Mental arithmetic and eye opening. An EEG frequency analysis and GSR study.

Abstract 1. 1. Twelve healthy subjects were examined. EEG and GSR were taken when the subjects were resting with their eyes closed (C), resting with their eyes open (O), performing mental arithmetic with their eyes closed (A), and performing mental arithmetic with their eyes closed and promised financial reward (M). 2. 2. The number of GSRs in condition M as singificantly higher than in any other condition. 3. 3. Frequency analysis was mad of the EEG of the right parieto-temporal region and the number of GSRs was ascertained according to precisely specified criteria. 4. 4. In condition O relative quantities were on the average lower in all frequency bands than in conditions A and M. 5. 5. In conditions O, A and M theta and alpha activities registered a lower level than in condition C. 6. 6. In condition O beta activity decreased, while increasing on the average in conditions A and M. 7. 7. Compared with conditions C and O, the variability of beta activity in conditions M and A was lower. 8. 8. Frequency analysis did not disclose any significant difference between conditions A and M. 9. 9. The results indicate that beta activity (both its mount and variability) is more closely realted to the general level of activation than are the brain waves in any other frequency band under study.