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2 Brainwave Connections Spring 2005

Text Box: The foundations of neurofeedback have been built on single channel recording and training. From Joe Kamiya and Barry Sterman through Margaret Ayers and Joel Lubar, a single EEG lead has provided a wealth of information and material for brain training. What, then is the importance in 2-channel training, and what are the limitations and realities of 1- versus 2-channel neurofeedback? 1-channel training has the benefit of simplicity and directness. Once the leads are determined, it really does not matter whether or not the active and reference are switched, and the training signal has one datastream to interpret and work with. Two-channel training is important when you consider the complexity of the brain, and the implications of training, both hemispheres simultaneously. Richard Davidson of the University of Wisconsin, for example, has discovered that mood is intimately connected to asymmetry in frontal activation. Briefly put, the left frontal lobe needs to be 15% more activated than the right, for a normal individual to have a positive mood. If the right hemisphere becomes more activated, then a negative mood, and depression, can result. It has also been found that immune responses track these changes, and that mood and immunity are therefore also linked.

Text Box: Therefore, it is important in any EEG training to ensure that the right hemisphere does not become overactivated. (Note that activation in this sense is associated with lower overall EEG amplitudes, and higher EEG frequencies). It can thus be argued that 1-channel training is potentially problematic for anyone with possible mood or activation issues, since it does not specifically address differential activation of the hemispheres, and could result in an undesired effect if not carefully planned. In such cases, experience and observation, and reacting to subjective or clinical changes would be of value. Otherwise, 1-channel training could offer inadequate control and specificity relative to these dimensions. When you think about it, single-hemisphere training is a little like learning to ride a bicycle with one hand. While you can certainly get moving, it may be difficult to learn or achieve balance, especially dynamic balance. Of the 1-channel protocols, the simple “Cz to an ear” Sterman/Tansey protocol has been found particularly benign. This is likely due to the fact that it effectively records both hemispheres, since the sensor sits right above the central fissure. Therefore, this protocol effectively trains symmetrically, and avoids abreactions that

Text Box: could be produced by training differentially on one hemisphere. In contrast, the classic “C3 beta” and “C4 SMR” protocols work well, but can lead to tonic changes in arousal. For example, overarousal of the right hemisphere can lead to negative mood, defiant behavior, and related outcomes. In contrast, underarousal of the left hemisphere can lead to sleepiness or lethargy. When using either of these protocols, it may be necessary to switch between them, to provide balance and facilitate self-regulation. 2-channel bihemispheric training can be achieved by training one protocol on the left and another on the right. For example, training left beta and right SMR simultaneously, can provide the benefits of both types of training. hemispheric balance, along with Coherence Training also becomes possible only when using a 2-channel protocol. While it is clear that one can perform desynchronization training using one channel and a bipolar hookup, it is not possible to perform true coherence or synchrony training with only one EEG channel. Specifically training for coherence (or synchrony) can provide the benefits of having both hemispheres coordinated, producing a very deep and focused relaxation accompanied by synchronized bilateral thalamocortical activity.

Text Box: Two-channel training is important when you consider the complexity of the brain, and the implications of training both hemispheres simultaneously.

Article by:

Thomas F. Collura, Ph.D., P.E., BCN