Long range frontal/posterior phase synchronization during remembered pursuit task is impaired in schizophrenia

Abstract

Although smooth pursuit eye movement (SPEM) is a reliable endophenotype of schizophrenia., exact underlying cognitive and neural substrates remain unknown. A simple mechanistic model of SPEM assumes an efficient interaction in integrating sensory input from the medial temporal (MT)/ medial superior temporal (MST) brain regions and subsequent motor response through the frontal eye field (FEF). Poor functional connectivity between these two regions could explain impaired motion perception and SPEM maintenance in schizophrenia. In the present study, we combined an eye tracking paradigm with electroencephalography (EEG) recordings to investigate the putative functional connectivity among frontal/posterior brain regions in mediating the modulation of SPEM. Twenty four schizophrenic (SZ) and 22 healthy control (HC) participants performed remembered pursuit tasks with EEG recordings. Behaviorally, HC subjects showed significant improvement in SPEM response on repeated presentations of target compared to SZ subjects. Neurophysiologically HC subjects showed higher frontal/posterior phase synchronization in the beta to low gamma range frequency bands during all target presentations. In addition there was a significant increase in phase synchronization in the beta-2 frequency band in HC subjects during late compared to early target presentation. In contrast, higher frontal/posterior phase synchronization in the beta-2 frequency predicted better performance during late target presentation and lower enduring psychosis in SZ subjects. These data suggest a pathologically perturbed connectivity between frontal and posterior cortical regions during SPEM in SZ. The integrative eye tracking-EEG approach used in this study to dissect the endophenotype may reveal novel targets for studying schizophrenia psychopathology.

Electrophysiological insights into connectivity anomalies in schizophrenia: a systematic review

“…Two studies [42,43] reported a reduction of phase-synchronization during visual processing requiring perceptual binding along different stages of the visual hierarchy. Alterations in fronto-posterior high-frequency connectivity in ScZ have been also reported during smooth pursuit eye movements [44], a reliable endophenotype of ScZ. Furthermore, alterations in alpha connectivity have been related to impaired recognition of facial emotional expression in ScZ [45].…”

Visual Attention Decits in Schizophrenia Can Arise From Inhibitory Dysfunction in Thalamus or Cortex

“…Future extensions of our model can address many more schizophrenia symptoms by linking the FEF with other areas. For example, the FEF normally synchronizes with LIP just prior to saccades (Buschman & Miller, 2007), a phenomenon that may be mediated by a thalamic relay (Gollo, Mirasso, & Villa, 2010; Viriyopase, Bojak, Zeitler, & Gielen, 2012), and is deficient in many schizophrenic patients (Gonzalez-Burgos, Cho, & Lewis, 2015; Hirvonen et al, 2017; Krishna, O’Neill, Sánchez-Morla, & Thaker, 2014; Uhlhaas & Singer, 2011). In addition, FEF exhibits hypoconnectivity with the central thalamus, striatum, and cerebellum in schizophrenia patients.…”

Reduced Theta-Band Power and Phase Synchrony during Explicit Verbal Memory Tasks in Female, Non-Clinical Individuals with Schizotypal Traits

“…Baving et al showed that the old/new effect in ERPs was lower in schizophrenic patients than in normal controls [ 26 ]. In addition, theta rhythm abnormalities in schizophrenic patients have been observed during resting-state and memory functions [ 39 , 62 , 63 ]. Our results regarding the old/new effect on theta power and its decrease in the schizotypal trait group are in accordance with these previous findings.…”