Yazdi-Ravandi Saeid, Mohammadi Arezooji Dorsa, Matinnia Nasrin, Shamsaei Farshid, Ahmadpanah Mohammad, Ghaleiha Ali, Khosrowabadi Reza
Behavioral Disorders and Substance Abuse Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
Institute for Cognitive and Brain Sciences, Shahid Beheshti University GC, Tehran, Iran.
EXCLI J. 2021 Mar 15;20:462-654. doi: 10.17179/excli2020-2783. eCollection 2021.
The human brain is considered as a self-organizing system with self-similarities at various temporal and spatial scales called "fractals". In this scale-free system, it is possible to decode the complexity of information processing using fractal behavior. For instance, the complexity of information processing in the brain can be evaluated by fractal dimensions (FDs). However, it is unclear how over-elaboration of information processing impacts the dimensionality of its fractal behavior. In this study, we hypothesized that FDs of electroencephalogram (EEG) in obsessive-compulsive disorder (OCD) should be higher than healthy controls (HCs) because of exaggeration of information processing mainly in the frontal regions. Therefore, a group of 39 OCDs (age: 34.76±8.22, 25 female, 3 left-handed) and 19 HCs (age: 31.94±8.22, 11 female, 1 left-handed) were recruited and their brain activities were recorded using a 19-channel EEG recorder in the eyes-open resting-state condition. Subsequently, fractal dimensions of the cleaned EEG data were calculated using Katz's method in a frequency band-specific manner. After the test of normality, significant changes in the OCDs as compared to the HCs were calculated using a two-sample t-test. OCDs showed higher FDs in the frontal regions in all frequency bands as compared to HCs. Although, significant increases were only observed in the beta and lower gamma bands, mainly at the high beta. Interestingly, neurophysiological findings also show association with severity of obsessive behaviors. The results demonstrate that complexity of information processing in the brain follows an intimate nature of structural and functional impairments of the brain in OCD.
人类大脑被认为是一个自组织系统，在各种时间和空间尺度上具有自相似性，即所谓的“分形”。在这个无标度系统中，可以利用分形行为来解码信息处理的复杂性。例如，大脑中信息处理的复杂性可以通过分形维数（FDs）来评估。然而，目前尚不清楚信息处理的过度精细化如何影响其分形行为的维数。在本研究中，我们假设强迫症（OCD）患者脑电图（EEG）的FDs应高于健康对照（HCs），因为主要在额叶区域信息处理过度。因此，招募了一组39名强迫症患者（年龄：34.76±8.22，25名女性，3名左利手）和19名健康对照（年龄：31.94±8.22，11名女性，1名左利手），并在睁眼静息状态下使用19通道脑电图记录仪记录他们的大脑活动。随后，使用Katz方法以特定频段的方式计算清理后的EEG数据的分形维数。在进行正态性检验后，使用双样本t检验计算强迫症患者与健康对照相比的显著变化。与健康对照相比，强迫症患者在所有频段的额叶区域均显示出更高的FDs。虽然仅在β和较低的γ频段观察到显著增加，主要是在高β频段。有趣的是，神经生理学结果也显示与强迫行为的严重程度有关。结果表明，大脑中信息处理的复杂性与强迫症患者大脑的结构和功能损伤的密切性质相关。
