Browsing by Author "Ford, Martin Randall"
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Item Biofeedback training of 40Hz EEG in humans: follow-up on control, generalization of effect, and maintenance of control during problem solving(1976) Ford, Martin Randall; Sheer, Daniel E.; Day, Mary Carol; Stewart, Robert L.; McCary, James L.Long-term voluntary control of 40Hz EEG activity was investigated in six subjects, originally trained to increase and suppress 40Hz EEG in a previous study. The elapsed time between initial biofeedback training and follow-up control testing varied from one to three years. No practice sessions were held during this period. Subjects were first instructed to alternately produce and suppress 40Hz EEG with feedback. Feedback was terminated for subsequent periods if and when consistent control was shown. During the final session, subjects were given a battery of test items and were instructed to alternately produce and suppress 40Hz EEG while solving problems. Forty Hertz EEG was monitered from the O[lowered 1]-C[llowered z]. O[lowered 2]-C[lowered z]. P[lowered 3]-C[lowered z], P[lowered 4]-C[lowered z] leads during training and problem solving periods. Forty Hertz EMG was recorded from neck-temporal muscles. On-line comparator circuits prevented counting 40Hz EMG as 40Hz EEG. Significant control of 40Hz EEG, without feedback, was shown for five of the six subjects. One subject was erratic only in the production of 40Hz EEG. Significant control was shown to generalize to the O[lowered 1]-C[lowered z], O[lowered 2]-C[lowered z], and P[lowered 3]-C[lowered z] leads, regardless of which lead had been reinforced. The amount of 40Hz EEG during the suppression periods, while solving problems, was significantly greater than during the suppression periods without feedback. It was concluded that, following biofeedback training, long-term voluntary control of 40Hz EEG can be maintained for long periods—of time. Furthermore, though the greatest control was demonstrated at the conditioned lead, the effects did generalize to other nonconditioned leads, indicating that it is an overall state that is learned. Finally, 40Hz EEG could not be suppressed during problem solving periods as compared to suppression periods without feedback. This further supports the association between 40Hz EEG and mental activity. Other topics which were investigated were the changes in alpha and beta production during the training and problem solving sessions and the performance aspect during the 40Hz EEG production and suppression periods while problem solving. Relevance of the results of this study to the training of MBD children was discussed.Item Spectral analysis of nonsynchronous EEG activity and problem solving(1980) Ford, Martin Randall; Sheer, Daniel E.; Breitmeyer, Bruno G.; Howard, George S.; Yonovitz, AlbertRight and left side electroencephalograms (EEG) and electromyograms (EMG) were recorded in 20 right-handed, male adults during a verbal and a spatial task. EEG and EMG activity was quantified with spectral analysis, and bands of energy centered at 14 Hz (cycles per second), 20 Hz, 30 Hz, 40 Hz, 50 Hz, and 70 Hz were formed. From preliminary analyses of EEG and EMG data, three criteria were determined which demonstrated consistent and reliable dissociations between distributions of energy in EEG and EMG leads. Thorough analyses of the corrected EEG data were then conducted. It was found that for right and left EEG leads, during both tasks, there were slight, yet in most cases highly significant decreases in 14 Hz and 20 Hz bands, with concomitant increases in 40 Hz, 50 Hz, and 70 Hz bands. During spatial items, 30 Hz also increased on both sides. It was also found that 40 Hz was significantly correlated with 50 Hz and 70 Hz for corrected and uncorrected data. No significant indications of lateralization were found. No significant changes in 14 Hz, 20 Hz, or 30 Hz occurred as a result of applying the correction criteria. The major finding of this project was the demonstration of clear differences in the distribution of energy between EEG and EMG leads. The importance of this for future 40 Hz research is that EMG corrections can be made with activity in the high frequency range of the EEG leads alone. Simultaneous recording of EMG activity is not required for elimination of EMG contamination. It was also concluded that there is a shift in energy from the lower frequency bands (14 Hz and 20 Hz) to the higher frequency bands (40 Hz, 50 Hz, and 70 Hz) during problem solving. The changes in the lower bands are consistent with similar research using spectral analysis. The changes in the 50 Hz and 70 Hz bands clearly indicate increased EMG activity. That increases in 40 Hz activity correlated with increases in 50 Hz and 70 Hz activity indicates insufficient EMG artifact elimination. Refinements in the criteria are suggested, and limitations in the application of spectral analysis in fast-frequency EEG research are discussed.