A Cognitive Neuroscience View of Schizophrenic Symptoms: Abnormal Activation of a System for Social Perception and Communication

We will review converging evidence that language related symptoms of the schizophrenic syndrome such as auditory verbal hallucinations arise at least in part from processing abnormalities in posterior language regions. These language regions are either adjacent to or overlapping with regions in the (posterior) temporal cortex and temporo-parietal occipital junction that are part of a system for processing social cognition, emotion, and self representation or agency. The inferior parietal and posterior superior temporal regions contain multi-modal representational systems that may also provide rapid feedback and feed-forward activation to unimodal regions such as auditory cortex. We propose that the over-activation of these regions could not only result in erroneous activation of semantic and speech (auditory word) representations, resulting in thought disorder and voice hallucinations, but could also result in many of the other symptoms of schizophrenia. These regions are also part of the so-called "default network", a network of regions that are normally active; and their activity is also correlated with activity within the hippocampal system.