Quantitative EEG Changes during Verbal Memory Task Performance in Schizophrenia

Jon, Duk In; Lee, Hong Shick; Lee, Sung Hoon; Min, Sung Kil

Abstract

OBJECTIVE
Under the hypothesis that activated brain regions of patients with schizophrenia differ from those of normal subjects during memory task performance, this study was aimed to investigate topographic changes related to memory functions in schizophrenia. METHOD: Subjects of this study consisted of 20 unmedicated patients with schizophrenia and 19 normal controls who were matched for age, sex, and handedness. Quantitative EEG(QEEG) with 32 channels was recorded with eyes closed(EEG0) and open(EEG1) in a resting condition and during computerized verbal encoding(EEG2) and recognition(EEG3) tasks.
RESULTS
During EEG1, 2, and 3, there was a decrease in alpha activity in both groups compared to EEG0 and the change in alpha activity of patients was significantly lesser than normal controls in the occipital region. Pairwise comparison showed that the alpha activity of normal controls significantly increased from EEG1 to EEG2 in the parietal region and from EEG1 to EEG3 in all regions except both frontal regions while those of patients did not change. The beta activity of normal controls significantly increased from EEG1 to EEG2 in both temporal regions and from EEG1 to EEG3 in the frontal, temporal, and parietal regions while those of patients significantly increased only in the parieto-occipital region.
CONCLUSION
These results indicate that the frontal lobe, temporal lobe, and thalamus are not appropriately activated during memory tasks in schizophrenia. It may be proposed that the learing of visually presented words in patients with schizophrenia depends on distinct memory process such as priming.