sleep Flashcards
why are EEGs negative?
because sodium is rushing into the cell and depolarizing it
synchronized activity description?
- when, shape
- neurons “in phase”
- summation causes large amp, low frequency EEG
- during sleep
desynchronized activity description?
- when, shape
- neurons “out of phase”
- get a complicated rhythm
- low amp, high frequency
- when brain is active
- seen in REM sleep
what are neural pacemakers?
- multiple VG channel types
- neurons can fire in rhythmic bursts of APs
- synchronized by thalamic input
oscillator circits
- steady rate, drives inhibitory cell, then theres bursts of spikes, then quiet.
- delicate balance similar to adaptation in vision
- synchronized by each-other
define a seizure?
abnormal synchronized brain activity
what are the two main categories of seizures?
define them.
generalized
- affects entire brain, loose consciousness
partial/focal
- affects only a portion of the brain
- commonly associated with brain damage and tumors
- temporal lobe
what are the types of generalized seizures?
grand mal / tonic-clonic
petit mal/focal
describe grand mal
sudden onset
- recovery takes up to hours
- tonic phase: stiff limbs, may stop breathing
- clonic phase: rapid muscle contractions
describe petit mal
Patient is completely dissociated from everything around them, only subtle motor signs
what are the types of partial seizures?
simple
complex
define simple partial
- retain awareness
- spasms
complex partial
- loose consciousness (seem in a daze)
- graded start ans stop
- can last minutes
- temporal lobes are most commonly involved
- aura often precedes seizure
what is eplilepsy?
- reoccurring seizures
how to anticonvulsants work?
- shift excitatory/inhibitory balance
- can block Na+ channels, Gu receptors
- can inhibit metabolism or increase release of GABA
what are other treatments for seizures?
- deep brain stimulation
- surgery
- keto diet (decrease neuron excitability)
what are status seizures?
- rare seizures that last longer than 5 minutes
- can be fatal
why do we sleep?
- conserve energy at night
- rest and recover
- memory consolidation
- disease prevention (obesity, alzheimers)
- self protection when most vulnerable
what happens when rats did not sleep?
- weight loss
- temperature regulation disrupted
- weakened immune system
- death
what would happened to randy when he did not to sleep?
- fatigue
- hallucinations
- speech
- memory
- he was fine after he slept
how does sleep relate to memory?
hippocampus activity is increases
how does sleep relate to memory?
hippocampus activity is increases
what are the effects of sleep deprivation in humans?
- inc heart rate, blood pressure, heart attack and cortisol levels
- leptin decreases, ghrelin increases
- male and female hormone levels are reduced
- type 2 diabetes
what is the glymphatic system?
what does it do?
- glial cells form channels along arteries and veins in the brain
- extracellular fluid carries away proteins and waste some of which can be toxic through cerebral spinal fluid
what impact does loss of sleep have on the glymphatic system?
- removal of beta amyloid via the glymphatic system is impaired in alzheimers patients
- sleep loss may contribute to this
what is fatal familial insomnia disease?
what causes it?
- rare disease triggered by mutation in gene that codes a prion protein
- causes cell death in the thalamus (relay center), which leads to an inability to sleep
symptoms
- onset in 50s
- insomnia
- weight loss
- dementia
- uncoordinated movement
- unable to walk or talk
- death after 1-3 years
what are the differences between REM and non-REM sleep?
REM = rapid eye movement, paradoxal sleep
non-REM = slow wave
what is the relationship between wave shape and sleep?
deeper sleep= bigger waves
describe non-REM sleep?
- 75% of sleep
- 4 stages based on EEG
- low muscle tone and body movements
- slow to no eye movement
- occasional dreams
- increased parasympathetic nervous system
- dec heart rate, bp, breathing rate
describe REM sleep?
- 25% of sleep
- rapid eye movements
- EEG looks awake
- atonia=no muscle tone
- increased sympathetic activity
- complex dreaming
what causes atonia in REM sleep?
what are the results?
- inhibition of lower motor neurons
- eyes, toes, fingers uninhibited
what is atonia and REM sleep behavior disorder?
- loss of REM atonia
what is the typical sleep cycle?
- progression from light to deep sleep to light sleep
- there are about 5-7 cycles in a night
how long is first REM episode to the last REM epidose?
- first = 10 minutes
- last = 40-90 minutes
what is the reticular activating system (RAS)?
- “little net”
- consists of about 100 nuclei in the brain stem
what occurs when the RAS is stimulated?
- RAS activates the brain
- makes EEG jump from sleep to awake
what happens when the rostral RAS is lesioned in an animal?
- animal is put into non-REM sleep or coma
what does ATP have to do with sleep?
- the active brain uses more ATP which is broken down into adenosine and phosphate
- less adenosine = more awake
- more adenosine = more sleep pressure = neurons are more hyperpolarized
as day goes on, more ATP is used and more adeonsine builds up in the system
what is the suprachiasmatic nucleus (SCN)?
what does it synchronize with?
- SCN is synchronized to light, but not dependent on it
- SCN spikes when “light inhibits the Pineal gland for less release of melatonin”
how does melatonin work?
- it is released when night begins to fall
- makes us more aware that it is is dark outside
- also associated with temperature
what areas in the brain are most active during REM sleep and dreams?
- visual cortex
what are the 3 principles of narcolepsy?
- REM sleep attacks
- cataplexy - sudden atonia triggered by intense emotions
- sleep paralysis - atonia that extends into time awake
what is narcolepsy caused by?
degeneration of hypocretin neurons in the lateral hypothalamus
