Increased activation of the neural reward network occurred when patients with schizotypal personality disorder watched points-of-light animations of biological motion, according to a controlled functional MRI study published online Jan. 19.
“These findings may help to characterize the interaction between disturbed reward circuitry and the bizarre ways of perceiving and experiencing social stimuli observed in individuals with schizotypal personality disorder, whose condition tends to isolate them from everyday social interaction,” said Ji-Won Hur, Ph.D., of Seoul National University in South Korea, and associates.
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Interpreting motion is key to social communication, and humans assign intentions and emotions to points of light depicting a moving body. Brain imaging during these animations shows that the posterior superior temporal sulcus (PSTS) works with the ventral lateral occipital cortex, lingual gyrus at the cuneus border, and cerebellum to form a “social cognition network,” the researchers noted. Patients with schizophrenia perceive biological motion abnormally and have abnormal PSTS activation. To understand the neural response in schizotypal personality disorder, the investigators asked 21 patients and 38 matched controls to distinguish biological point-light animations from scrambled sequences during functional MRI (JAMA Psychiatry. 2016 Jan 20. doi: 10.1001/jamapsychiatry.2015.2985).
Brain imaging of both groups showed neuronal activation specific to biological motion within the PSTS, the investigators reported. But participants with schizotypal personality disorder had abnormally high activation of brain regions that form the reward network, including the dorsal striatum and bilateral superior medial frontal cortex (P of clusters less than .002). Participants with schizotypal personality disorder also had less activation of the anterior and middle cingulate cortices, as well as the lingual and superior occipital gyri, which are normally involved in executive function (P of clusters less than .001). Furthermore, activation of dopaminergic regions of the brain correlated significantly with symptoms of schizotypal personality disorder (P less than .02).
Taken together, the findings “suggest that enhanced responses arise within the reward network in individuals with [schizotypal personality disorder], and are possibly related to the peculiar ways that individuals with [schizotypal personality disorder] behave in social contexts,” said the researchers. “We are reminded of the social deafferentation hypothesis, which states that social withdrawal may produce abnormal cognitive attributions in individuals with an unfulfilled desire for social contact. Perhaps abnormal neural activations seen in people within the spectrum of schizophrenia disorder promote misinterpretation of cues guiding social interactions.”
The study was supported by the Ministry of Science, ICT, and Future Planning, and by the Ministry of Education, Science, and Technology. The investigators had no disclosures.