinds of object working memory to discern whether other domains of working memory are also impaired. The modularity of working memory domains has consequences for specifying the pathophysiology of schizophrenia. We will compare performance on spatial and object working memory, the latter using two very different kinds of stimuli: memory for faces and memory for snowflakes. The first has an immediacy and cogency not present in the perception of other objects, and there probably is also a dedicated neural hardware for face perception. Perception of snowflakes, on the other hand, tests object working memory without a verbal component. fMRl of patients and relatives while performaning these working tasks will also be undertaken.
Showing the most recent 10 out of 73 publications
