History of the EEG in the United States

Since the initial discovery of the EEG in 1875 by Caton and the first description of the human EEG in 1929 by Berger, much research has been conducted using this technique. In those days, most research efforts were from Europe. In late 1933, Hallowell Davis an American physiologist at Harvard, learned of the early work from Berger and at that time thought that Berger’s alpha rhythm was ‘undoubtedly artifact’, since they considered it unlikely that enough axons in the brain could be synchronized to yield such a slow regular 10 Hz rhythm that could also be recorded without exposing the cortex. They therefore decided to replicate Berger’s results, and it almost turned out not to replicate hadn’t it be for the persistence of Davis as nicely illustrated in the following: “…In January 1934… Bill Derbyshire and Howard Simpson failed in their attempt to record the Berger rhythm using needle electrodes in the scalp…” As Davis later related: “About three weeks later Bill and Howard (who had been working on this in their evenings) came to my office again, looking a bit sheepish. ‘You are right, chief’, said Bill. ‘We have stuck needles in each other’s scalps (vertex and occipital). The baseline is unsteady, but we can’t see anything like the 10/sec rhythm on the scope. But come and see if we are doing it right before we say anything about it.’

Bill stuck needles into Howard’s scalp

I went with them to the lab and Bill stuck needles into Howard’s scalp. Howard sat in the shielded room and closed his eyes. The spot wobbled unsteadily across the scope. That’s what I thought, I said, but three heads are better than two. Put the electrodes on my head. They did, and I sat in the room and closed my eyes. Immediately there were shouts outside: There it is! There it is! It was indeed the Berger rhythm. It seems that I have very strong alpha waves. Bill’s and Howard’s are weaker, and they were excited, anxious, and perhaps more uncomfortable than I was. Other members of our staff volunteered and they were divided about evenly into ‘Bergers’ (Davis, Cannon, Lindsley), and ‘non-Bergers’ (Derbyshire, Simpson, Forbes, Pauline Davis). We were convinced Berger was right. It was some time later that we learned that Adrian had already confirmed him; but at least my alpha rhythm was the first to be recognized as such in the Western Hemisphere. I also soon realized that we were probably watching a new slow potential of neural origin.”

This thus turned out to be the first demonstration of alpha activity in the US, albeit not published as a manuscript in the literature. The first real published replication of Berger’s work – and the first publication on EEG from the US – was published in Science in 1935 by Jasper and Carmichael. In that study they already confirmed the stability of the alpha frequency over repeated assessments, as well as the existence of a slower rhythm “…In one or two pathological cases which we have studied a frequency of alpha waves as low as 2 or 3 per second has been observed” which would later be labeled as delta or theta. Their conclusion “…It is even possible that this technique may provide information in regard to brain function which will be comparable in significance to the information in regard to heart function which is provided by the electrocardiograph…” indeed heralded the wider adoption and progress in research on EEG in the US. Soon followed the descriptions of clear three per second spike and wave complexes in patients with epilepsy, first in Davis’ lab, that started the field of clinical EEG as a discipline in neurology.

Alfred Lee Loomis

Alfred Lee Loomis was an eccentric Wall Street tycoon, with a passion for science. He initially started as an independent physicist, who built his own private laboratory, the Loomis Laboratory, in Tuxedo Park, near New York, also locally known as the ‘Tower House.’ In his lab, mainly active during the 1930’s, he would come to work on various topics with some of the greatest scientists at that time including Albert Einstein, Werner Heisenberg and Niels Bohr, and possessed the best laboratory equipment available those days. In the early years from 1926 to the 1930’s he mainly focused on physics experiments and combined it with his Wall Street activities at Bonbright. In 1928, just before the big Wall Street Crash in 1929, he had converted most of his holdings and investments in gold and several years later he also sold the law firm Bonbright, providing him with substantial wealth, that allowed him to further indulge his scientific hobby and private lab. At that time, he had available the best amplifiers and conducted studies in a ‘screen cage’, or sort of Faraday cage, that eliminated interfering electrical noise. At this time, he could dedicate himself full time to the further exploration of brain waves as described by Berger.

As described by Herbert Jasper, on one of his visits to Tuxedo Park, Newton Harvey from Princeton was also present, and brought Albert Einstein with him, so they could study Loomis’ brain waves: “…They put him to sleep, and at first he showed the typical slow waves of sleep. Then the EEG changed to the rapid waves of arousal. He awoke suddenly, asking for a telephone. He called his laboratories in Princeton to tell his colleagues there that he had been reviewing his calculations of the day before and discovered an error which should be corrected. This done, he was able to go back to sleep again. We thus had a dramatic demonstration of the sensitivity of the EEG to mental activity…”. In August 1935, this thus resulted in the first published study by Loomis, together with Harvey and Hobart, on the human sleep EEG and stages of sleep. This was among the first series of US publications on the human EEG, after Jasper’s first report in January 1935. Already in this early 1935 report Loomis was the first to describe sleep spindles, also referred to as sigma waves, where they described: “…but frequently very regular bursts lasting 1 to 1.5 seconds of 15 per second frequency appear. The amplitude builds regularly to a maximum and then falls regularly so that we have designated these ‘spindles’, because of their appearance…” , with the first published example of sleep-spindles. Sleep spindles are generally considered the hallmark of light sleep and often considered the ‘guards of sleep.’ In addition, in those publications already the A (alpha EEG states) and B stages (non-alpha stages) were proposed and their relationship to levels of consciousness or vigilance, that are still current and used in for example the EEG vigilance model.

the first ever published sleep EEGs that would form the basis of polysomnography as it is currently known. The inserts B, C, D and E are enlargements of what Loomis described with the vertical markings above B indicating seconds. Loomis described these examples as (B) ‘random’, (C) ‘saw-tooth’, or essentially the typical slow wave activity characteristic for deep sleep, (D) ‘trains’ and (E) ‘spindles’ which are now known as sleep spindles, here of a nice 14 Hz rhythm.

Conditioning

This period also marked the earliest period where conditioning was applied to EEG activity, thereby being the first basic demonstration of neurofeedback. As Loomis and colleagues stated on page 270 under ‘Conditioning’: “…Another interesting experiment may be described as ‘conditioning.’ If the subject lies in complete darkness with eyes open, a low tone stimulus lasting 5 seconds will not stop the alpha waves. If the low tone and also light stimulus are both presented simultaneously several times in succession at half minute intervals, the waves will of course stop, due to the attempt to see induced by the light, but if now the tone alone is sounded the waves also stop as the attempt to see is now induced by the sound. However, the effect of the tone alone will not last more than two or three times as the conditioning is not permanent and the sound no longer induces the attempt to see. We have observed this effort on several persons and regard it as quite analogues to a conditioned reflex…” In addition, the effects of hypnosis were investigated on EEG, and already quickly it was concluded that hypnosis could not be seen as a ‘sleep’ state due to the clear presence of alpha waves during hypnosis. A further experiment Loomis conducted using hypnosis is reminiscent of what Joe Kamiya would later demonstrate, but then based upon voluntary control and here with hypnosis. In this experiment, Loomis used adhesive tape to keep the eyes of his subject closed and use hypnotic suggestion to induce ‘temporary blindness’ i.e. suggest the subject saw nothing, resulting in synchronous alpha. When subsequently, with eyes closed, they suggested he saw a spot on the ceiling, the alpha rhythm desynchronized and disappeared, only appearing again when they told the subject he saw nothing. This could be reliably repeated 16 times. Hence, alpha was already brought under control of the ‘mind’ in this case using hypnotic suggestion.

In 1939, with the unrest and war looming in Europe, Loomis decided to donate his EEG equipment to Davis’ group at Harvard Medical School. At that time, he turned his scientific interest to experimental waveform physics and shifted the emphasis from pure science to war-related technology. His efforts would become pivotal in the development of radar technology, long-range radio navigation and the atomic bomb. President Franklin Roosevelt is said to have credited Loomis as second to Winston Churchill in turning the tide of World War II in the Allies favor. Hence, this intriguing pioneer of EEG in the US, Alfred Loomis – without him knowing or realizing – can be credited with two crucial discoveries and descriptions that would play a major role in the history of neurofeedback, namely applying conditioning principles to the EEG, and the description of sleep spindles, that we later will understand to be a fundamental aspect in understanding the working mechanism of SMR neurofeedback. In addition, his hypnosis experiments actually were already reminiscent of the notion that alpha and alpha-desynchronization can be controlled by the mind, which would be investigated further in the 1950’s by Joe Kamiya.

The EEG as experimental tool in psychology

Soon after, in 1936, experimental psychologist Lee Travis at Iowa was one of the first American’s to obtain EEG equipment for human recordings, to study brain activity in relation to speech and stutterers, demonstrating the utility of EEG as an experimental tool in psychology. Travis has trained some of the – soon to be – prominent EEG pioneers from the US including Herbert Jasper, John Knott, Charles Henry and Donald Lindsley. Lindsley was also exposed to EEG as a student at Davis’ lab at Harvard, where he belonged to the group of ‘Bergers’ and was able to produce good alpha activity, which resulted in him being the subject of the first demonstration at Davis’ lab. Lindsley continued to study maturation of the EEG in children and published his first description of maturational differences between children and adults in 1936, where he described that rhythmic alpha was already present at age 3-6 months at a frequency of 4 Hz, that matured to an adult 8-12 Hz alpha at the age of 8-10 years of age. During the mid 1940’s, Lindsley worked at the department of psychology at Northwestern University, but had no facilities for his experimental program. In 1947 he was invited by Horace Magoun to set-up his EEG equipment at the medical school in Chicago where their collaboration started.

Quantitative EEG (QEEG)

Thus far, most of the EEG analysis were conducted by visual inspection, especially in the clinical EEG area. An important development that originated out of UCLA in this early era, was the first demonstration of quantitative EEG or QEEG, where EEG was submitted to computerized analysis, often spectral power decomposition, as well as comparison to a normative group. Ross Adey pioneered the QEEG at UCLA.

Adey arrived at UCLA in 1957, where he became a professor of anatomy and physiology. His group pioneered the use of QEEG at the UCLA Brain Research Institute in the period 1961-1974. They were the first to use digital computers in the analysis of EEG with the production of brain maps and developed the first normative library of brain maps. See figure for some photos with the first equipment developed to measure EEG in outer space and during driving. As part of the Space Biology Laboratory they studied the effects of outer space and space travel on the brain, to determine whether prolonged space flight would be possible for the human body. As part of this NASA program Graham and Dietlein were the first to coin the term Normative EEG. In addition, Adey was well known for the ‘Adey window’, which describes the confined parameters under which a very weak electromagnetic signal could exert physiological effects. It could for example explain phenomena such as high-power electric lines’ effect on cell growth, or his work showing that brain tissue is sensitive to electromagnetic field radiation at levels that are orders of magnitude lower than classical synaptic excitation. Although this has been received with skepticism, this topic is currently investigated with great detail again in the area of neuromodulation, with Low-Field Magnetic Stimulation or Pulsed Electromagnetic Fields (PEMF).

One other remarkable person from this period was Arnold Scheibel. His initial interest was cardiology, however given the pervasiveness of emotional factors in the disease patterns he saw, he eventually switched to psychiatry. In 1955 he joined the UCLA faculty at the department of anatomy where he eventually became a professor of neurobiology and psychiatry at UCLA and the BRI. Arnold Scheibel did not publish a lot, he was actually a psychiatrist, but he was also a really good neuroscientist and fabulous teacher. He is especially known for having dissected Albert Einstein’s brain among others on the basis of which Scheibel and his colleague – and at that time his wife – Marian Diamond proposed the ‘efficiency-intelligence’ theory, based on the finding that Einstein had 73% more glial cells per neuron in the left hemisphere relative to others. They reasoned that the more glial cells per neuron the brain has, the ‘cleaner’ and more efficient the brain can operate, and thus the better the intelligence.

Ross Adey EEG in space Brainclinics

A photo from 1963 showing the equipment developed by Ross Adey and colleagues to measure EEG in space. Ross Adey – who pioneered QEEG – is the person on the right in the top left picture. The top-right image also shows the UCLA BRI building in the background (Courtesy of the Computer History Museum).