Electroencephalography (EEG)-based detection, management ...
Electroencephalography (EEG) - Eötvös Loránd...
Transcript of Electroencephalography (EEG) - Eötvös Loránd...
Electroencephalography (EEG)
Human neocortex – lobes and areas
parietal lobe
frontal lobe
occipital lobe
temporal lobe
Mediansagittal section of human brain
parietal lobe
frontal lobe
corpus callosum
thalamus
amygdala
occipital lobe
temporal lobe hippocampus
Structure of human neocortex - pyramidal neurons
Generation of EEG Piramissejt
sink
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Thalamocortikális EPSP
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EEG waves represent the contributions of summed
synaptic potentials in the apical dendrites of the cortical pyramidal neurons
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Generation of EEG
EEG recording
Different EEG electrodes
The first human EEG - Berger
1920s
Hans Berger
International 10-20 system
Characteristic EEG waves
beta (β)
alpha (α)
theta (θ)
delta (δ)
50 µV
Awake: low-voltage random, fast, > 13 Hz, < 10 µV
Drowsy: 8-13 Hz, 10 -50 µV
Sleep stage 1: 4-8 Hz, 50 µV, theta waves
Sleep stage 2: 12-14 Hz, sleep spindles and K complexes
Deep sleep (sleep stage 3-4): 0-4 Hz, >75 µV
REM sleep: low-voltage random, fast with sawtooth waves
beta (β)
1 s
Main EEG characteristics • synchronisation:
- nearby cortical pyramidal neurons function in synchrony e.g. lack of sensory stimulation in the sensory cortex - EEG waves: amplitude increases, frequency decreases - open -> closed eyes: β -> α waves over the occipital lobe (primary visual center)
• desynchronisation: - nearby cortical pyramidal neurons behave differently:
e.g. sensory stimulation in the sensory cortex
- EEG waves: amplitude decreases, frequency increases, irregular waves - closed -> open eyes: α -> β waves over the occipital lobe (primary visual center)
Normal, awake EEG recorded from an adult
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1: small amplitude β activity 2: λ waves in the occipital region, during picture viewing 3: α rhythm (α spindles) in the occipital region, minimal β activity
4: desynchronization due to the opening of the eyes
Sleep cycles
time (h)
NREM: slow-wave sleep (SWS)
REM: rapid eye movements, paradoxical sleep
Normal EEG recorded from an adult during sleep 1
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1: stage 2 of slow-wave sleep with K complex (a) and sleep spindle (b) 2: deep slow-wave sleep (stage 4) with consecutive delta waves (e) 3: REM sleep with artefacts due to eye movements
Normal EEG activity from a 8-month-old child
1: awake, resting state 2: light sleep (drowsiness) 3: asynchronous activity, deep sleep
Recording artefacts
1: blink,
2-EO: opening of the eye,
3-EC: closing the eye, 4-EM: slow eye movements, 5-EM: saccadic eye movements
Recording artefacts II
1-2: muscle movements, 3: ECG artefacts, 4: muscle movement artefacts due to talking
5: muscle movement artefacts due to chewing
Asymmetric hemispheral activity
Synchronizing effects of rhythmic light flashes
1: normal EEG 2-8: 1, 3, 6, 9, 12, 15 and 18 Hz flashes
Generalised grand mal epilepsy
1: tonic phase, 2: clonic phase
Generalised petit mal or “absence”, "spike and wave" epilepsy