Absence of Auditory M100 Source Asymmetry in Schizophrenia and Bipolar Disorder: A MEG Study

Abstract

BackgroundWhether schizophrenia and bipolar disorder are the clinical outcomes of discrete or shared causative processes is much debated in psychiatry. Several studies have demonstrated anomalous structural and functional superior temporal gyrus (STG) symmetries in schizophrenia. We examined bipolar patients to determine if they also have altered STG asymmetry.MethodsWhole-head magnetoencephalography (MEG) recordings of auditory evoked fields were obtained for 20 subjects with schizophrenia, 20 with bipolar disorder, and 20 control subjects. Neural generators of the M100 auditory response were modeled using a single equivalent current dipole for each hemisphere. The source location of the M100 response was used as a measure of functional STG asymmetry. ResultsControl subjects showed the typical M100 asymmetrical pattern with more anterior sources in the right STG. In contrast, both schizophrenia and bipolar disorder patients displayed a symmetrical M100 source pattern. There was no significant difference in the M100 latency and strength in bilateral hemispheres within three groups.ConclusionsOur results indicate that disturbed asymmetry of temporal lobe function may reflect a common deviance present in schizophrenia and bipolar disorder, suggesting the two disorders might share etiological and pathophysiological factors.

40 Hz Auditory Steady-State Response: The Impact of Handedness and Gender

“…However, in both schizophrenia and bipolar disorder, a diminished left-right hemispheric asymmetry for the 40Hz ASSRs has been shown (Teale et al 2003;Reite et al 2009;Tsuchimoto et al 2011). This is in line with an overall reduction of brain asymmetry on both the structural and functional level in neuropsychiatric disorders (Wang et al 2013;Ribolsi et al 2014;Royer et al 2015;Delvecchio et al 2017).…”

Alteration of Red Nucleus Microstructure in Depressive Bipolar II Disorder and Unipolar Depression: A Diffusion Kurtosis and Perfusion Imaging Study

“…Pearson correlation coefficients were used to assess the correlation between patient clinical variables and their DKI/3D ASL parameters, as well as to assess the correlation between the size of the red nucleus and the DKI/3D ASL parameters. Asymmetry indexes were calculated using the formula (R − L)/(R + L) × 100 36 , for the direct evaluation of lateralization of each DKI-and 3D ASL-generated parameter among the three groups. Inter-rater reliability was assessed using the intraclass correlation coefficient (ICC) analysis.…”

“…Many previous studies have reported a certain degree of asymmetry in various parameters of BD or UD. For example, disrupted asymmetry of temporal lobe function was revealed by magnetoencephalography [36] in BD patients; the cerebral perfusion [61] and the magnetization transfer ratio [62] both showed an asymmetric pattern in these patients. However, the present study revealed that the asymmetry index of each parameter that was generated by DKI and 3D ASL, using the formula (R − L)/(R + L) × 100, did not differ among depressive BD-II, UD, and HC groups.…”

“…Alteration of Red Nucleus Microstructure in Depressive Bipolar II Disorder and Unipolar Depression: A Diffusion Kurtosis and Perfusion Imaging Study disease [35], normal aging1 [7,36], Alzheimer's disease [37,38], attention-deficit hyperactivity disorder [39], and schizophrenia [40]. However, few studies related to BD and UD have used DKI to evaluate the microstructural integrity of red nucleus.…”