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Electroencephalography (EEG) – Brainwaves

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Presentation on theme: "Electroencephalography (EEG) – Brainwaves"— Presentation transcript:

1 Electroencephalography (EEG) – Brainwaves

2 Hans Berger ( ) Trauma as a soldier threatened emotional connection between him and his sister, experienced as psychic transmission. After the war he became a psychiatrist and worked on the technology until he obtained first recording in 1924. From 1929 to 1938 he published 14 scientific papers investigating EEG in clinical and normal populations.

3 Brain waves were first studied to help explain a psychic experience
As a soldier in the German Army in first decade of 1900, Berger fell off his horse directly in front of artillery cart and was nearly run over When he returned to HQ, telegram from his father saying his sister had feeling that he had been injured Berger would explore physical means of such psychic transmissions WWI German soldier

4 Brain activity & psychic action
He studied blood circulation in brain (1901). He investigated influence of heartbeat, respiration, vasomotor functions, and position of the head and body on brain pulsations measured through an opening (trephined) in the skull, but information was limited and ultimately disappointing. In 1902 he measured electrical activity above skull defects with capillary electrometer; later a galvanometer.

5 Previous Research leading to EEG
Berger was fully aware that Richard Caton ( ), a Liverpool surgeon, had succeeded in 1875 in measuring electrical potentials on the exposed cortex of experimental animals (rabbit and monkey). Berger also knew of Polish physiologist Adolf Beck (1891) and Russian physiologist Pravdich-Neminski ( ) who recorded photographic record of the electrical activity of dog’s brain through the skull.

6 Secrecy Berger's experiments carried on in spare time and utter secrecy. As a diversionary measure he gave public discourses on telepathy, offering hypotheses of wave propagation to explain it. 1926 lab

7 First EEG (1924) Berger made 73 EEG recordings from his 15y son, Klaus. First frequency encountered was in 10-hertz range, (8 to 12 Hz) which he named alpha (others called the Berger rhythm). After 5 years of investigation, he published his findings. In 1929 he reported how brain waves changed dramatically if subject simply shifts from eyes closed to eyes open state. Furthermore, brain waves also changed when the subject sat quietly with eyes closed "focusing" on solving a math problem.

8 Recognition came late In 1937 invited to preside with Adrian at symposium on electrical activity in the nervous system at the Congress of Psychology in Paris. They hailed Berger as the most distinguished of all the visitors. He was ordered by Nazi authorities in 1938 to fire all Jewish employees at his lab. He refused and was forced to retire. He hung himself at his clinic on June 1, 1941 He studied normal subjects and brain-injured, thereby laying the foundation for the application of the technique to clinical technology.

9 Electrophysiology spontaneous activity, evoked potentials, and
single neuron recordings

10 MEG


12 Instrument sensitivity
102 volts - Wall socket 10-3 volts - EKG (millivolts) 10-6 volts – EEG (microvolts)


14 10-20 System of Electrode Placement
F = Frontal P = Parietal T = Temporal O = Occipital C = Central A = Auxiliary Odd # = Left Even # = Right



17 Acquisition

18 How do you study this?

19 … manipulate behavioral context, stimulus presentations


21 Energy (Amplitude) & Speed (Frequency)


23 Energy distribution by Frequency


25 Clinical EEG Rhythms

26 Sleep Stages

27 Inhibitory forces generate population rhythmicity

28 Alpha rhythm = idling rhythm, prepared to response, easier to recruit neurons in such states than if in active processing states


30 Eyes Closed Baseline

31 Eyes Open Baseline


33 Role of Topography and “Timing”

34 Posterior Alpha during Eyes Closed Rest : Normal

35 Frontal Slowing during Math: Abnormal


37 Brain (surface) Maps Normal Abnormal

38 AUTISM a neurodevelopmental disorder that impacts cognition and behavior “Auto” –child is locked within him/herself



41 Sleep Spindle matures by 3 months of age


43 1969 study where spindles in autistics ranged from 10.5-15 Hz

44 Heartbreak of autism Lack of reciprocity, little connection with mother 1 in 10 chance of having another autistic child

45 4 times more likely for boys to be autistic than girls

46 Fully Matured Spindle in 4 month old infant at risk for autism

47 Perfectly Normal Boy

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