Theta1 and Theta2

When I first started doing Decrease training, I began with Decrease Theta at 48 Hz. Results were admittedly quite good, at least in regard to increasing SMR and Beta. When I read about Theta2, however, I realized that there could possibly be some interference with cognitive processing by decreasing Theta above 5.5 Hz- As a result, I changed my primary Theta band to 3-6 Hz, calling it Thetal, and created a new secondary frequency band of 5.5-8 Hz, which became Theta2.

Frontal Midline Theta Activity ("Theta2")

For the past several months, I have been clinically exploring "Frontal mid Theta activity," a rhythmic frontal Theta activity that is reported to occur during the performance of a mental task. While the original reports go back to the 1940s (Kennedy, Gottsdanker, Armington, & Gray, 1948, 1949; Arellano & Schwab, 1950; Brazier & Casby, 1952; Mundy-Castle, 1951), all the recent research is reported by theJapanese (Inouye, Ishihara, & Shinosaki, 1984, 1985; Inouye, Ishihara, Shinosaki, & Tbi, 1985; Ishihara & Izumi, 1975, 1976; Ishihara & Yoshii, 1972; Mizuki, Tanaka, Osohaki, Nishijima, & Inanaga, 1976, 1980; Mizuki, 1987; Yamaguchi & Niwa, 1974; Yamaguchi, 1983). As "Frontal Mid Theta Activity" seems clumsy, I refer to this rhythm as "Theta2."
Theta2 consists of trains (long runs) of rhythmic frontal activity centering at 6.5 Hz with amplitudes reaching the 50-100 yV (microvolt) range. The maximum amplitude is just anterior to the Fz electrode and a few millimeters to the left of midline. The field spreads anteriorly to an area near the Fpz electrode site and posteriorly to the Cz, C3, and C4 electrodes.
Theta2 is induced in some people by the performance of a mental task such as mental arithmetic, tracing a maze, counting the number of cubes piled in a three-dimensional representation, and imaging a scene. Because Theta2 is associated with mental tasks and its influence is seen in evoked potential latencies, Mizuki (1987) believes that the appearance of Theta2 closely relates to mechanisms of attention or arousal. The incidence of Theta2, if measured during a mental task, is 32-73% of the normal population (Yamaguchi, 1983).



Theta at 4Hz
According to Cavanagh (1972), Theta at 4 Hz corresponds to a full memory search. Theta, then, like Alpha, is a scanning frequency. Cavanagh began by compiling a number of studies dealing with different classes of stimuli (digits, colors, letters, words, geometrical shapes, random forms, and nonsense symbols). Each class of stimuli was found to have a characteristic reaction time. However, he found a constant of 243.2 ms when multiplying the reaction time for a single item by the maximum number of items in a given class. This indicated to Cavanagh that each item class was scanned at a different speed, but that scanning of the full memory is always executed at a speed of 4 Hz.


Giannitrapani (1985) states that according to the Cavanagh (1972) research, the brain has different scanning frequencies available for items of different degrees of complexity. I assume, based on the comments, that these scanning frequencies are all in the Theta range. The Giannitrapani study also shows a positive relationship between the level of performance for certain verbal subtests (WISC Information, Comprehension, Vocabulary, Block Design, and Verbal IQ) and 3-7 Hz Theta activity.
A conclusion one could make from these data are that the brain uses Theta band frequencies for important scanning and memory functions.

Therefore, inhibiting Theta during neurofeedback training could conceivably be detrimental to memory storage and cognition

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Theta2 Training Recommendations


1.
My present training objective with Theta2 training is to make Thetal (3-5.5 Hz) and Theta2 (5.5-8-0) autonomous. That is, while the trainee is under cognitive challenge, Thetal should independently decrease over the session as Theta2 increases. When Theta2 stabilizes (remains the same over a session or two) as Thetal decreases, I consider Theta2 training to be complete.
2.
Theta2 training session time may be shorter than my usual training session time of 20 to 25 minutes. At the first clear indication of Theta2 downtrending (two quick decreases in the Theta2 magnitude averages while the trainee is under continuous cognitive challenge), stop the session. If the session is continued, Theta2 averages tend to downtrend and advances quickly decay. The Theta2 downturn can occur as early as 10 minutes into the session so the clinician should constantly monitor the magnitude average.
3.
Only a few sessions are indicated for Theta2 training. Sessions should only continue until Theta2 increases and Thetal downtrends while the trainee is doing a cognitive task. If sessions are continued after this point, the trainee seems to rapidly lose Theta2 magnitude gains. Only around five or seven sessions have been required in those trained to date.
4.

While doing Theta2 training, the client/patient should be continuously engaged in a cognitive task such as Tetris". Non-verbal tasks and tasks with low potential for EMG contamination are preferred.






Theta and Working Memory





Abstract In a task switching design, we investigated the question whether long-range theta coupling primarily reflects top�down control processes. Switch and stay trials did not differ with respect to memory load or global working memory (WM) demands. The results revealed significantly stronger theta coupling (in a range of 4�7 Hz) between prefrontal and posterior regions during switch as compared to stay trials. Power differences, reflecting more local effects, were largest in the upper alpha band (10�13 Hz) and over posterior brain areas, possibly reflecting long-term memory activation. The conclusion of the present study is that long-range coherent oscillatory activity in the theta band reflects top�down activation rather than global WM functions.





It is well documented that an increase in theta power is functionally related to increased WM storage demands (Mecklinger et al. 1992; Gevins et al. 1997; Gevins et al. 1998; Grunwald et al. 1999; Klimesch et al. 1999; Gevins and Smith 2000; Raghavachari et al. 2001; Jensen and Tesche 2002; Fingelkurts et al. 2002).

Research on coupling between brain areas documented increased theta coherence in a widespread fronto-parietal network during the transient maintenance of information in WM (Sarnthein et al. 1998; Weiss et al. 2000; Sauseng et al. 2004). In these studies the influence of memory load and increased central executive processing demands can not be distinguished.