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What Does 4 Channel Alpha Feedback Do to Whole Head
(8 Channel)
Alpha Activity?
Society for Study of Neuronal Regulation 7th International Congress
James V. Hardt, Ph.D.
Eight channel EEGs (O1, O2, C3, C4, T3, T4, F3,
F4) were recorded, filtered, and digitized for 17 right handed
non-meditators, who received broad band alpha feedback
simultaneously on 4 channels (O1, O2, C3, C4). Alpha feedback was both
4 auditory tones and 4 periodically presented digital integrated
amplitude alpha scores. Auditory feedback on each of the 4 feedback
channels was presented through 4 spatially separated speakers, and
employed separate pitches for the tones which signaled activity at
each of the 4 cortical feedback sites. Auditory feedback was driven by
the envelope of the filtered, full wave rectified broad band alpha
activity. Auditory feedback was presented to Ss sitting
upright, eyes closed, in a totally dark, climate controlled, sound
proof (Industrial Acoustics Corp.) chamber. Auditory feedback was
continuous, except for an 8 second interruption every 2 minutes,
during which 8 second interruption all the feedback tones shifted to
resting pitches, which signaled the S to open his/her eyes to
view the digital scores, which were illuminated only during these 8
seconds.
Training protocol was the standard Biocybernaut
Process: Six Personality Tests administered twice before and once
after the 7 consecutive days of EEG feedback training, with six daily
administrations of three different mood scales, 8 channel EEGs,
Frontal EMG, Heart Rate, and Temperature (Ambient and Left and Right
Hands) data were continuously recorded, and there were daily baselines
in eyes open and eyes closed conditions, also 16 minutes of daily
alpha suppression feedback, and daily enhancement feedback which
ranged from 60 minutes on days 1-2, 90 minutes on days 3-4, to at
least 120 minutes on days 5-7. Also on days 5-7 Ss were offered
the opportunity to do as much additional alpha enhancement feedback as
they wished, and all Ss did additional training. At the end of
each daily session there was a depth interview with a Trainer and a
review of results.
EEG polygraph records were screened for artifacts,
and the BIOCAL software package was used to incorporate pre- and
post-session calibration records to correct the digitized EEG scores
for gain nonlinearities in the amplifiers, and for gain drift across
time, to screen out mechanical artifacts, and to convert EEG scores to
true microvolts. The daily integrated amplitude broad band alpha
scores in microvolts were then studied with descriptive statistics:
Mean, Maximum, Minimum, Standard Deviation,
Kurtosis, Skewness, and Slope. Statistical Comparisons were made with
t-tests between an appropriate Day 1 eyes closed baseline and
the alpha enhancement scores (Mean, Max, Min, etc.) on each of the 7
days of training.
MEANS: The alpha enhancement feedback Means were
significantly higher on each of the 7 days of training than during the
Day 1 baseline. This was true for the 4 feedback sites and also the
four non feedback sites. Surprisingly, there were strong upward trends
in the Means even though alpha enhancement training times lengthened
across the 7 days.
MAXIMA: The alpha enhancement feedback Maxima were
significantly higher on each of the 7 days of training than during the
Day 1 baseline for all cortical sites except the Temporals (T3,
T4). There were strong uptrends in the Maxima at the Occipital,
Central and Frontal sites.
MINIMA: The alpha enhancement feedback Minima were
significantly higher on each of the 7 days of training than during the
Day 1 baseline for all cortical sites except the Left Temporal
(T3). There were no clear uptrends in the Minima across the 7 days,
perhaps because the fatigue of longer sessions would cause downturns
at least once during a long session.
STANDARD DEVIATIONS: Standard Deviations of alpha
scores were significantly lower during each of the 7 alpha enhancement
feedback periods than during the Day 1 baseline. This was true for all
cortical sites except O1, O2 and T3 (T3 missed unanimous significance
by only one day). The Standard Deviation of T3 alpha scores was
significantly lower than Day 1 baseline on all days except Day 7. The
two Occipital sites had significantly lower Standard Deviations of
alpha enhancement scores (feedback compared to Day 1 baseline) on days
4, 5, and 6. It is quite remarkable that significantly increasing
Means, Maxima, and Minima could be associated with significantly
reduced Standard Deviations, which shows the power of the feedback
setting to constrain variability.
KURTOSIS: The Kurtosis effects of feedback were
less wide spread. Kurtosis of alpha scores was significantly lower in
alpha enhancement feedback (compared to Day 1 baseline) for days 2-7
at O1, with 2 significantly lower days for F4 and 1 significantly
lower day for C4.
SKEWNESS: The Skewness of alpha scores was
significantly higher in alpha enhancement feedback than on Day 1
baseline for all 7 days at O1, O2, C3, and T3. The other 4 cortical
sites had from 1-3 days of significantly higher Skewness than the
baseline.
SLOPE: The Slope was significantly higher in alpha
enhancement feedback than on Day 1 baseline for all 7 days at O1, O2,
C3, C4, and T3. And 6 days of significantly higher Slope was seen
during enhancement feedback at T4 and F3.
Feedback produces many shifts in the baseline EEG
patterns, and use of 4 simultaneous channels of feedback reduces or
eliminates development of localization of control. Further studies
should consider changes in higher order patterns involving multiple
channels (cortical sites).
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