Electroencephalography (EEG) – Brainwaves

Hans Berger (1873-1941)Hans Berger (1873-1941) Trauma as a soldier Trauma as a soldier

threatened emotional threatened emotional connection between him and connection between him and his sister, experienced as his sister, experienced as psychic transmission.psychic transmission.

After the war he became a After the war he became a psychiatrist and worked on psychiatrist and worked on the technology until he the technology until he obtained first recording in obtained first recording in 1924. 1924.

From 1929 to 1938 he From 1929 to 1938 he published 14 scientific papers published 14 scientific papers investigating EEG in clinical investigating EEG in clinical and normal populations.and normal populations.

Brain waves were first studied to Brain waves were first studied to help explain a psychic experiencehelp explain a psychic experience

WWI German soldierWWI German soldier

As a soldier in the As a soldier in the German Army in first German Army in first decade of 1900, Berger decade of 1900, Berger fell off his horse directly fell off his horse directly in front of artillery cart in front of artillery cart and was nearly run overand was nearly run over

When he returned to HQ, When he returned to HQ, telegram from his father telegram from his father saying his sister had saying his sister had feeling that he had been feeling that he had been injuredinjured

Berger would explore Berger would explore physical means of such physical means of such psychic transmissionspsychic transmissions

Brain activity & psychic actionBrain activity & psychic action He studied blood He studied blood

circulation in brain (1901). circulation in brain (1901). He investigated influence He investigated influence of heartbeat, respiration, of heartbeat, respiration, vasomotor functions, and vasomotor functions, and position of the head and position of the head and body on brain pulsations body on brain pulsations measured through an measured through an opening (trephined) in the opening (trephined) in the skull, but information was skull, but information was limited and ultimately limited and ultimately disappointing.disappointing.

In 1902 he measured In 1902 he measured electrical activity above electrical activity above skull defects with capillary skull defects with capillary electrometer; later a electrometer; later a galvanometer. galvanometer.

Previous Research leading to EEGPrevious Research leading to EEG Berger was fully aware that Berger was fully aware that

Richard Caton (1842-1926), Richard Caton (1842-1926), a Liverpool surgeon, had a Liverpool surgeon, had succeeded in 1875 in succeeded in 1875 in measuring electrical measuring electrical potentials on the exposed potentials on the exposed cortex of experimental cortex of experimental animals (rabbit and animals (rabbit and monkey). monkey).

Berger also knew of Polish Berger also knew of Polish physiologist Adolf Beck physiologist Adolf Beck (1891) and Russian (1891) and Russian physiologist Pravdich-physiologist Pravdich-Neminski (1879-1952) who Neminski (1879-1952) who recorded photographic recorded photographic record of the electrical record of the electrical activity of dog’s brain activity of dog’s brain through the skull. through the skull.

SecrecySecrecy

1926 lab1926 lab

Berger's experiments Berger's experiments carried on in spare time carried on in spare time and utter secrecy. and utter secrecy.

As a diversionary As a diversionary measure he gave public measure he gave public discourses on telepathy, discourses on telepathy, offering hypotheses of offering hypotheses of wave propagation to wave propagation to explain it. explain it.

First EEG (1924)First EEG (1924) Berger made 73 EEG recordings Berger made 73 EEG recordings

from his 15y son, Klaus. from his 15y son, Klaus. • First frequency encountered First frequency encountered

was in 10-hertz range, (8 to was in 10-hertz range, (8 to 12 Hz) which he named 12 Hz) which he named alpha (others called the alpha (others called the Berger rhythm).Berger rhythm).

After 5 years of investigation, After 5 years of investigation, he published his findings. he published his findings.

In 1929 he reported how brain In 1929 he reported how brain waves changed dramatically if waves changed dramatically if subject simply shifts from eyes subject simply shifts from eyes closed to eyes open state. closed to eyes open state. Furthermore, brain waves also Furthermore, brain waves also changed when the subject sat changed when the subject sat quietly with eyes closed quietly with eyes closed "focusing" on solving a math "focusing" on solving a math problem. problem.

Recognition came lateRecognition came late

He studied normal subjects He studied normal subjects and brain-injured, and brain-injured, thereby laying the thereby laying the foundation for the foundation for the application of the application of the technique to clinical technique to clinical technology. technology.

In 1937 invited to preside In 1937 invited to preside with Adrian at symposium with Adrian at symposium on electrical activity in on electrical activity in the nervous system at the the nervous system at the Congress of Psychology in Congress of Psychology in Paris. They hailed Berger Paris. They hailed Berger as the most distinguished as the most distinguished of all the visitors. of all the visitors.

He was ordered by Nazi He was ordered by Nazi authorities in 1938 to fire authorities in 1938 to fire all Jewish employees at all Jewish employees at his lab. his lab.

He refused and was He refused and was forced to retire. He hung forced to retire. He hung himself at his clinic on himself at his clinic on June 1, 1941June 1, 1941

Electrophysiology Electrophysiology

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

MEGMEG

Instrument sensitivityInstrument sensitivity 101022 volts - Wall socket volts - Wall socket

1010-3-3 volts - EKG volts - EKG (millivolts)(millivolts)

1010-6-6 volts – volts – EEGEEG (microvolts)(microvolts)

10-20 System of 10-20 System of Electrode Electrode PlacementPlacement

F = FrontalF = Frontal P = ParietalP = Parietal T = TemporalT = Temporal O = OccipitalO = Occipital C = CentralC = Central

A = AuxiliaryA = Auxiliary

Odd # = Left Odd # = Left Even # = RightEven # = Right

AcquisitionAcquisition

How do you study this?How do you study this?

… … manipulate behavioral context, manipulate behavioral context, stimulus presentationsstimulus presentations

Energy (Amplitude) & Energy (Amplitude) & Speed (Frequency)Speed (Frequency)

Energy distribution by FrequencyEnergy distribution by Frequency

Clinical EEG RhythmsClinical EEG Rhythms

Sleep Sleep StagesStages

Inhibitory forces generate Inhibitory forces generate population rhythmicitypopulation rhythmicity

Alpha rhythm = idling rhythm, prepared to Alpha rhythm = idling rhythm, prepared to response, easier to recruit neurons in such states response, easier to recruit neurons in such states

than if in active processing statesthan if in active processing states

Eyes Closed BaselineEyes Closed Baseline

Eyes Open BaselineEyes Open Baseline

Role of Topography and “Timing”Role of Topography and “Timing”

Posterior Alpha during Eyes Closed Rest :Posterior Alpha during Eyes Closed Rest :NormalNormal

Frontal Slowing during Math: Frontal Slowing during Math: AbnormalAbnormal

Brain (surface) MapsBrain (surface) Maps

NormalNormal

AbnormalAbnormal

AUTISMAUTISM a a neurodevelopmental disorderneurodevelopmental disorder that impacts that impacts

cognition and behaviorcognition and behavior ““Auto” –child is locked within him/herselfAuto” –child is locked within him/herself

Sleep Spindle matures by 3 months of ageSleep Spindle matures by 3 months of age

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

Heartbreak of autismHeartbreak of autism

Lack of Lack of reciprocity, reciprocity, little connection little connection with motherwith mother

1 in 10 chance 1 in 10 chance of having of having another another autistic autistic childchild

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

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

Perfectly Normal BoyPerfectly Normal Boy