Cortical Suppression to Delayed Self-Initiated Auditory Stimuli in Schizotypy

Abstract

Schizophrenia patients have been shown to exhibit subnormal levels of electrophysiological suppression to self-initiated, button press elicited sounds. These self-suppression deficits have been shown to improve following the imposition of a subsecond delay between the button press and the evoked sound. The current study aimed to investigate whether nonclinical individuals who scored highly on the personality dimension of schizotypy would exhibit similar patterns of self-suppression abnormalities to those exhibited in schizophrenia. Thirty-nine nonclinical individuals scoring above the median (High Schizotypy) and 41 individuals scoring below the median (Low Schizotypy) on the Schizotypal Personality Questionnaire (SPQ) underwent electroencephalographic recording. The amplitude of the N1-component was calculated while participants (1) listened to tones initiated by a willed button press and played back with varying delay periods between the button press and the tone (Active conditions) and (2) passively listened to a series of tones (Listen condition). N1-suppression was calculated by subtracting the amplitude of the N1-component of the auditory evoked potential in the Active condition from that of the Listen condition, while controlling for the activity evoked by the button press per se. The Low Schizotypy group exhibited significantly higher levels of N1-suppression to undelayed tones compared to the High Schizotypy group. Furthermore, while N1-suppression was found to decrease linearly with increasing delays between the button press and the tone in the Low Schizotypy group, this was not the case in the High Schizotypy group. The findings of this study suggest that nonclinical, highly schizotypal individuals exhibit subnormal levels of N1-suppression to undelayed self-initiated tones and an abnormal pattern of N1-suppression to delayed selfinitiated tones. To the extent that these results are similar to those previously reported in patients with schizophrenia, these findings provide support for the existence of a neurophysiological "continuum of psychosis".

Theta phase synchrony is sensitive to corollary discharge abnormalities in early illness schizophrenia but not in the clinical high-risk syndrome

“…We suggest that deficits in suppression of theta ITC may be a biomarker of schizophrenia, while deficits in N1-suppression may be a biomarker of more general psychosis vulnerability; it is apparent in patients with schizophrenia (Ford et al, 2007a, Ford et al, 2001c, Ford et al, 2013, Ford et al, 2007b), psychotic bipolar patients (Ford et al, 2013), patients with schizoaffective disorder (Ford et al, 2013), non-help-seeking people with schizotypy (Oestreich et al, 2016), CHR samples (Mathalon et al, 2018), and it is reduced at intermediate levels in unaffected first-degree relatives of patients with schizophrenia, psychotic bipolar disorder, and schizoaffective disorder (Ford et al, 2013).…”

“…Importantly, this effect is disrupted in people with schizophrenia (Ford et al, 2013, Ford et al, 2007a, Ford et al, 2001a, Ford et al, 2001b, Ford et al, 2007b, Ford et al, 2010, Heinks-Maldonado et al, 2007), bipolar disorder (Ford et al, 2013), schizotypy (Oestreich et al, 2016), and in people at clinical high risk (CHR) for psychosis (Mathalon et al, 2018). In first-degree relatives of people with schizophrenia and psychotic bipolar disorder, suppression values are intermediate between healthy controls and ill probands (Ford et al, 2013).…”

Auditory prediction errors as individual biomarkers of schizophrenia

“…Similarly, healthy controls may experience mild schizotypal symptoms which do not warrant clinical diagnosis, but suggest a ‘continuum of psychosis’ (Oestreich et al, 2016). In keeping with this idea, in a study by Light and Braff (2005), links have previously been made between MMN and GAF scores in schizophrenia patients using individual EEG sites and a duration stimulus paradigm, with a correlation of 65% that accounted for 42% of the total variance.…”

The functional anatomy of self-generated and predictable speech

“…Individuals at high-risk for developing a psychotic disorder exhibit auditory attenuation that is intermediate between healthy participants and patients with schizophrenia (Perez et al, 2012). Moreover, healthy individuals with psychotic-like experiences show less auditory attenuation compared to healthy individuals without psychotic-like experiences (Oestreich et al, 2015(Oestreich et al, , 2016.…”