The Electropsychogram

The Electropsychogram
How to Measure Mental Fitness and Emotions

The electropsychogram is based on electric activity, a „language of the brain“. It was the year 1929, when German medical doctor Hans Berger published the first discovery of electric activity of the human brain. Since this time thousends of publications appeared and every neurologist in the world has to learn to measure and interpret this electric changes which are recorded from the scalp by a set of electrodes connected to an amplifier. The signals are not very large (about 1 to 100 microVolt amplitude) but they contain a large amount of information. The so-called raw-signal - as it is written on paper or computer screens - does not provide direct quantitative information. It has to be mathematically transformed. The most common way to analyse this kind of information is frequency analysis named after the French mathematician Fourier as Fourier Transformation (FT). Frequency analysis is more familiar to us from its use in astronomy, where even the composition of far distant stars can be derived from the obtained spectra. Thus, spectral frequency content is a proper method to mathematically describe information contained within the electric potential changes of human brains. This was recognized also already by Hans Berger who published his first approach in this direction with Dietsch in 1932. At that time it took him several weeks to transform the signal of few seconds of recording. Today with modern computer aid we calculate it online and real time on 99 channels continuously. With a time resolution of 4 seconds we can follow now mental work and emotions as well as drug effects. Even sleep can now be looked at automatically. A major break through was reached nearly twenty years ago when Hans Carlos Hofmann and myself developed a method for transforming the spectral information into spectral colours leading to a new type of brain mapping. We called it Computer Aided Topographical ElectroEncephaloMetry (CATEEM®). A large amount of data has been recorded since that time and resulted in ever safer interpretation of this language in the presence of different experimental conditions. It has been used in many set ups and has passed now its biggest challenge, namely the quantitative decription of mental fitness and emotions. The electropsychograms of „reading“ and during a memory task is given in Fig. 1.

Fig. 1 Average Electropsychogram obtained during a period of 5 min of reading. Difference of spectral content is shown to the relaxed state with open eyes (100%) fixing a distant point. Horizontal line represents „no change“. The bar graph shows single frequency ranges (red to blue) at 17 electrode positions (C=central, F=frontal, P=parietal, T=temporal, O=occcipital). Maps are constructed by additive colour mixture of spectral colours representing spectral frequencies (average of 10 people). During „reading“ it appears that the frontal brain areas (in the center of the spheric projection) lightens up due to increase of slow frequencies (red and orange). It looks different during a performance of a memory task, where „more brain“ is involved mainly within frontal parts of the brain (pointing to the middle of the picture).

Changes in different frequency ranges within several regions can now be used to follow the individual conscious and unconscious communication structure of the brain. In order to evaluate these many regional changes quantitatively, again a mathematical procedure has to be used: so-called discriminant analysis. This procedure allows to classify the observed changes of electric activity. In this analysis different psychic conditions can be compared with each other quantitatively by regarding the electric power within six frequency ranges (red to blue) in the polydimensional space. Projection into the six-dimensional space documents very clearly the different information processing of the brain in response to various challenges, based on its electric activity. Mental work or watching TV are reflected in a completely different manner as one can see from Fig. 2. In this type of analysis similar colours reflect similar responses of the brain. Spatial coordinates give additional information on difference between for example different emotional contents of the 5 minute lasting movies (comedy, animal film, disney excerpt, erotic and sex film).


Fig. 2 Example of representation of different electropsychograms in the polydimensonal space obtained during performance of cognitive tasks or watching TV film excerpts with different contents. Similar colours signalize similar reactions.

Using this methodology of constructing electropsychograms during the relaxed state or during cognitive or emotional challenges allows for classification of neutraceuticals as is documented in Fig. 3 for a number of herbal preparations (for details please contact us). Thus, two goals can be reached by this method: 1) to achieve clinical proof of a health claim using cognitive or emotional testing and 2) classification of the preparation with respect to other preparations or standard drugs.

Fig. 3 Classification of different neutraceuticals according to electropsychograms obtained in the relaxed state during eyes open (Aa) and eyes closed (Az) condition during recording of electric activity. Please remark that Hypericum (St. John`s wort) approaches the standard drug fluoxetine (an antidepressive chemical). Data are given for the third hour after administration.

The Electropsychogram can now be used to quantify the reaction of subjects to cognitive or emotional challenges in order to evaluate effects for example of nutraceuticals on the brain or to pretest TV commercials with respect to memory and/or emotion.