Chapter 34 Electroencephalogram (EEg Wakefulness and sleep
Chapter 34 Electroencephalogram (EEG), Wakefulness and Sleep
I. Electroencephalogram (EEG)
I. Electroencephalogram (EEG)
Brain Waves and EEG o normal brain function involves continuous electrical activity ● Brain wave The undulations in the recorded electrical potentials Change with age, sensory stimuli, brain disease, and the psychoses o An electroencephalogram (EEG The entire record of the brain wave 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
I. Brain Waves and EEG ⚫ Normal brain function involves continuous electrical activity ⚫ Brain Wave – The undulations in the recorded electrical potentials – Change with age, sensory stimuli, brain disease, and the psychoses ⚫ An electroencephalogram (EEG) – The entire record of the brain wave – 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 Time(sec) Blink artifacts 3 6 8 9 → WAw/vww一 AwwA A-50 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
EEG Patterns o Alpha: low-amplitude, Slow. synchronous Alpha WrwhwMlMinua waves indicating an idling”br rain Beta Recorded from occipital, parietal and frontal regions Theta mn/ruM ● Person is awake, relaxed, with eyes close d ∧、w 50 uV Delta 8-13Hz sec 20~100uV
EEG Patterns ⚫ Alpha: low-amplitude, slow, synchronous waves indicating an “idling” brain – Recorded from occipital, parietal and frontal regions. ⚫ Person is awake, relaxed, with eyes closed. – 8-13 Hz – 20 ~100 V
Beta: high-frequency wMMwwwwwwMwwww but low amplitude alpha waves seen in deep sleep or persons attention is directed be eta to some specific type of mental activity *wwMwwwr Strongest from parietal and frontal theta obes produced by visual stimuli and mental activity delta -14-30Hz 5-20μV 1 second interval (b)
Beta: high-frequency but low amplitude waves seen in deep sleep or person’s attention is directed to some specific type of mental activity –Strongest from parietal and frontal lobes •Produced by visual stimuli and mental activity. –14-30 Hz –5-20 V
Eyes open Eyes closed mULV Alpha Block: Replacement of the alpha rhythm by an asynchronous low-voltage beta rhythm when opening the eyes
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 wMWwM4MwnaAwc emitted from temporal and Beta parietal lobes o Common in newborn and Theta sleep in adult Adult indicates 50 severe emotionalDelta stress sec 4-7Hz 100-150uV
•Theta :more irregular than alpha waves –Emitted from temporal and parietal lobes. •Common in newborn and sleep in adult. •Adult indicates severe emotional stress. –4-7 Hz –100-150 V
Delta: high amplitude waves alpha Emitted from temporal and wr.AM M IW MdM occipital lobes beta Common during wiw sleep and awake Mw infant theta in awake adult indicate brain damage delta 0.5-3Hz 20-200uⅤ 1 second interval b)
•Delta: highamplitude waves; •Emitted from temporal and occipital lobes. •Common during sleep and awake infant. •In awake adult indicate brain damage. –0.5-3 Hz –20 – 200 V
EXCITED 足 ELAXEC SPONTANEOUS DRowsy CORTICAL w ELECTRICAL AsLEEP POTENTIALS THE EEG DEEP SLEEP Figure 10.30. Typical EEG records from normal subjects in different states of arousal and from a comatose subject
SPONTANEOUS CORTICAL ELECTRICAL POTENTIALS: THE EEG