Central Nervous System
A person with eyes closed and mind wandering will have the following wave in EEG
I. ELECTROENCEPHALOGRAM: (EEG) –
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 — 1→theta (θ) activity Q
iii. Stage —2→Sleep spindle (13-15 cycles/sec) and K-complexes (high voltage spikes) Q
iv. Stage 3→theta 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
Central Nervous System