Section 6 Electroencephalogram (EEG), Wakefulness and sleep
Section 6 Electroencephalogram (EEG), Wakefulness and Sleep
I. Electroencephalogram (EEG) 1. Brain Waves
I. Electroencephalogram (EEG) 1. Brain Waves
Brain Waves State of the brain o normal brain function involves continuous electrical activity o Patterns of neuronal electrical activity recorded are called brain waves o Brain waves change with age, sensory stimuli, brain disease. and the chemical state of the body o An electroencephalogram(EEG)records this activity o EEGs can be used to diagnose and localize brain lesions tumors, infarcts, infections, abscesses, and epileptic lesions o a flat EEG(no electrical activity) is clinical evidence of death
Brain Waves: State of the Brain ⚫ Normal brain function involves continuous electrical activity ⚫ Patterns of neuronal electrical activity recorded are called brain waves ⚫ Brain waves change with age, sensory stimuli, brain disease, and the chemical state of the body ⚫ An electroencephalogram (EEG) records this activity ⚫ EEGs can be used to diagnose and localize brain lesions, tumors, infarcts, infections, abscesses, and epileptic lesions ⚫ A flat EEG (no electrical activity) is clinical evidence of death
The eEG be recorded with Scalp electrodes through the unopened skull or with electrodes on or in the brain Blink artifacts Time(sec) 2 3 4 5 6 8 9 wrwywwwMv-nMmw www灬 wwlwywAnMh WON AA wwww Electrode Alpha rhythms Beta rhythms positions A normalEEg
The EEG be recorded with Scalp electrodes through the unopened skull or with electrodes on or in the brain. A normal EEG
Electroencephalogram(EEG) Copyright e The MeGraw-Hill Companies, Inc, Permission required for reproduction or display ● Measures synaptic potentials Alpha任 produced at cell bodies and Beta Hwrwwm个以的 dendrites Create electrical currents Theta HwunnMMn/M ● Used clinically diagnose epilepsy and brain death Delta 1 sec
Electroencephalogram (EEG) ⚫ Measures synaptic potentials produced at cell bodies and dendrites. – Create electrical currents. ⚫ Used clinically diagnose epilepsy and brain death
EEG Patterns Alpha: low-amplitude, SloW. Synchronous waves indicating an Alpha idling” brain Recorded from Beta wMwmM//ww parietal and occipital regions ● Person is awake, Theta wnw/+/Umw relaxed. with eyes closed 50uV 10-12 cycles/sec 1 sec 50~100uV
EEG Patterns ⚫ Alpha: low-amplitude, slow, synchronous waves indicating an “idling” brain – Recorded from parietal and occipital regions. ⚫ Person is awake, relaxed, with eyes closed. – 10-12 cycles/sec – 50 ~100 V
.Beta: high-amplitude waves seen in deep alpha sleep and when reticular activating system is damped be eta strongest from frontal lobes near precentral gyrus *wwMwwwr Produced by theta visual stimuli and mental activity Evoked activity delta 13 cycles/sec 1 second interval (b)
•Beta:high-amplitude waves seen in deep sleep and when reticular activating system is damped –Strongest from frontal lobes near precentral gyrus. •Produced by visual stimuli and mental activity. •Evoked activity. –13-25 cycles/sec
Eyes open Eyes closed Alpha Block: Replacement of the alpha rhythm by an asynchronous low-voltage beta rhythm when opening the eye
Alpha Block: Replacement of the alpha rhythm by an asynchronous, low-voltage beta rhythm when opening the eyes
Theta. more Irregular than alpha waves Alpha Emitted from temporal and Beta occipital lobes Common in newborn some Theta w(n oulU sleep in adult Adult indicates 50 severe Delta emotional stress sec cycles/sec
•Theta :more irregular than alpha waves –Emitted from temporal and occipital lobes. •Common in newborn some sleep in adult. •Adult indicates severe emotional stress. –5-8 cycles/sec
Delta: high- alpha amplitude waves common during Sleep and awake beta infant In awake adult * */wMMwNwr indicate brain theta damage cycles/sec delta 1 second interval b)
•Delta: highamplitude waves; •Common during sleep and awake infant. •In awake adult indicate brain damage. –1-5 cycles/sec
