Cognitive dysfunction is a hallmark of schizophrenia. However, underlying deficits in basic sensory processing are a contributing factor to higher order processing deficits. In the auditory system, there is evidence for functionally distinct ventral and dorsal pathways, governing sound object recognition ('what') and sound localization ('where'), respectively. The event-related potential known as mismatch negativity (MMN) has been used to index sound object recognition. It is robustly elicited in healthy subjects when a deviant tone is interjected in a train of standard tones. In schizophrenia, the MMN is significantly attenuated, providing strong evidence for deficits in early auditory processing, namely, 'what' pathway impairment. To this author's knowledge, no research has yet shown deficits in both the 'what' and 'where' pathways in schizophrenia. In the proposed study, integrity of the ventral and dorsal pathways in schizophrenia patients will be assessed through behavioral and electrophysiological tasks. For the dorsal, or 'where' pathway, a sound localization experiment will be conducted. For the ventral, or 'what' pathway, we will conduct a sound object recognition experiment. As our understanding of the specific nature of auditory system deficits in schizophrenia increases, so will avenues for diagnosis, treatment, and etiological understanding of the illness. ? ? ?
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