Spectral Dynamics and Therapeutic Implications of the Theta/Alpha Crossover in Alpha-Theta Neurofeedback

Abstract

The theta-over-alpha frequency crossover seen in alpha-theta neurofeedback, considered an important factor in the treatment's success, has had little definitive research. This study examined 182 alpha-theta session graphs from 10 subject case files for interactions between frequency band activity and subject reports of imagery or biographical memories during crossovers, as well as treatment outcomes. Statistical analyses revealed significantly more reports of imagery/memories during crossover conditions having specific spectral, amplitude, and duration characteristics. Imagery reports were more likely to occur during crossover activity of 1 microvolt or more, lasting at least 3 minutes, and including 3.75µv of 15–20 Hz beta. This defined therapeutic crossover condition also was significantly related to better treatment outcome measures.

Notes

* Beta 2 refers to a specific range of beta involved in focused cognitive activity.

(χ² _{(df = 8,N = 182)} = 47.4, p < .001).

Note. N represents the total number of sessions (182) which are characterized by no crossover activity (51), Non-therapeutic crossover activity (with or without sufficient beta) (62), or Therapeutic crossover activity (with or without beta) (69). The 5 table columns sum to illustrate 100% of the session graph activity examined.

Note. The five table columns collectively sum to reflect 100% of client reported imagery of salient material while excluding no imagery and hypnagogic imagery categories.

*N = 182. Cox & Snell's R ²  = .367; Nagelkerke R ²  = .457; McFadden R ²  = .281.

For this analysis, n = 44 for Biographical and n = 15 for Transpersonal. Positive B indicates that the group scored higher on the variable in question compared to the base group exclusive of other variables. The reference category was: ‘No imagery’.

Note. Mean amplitudes measured in microvolts are observed to increase from left to right and progress from lighter to deeper states of consciousness as indicated by Crosstabs Analysis. Analysis of Variance (ANOVA) indicated significantly higher mean amplitudes in microvolts of delta as level of imagery increased (F = 3.429, p = .011).