Neural soft signs are defined as minor impairments of motor coordination, sensory integration and disinhibition. They are prevalent in people with schizophrenia spectrum disorders, including individuals with schizotypal personality traits, patients with schizophrenia and their unaffected first-degree relatives.

Association between neural soft signs and schizophrenia symptoms found in previous studies suggests the role of neural soft signs in the development of schizophrenia.

Although empirical evidences have suggested the role of impaired cortical-thalamic-cerebellar-cortical circuit in neural soft signs especially the motor coordination function, the neural mechanism of dysfunction sensory integration in schizophrenia remains unclear yet.

Raymond Chan from the Institute of Psychology (IP) of the Chinese Academy of Sciences and his international cooperators designed an experiment that recorded the brain activation of 52 first-episode patients with schizophrenia and 52 matched healthy controls, 25 unaffected siblings of patients with schizophrenia, 56 heathy monozygotic twins and 56 dizygotic twins while performing a verifies sensory integration task.

They found that the patients with schizophrenia demonstrated lower cerebellar activation compared with their healthy controls when performing the sensory integration task. Besides, the siblings of patients with schizophrenia also demonstrated lower cerebellar activation than healthy controls, but higher cerebellar activation than their probands during integration the sensory stimuli. Finally, the cerebellar activation while performing the sensory integration task was found with significant heritability 0.37.

These findings suggested that the hypoactivation found in cerebellar during sensory integration plays a vital role in the impaired sensory integration found in people with schizophrenia spectrum disorders. Besides, the cerebellar activation underlying sensory integration is heritable, suggesting its role as a candidate endophenotype of schizophrenia.

The study was published online in Journal of Abnormal Psychology. It was supported by the National Key Research and Development Programme, Beijing Municipal Science & Technology Commission Grant, and the CAS Key Laboratory of Mental Health, Institute of Psychology.