cortical area function
Research Papers
EEG Connectivity Patterns in Childhood Sexual Abuse: A Multivariate Application Considering Curvature of Brain Space
Introduction. A limitation of the bivariate electroencephalogram (EEG) coherence measure is low precision in location specification in anatomical space and functional connectivity. A more powerful use of functional connectivity of distributed brain systems maybe evaluation of patterns of correlations obtained through the functional connectivity matrix of Principal Component Analysis. The eigenimages that result from such analysis represent a descriptive characterization of anatomically distributed changes in the brain. There is little research exploring the relationship between childhood sexual abuse (CSA) and connectivity patterns in the brain. This study explored the connectivity patterns between 24 high-functioning, unmedicated adults with a history of CSA and age, gender, and handedness matched high-functioning adults with no history of CSA. Method. Resting eyes closed quantitative EEG (QEEG) was recorded from 19 scalp locations with a linked ears reference from 60 unmedicated adult research participants. The QEEG was subjected to measures of connectivity for analysis. Results. A robust analysis of QEEG cortical coherence revealed moderate to large effect sizes indicating patterns of both increased and decreased connectivity between brain locations, which differentiated the groups. Conclusion. The EEG coherence information extended previous work in nonclinical, unmedicated adults and suggested CSA impacts cortical function resulting in lateralized differences. Statistical methods for preventing small distribution changes from making large changes in power or probability coverage because of small and nonnormal samples is also discussed.
View Full Paper →Biofeedback-produced hemispheric asymmetry of slow cortical potentials and its behavioural effects
Two studies served to examine behavioural effects of slow cortical potentials (SPs). SPs were manipulated by means of a biofeedback procedure. The ability of human subjects to alter SPs differentially between the two hemispheres - specifically over the lateral aspects of teh central sulcus - was tested by providing feedback ofthe SP difference betwrrn C3 and C4. In Expt. I, 21 of the 45 subjects produced hemispheric asymmetries of more than 2 μV between C3 and C4 on an average after 80 trials of analogue, continuous and immediate feedback. In Expt. II, SP changes were fed back digitally at the end of each trial. Within 120 trials, 20 of the 48 subjects reached the criterion of a minimum 2-μV difference in SPs between C3 and C4 on the average. Average differentiation remained significantly below the SP differentiations achieved for continuous feedback. Trials with feedback were followed by ‘task’ trials without feedback, during which subjects were still requested to produce SP changes but also had to complete a task: Either sensorimotor tasks (Expt. I) or forced choice handedness tasks (Expt. II) were presented to evaluate behavioural consequences of hemispheric SP differences. In subjects achieving the required SP differentiation it affected the behavioural output in agreement with the known functions of the respective cortical area.
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