Archive for the ‘Protocols’ Category
Wednesday, June 21st, 2006
It is possible to record and train on two channels of EEG data at the same time with most of the EEG amplifiers and software now available. We might choose to train the two channels separately at the same time. Or we might combine the two channels in order to train on the sum and/or difference of the signals, while allowing us to see the activity in each channel separately.
Two Channels Separately and Simultaneously
We usually combine training sites within a session so that we are moving electrodes left to right or front to back in order to train two or more sites in a thirty-minute session. Some clinicians prefer training two sites simultaneously using a two-channel hook-up. When training two sites at the same time, it is necessary to set the reward frequency appropriately for each channel separately. It is of course very important to keep straight which channel goes with which site and which reward frequency. The feedback is then contingent on meeting all reward criteria at both sites. With appropriate set-up the games work the same way they do for one-channel training. There are more ways the brain can fail with two channels, so we need to set the reward percentages a little easier for each variable. We can’t really comment from our own experience on the relative efficacy of training two channels simultaneously versus sequentially. Others are training this way with good results. We still prefer to see the effects of training different sites individually during the session. At this point it still helps us optimize and identify the effects of each training site and figure out what to do for each individual. (more…)
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Wednesday, June 14th, 2006
In the following I hope to demystify some of the aspects of neurofeedback training with bipolar placements, or at least provide substantiation for some of the statements I have been making about it. We are concerned with reward-based training with narrow-band filters that select a particular training frequency. The bipolar montage feeds a differential amplifier that senses the difference in voltage waveforms appearing at the two sites. The signal that is common to the two sites cancels out in the amplifier circuit. This helps us with respect to cancellation of electronic interference that is common to both electrodes, but the same considerations apply to the signal itself. We only get to see the differential signal between the two sites.
For reasons that will ultimately become clear, I am particularly interested in the phase dependence of the signal, mostly because this has been missing from the discussion to date. How can we best illustrate this? One would like to have the same waveform, for example a sinusoidal waveform at the center frequency of the filter, appearing at both electrodes, and to see what happens as we shift the phase between the two signals. The resulting signal would be time-dependent, which cannot be easily shown in a static graphic in a newsletter. So we will do the next-best thing: We will simulate two slightly different frequencies at the two sites. They will therefore progressively move out of phase and then back into phase in yet another sinusoidal pattern, namely at the beat frequency or the difference frequency. This can be shown as a frozen image, as we have done in Figure 1. (more…)
Posted in Protocols, Scientific | No Comments »
Wednesday, January 25th, 2006
There is a Buddhist saying, “you can never step into the same river twice.” And it may similarly be true that we never train the same brain twice. One of abiding mysteries about our way of training is that the advantages of optimizing reward frequency can be so obvious to us and yet remain so obscure to others. Many stay with the standard frequencies and their clients appear to do fine. Indeed we used and taught those techniques for many years; we saw nothing wrong with them then; and we got good results overall with the people who stayed with the program.
An answer may lie in a fairly common experience that we encounter in training, to which attention should finally be drawn. When we walk down the reward frequency in the hunt for the optimum, we will often end up toggling back and forth when we near the endpoint in order to verify our observations. In taking the reward frequency back up the person will often respond very differently than what they reported on the way down. This is not an isolated finding. It is more typical than not. We know this phenomenon from the field of magnetism, where it is referred to as hysteresis. The current state of the magnetization of the lump of material is given not only by the current magnetic field in which it is embedded, but also by the prior exposure history. The magnetic material remembers its past history. Matters may be similar with the brain. It responds not only to what we are reinforcing in the moment, but to a certain extent it is affected by its cumulative training history. That is also where the analogy ends. One response to this phenomenon is for us to consider the neurofeedback training as more of a journey, with each step to a certain extent another venture into the unknown rather than being merely a repetition. (more…)
Posted in Professional Issues, Protocols | No Comments »
Thursday, November 24th, 2005
In newsletters #40 and #41 we showed cumulative data on clients for whom the dominant protocol consisted of inter-hemispheric training with single-channel bipolar placement. The results have proved to be generally better than what we were able to do with our prior lateralized placements. The reality is even more compelling than what is shown by the data, for two reasons that have been previously mentioned: 1) the clinical populations are much more challenging now than they were a decade ago; and 2) more of these difficult clients are brought successfully to the point of re-testing, so that they actually appear in the data set. Dropouts from training were more commonplace years ago, particularly of course among those for whom our conventional ministrations were not the appropriate remedy.
With this state of affairs as a background, the bar is inevitably raised (in our heart of hearts if nowhere else) for expectations that we hold for new cases coming in the door. Increasingly, there is a fairly established expectation of some significant clinical success for what has become an inclusive set of clinical challenges. It has reached the point where we might hold out the eventual goal of “zero-defect neurofeedback,” the expectation that we can through neurofeedback move nearly everyone to a more functional place, and more particularly, come close to having the assurance that no one will be worse off for the experience. Even if the initial experience with neurofeedback were to be negative in a particular case, protocols exist that would allow recovery. These protocols aren’t just postulated to exist in principle–we actually believe that we know what they are. So, given the opportunity, we should be in a position to benefit nearly everyone who comes for our services with the relevant clinical complaints. (more…)
Posted in Protocols, Scientific | No Comments »
Thursday, October 27th, 2005
Last week we presented data on the impulsivity subtest of the TOVA CPT for clients who received neurofeedback training exclusively with the inter-hemispheric placements. This week we present companion data on the inattention subtest. The data were compiled for us by John Putman, and were recently published in the Journal of Neurotherapy (Volume 9 (1), pp 37-52). Complementary data are also shown where the inter-hemispheric training predominated, but where lateralized placements were also used. Comparison of results is then made to data analyzed for us years ago by David Kaiser, data that refer to the lateralized training that was done at that time. By folding the lateralized placements in with the inter-hemispheric we are essentially comparing the best we are capable of doing now with the best we were capable of doing earlier. An improvement in results is indicated for the current methods.
Last week we made the case for impulsivity as the best possible index of that we can derive from CPTs for our purposes. We argued that impulsivity indexed the very disregulation that we address with neurofeedback. Nevertheless, we should also look at inattention. In this measure we may be dealing with “organicity” that cannot be remedied with neurofeedback, regardless of methodology, and we have no independent assessment of this available. The issue of organicity must remain a confound in our comparisons. (more…)
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Thursday, October 20th, 2005
To accompany Sue’s description of the historical development of our clinical approach at the 2005 ISNR meeting, I presented our current data obtained with inter-hemispheric training. These results were compiled by John Putman, and were also just published in the Journal of Neurotherapy (Volume 9 (1), pp 37-52). The published data were restricted to those cases where inter-hemispheric placement was used exclusively. This necessarily left out quite a number of cases where the inter-hemispheric protocols predominated, but where we also employed more traditional lateralized trainings to address particular concerns. We see the inter-hemispheric training possibilities simply as an expansion of the “space” in which we can operate to good effect. There is no reason to abandon the techniques carefully worked out in prior years.
In the following, I would therefore like to “expand the space” of our considerations as well. What is the best that we currently know how to do, irrespective of protocol particulars, and how does that compare with the results we have obtained in the past? We still operate under the rubric of inter-hemispheric training because the latter has come to dominate our clinical work. In this comparison, it may be best to focus on impulsivity as an index. Firstly, we have good data on this from the TOVA measurements that we have been doing since about 1992. Out of all the TOVA data that could be surveyed, we want to focus on impulsivity particularly because it is most likely to reflect the state of disregulation of the system. A certain cerebral functionality has to exist for a person to show up as impulsive in the first place. So one might readily postulate that a brain sufficiently functional to show up as impulsive might also be capable of operating in the normal range. In other words, we can anticipate that nearly universal success might be achievable in the regulation of impulsivity through neurofeedback. The same cannot be said about the inattention measure in the TOVA, where organicity could be much more of an issue. Results on the attention subtest might therefore depend much more strongly on client characteristics about which we know very little at the outset. (more…)
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