Interhemispheric Versus Single Hemisphere Training

by Sue Othmer | June 14th, 2006

We have explored interhemispheric training over the past years, optimizing reward frequencies, and learning the specific effects of training different sites. Now that we have started also training left and right side separately again, we need to ask when and why we would choose to do one rather than the other. At first we moved to left and right side training in order to get low enough, especially when moving to prefrontal or parietal training. With our ability to train lower with narrower filters near zero, we can now separate the issues of frequency and placement. (See EEG Newsletter 14 May 2006.) Are there some people and some symptoms for which one approach is more effective?

We have moved people from one approach to the other at times in search of a stronger or more specific effect. We are now beginning to see that many people do clearly benefit more with interhemispheric or with single side training. Our task is to sort out any general rules that might guide us in fitting the protocol to the individual client. The emerging model is one of separating problems of instability of state from those of specific activation and arousal deficits. This of course brings us full circle to the initial need and rationale for interhemispheric training — stabilizing the brain against migraines with T3-T4.

We are finding that interhemispheric training (often specifically T3-T4) is proving more effective with global instabilities of state such as migraine, seizures, asthma, panic, vertigo, irritable bowel, mood swings and traumatic brain injury. I am expecting that it will also be more effective with PTSD, night terrors, sleepwalking and fibromyalgia. It may well be that interhemispheric coherence abnormalities will prove useful in pointing to specific interhemispheric sites that need training.

Left and/or right side training is giving stronger effects with activation and arousal deficits as with ADHD, anxiety and depression, OCD and tics, agitation, muscle tension, the autistic spectrum and probably RAD. In these cases we seem to get cleaner, more targeted effects and have an easier time finding an optimum reward frequency. We will need to rethink our categories of instability and sensitivity to fit these differential effects. It may be that hyperexcitabilities are impacted more strongly with interhemispheric training, while symptoms of disinhibition respond better to left or right prefrontal training.

So should we still start with T3-T4 or move directly to left and/or right side training with some individuals? The rationale for beginning with T3-T4 was that it asked the simplest question possible so as to give us the clearest answer. It was not left or right or front or back — just up or down to find the best reward frequency. More specific placements and effects could build on that. But we have already moved to right-side T4-P4 as the starting placement for RAD and autistic clients. Here the priority is to get individuals physically calm and settled and in their bodies. T4-P4 can be easier to figure out for many people because it specifically impacts body tension and agitation and awareness. This is a good place to start and continue for some sessions with autistic and RAD clients, but ADHD and anxiety/depression clients typically need to balance right posterior training with left prefrontal. So then the starting protocol would need to be both T4-P4 and T3-Fp1. Finding the optimum reward frequency at two sites might be a large task for the first session. We have a lot of history with T3-T4 as a starting place, so this may take time to evolve. If we do start T3-T4 and then shift to left and/or right side training, there are no firm rules to guide reward frequency selection. A reasonable solution is to start on the right side with the optimal reward at T3-T4 and expect to adjust as needed. The expected reward frequency on the left side is 2 Hz higher than that on the right.

We also expect that both approaches might be useful for some clients. It would make sense to stabilize first with interhemispheric training and then add more specific single sided placements for residual symptoms. We often see migraine clients benefit from T3-T4 very specifically, but then also need work on OCD or muscle tension symptoms. In such cases we would keep the T3-T4 in the mix, while adding other sites as needed and as they prove useful.

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