Background: Alpha-theta biofeedback training has been employed in clinical addictions treatment since the first reports of successful application by Peniston and Kulkosky. Several studies have questioned the theta crossover component of this feedback protocol as necessary to the training condition. Methods: We observed theta and alpha amplitudes, percentage of theta/alpha crossover, and self-reports of visualization in 191 sessions of three different protocols of brain wave biofeedback. Feedback conditions studied were alpha only, alpha-theta, and a type of EMG training. Subjects with identical electrode placement in all conditions, and not informed as to the nature of the feedback received, were given the same induction and expectations. They were asked to describe imagery occurring during feedback. Results: Visualization was found to be not exclusive to alpha-theta neurofeedback, but instead was present in all three modes of feedback. In addition, an inverse relationship was found to exist between the degree of theta-greater-than-alpha states and the presence of visual imagery. EMG sessions produced a greater percentage of time in theta/ alpha crossover states than alpha training alone, but the differences were small. Conclusions: Alpha only feedback, EMG feedback and alpha-theta feedback sessions were associated with similar amounts of average theta/ alpha ratio and percentage of theta/alpha crossover across sessions. Neither alpha-theta biofeedback nor biofeedback associated theta/alpha ratio increase is specific to the self-reported production of imagery.
- theta crossover