ABSTRACT
Objective: To study the differences of activated brain areas during brain error monitoring in schizophrenia patients. Methods: The latencies and amplitudes of error related negativity (ERN) were obtained in 16 patients with first episode schizophrenia and 25 normal controls by high-density event related potential (ERP) technique, and the activated areas were analyzed by low resolution electromagnetic tomography (LORETA). Results: The correct response rate was significantly lower in the schizophrenia participant group than in the control group (P<0.01), and the reaction periods of correct responses and incorrect responses were significantly longer in the schizophrenia group than in the control group (P<0.05, P<0.01). The ERN latencies in the schizophrenic patients were significantly longer on Cz and Pz electrodes compared with those in the control subjects (P<0.05) and ERN amplitudes were significantly smaller than those in the controls (P<0.05). The activation of insula, superior temporal gyrus, middle temporal gyrus, and inferior parietal lobule were obviously lower in the schizophrenic participants than in the controls. Conclusion: Some brain area, such as insular, may contribute to the dysfunction of error monitoring in schizophrenia patients.
ABSTRACT
Objective:To explore the spatio-temporal dynamics of brain mechanisms in visual change detection by 256-channel event-related potential (ERP) and low-resolution electromagnetic tomography (LORETA) analyses.Methods：ERP were recorded in 12 healthy participants during performing an S1-S2 matching task.Visual stimuli defined by color and shape.Each trial consisted of two sequentially presented stimuli (S1 and S2),where S2 was either the same as S1,different from S1 in shape only,different in color only,or different in both color and shape.Subjects matched the stimuli according to task demands：attending to color and attending to shape.Result：Change condition elicited change-related positivity (CRP) ranging 135～165 ms.The estimated source regions contributing to CRP were lingual gyrus and cuneus of occipital lobe.N200 was elicited in no change and task-irrelevant change condition ranging 235～275 ms.The source for N200 was in the right temporal fusiform gyrus,middle temporal gyrus and parahippocampal gyrus.In the time window of 240～320 ms,N270 was elicited in all change conditions.The N270 source was localizable to the anterior cingulated cortex and amygdala.Conclusion：In the early stage,CRP reflects the preattentive processing of visual changes.The LORETA result confirms that CRP is generated in the early visual areas.N200 may be related to the active ignored processing of task-irrelevant change.The source for N200 is in the right temporal fusiform gyrus,middle temporal gyrus and parahippocampal gyrus.In the late stage,N270 reflects the advanced processing of visual change in the human brain.The N270 source may be in anterior cingulate cortex (ACC) and amygdala.
ABSTRACT
OBJECTIVE: The purpose of this study was to identify the regions of the brain associated with recurrent nocturnal chronic hypoxic episodes in patients with untreated obstructive sleep apnea syndrome (OSAS) using low-resolution electromagnetic tomography (LORETA) and quantitative electroencephalography (QEEG). METHODS: Nocturnal polysomnograph (NPSG) and subsequent morning electroencephalograph (EEG) were measured in 20 subjects with OSAS. Mild (n=10 ages 39.5+/-12.1 years) and severe (n=10 ages 41.7+/-13.6 years) right-handed male OSAS subjects were selected by interview and questionnaires including the NPSG, Beck Depression Inventory, Beck Anxiety Inventory, Epworth Sleepiness Scale, and Pittsburgh Sleep Quality Index. The LORETA and QEEG were compared between the severe and mild OSAS groups by frequency bands (delta 1-3 Hz, theta 4-7 Hz, alpha 8-12 Hz, beta1 13-18 Hz, beta2 19-21 Hz, beta3 22-30 Hz, and total 1-30 Hz) made by spectral analysis during resting with the eyes closed. RESULTS: The LORETA analysis showed decreased alpha activity at the right posterior cingulate gyrus (Brodmann area 23) in cases with severe OSAS compared to mild OSAS (p<0.05). For the QEEG, the absolute power of the alpha activity (8-12 Hz) was decreased in P3 (p=0.047), PZ (p=0.039) and O2 (p=0.04) in cases with severe OSAS compared to mild OSAS cases. The LORETA and QEEG analyses had similar results with regard to band, activation and location. CONCLUSION: The decreased activity of the alpha frequency in the right posterior cingulate gyrus, in patients with severe OSAS compared to those with mild OSAS, suggests that chronic repeated short-term hypoxia during sleep, in OSAS, could provoke cortical brain dysfunction associated with cognitive dysfunction such as memory and attention.
Subject(s)
Humans , Male , Hypoxia , Anxiety , Brain , Depression , Electroencephalography , Gyrus Cinguli , Hypoxia, Brain , Magnets , Memory , Surveys and Questionnaires , Sleep Apnea, ObstructiveABSTRACT
BACKGROUND: Although olfactory stimulation has been known to produce effects on human mood and cognition, the specific EEG patterns of activity was reported diversely. The purpose of this study was to investigate EEG changes by odorant using low resolution electromagnetic tomography (LORETA) in young healthy subjects. METHODS: The EEG's of nineteen (10 males, 9 females) non-smoking right-handed college students were recorded after odorant stimulation. A nineteen-channel EEG was recorded referenced to linked ears before and during olfactory stimulation. Olfactory stimulation was presented with lavender essential oil by blotter method. The LORETA power was computed from ten 2-s epochs, separately for the different EEG frequencies. The power values were logarithmically transformed and paired sample t-tests were done for each voxel and frequency band (1.5-30 Hz). Statistical results were displayed 3-dimensionally on the standard brain template. RESULTS: All subjects experienced positive feelings (relaxed and pleasant) by olfactory stimulation with lavender oil (p<0.01). The LORETA power of theta and alpha band was increased in the dorsolateral and medial frontal areas, predominantly in the posterior cingulate gyri. The alpha LORETA power was also increased in bilateral orbitofrontal regions and the left perisylvian region including the insular cortex. Beta power was increased in the posterior cingulated gyri and mesial temporal region, predominantly on the left side. CONCLUSIONS: These results suggest that olfaction associated with emotional feeling might induce brain electrical power changes not only in the limbic system but also in the neocortex with lateralization to the dominant hemisphere.