Speaker: Thomas Whitford (UNSW)
Topic: Distinguishing self from world in schizophrenia and schizotypy.
Self-generated sensations typically feel less salient than externally-generated sensations, with the fact that it is difficult to tickle oneself as a well-known example. Consistent with this phenomenon, it is well-established that self-produced sensations, such as the sound of one’s own voice, evoke less activity in the electroencephalogram (EEG) than do physically identical, externally-produced sensations.
There is growing evidence to suggest that this normative process of ‘sensory self-suppression’ is abnormal in people with schizophrenia. Schizophrenia patients do not appear to exhibit the normative suppression of EEG activity to self-generated speech; that is, they do not appear to make a fundamental sensory distinction between self-generated and externally-generated stimuli. These ‘sensory self-suppression’ abnormalities have been argued to underlie some of the most bizarre yet characteristic symptoms of schizophrenia, such as delusions of control, in which patients misattribute self-generated actions to external agents.
In this talk I will review evidence from the human and animal literature for the process of ‘sensory self-suppression’, as well as the evidence that that this process is abnormal in people with schizophrenia. I will also discuss studies (both EEG and behavioural) from my own laboratory which suggest that self-suppression abnormalities may not be limited to people with established schizophrenia, but may also be present in non-clinical, highly schizotypal individuals.