Page 291 - MEGIN Book Of Abstracts - 2023

M13 9PL, United Kingdom UPMC Western Psychiatric Hospital, Department of Psychia-
try, University of Pittsburgh School of Medicine, Pittsburgh,
ABSTRACT Magnetoencephalography (MEG) measures PA, USA; Department of Psychology, University of Pittsburgh,
magnetic fields generated by synchronised neural Pittsburgh, PA, USA; VA Pittsburgh Healthcare System and
current flow and provides direct inference on brain VISN 4 MIRECC, U.S. Dept of Veterans Affairs, Pittsburgh, PA,
electrophysiology and connectivity, with high spatial USA; Laboratory of Cognitive Neurodynamics, Department of
and temporal resolution. The movement-related beta Neurosurgery, Presbyterian Hospital, University of Pittsburgh
decrease (MRBD) and the post-movement beta re- School of Medicine, Pittsburgh, PA, USA; Department of Psy-
bound (PMBR) are well-characterised effects in mag- chiatry, Baylor College of Medicine and Michael E. DeBakey
netoencephalography (MEG), with the latter having VA Medical Center, Houston, TX, USA; Clinical Neurophysiol-
been shown to relate to long-range network integrity. ogy Research Laboratory, UPMC Western Psychiatric Hospital,
Our previous work has shown that the PMBR is dimin- Department of Psychiatry, University of Pittsburgh School
ished (relative to controls) in a group of schizophrenia of Medicine, Pittsburgh, PA, USA; UPMC Western Psychiatric
patients. However, little is known about how this effect Hospital, Department of Psychiatry, University of Pittsburgh
might differ in patients at different stages of illness School of Medicine, Pittsburgh, PA, USA. Electronic address:
and degrees of clinical severity. Here, we extend our salisburyd@upmc.edu
previous findings showing that the MEG derived PMBR
abnormality in schizophrenia exists in 29 recent-onset BACKGROUND Knowledge is lacking regarding deficits
and 35 established cases (i.e., chronic patients), com- in selective attention and their underlying biological
pared to 42 control cases. In established cases, PMBR mechanisms during early stages of schizophrenia. The
is negatively correlated with severity of disorganiza- present study examined the N2pc, a neurophysiological
tion symptoms. Further, using a hidden Markov model index of covert spatial attention, and its cortical sources
analysis, we show that transient pan-spectral oscilla- at first psychotic episode in the schizophrenia spec-
tory "bursts", which underlie the PMBR, differ between trum (FESz).
healthy controls and patients. Results corroborate that
PMBR is associated with disorganization of mental METHODS Neurophysiological responses measured
activity in schizophrenia. simultaneously with magnetoencephalography (MEG)
and electroencephalography (EEG) during pop-out and
Keywords: Oscillatory bursts, Post-movement beta re- serial search tasks were compared between 32 FESz
bound, Psychosis, Schizophrenia, Transient beta events and 32 matched healthy controls (HC). Mean scalp-re-
corded N2pc was measured from a cluster of posterior-
NeuroImage. Clinical (2021), Vol. 29 (33340975) (7 lateral EEG electrodes. Cortical source-resolved MEG
citations) activity contributing to the N2pc signal was derived
for the intraparietal sulcus (IPS) and lateral occipital
complex (LOC).
Inefficient visual search strategies in the first-
episode schizophrenia spectrum (2020) RESULTS Group differences in EEG N2pc varied by
task demand. FESz exhibited reduced N2pc amplitude
Sklar, Alfredo L; Coffman, Brian A; Haas, Gretchen; during pop-out (p < .01), but not serial search (p = .11).
Ghuman, Avniel; Cho, Raymond; Salisbury, Dean F Furthermore, group differences in N2pc-related MEG
cortical activity varied by task demand and cortical
Clinical Neurophysiology Research Laboratory, UPMC West- region. Compared to HC, FESz exhibited greater IPS
ern Psychiatric Hospital, Department of Psychiatry, University during serial search (p < .01).
of Pittsburgh School of Medicine, Pittsburgh, PA, USA; UPMC
Western Psychiatric Hospital, Department of Psychiatry, Uni- DISCUSSION Reductions in EEG N2pc amplitude indi-
versity of Pittsburgh School of Medicine, Pittsburgh, PA, USA; cate an impairment of visuo-spatial attention evident

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