states of brain activity: sleep,brain waves,epilepsy,psychoses and dementia. Flashcards
difference between sleep and coma:
sleep: is the unconscious state of mind from which an individual can be aroused if provided with any sensory or other stimulus.
whlie…
coma: is the unconsious state of mind from which an individual cant be aroused by any stimulus.
sleep is divided into:
REM / fast wave sleep: in which the eyes undergo rapid movements even if the individual is asleep. it constitudes about 25 % of the total sleep duration. its can be called nap which is not really restful. it is also characterized by vivid dreams. and an individual is vaguely aware of its surroundings during rem.muscle coordination is slightly active during rem.
NonREM / slow wave sleep: its comparatively very peaceful and a restful sleep./ deep sleep. during nonrem sleep heart rate, bp, metabolic rate and respiratory rates are all reduced. we dont remeber the dreams that occur during non rem since brain activity is highly reduced hence memories dont form.
differences between rem and Non rem:
- duration of rem : 5 to 30 minutes in young adults duration of Nrem: 90 mins to 3 hrs
2.
Nrem is restful, peacful and deep sleep as compared to the restless rem sleep.
3.
Nrem body and brain activity are highly reduced while in case of rem muscle coordination is quite active such as rapid movement of eye. - rem is fast wave is sleep
nrem is slow wave sleep
5.
we remember the dreams of rem sleep
we dont remember the dreams of nrem sleep. - rem: high freq low amplitude waves
nrem: high amplitude slow waves.
what happens to the sleep cycle of the person whose extremely tired?
the duration and freq of rem bouts or intervals are reduced in order to increase the nrem cycle to provide the individual with restful sleep.
whats the difference between dreams of rem and nrem?
the dreams of rem are comparatively associated with more muscle activity.
the dreams of nrem are not remembered since brain activity quite low during the nrem cycle and thus we dont remember those dreams.
what are the basic theories of sleep?
- previously it was believed that sleep occurs simply because our excitatory areas of upper brain parts becomes fatigued from the waking life activities as a result it inactivates at night.
- but recently an experiment on rats proved that sleep is actually induced by an active inhibitory process.
This was proved when the the midpns and brain stem were sliced from the rats brain only to leave a cerebral cortex. it was observed that the rat became insomniac; which hereby proves that the mid pons and lower parts of brain help inhibit the active cerebral cortex and other parts of the brain.
to promote sleep what type of signals should be provided to the reticular formation?
inhibitory signals should be provided for promoting sleep and vice versa.
which neurotransmitters are involved with sleep?
serotonin, norepinephrine, dopamine, acetylcholine.
where are the raphe nuclei present and how do they help in stimulating sleep?
raphe nuclei are the most conspicous sites of sleep stimulation , present in the lower pons and medulla. their nerve fibers extend to the thalamus, hypothalamus, reticular formation, limbic system, neo cortex of the brain and also to the posterior horn of the spinal nerve where they inhibit signals of pain.
The nerve ends of raphe nuclei fibers secrete serotonin which is associated with sleep.
how does serotonin help in inducing sleep?
serotonin( also known as happy hormone) basically is associated with the formation of melatonin and promotes better quality of sleep by initially causing insomnia.
Thats why whenever a person is provided with anti serotonin drugs they suffer from insomnia.
depressed individuals usually lack serotonin and are insomiacs so they are provided with antidepressants that stimulate serotonin secretion to help with sleep production.
apart from the raphe nuclei how is sleep induced ?
- by the stimulation of the nucleus of the tractus solitarus.
- by the stimulation of the several regions of the diencephalon including ;
..the rostral ( in front of ) part of the hypothalamus mainly in the superchiasmal area.
..and an occasional area in the diffuse nuclei of the thalamus.
which lesions cause the state of high wakefulness?
- the dicrete lesions of raphe nuclei cause high state of wakefulness.
2.the same is true for the superchiasmal regions of hypithalamus.
in both the cases the the nuclei of the reticular system and the pons seem to become released which cause intense wakefulness.
their inhibition induces sleep.
sometimes the lesions of hypothalamus cause such intense wakefulness that the animal dies of exhaustion.
which substance has been found to be accumulated inthe CSF and urine of the animals that were kept awake foor several days?
a high molecular weight compund called muryl peptide was found to be accumulated in the urine and csf of those animals.
this compound is associated with producing slow wave sleep.
Another substance which is nonpeptide in nature with similar effects was also found in the blood of sleeping animals.
which drugs increase the occurence of rem sleep?
drugs that mimic the action of acetylcholine increase rem cycles.
why is our brain active during rem cycle?
it might be because the large acetylcholine secreting neurons in the upper brain stem reticular formation might activate brain through their extensive fibers resulting in our brain being active during rem. but these signals are not approriate enough becasue if they are appropriate then this is the charachteristic of wakefulness not rem.
