Article: Musing, Speculations on Delta Frequencies in the EEG

Here we meet a stereotype: so far with men, it has always been the right hemisphere which switches off, the left going into overdrive, while with women it is the opposite.

In two cases involving women, they were in the midst of dealing with relationship problems. One knew enough about Mind Mirror patterns to realise that the assymetry portended fundamental changes in her life, but at that moment, with the left hemisphere not functioning, it was impossible to express anything meaningful in words. In the second case, I sat with a subject during guided imagery given by my colleague Max Cade which lasted for an hour. I quietly gave her very simple feedback in the form of a whispered "yes" and "no" as she hovered between symmetry and asymmetry. At the end she felt the feedback had shown her clearly the difference between the two modes. She said that in the asymmetric mode she could intend to say something but hear her voice saying something quite different. From this, she understood why it was so impossible to discuss the situation with her male friend and why he had found it impossible to make sense of what she was saying. He commented: "She seemed like the witch in the village". He knew enough about the technology to realise that the Mind Mirror was demonstrating clearly that at certain times it was meaningless to try to make verbal sense of what was happening between them. I believe that this simple demonstration helped them to come to a new understanding in their relationship; they are still together many years later.

With one healer who was working with a client, we noted a very interesting pattern. He showed an excellent state 5 pattern from his left hemisphere but the right showed only LFs, as shown in the diagram (pattern-2). He said that during this phase he was searching for ways to help his client. We were interested to note the pattern afterwards came into balance, a state he called "charging his batteries". We have seen this pattern once only but it shows the startling potential in the available plasticity of our mind.

Anna Wise has noted in her book that many of her clients show delta LFs while she is working with them. She herself had an experience at one of the Body, Mind and Spirit festivals in England. She was connected to the Mind Mirror on one of the stands devoted to healing. At the end of the session with one very effective healer, she was showing nothing but delta. She was able to move around and talk in this state. Remembering the feeling afterwards, she felt that she remained in it for hours.

When we first connect a subject to the Mind Mirror, there is almost always a LF response coupled with beta for the first five minutes. We call it the alpha-blocking response and on the Mind Mirror the visual pattern looks like two saucers back to back. (pattern-3) and confirms to us that the machine is functioning and the connections correctly made. As the subject's apprehension caused by the novelty of the situation of being connected to the Mind Mirror dies away over the next few minutes, so does the low-frequency response. It is not caused by the machine settling down because this only takes a few seconds and affects all the channels. At the peak period of a few years when Max Cade was giving courses in London, as many as forty subjects a week were being wired up on the Mind Mirror. The first response most subjects showed was the pattern just described which became our "standard event".

Len Ochs works with a strobe light which is offset slightly to the dominant EEG frequency. He also reports that high levels of LFs are found from his clients and that success in his therapy is accompanied by a reduction in these levels. He says: "The amplitude of theta and delta has been observed to rise as patients experience anger, sadness and hurt..." and "high-amplitude delta and theta seem to parallel the active influence of a past filled with anger, sadness, hurt, or head injury". His colleague Elaina M. Jannell says: "It is the lower frequency activity that is prominent in both physical and psychological trauma". Our only point of difference with Len Ochs is that we prefer not to use the term "delta" for these LF responses.

The first report which we found describing these LFs was in a 1975 paper on low frequencies during paranormal research by Dr Joel Witton published by the Toronto Society for Psychical Research (Ref 2). It is interesting to note that they are not linked to the success or failure of the research but rather to its novelty, a point that will be amplified in the discussion on the source of these LFs. There is no suggestion that LF waves are linked to paranormal effects, though it may be that Dr Whitton had hoped they might be some kind of carrier wave for psychic energy.

We believed at the time that the above report was the first that we had seen giving an independent corroboration of our findings. We ought to have read more thoroughly W. Grey Walter's 1953 book "The Living Brain" (Ref 3). In it he says: "As long ago as 1938, I suggested ... that delta waves represent a change which is usually ominous ... a defence mechanism ... Sometimes we may suspect them of paralysing the cortex by electrocution, as it were ..." He goes on to say that the need for these low frequencies, "these wardens of brain function", may lie in the necessity of "protecting the brain from the consequences of its own complexity". These comments seem dramatic because he was applying them to brain injury and organic disease, but in calling them "a warden of brain function", he seems to be suggesting that they might be caused the trauma of an injury as well as its physical impact.

The Source of the Low Frequency Potentials.
The brain contains upwards of 10,000 million neurons. Many operate in small groups dealing with aspects of specific tasks, these small groups are then found as components in higher order brain activities. Many are also connected in large groups which alter the whole mood or ambience of the brain. It is useful to use the computer programme as an analogy; when we are learning to recognise a word, we are in effect creating a programme for that functions. But the computer analogy breaks down in many ways; the brain is capable of carrying out many tasks simultaneously with a degree of complexity in both analogue and digital modes that cannot be envisioned in computers; and further we have no idea how the brain collates the results of separate processes and presents them as a unified experience to our consciousness.

When a neuron "fires", ie switches, it generates a voltage. When a large number fire together, the voltage is large enough to be measured at contacts placed on the surface of the head. These low frequency (LFs) voltages are called Event Related Potentials (ERPs) when they appear in response to a stimulus such as a flash of light. This technique has provided a very powerful non-invasive technique for studying brain function and developing cognitive maps of the brain. Two important qualities of a brain response have been identified: the time taken to complete a particular task - the latency; and the amplitude of the response which is linked to the element of surprise.

At this point we should note again that there are two categories of low-frequency response, firstly, the ERP just described which are responses to known events, and secondly those LFs generated by the brain's own reflections about events for which a cause may not be identifiable. Yet the brain processes seem to be the same in each case and as ERPs have been widely studied it is useful to see what can be learnt from them.

Consider first the time taken. For a single neuron the switching time is very short, a thousandth of a second or less. The time taken for a complete sequence, for example, word recognition, is very much longer and will involve thousands of neurons. Many of these sequences or subroutines appear to be used very often by the brain as elements in more complex tasks and can usefully be imagined as computer programmes which can be applied to many different functions. Various subroutines have been identified as the P100, P300, P550, N140, N400 etc. The N - negative and P - positive indicate the relative direction of the change of potential and the figure is the time taken in milliseconds. To remind you of the time scales involved 500ms equals half a second. The P300 response has been widely studied and appears as a part of many brain processes. It is visually recognisable on a graph as beginning with a negative going change of voltage followed by a larger positive one, the total response taking about 300 milliseconds to complete, hence its name. While there is on-going discussion about its precise function, it seems to be a recognition programme or routine which contacts various parts of the brain to find meanings and associations linked to the stimulus. If one says "the cat is green" then one finds a different response - the N400 after green. This second response must be linked to the contradiction of a green cat. While information is often stored near the area which needs it - action data will be found near the sensory motor cortex, other information such as colour may apply in many different contexts such as perception or hearing a description of an object. We know from PET scans which can indicate areas of brain function by change of blood flow, that seeing an object can activate many different centres in the brain, making available everything we know about it; the meaning the object conveys is very quickly linked to the original perception. The emotional "colour" is also added equally quickly.

The second quality of the event-related potential is its amplitude and this divides into two categories; those which are large enough to be recognised without special processing and those which are so small that they are overwhelmed or hidden by other brain activity such as the alpha and beta described in the previous chapter. When they relate to simple house-keeping events of the brain such as recognising a word, the amplitude may be a microvolt or less and impossible to recognise from a single stimulus. There are two techniques to separate these voltages so that the response can be seen; a filter will separate the response if the stimulus is repetitive; if not averaging techniques can separate the response. The repetitive stimulus may be flashing light or a clicking metronome. An analogue filter or digital one based on Fourier analysis at the same frequency as the light, will filter out other brain activity so displaying the desired response while eliminating other brain activity. The second method of separating these tiny LFs, averages the voltages from a stimulus repeated many, many times; the mean value of all the readings giving the true response. Other brain activity is averaged out to zero because it is not synchronised to the stimulus. Because both methods require that the stimulus is repeated many times; both suffer from habituation, an effect which means that the average of a number of responses may not be the same as one to the very first stimulus but we have no way of telling. They both require a known event as a starting point and therefore cannot be used to identify the Mind Mirror LFs.

An element of surprise will increase the ERP from a single stimulus to a level where it can be easily discerned on its own. Emanuel Donchin in his presidential address to the Society of Psychophysiological Research in 1980 (ref 4), showed how a video game could be used as a reproducible stimulus. In this game, the player bargains with the computer over the price of a car. During the game the computer changes tactics and the resulting ERP potentials are much greater due to the active involvement of the player with the bargaining. Instead of fractions of a microvolt, ERPs measuring tens of microvolts, were easliy shown on a graph without the distortion of filtering or averaging. Many examples of traces of graphs are given showing that the response may continue changing for a second or more. Donchin says:

"Rare events elicit a P300. The rarer the event , the larger the P300" and "The amplitude of the P300 can be used to measure the subjective probability or expectancy of events".

There is another response, very similar to the P300, which seems to play a part in the LFs which we see on the mind mirror: the Orienting Reflex (OR). The following description of the OR is taken from "Neuronal Models and the Orienting Reflex" by E.N. Solokov. "The OR is a special functional system which increases the discriminatory power of analysers....I believe that one of the mechanisms for this is a direct stimulation through the special descending pathways to the receptors from the reticular formation and from the cortex, which can change this discriminatory power." (Ref 5) Both seem to compare inner expectations or schemas for dealing with world with the effect of the stimulus; the mismatch manifesting as an ERP. A major difference between them is shown by habituation, ie how quickly the brain decides that the event is of no significance. In the main, the P300 only shows when the event is of an unexpected type, whereas for the OR the first stimulus is always unusual. One could say that the P300 is always habituated that is to say the event is immediately checked for inner significance and if none is found then there is no ERP, whereas the OR always checks the first presentation for significance and only then relaxes its guard if none is found. Even here the picture can be confused; it is well known that in a P300 study, a P300 response will be found from the very first presentation of the stimulus regardless of its significance. There is another difference; the OR may habituate ie no longer respond to a situation which is seen as benign, but it does not relax its guard. If the test involves attention to a series of tones then the absence of an expected tone may produce an OR. (ref?)

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