Page 38 - MEGIN Book Of Abstracts - 2023

ence and Physiology, Sahlgrenska Academy, The University of CONCLUSIONS The atypically flattened spectral slope
Gothenburg, Gothenburg, Sweden; Center for Neurocognitive of aperiodic activity in children with ASD and below-
Research (MEG Center), Moscow State University of Psychol- average IQ suggests a shift of the global E-I balance
ogy and Education, Moscow, Russian Federation. orekhova. toward hyper-excitation. The spectral slope can provide
[email protected] an accessible noninvasive biomarker of the E-I ratio for
making objective judgments about treatment effec-
BACKGROUND Altered neuronal excitation-inhibition tiveness in people with ASD and comorbid intellectual
(E-I) balance is strongly implicated in ASD. However, disability.
it is not known whether the direction and degree of
changes in the E-I ratio in individuals with ASD corre- Keywords: 1/f power law, Autism spectrum disorders
lates with intellectual disability often associated with (ASDs), Biomarkers, Excitation–inhibition balance, Intel-
this developmental disorder. The spectral slope of the ligence, Magnetoencephalography, Power spectrum
aperiodic 1/f activity reflects the E-I balance at the scale
of large neuronal populations and may uncover its Molecular autism (2022), Vol. 13, No. 1 (35550191) (2
putative alternations in individuals with ASD with and citations)
without intellectual disability.

METHODS Herein, we used magnetoencephalography Cortical signatures of auditory object binding
(MEG) to test whether the 1/f slope would differentiate in children with autism spectrum disorder are
ASD children with average and below-average (< 85) anomalous in concordance with behavior and
IQ. MEG was recorded at rest with eyes open/closed in diagnosis (2022)
49 boys with ASD aged 6-15 years with IQ ranging from
54 to 128, and in 49 age-matched typically developing Bharadwaj, Hari; Mamashli, Fahimeh; Khan, Sheraz;
(TD) boys. The cortical source activity was estimated Singh, Ravinderjit; Joseph, Robert M; Losh, Ainsley;
using the beamformer approach and individual brain Pawlyszyn, Stephanie; McGuiggan, Nicole M; Graham,
models. We then extracted the 1/f slope by fitting a Steven; Hämäläinen, Matti S; Kenet, Tal
linear function to the log-log-scale power spectra in the
high-frequency range. Weldon School of Biomedical Engineering, Purdue University,
West Lafayette, Indiana, United States of America; Athinoula
RESULTS The global 1/f slope averaged over all corti- A. Martinos Center for Biomedical Imaging, Massachusetts
cal sources demonstrated high rank-order stability General Hospital, Charlestown, Massachusetts, United States
between the two conditions. Consistent with previous of America; Boston University School of Medicine, Boston,
research, it was steeper in the eyes-closed than in the Massachusetts, United States of America; Department of
eyes-open condition and flattened with age. Regardless Neurology, Massachusetts General Hospital, Boston, Massa-
of condition, children with ASD and below-average IQ chusetts, United States of America
had flatter slopes than either TD or ASD children with
average or above-average IQ. These group differences ABSTRACT Organizing sensory information into coher-
could not be explained by differences in signal-to-noise ent perceptual objects is fundamental to everyday
ratio or periodic (alpha and beta) activity. perception and communication. In the visual domain,
indirect evidence from cortical responses suggests that
LIMITATIONS Further research is needed to find out children with autism spectrum disorder (ASD) have
whether the observed changes in E-I ratios are char- anomalous figure-ground segregation. While auditory
acteristic of children with below-average IQ of other processing abnormalities are common in ASD, espe-
diagnostic groups. cially in environments with multiple sound sources, to
date, the question of scene segregation in ASD has not
been directly investigated in audition. Using magne-

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