Working Memory Tasks Reflections on Electrical Activity of the Brain

Abstract

Introduction & rationale: Recent theoretical and experimental work has focused on the changes of electro encephalographic waves in working memory and there has been particular interest in oscillations in the theta and alpha frequency bands. It is apparent that there are a lot of discrepancies among findings of different studies concerning EEG during memory tasks. Aim of the work: was to assess changes in the electric activity of the brain during working memory tasks. Subjects & Methods: A cross-sectional descriptive study was done in the EEG unit in Suez Canal University hospital to reveal the changes that occur in the electric activity of the brain during Sternberg memory task performance. 43 subjects volunteered to our study. They all underwent EEG recording during performance of a visual Sternberg memory task. This EEG record was compared to another baseline EEG record done before task performance to monitor the changes that occurred in the electric activity of the brain. Results: Analysis of the EEG waves in parietal temporal and occipital brain areas revealed that: There is significant difference between peak power frequency (PPF) before and during task performance. As PPF in the theta band was significantly more frequent during the task performance than before task performance (P< 0.05). While PPF at central electrodes, in most of the subjects, have no significant difference before and during task performance in the theta band. While theta waves are significantly more frequent during the task performance than before task performance at CZ (P< 0.05). There was a significant change in the Relative Power of beta1, beta 2 frequency band before and during task performance with P value<0.05. There was non-significant change in the Relative Power of other frequency bands before and during task performance (P>0.05). in addition the degree of task performance was strongly correlated with power of beta 1 and delta bands before task performance. Conclusions: We concluded that working memory task is reflected on the electric activity of the brain in the form of peak power frequency in the range of theta oscillations in parietal, occipital, temporal areas of the brain. There was a significant increase in the relative power of beta 1, beta 2 frequency bands during task performance. However, degree of task performance was strongly related to the relative powers of beta 1 and delta frequency bands before task performance.