Akademik Veri Yönetim Sistemi
MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING, cilt.56, ss.331-338, 2018 (SCI-Expanded)
https://link.springer.com/article/10.1007%2Fs11517-017-1689-8
https://pubmed.ncbi.nlm.nih.gov/28741170/
ABSTRACT
Global field synchronization (GFS) quantifies the
synchronization level of brain oscillations. The GFS method has been introduced
to measure functional synchronization of EEG data in the frequency domain. GFS
also detects phase interactions between EEG signals acquired from all of the
electrodes. If a considerable amount of local brain neurons has the same phase,
these neurons appear to interact with each other. EEG data were received from
17 obsessive-compulsive disorder (OCD) patients and 17 healthy controls (HC).
OCD effects on local and large-scale brain circuits were studied. Analysis of
the GFS results showed significantly decreased values in the delta and full
frequency bands. This research suggests that OCD causes synchronization
disconnection in both the frontal and large-scale regions. This may be related
to motivational, emotional and cognitive dysfunctions.
DISCUSSION
Our results are similar to previous results that
indicate decreased GFS in neuroleptic-naive patients with schizophrenia [24,25,26, 47].
Moreover, our recent findings are also consistent with earlier EEG
synchronization works, including different signal processing methods used to
understand the mechanism of OCD [34, 53]. We
have focused on synchronization analysis of EEG frequency band activities
because the literature indicates that synchronous brain oscillations in slow
frequency bands provide important information about both motivational and
cognitive processes (memory, attention, perception, decision-making and
planning) [1, 39, 50] Neuroimaging
studies analyse both PET and fMRI slices for estimation of brain dynamics and
detection of the location generated delta band activity. In these studies, it
was reported that the subcortical centres generating delta band activity are in
both the medial prefrontal cortex and the orbitofrontal cortex [2, 17, 21,22,23, 35, 43] EEG
methods such as synchronization, complexity analysis, etc. are used only for
exclusion of the comorbid disease (for instance depression with OCD) with
obsessive-compulsive symptoms in clinical practise. In treatment or therapeutic
use of EEG methods is very limited. This study was shown that global field
synchronization analysis (GFS) values may be used as biomarker for OCD, and it
can be used also for monitoring course of disease and treatment. GFS studies
are shown that synchronization power is important marker for diagnosis of
neuropsychiatric diseases.
In future work, we
plan to compare the performance of those global synchronization metrics as
follows: OC, GFS, GSI and GCI in detecting the severity of OCD. In addition, we
will investigate the relationship between interneuronal synchronization and the
degree of EEG complexity within a short time interval.
CONCLUSION
Some of the investigations on OCD effects on the brain sites have shown important patterns. Neuropsychological tests indicated that OCD causes functional dysfunctions on frontal lobe [10], neuroimaging studies also support these findings [49]. One of our results is decreased synchronization on frontal site is consistent with this study.
EEG synchronization level of OCD patients was investigated, and the level was found low for delta and full frequency range. Loss of phase synchronization would have relevance with functional connectivity. The major findings of the present study are that the loss of synchronization in delta band and functional connectivity of the brain changes with OCD. Studies using low resolution brain electromagnetic tomography (LORETA) have founded delta activity at maximum level in medial prefrontal cortex and orbito-frontal cortex [2]. In addition to this, investigations with fMRI have detected abnormal and dysfunctional activity in orbito-fronto striatal networks of OCD patients [39] and fronto-subcortical network dysfunctional causes a loss of functional connectivity in the brain [2, 15, 35, 37]. Our results that functional connectivity and desynchronization in delta band for frontal and global site are also consistent with previous findings.