EEG and Sleep Flashcards
(48 cards)
1
Q
What is EEG?
A
Electroencephalogram
- recording of the rhythmic activity of the brain
- made from the cerebral cortex
- electrodes placed on the skull
2
Q
Richard Caton
A
- first person to probe the brain of animals with electrodes
- Discovered electrical brain signals
- used a reflecting galvanometer
- measure micro-amperes
- primitive form of amplification
3
Q
Hans Berger
A
- First to record EEG from humans
- defined all major EEG rhythms
4
Q
Basic EEG Frequencies:
A
- Alpha Rhythm
- 8-13 Hz
- awake, relaxed adults
- closed eyes
- Beta Rhythm
- 13-30 Hz
- higher frequencies
- awake adults
- open eyes
- 13-30 Hz
- Theta Rhythm
- 4-7 Hz
- slower higher amplitude
- drowsiness
- 4-7 Hz
- Delta Rhythm
- 0.5-4Hz
- very slow, high amplitude
- Sleep
- 0.5-4Hz
5
Q
Mechanism of EEG
A
- All the action potentials on the neuronal cell bodies
- EEGs are derived from alternating excitatory or inhibitory synaptic potentials
- in cortical neurons as a result of thalamocortical inputs (and other inputs)
6
Q
What is the principle source of EEG electrical activity?
A
- Pyramidal cells
- projects from the thalamus to the contralateral cortex
- sum of all excitatory or inhibitory synaptic potentials
7
Q
EEG as a diagnostic tool:
A
- Coma-EEG
- Mainly Delta Activity
- Brain Dead:
- sustained flat EEG reading
- Epilepsy: (petit mal)
- Epilepsy (grand mal)
- Partial Seizures
- spikes in affected areas
8
Q
EEG: Test the integrity of sensory pathway
A
- SEP
- somatosensory evoked potentials
- cortical potentials generated by the response of sensory neurons to the stimluation of peripheral nerves
- ex: stimulate skin on hand
- If no conductance= peripheral nerve has been severed/damaged
9
Q
Types of EEG: Comatose patient
A
- centralized slow waves
- mainly delta activity
10
Q
Type of EEG: Epilepsy different types
A
- Generalized seizures:
- Grand Mal:
- Petit Mal
- Partial Seizures (aka focal seizures)
- Temporal lobe seizure
- Focal seizure
- Secondary Generalized Seizures
11
Q
Seizure: Definition
A
- Latin-to take possesion of
- the clinical manifestation of abnormal, excessive, hypersynchronous discharge of a population of cortical neurons
12
Q
Epilepsy
A
- Chronic disorder of CNS
- recurrent unprovoked seizures
13
Q
Seizure initiation is characterized by:
A
2 concurrent events:
- high frequency bursts of action potentials
- hypersynchronization of neuronal population
14
Q
Pathway for seizure propagation
A
- Seizures may start in certain regions then spread
15
Q
Petit Mal attack (seizure)
A
- EEG
- Symmetrical
- highly synchronized activity
- aka Absence seizure
- Milder type of activity
- causes unconsciousness with no convulsions
- begins and ends abruptly and without warning
- blank stare
- No confusion
- can Resume activity immediatelly
- After there is no memory of the seizure
16
Q
Grand Mal attack (seizure)
A
- AKA Generalized tonic-clonic seizure
- usually short cry and fall to the ground
- Tonic phase
- muscles will stiffen
- Clonic phase
- extremities will jerk and twitch
- Bladder control may be lost
- Loss of consciousness and regained slowly
- Wide distribution of seizure activity to both hemispheres
17
Q
Similarity between Grand Mal and Petit Mal
A
- Consciousness is slowest
- no recollection of the seizure
- Memory is often lost just in recent events just before the seizure along with the seizure
18
Q
Focal Cortical Seizures
A
- AKA Simple partial seizures
- Result from epileptic activity
- localized in one hemisphere
- usually cortex or limbic system
- Consciousness is not impaired
- May have abnormal muscle contraction
- ex: abnormal head movement
- can usually talk and answer questions
19
Q
Temporal Lobe seizure
A
- starts in the temporal lobe
- Involves sensory changes
- Ex: smelling an unusual odor
-
Most common cause is:
- mesial temporal sclerosis
- hippocampal sclerosis
- Risk factors
- Aging
- Stroke
- Vascular
20
Q
Mechanism of Seizure initiation
A
- Poorly understood
- initially- local changes in permeability for potassium and calcium ions
- __Increase in extracellular K+ brings membrane closer to threshold
- Accumulation of Ca2+ in presynaptic terminals, leading to enhanced neurotransmitter release (depolarization)
- So the depolarization-induced activation of the NMDA subtype of the excitatory amino acid receptor (glutamate)
- opens more Ca2+ channels–>Ca2+ influx
- Neuronal activation (from further depolarization due to influx)
21
Q
Seizures: Sensory Stimulations
A
- May be induced by strong sensory experiences
- Audiogenic seizures
- high frequency of sound=Sensory
- Visual Seizures
22
Q
Sleep
A
- Normal, easily reversible, recurrent, and spontaneous state of decreased and less efficient responsiveness to external stimuli
- Eyes closed
- consciousness completely or partial lost
- In humans and other mammals the brain undergoes a cycle of brain-wave activity that includes intervals of dreaming.
23
Q
Moruzzi and Magoun: late 1940s
A
2 observations:
- transection of ascending sensory pathway in the brainstem did not interfere with wakefullness
- Lesion of RF produced stupor with EEG pattern resembled sleep
Conclusion:
- tonic activity of RF keeps brain awake
24
Q
Moruzzi & Colleague: Late 1950s
A
- Transection of the brainstem including RF through the pons
- greatly reduced sleep
- Rostral portion of RF
- above pons
- contains neurons whose activity-wakefullness
- Activity was inhibited by neurons in the RF below the pons
25
What are the different areas of the brain that can put someon to sleep or awake if stimulated?
* Awake
* Rostral Reticular formation
* Ascending reticular activating system
* * Sleep:
* Thalamic nuclei
* intralaminar nucleus
* Caudal RF
* Hypothalamus
26
ARAS
Ascending Reticualr Activating System
* aka extra thalamic control modulators system
* set of connected nuclei in the brain of vertebrae
* Regulate:
* Wakefulness
* sleep-wake transitions
* Part of the RF
* Projects to various nuclei in the thalamus and other Brian nuclei associated with NTs
* Awake
* RF
* Rostral part=ARAS
* project to limbic system and cortex
* sleep
* RF
* caudal part
* Hypothalamus
* Thalmic nuclei
27
Brain Nuclei that contribute to sleep-wake
* Sleep:
* Raphe nuclei
* serotoninergic
* brainstem
* Cholinergic nucleus
* brainstem
* Wake
* Locus Coeruleus
* brainstem
* noradrenergic
* Tuberomammillary nucleus of hypothalamus
* Hypothalamus
28
Hypothalamic Nuclei: involved in regulation of sleep-wake cycle
* Suprachiasmatic Nucleus
* control circadian rhythm
* central pacemaker of circadian timing
* receives direct input from the retina
* sends oscillations to other areas of the brain ==\>"Slave oscillators) in pineal gland
* bilateral structure
* anterior part of hypothalamus
* Tuberomammillary nucleus
* histminergic nucleus
* located in posterior third of hypothalamus
* consists largely of histaminergic neurons
* involved in:
* arousal
* learning
* memory
* sleep
* energy balance
* VLPO (Ventrolateral preoptic nucleus)
* Active during non-REM sleep
* released inhibitory NTs
* GABA
* galanin
29
Regulation of Sleep-wake Cycle
* Balance between hypothalamus nuclei and brainstem nuclei
* Hypothalamus Nuclei
* VLPO (Ventrolateral preoptic area)
* Inhibits Tuberomammillary Nucleus
* GABA
* galanin
* Brainstem Nuclei
* Cholinergic nuclei
* Locus Coeruleus
* Raphe Nuclei
* Orexin Nucleus
* Hypothalamic neurons produce Orexin
* Stimulates:
* Tuberomammillary nucleus
* cerebral cortex and basal forebrain
* Raphe nucleus in brainstem
* keep Brain awake
30
Suprachiasmatic Nuclei
Suprachiasmatic Nucleus
* control circadian rhythm
* central pacemaker of circadian timing
* receives direct input from the retina
* sends oscillations to other areas of the brain ==\>"Slave oscillators) in pineal gland
* bilateral structure
* anterior part of hypothalamus
* Pathway:
* Light hits the retina and stimulates photosensitive receptor ganglion cells
* not rods and cones
* send info to suprachiasmatic nucleus(hypothalamus)--\> brainstem--\> spinal cord--\> intermedia lateral column--\> enters Peripheral nervous system--\>Superior Cervical Ganglion --\> pineal gland
*
31
Sleep-wake cycle mechanism
2 parallel mechanisms
* Homeostatic regulation (AKA sleep-wake homeostasis)
* at the end of the day you feel tired and you want to get rest
* homeostasis energy balance needs to be restored=SLEEP
* Circadian regulation
* stimulated by light cycle
* light stimulates us to stay awake --\>suprachiasmatic nucleus and pineal gland-Melatonin
Controlled by the:
* hypothalamus
* control homeostatic regulation
* suprachiasmatic nucleus
* control circadian rhythm
32
EEG during different stages of sleep
33
EEG during first hour of sleep
* General Trend: from stage to stage
* Desynchronized activity
* as we fall asleep=brain activity Slower
* Smaller Hz
* Smaller Frequency
* Higher Amplitude
* Awake stage
* Beta activity
* first 15 mins
* Stage I
* 15-25 mins
* Stage II
* 25-35 mins
* Sleep Spindles
* Stage III
* 35-50 mins
* Stage IV
* Delta activity
* 50-60 mins
* REM Sleep
* 65+ mins
* Aka Paradoxical sleep
* rapid eye movement
34
Pattern of night sleep
* Initially:
* Very long delta sleep stage
* As you sleep more hours,
* delta sleep decreases
* Incrase in REM sleep
* Morning hours
* mostly REM sleep
* Always cycle throughout the night
* several points of REM and deep sleep
35
Physiological changes during various sleep states
* REM sleep
* rapid eye movment
* Early morning hours: EEG=lower activity
* muscle paralysis
* relaxed
* Increases:
* Heart Rate
* Blood Pressure
* Respiration
* Penile errection (early morning)
36
Areas of the brain that are activated or inactivated during REM sleep?
* Activated:
* Anterior Cingulate COrtex
* Amygdala
* Parahippocampal gyrus
* Pontine Tegmentum
* Inactive:
* Posterior CIngulate cortex
* Dorsolateral prefrontal cortex
37
ARAS: NTs during different stages of sleep
* Awake:
* ARAS=ALL active: All excitatory
* Acetylcholine
* Colinergic nuclei
* Glutamate
* Norepinephrine
* Locus COerulus
* Serotonin
* Raphe nuclei
* Orexin
* Tuberomammilary nuclei
* SLow-Wave Sleep
* All have reduced output
* Acetylcholine
* Norepinephrine
* Serotonin
* REM:
* All reduced except Acetylchoine
* Acetylcholine-active
* Cholinergic Nuclei
* PGO Waves
* REM Sleep off:
* Norepinephrine active
* Locus coruleus
38
Pattern of sleep throughout life
* Sleep less as we age
* embryo/babies-sleep the most
* Total Sleep time:
* Decreases then plateaus (6.5 hours)
* REM sleep:
* decreases, then plateaus, then rapidly declines
* reduces more than any other stage
* decreases as we age
* Stage 4 slow wave
* high in younger people
* slowly decreases
* Childhood:
* long delta sleep and REM
* Adulthood:
* Decreased delta and REM sleep
* Elderly
* Continues to decrease
* Parts of delta sleep almost missing
39
Drugs and sleep
* Barbituates
* reduces delta sleep
* No influence on REM sleep
* Chronic use:
* no Delta or REM sleep
* Benzodiazepines
* Reduces Delta sleep and REM sleep
* Caffeine
* reduces Delta and REM Sleep
40
Sleep during Drug withdrawal
* Rapid Increase in REM sleep
* strong REM rebound
41
Sleep Related Disorders
* Insomnia
* Sleep apnea
* Sleep paralysis
* Parasomnias
* Narcolepsy
* Restless leg syndrome
42
Insomnia
* Unable to fall asleep or get enough sleep
* Affects 20% of people
* triggered by stress
* results in worrying that inhibits proper sleep
43
Sleep apnea:
* Lapses of breathing during sleep
* mainly during REM sleep
* connected to:
* obesity
* snoring
* Results in being tired during the day
44
Sleep Paralysis
* Common but rare as a severe disorder
* occurs during sleep when a person partially awakens but is unable to move
* Can be frightening
* nor dangerous
45
Parasomnias
* Class of disorders which includes:
* nightmares
* sleep walking
* sleep talking
* Wetting the bed
* Grinding
* Night terrors
46
Night terrors vs Nightmares
Night Terrors:
* occur during non-REM sleep
* intense
* less recall of dream content
* panic/screaming/heart pounding
47
Function of sleep and Dreaming
* Not known
* Hypothesis:
* conservation of metabolic energy
* thermoregulation
* neural maturation
* memory and cognition
48
How do we diagnose epilepsy?
EEG only
