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ABSTRACT: To characterize the altered directed connectivity within a distributed cortical network, as is associated with the impaired attention modulation involved in the manifestation of mood disorder in depression, short-window partial directed coherence (PDC) combining with the event-related brain potentials (ERPs) was applied in this study. ERPs were recorded from 13 normal subjects and 12 depressed patients during visual search for facial expressions. The evoked N2 component of ERPs by responding to all neutral faces (F(1,22)=5.51, P<0.05) and the positive face was reduced in the depressed patients as compared to the normal subjects (F(1,22)=5.71, P<0.05), while the evoked N2 component by detecting the negative face showed no significant between-group effect (F(1,22)=2.10, P=0.16). The reduced N2 amplitude reflected deficits in effortful attentional modulation in depression. Obtained PDC values within the N2 time-window (150-300 ms post stimulus) showed weaker intra-frontal and intra-central directed interactions and enhanced occipital information output when responding to all neutral faces in depression relative to those in the normal group. Few decreased intra-frontal directed interactions were observed when detecting the emotional face in depression. The altered cortical directed connectivity contributed to the impairment occurring in the effortful attention modulation in depression. Our findings supported that the impaired attention modulation processing in depression was associated with the altered cortical connectivity.
Progress in Neuro-Psychopharmacology and Biological Psychiatry 08/2011; 35(8):1891-900. · 3.25 Impact Factor
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ABSTRACT: Cognitive control of emotion plays an important role in maintaining emotional stability in people's daily life. However, the neural mechanism remains unclear. This study examined the induced gamma activity in response to emotional expressions which was associated with the cognitive regulation. Electroencephalogram (EEG) was recorded in fifteen normal subjects when detecting emotional expressions. The mean energy was estimated using time-frequency representations in two gamma bands, low gamma band (25-50 Hz) and high gamma band (50-70 Hz), and eight time windows from 0 to 800 ms after the stimulus onset. Two typical gamma activities were observed: (1) the early gamma activity in the 100-200 ms time window was attenuated along with the increased detection difficulty, reflecting the bottom-up attention regulation; (2) the late gamma activity after 400 ms post-stimulus was enhanced with the increased detection difficulty, reflecting the top-down cognitive control. The characteristics of the induced early gamma activity distinguished different mechanisms of attention regulation in the early stage for detecting the negative expression and detecting the positive one. Our study suggested the induced gamma activity was a useful tool to uncover the mechanism of cognitive control of emotion.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2011; 2011:1717-20.
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4th International Conference on Biomedical Engineering and Informatics, BMEI 2011, Shanghai, China, October 15-17, 2011; 01/2011
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ABSTRACT: Enhanced error-related negativity (ERN) has been associated with anxiety among both non-clinical and clinical populations. However, whether it is abnormal among adult patients with generalized anxiety disorder (GAD) is still unknown. The present study investigated it across GAD and obsessive-compulsive disorder (OCD). Event related brain potentials (ERPs) were recorded from a group of 27 GAD patients, 25 OCD patients and 27 healthy control participants during a modified Erikson Flankers task. ERP difference waveforms were obtained by subtracting ERP to correct response (CRN) from ERP to error response (ERN). The Ne component of ERPs at medial frontal electrodes were analyzed and reported. The Ne component of ERP difference waveform was enhanced only in OCD patients, but not in GAD patients, as compared to the healthy controls. An exploratory analysis also revealed higher Ne amplitude of error trial waveforms in both GAD and OCD patients than in healthy controls, and an insignificant group difference in Ne component of correct trial waveforms. The Ne amplitude of error trial waveforms also correlated with Hamilton Anxiety Rating Scale (HAMA) scores and with Hamilton Depression Rating Scale (HAMD) scores across the three subject groups. The main findings of the present study suggest that error processing is altered in OCD but not in GAD, and that ERN abnormalities in GAD are possibly associated with an overactive response checking process or excessive response monitoring.
Progress in Neuro-Psychopharmacology and Biological Psychiatry 01/2011; 35(1):265-72. · 3.25 Impact Factor
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Advances in Neural Networks - ISNN 2010, 7th International Symposium on Neural Networks, ISNN 2010, Shanghai, China, June 6-9, 2010, Proceedings, Part II; 01/2010
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ABSTRACT: Decreased P300 amplitude has been reported in schizophrenics during their first episode. The brain sources that contribute to this abnormality have not yet been well documented, and were investigated in the present study using high density EEG recordings. Nineteen drug-naive first episode schizophrenics were compared to 25 normal controls. Auditory P300 was elicited using an oddball paradigm. The brain sources of P300 ERP were reconstructed by performing low resolution of electromagnetic tomography (LORETA) analysis. No group difference in P300 latency was found. P300 amplitude was smaller for schizophrenics than for controls. Topographical analysis revealed that P300 amplitude reduction in schizophrenics was significant over left and medial regions of interest (ROIs). LORETA analysis of the P300 peak revealed that, the brain sources of P300 were symmetrically distributed over left and right hemispheres among the normal controls, but were asymmetrically distributed among the patients, with a reduction predominantly over the left temporal area. Statistical non-Parametric Mapping analysis identified 29 voxels of a significant group difference, which focused on left insula, left superior temporal gyrus (STG) and left postcentral gyrus (PCG). In addition, the mean P300 current source density over left insula, left STG and left PCG correlated inversely with the patients' Positive and Negative Syndrome Scale scores. The neural substrates that contributed to the decreased P300 amplitude in drug-naive first episode schizophrenia relatively focused on left STG and its nearby areas. These areas are probably involved in the pathogenesis of schizophrenia, and possible mechanisms for pathology need to be further clarified.
International journal of psychophysiology: official journal of the International Organization of Psychophysiology 12/2009; 75(3):249-57. · 3.05 Impact Factor
