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Central Nervous System

3 out of 5

A person with eyes closed and mind wandering will have the following wave in EEG

A Beta waves
B Alpha waves

C Delta waves
D Theta waves

Ans. B Alpha waves


German psychiatrist Hans Berger, who introduce the term electroencephogram (EEG) to denote the record of the variations in brain potential

a. Alpha rhythm 8-12 HZ Q and an amplitude of 50-100 V recorded when the persons are awake Q, at rest, with the mind wandering Q and the eyes closed Q It is most marked in the parieto-occipital area Q.

b. Beta rhythum(wave) 18-30Hz Q seen over frontal regionQ

c. Theta (θ) rhythm 4-7Hz Q with large amplitude occurs in children and is generated in the hippocampus Q

d. Delta waves <4 Hz Q with large amplitude

e. Gamma oscillations: 30-80Hz Q, are often seen when on individual is aroused and focuses attention on something.

II. Sleep pattern –

a. Types —

i. REM Sleep, or D-sleep (desynchronized, or dreaming sleep) or active sleep or paradoxial sleep

ii. NREM sleep or quiet sleep or orthodox sleep or S-sleep (synchronized sleep)

b. As the person falls asleep, the person first passes through, stages of NREM sleep.

c. Over all REM sleep constitues 20 to 25% of total sleep and NREM Sleep stages (1 and 2) are 50 to 60 persent.Q

d. NREM sleep: 4 stages (1 to 4) C/B

i. Wakefulness -

· Alert wakefulness with Eye open α-wave

· Quiet wakefulness with eye closed α-waves

ii. Stage — 1theta (θ) activity Q

iii. Stage —2Sleep spindle (13-15 cycles/sec) and K-complexes (high voltage spikes) Q

iv. Stage 3theta and delta activity Q

v. Stage 4 (Deep sleep or cerebral sleep) Delta activity (δ) predominate Q

vi. Stage 3 and 4 togather called slow-wave sleepQ

vii. Disorders of the NREM stage 4 and 3 sleep: - i.e. during deep sleep Q

· Sleep walking (somnabulism)

· Sleep terrors or night terrors (Pavornocturnus) C/B →↑Autonomic sympathetic activity the dream is not remembered.

· Sleep-related enuresis (but CMDT says that it is not limited to a specific stage of sleep)

· Bruxism (tooth grinding)

· Sleep talking (Somniloquy)

e. REM sleep (Paradoxical sleep) C/B

i. EEG resembles stage I NREM sleep theta activity REM sleep is c/b a low amplitude, mixed frequency EEG similar to NREM stage I

ii. Associated with active dreaming (remember on wakening) Q

iii. Muscle tone depressed (paralysis)

iv. HR and Resp. rate irregular

v. Few irregular muscle movement occurs.

vi. Brain metabolism may increased by 20%

[Note another characteristic of REM sleep is the occurance of large phasic potentials, in groups of 3 —5, that originate in the pons and pass rapidly to LGB and from there to the occipital cortex, and therefore, they are called Ponto-geniculo-occipital (PGO) spikes]

vii. Sleep disorder of REM sleep: - eg.

· Narcolepsy: [(Sleep attack (m.c.), cataplexy, Hypnagogic hallucinations, sleep paralysis (least common)]

· Night mares dream is remembered