A Discussion of Mechanisms
To date, biofeedback in general has been largely oriented toward conditions of over-arousal, i.e. anxiety, hypervigilance, adverse stress response, etc. Biofeedback has had little to offer for conditions of underarousal such as depression. EEG biofeedback is the singular exception. EEG biofeedback has been used most extensively to date with epilepsy and with Attention Deficit Disorder. The latter is fundamentally a condition of underarousal, and remediation with EEG biofeedback is understood to be facilitated by restoration of autonomous regulation of arousal. With epilepsy the matter is less immediately clear. However, epilepsy can be subsumed in the larger category of traumatic brain injury, inasmuch as at least forty percent of epilepsy cases are traceable to known instances of traumatic brain injury. And depression is an almost universal concomitant of traumatic brain injury. It may also be noted that behavioral management techniques for epilepsy revolve almost completely around overt management of arousal level by the individual. Hence, efficacy of the EEG training for epilepsy may also be seen in terms of “re-regulation of arousal”, as well as increasing the stability of a hyperexcitable cortex.
It is likely that both elements are present in the remediation of PMS by EEG biofeedback: normalization of control of arousal, and broadening the range of cortical stability. The former is applicable to the emotional symptoms and to pain. The latter is applicable specifically to such symptoms as migraine headaches, as well as perhaps to the more extreme behaviors sometimes observed with sudden onset, such as rages and paranoias.
EEG Training Protocols
EEG biofeedback training fits a learning model. The brain is challenged in a particular way, and over time, it acquires the skill to meet the challenge. As it does so, the threshold of success is adjusted to maintain the challenge. The process is continued until symptomatic relief is obtained. The training goals relate to narrow frequency bands within the lower end of the beta frequency range, 12-18 Hz. Most commonly, the frequency bands trained are 12-15 Hz (SMR band), or the 15-18 Hz band (which we call “beta”). For some cases, a filter intermediate to these is found to be appropriate: 13.5-16.5 Hz (which we call “15 Hz”). Accompanying the training of activity in these narrow bands is an inhibit function which is used to discourage large amplitude activity in the low frequency bands (“theta”, or 4-7 Hz), and in the higher beta range (22-30 Hz, in our implementation). The lower frequency activity is a concomitant of underarousal or a deficiency in cortical stability. Excessive high-frequency activity is a concomitant of anxiety, alcoholism, drug addiction, hypoglycemia, or mania. Excessive EMG activity also is observable in this band.
The training in the low beta range is deemed to be successful because the mechanisms by which activation is modulated, and by which the intrinsically excitable cortex is stabilized, is operative in this frequency range. This thalamocortical regulatory mechanism, which also governs the sleep/wake cycle, has recently been elucidated by M. Steriade. Confirmation of this mechanism is found from the fact that training slightly different frequency bands within the low beta region achieves quite different results in terms of physiological arousal.
The intake interview, baseline EEG, family history questionnaire, and results of testing are all used to specify the appropriate EEG training protocol at the outset. Testing in connection with PMS consists of the T.O.V.A., a computerized continuous performance test. This test helps to clarify where the individual is functioning with respect to the variable of arousal (underarousal/overarousal). This information is then used to specify the appropriate training frequency band. The clinical choices to be made consist not only of selection of the appropriate reward frequency band, but also the selection of the appropriate cortical site.
Nearly all of the training for PMS with the SMR/beta protocols is performed at the standard sites C3, Cz, or C4. In fact, the vast majority is done with beta training (15-18 Hz) at C3. The results of the training observed from session to session will then confirm the initial site and band-pass filter selection, or indicate the need for a change to a different training configuration. Since the training is not necessarily being conducted during a symptomatic period, the cues may be subtle. The client is questioned in detail about changes in sleep patterns, pain symptoms, mental functioning, etc. Changes in PMS symptoms are usually seen with the very next period after onset of the training. Any training sessions conducted during the symptomatic period are particularly illuminating with respect to the clinical choice of protocol.