Article: Musing, Speculations on Delta Frequencies in the EEG

During a study, the stimulus may be a real external event or it may consist of imagining a real event. Studies have shown that perception and mental imagery involve some of the same internal representations, have functional similarities and will therefore show similar ERPs (Ref 6), therefore it is reasonable to suppose that the brain uses the same processes to find meaning in stimuli whether they come from a known external source or an internal. ERPs can be measured from the visual cortex both when an object is presented to a subject, or when the object is being imagined by the subject ie. being seen with the mind's eye.

We have shown that there have been many studies of brain processes which have made use of ERPs. Cognitive maps have been developed of how the brain evaluates and assembles information to present to our conscious awareness. Donchin says:

"ERP components are best viewed as manifestations of the activities of subroutines invoked during the informational transactions of the brain".

He makes it clear that he sees the P300 as part of a larger process, a "primary task" which makes use of subroutines. For us it is the "primary task", ie the whole routine, which is of greatest interest. The primary task is also accompanied by low- frequency (LF) changes. But we can no longer call it an event- related potential (ERP) if we do not know the timing of the primary stimulus. What does "primary stimulus" mean for us? These are the events described earlier: the airline pilot faced with a strobe light; the person being videoed without permission; the woman re-evaluating a relationship; the trainee healer exploring potential gifts; the subject taking part in psychic experiments: the traumatised clients seen by Len Ochs.

They are events which cannot be repeated for precise study. The event or its timing may not be predictable or when it can be predicted, it may not be ethical to use the opportunity.

For us, viewing LFs on the Mind Mirror through filters, the event must always be perceived as significant by the subject otherwise we would not see them. Perhaps in the future a way might be found to use alpha blocking as a marker and thus gain the possibility of using averaging techniques from many similar responses.

Method of Measurement of the slow potentials.
ERPs are studied as graphs of a change of voltage against time with a known event as a time marker at the left hand side of the graph. To people used to working in this field, our method of studying these voltages by means of filters must appear very crude because so much information is lost. The response time is given by the frequency of the filters; an output from the 1.0 Hz filter translates into a response time of a second whereas the 0.5 Hz filter indicates a response lasting for two seconds. (Graph relating ERPs to filter outputs). The time information is the same but it is not in a form which we are used to seeing. The amplitude of the response will agree but from the filters we have lost the information about the polarity of the LF.

We gain the ability to relate the LFs to other responses of alpha, beta and theta on the Mind Mirror. This is useful because in a real-life situation we do not know when the internal event may arrive. Externally it might be a word or situation with unexpected associations or internally, from an old memory, and yet when it does we want to gain as much information as we can. The filters are always in circuit, filtering out extraneous information and waiting for the unknown event.

Artifacts rather than genuine LF response.
When we first reported seeing these LFs on the Mind Mirror in 1975, two experts were quite dismissive of our reports. One demonstrated that a similar response could easily be generated by asking the subject to try to turn his head against a restraining hand. A slow headroll could also produce false readings. The sources of this apparent "delta" reading were the powerful neck muscles which were activated by the subject trying to turn or rotate his head. Because they are near the surface of the skin these muscle-tension voltages are readily picked up by our contacts and can overwhelm the LFs we wish to read. Added to that, the neck muscles also tend to vibrate against a restraining hand at about the same frequency as the ones for which we are looking. The signals we wish to read are from neurons inside the skull, the bone of which, being soaked in cerebrospinal fluid, is a very good conductor of electricity and thus acts as a shield and severely attenuates the brain voltages we wish to measure. However, on the very first Mind Mirror we had anticipated this and had included a sensitive muscle tension warning detector which alerted us when muscles were in excessive tension. We also reduce the muscle tension pick-up by using bipolar input from contacts placed fairly near together, which helps to cancel out muscle-tension voltages.

A second source of false readings can be found in the input amplifier. In a well-designed amplifier, a high level of interfering signals can be present without affecting the wanted reading. In one that is poorly designed, the wanted and unwanted signals can easily get mixed up and produce a whole range of spurious readings; an effect known as intermodulation.

We have always been confident that our LF readings were accurately representing the subject's response. In rare cases when the muscle-tension indicator alerted us that there was a problem, it could always be solved by shoulder and neck massage to reduce the tension reading. We could then be sure that our observations were accurate. We were finally very confident when we observed some of the high-level asymmetric readings described earlier because it seemed unlikely that a subject would tense the muscles on one side of the neck without operating the warning detector. It was also easy to make a physical check of the neck muscles to see whether one side was more tense than the other.

What the Low Frequencies seem to be telling us.
Studies of large Event Related Potentials (ERPs) have shown that they can be measured at many points simultaneously from the brain as though it was making use of all its resources in trying to find meaning when the stimulus is unusual. Solikov, quoted earlier, has suggested that the Orienting Response (OR) magnifies the effects through its links to the reticular activating system (RAS) in the brain stem (Ref 5). This system controls many aspects of consciousness such as the response to pain, wakefulness and relaxation. It is reasonable to suppose that the effects of this reticular activity will manifest as ERPs even when the cause is unknown.

One can imagine the LFs as an orienting radar which checks for meaning both externally and internally. In the laboratory, they are large enough to be studied reliably when the player is being challenged by a computer game. When the event is internal, they seem to accompany attempts to find new solutions and in a personal crisis may indicate a renewal in our basic and fundamental way of being in the world. The events can range from resolving trauma after an accident, to interest in the paranormal, or choosing a new direction in our life. We believe that they can give a new window on how the brain functions and are a resource in our quest for understanding the nature of our mind.

If we try to describe LFs, we find that we quickly reach levels of brain process where we cannot trust the words used by the Left Hemisphere (LH). This may be because the process is a feeling or an intuition rather than a fact or it may that the LH does not know but will invent an explanation rather than admit that it might be losing control. This has been demonstrated in split brain research which came about through trying to control very severe cases of epilepsy by severing the corpus callosum, the major link between the two hemispheres. It was hoped that fit could be confined to one hemisphere and allow the subject to function with the other. A subject who has had this operation can be shown a rude picture in such a way that it is only visible to the right hemisphere. This may well produce an embarrassed laugh. If one then asks the subject why they laughed, one is dealing now with the left hemisphere (LH) and one quickly finds that it does not have the foggiest notion of why the laugh happened. Rather than admit this, LH will invent and improvise with the weakest of excuses such as "it was the strange expression on your face" or "it was the tone of your voice".

There is another effect which demonstrates the difficulty of finding out what is wrong with someone by asking them. This is known as the false memory syndrome. Traumatic memories from the past may be blanked out so thoroughly that verbal or visual memory traces seem to have vanished but they can nevertheless be held as an emotional code in the deeper levels of the brain. When the intellect tries to decode these emotions back into facts, it may well have to invent situations, based on partial memories, to explain the feelings. These explanations are likely to be wrong. However, if the subject was connected to the Mind Mirror while this explanation was being given, and one saw high levels of low frequencies, one would know right away that there was a discrepancy and that a more accurate explanation might be available.

A German doctor Georg *(don't add the e)* W. Groddeck, in his "The Book of the It" (ref 8-7) expresses very well the challenge of trying to describe what may be happening in deeper levels of the brain. He influenced the psychoanalyst Freud, whose book "The Ego and The Id" pays tribute to Groddeck. Freud however saw the psyche as made up of the conscious and unconscious parts whose behavioral components could be analysed into psychological categories, whereas for Groddeck, both the conscious and unconscious seemed to be a function of something else which he chose to call the "It"; an unknowable principle which animates our lives and actions. For Freud and also our civilisation the ego is supreme. The components of the ego can be neatly described in the terminology of psychoanalysis but Groddeck did not believe that this could help us to understand the nature of the forces within the human organism which influence health and disease. To Groddeck "the ego appeared as a contemptible mask fathered on us by the intellect" which persuades us that we are motivated by forces within the control of our conscious mind. In practice we have no idea how we digest food, why we chose a particular career, or how we become ill or stay well but to him these were expressions in the language of the It. One can of course say that a germ caused the illness, but this only part of the story - we have all had the experience of staying well in the middle of a flu epidemic, so the germ cannot be the only cause.

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