Sleep/ARAS - Ruff Flashcards
What cells do EEGs measure? Why/How?
Pyramidal cells
- major cells in the cortex
- excitatory –> make electrical fields that EEGs can pick up
- are next to a lot of other pyramidal cells that do similar things (additive response)
What is EEG?
Non-invasive measurement of brain activity using scalp electrodes
What type of EEG wave is observed when someone is awake, has eyes open, or is actively thinking?
Beta wave
What type of wave on an EEG has the highest frequency, but lowest amplitude?
beta wave
What type of wave is observed on an EEG when someone is awake, has their eyes closed, and is relaxed?
alpha wave
What type of EEG wave has a high frequency and large amplitude?
alpha wave
What type of wave is observed on an EEG when someone is meditating or drowsy?
theta wave
What type of EEG wave has low frequency and high amplitude?
theta wave
What type of wave is observed on an EEG when someone is in slow-wave sleep?
Delta wave
What type of EEG wave has the lowest frequency and highest amplitude?
delta wave
What EEG changes occur during a seizure?
- General seizure: spike-wave pattern, wave patters everywhere
- Complex partial seizure: starts in a hemisphere and moves
Why is it important to put EEG electrodes on the entire cortex in the case of a seizure?
So you can localize where the seizure starts/what parts of the brain are effected.
What is seen in an EMG, EOG, and EEG while awake?
EMG - will have muscle tone
EOG - will have saccades
EEG - will have beta waves
What is seen in an EMG, EOG, and EEG while in Non-REM sleep?
EMG - less muscle tone
EOG - no saccades, will have rolling motions of the eyes
EEG - no beta waves, just slow waves
What is seen in an EMG, EOG, and EEG while in REM?
EMG - no muscle tone
EOG - the saccades will be present again
EEG - will have beta waves like when awake
What are the changes in wave patterns during sleep Stages I-IV?
Stage I - decrease in frequency
Stage II - higher amplitude (sleep spindle) and even more increase in frequency (more coherent)
Stage III - lower frequency
Stage IV - lower frequency, higher amplitude, where restorative sleep takes place
What system controls the sleep cycle?
Ascending reticular activating system
What does the Ascending Reticular Activating System (ARAS) promote?
AWAKE state
What monoaminergic nuclei/NT’s are involved in the sleep cycle (ARAS)?
Tuberomammillary nucleus - Histamine
Raphe nuclei - 5HT
Locus coeruleus - NE
VTA/Substantia nigra - DA
What state does histamine promote?
Awake! That’s why antihistamines make you tired!
What cholinergic nuclei/NT’s are involved in the ARAS?
Laterodorsal Tegmental Nucleus (LDT) - ACh Pedunculopontine Nucleus (PPT) - ACh Basal forebrain (BF) - ACh
What neuropeptides does the Lateral Hypothalamus secrete and what are their actions?
Orexin - promotes AWAKE, stimulates monoaminergic/cholinergic nuclei to release NT to promote arousal
Melanin-concentrating horomone (MCH) - promotes REM SLEEP
What condition is the result of the complete loss of orexin?
Narcolepsy
What two conditions have partial loss of Orexin?
- Parkinson disease
- Traumatic Brain Injury
What are Orexin antagonists used for?
sleep aids
What two nuclei promote sleep by releasing inhibitory GABA and Galanin?
- Ventrolateral Preoptic Nucleus (VLPO)
- Median Preoptic Nucleus (MNPO)
What inhibitory, “clear shield” structure that wraps around the thalamus contributes to sleep spindles and waves?
Thalamocortical Circuit
and corticothalamic projections
In waking, the Laterodorsal Tegmental Nucleus (LDT) and the Pedunculopontine Nucleus (PPT) have what action on the thalamus and reticular nucleus of the thalamus?
- Excite Thalamus
- Inhibit reticular nucleus of the thalamus
What action does the Reticular nucleus of the thalamus have when active?
Inhibition of the thalamus - wants you to SLEEP
What is Non-REM sleep characterized by?
- “Waves” or oscillations in the EEG
- Slow, rolling eye movements
- Decreases in HR, BP, Temp, & Metabolic rate
- Dreams are less frequent, vivid, and emotion than during REM sleep
During Non-REM sleep, the LDT/PPT is inhibited by Preoptic nucleui, resulting in what?
- Reticular nucleus of the thalamus = Active
- Reticular nucleus of the thalamus –> Inhibits thalamus in bursts
- Thalamus bursts of hyperpolarization –> send bursts of AP’s to the cortex –> excites pyramidal cells (oscillations)
- Cortex/pyramidal cells send bursts back to reticular nucleus (increase bursts) and to the thalamus (stop bursts)
During REM Sleep, the LDT/PPT are active, resulting in what?
- Inhibition of the reticular nucleus of the thalamus
- Activation of the Thalamus –> Transmission Mode
- Thalamus sends “sensory” info to cortex (about cortex, memories, experiences = crazy dreams)
What two areas of the brain are active while dreaming?
- Anterior Cingulate Cortex = emotions
- Parahippocampal Gyrus = memories
What area of the brain is inactive during dreaming and is the reason why you do crazy shit in your dreams?
Dorsolateral Prefrontal Cortex = responsible for impulse control
Why is motor suppression during REM important?
Critical so you do not act out your dreams!
Describe the Motor Suppression pathway during REM Sleep.
3-4 steps
- Lateral hypothalamus (MCH)
- inhibits LC/Raphe (usually excites motorneurons)
- activates Subceruleus nucleus - Subceruleus nucleus activates Ventromedial Medulla
- Ventromedial medulla (glycinergic) inhibits motor neurons in the spinal cord = REM atonia
What action does the LC/Raphe have during Non-REM/Wake states?
- Activates motor neurons of the spinal cord
2. Inhibits LDT/PPT
What are possible functions of sleep?
- Reducing energy expenditure
- Replenish brain glycogen
- Cognition = brain plasticity; consolidation, association, and pruning of memories; consolidation of learning
- Metabolic clearance = Glymphatic system
What are the short term consequences/effects of sleep deprivation?
-Cognitive impairment: reaction time, judgement
What are the long term consequences/effects of sleep deprivation?
- Cognitive decline
- Problems with homeostasis (metabolism, temperature)
- Infections
- Hallucinations, seizures
- Death
Is REM sleep necessary?
NO
What happens in sleep apnea?
Only get to STAGE II:
- muscle tone decreases in Non-REM sleep
- palate muscle becomes relaxed and airway gets blocked
- body wake you up to start breathing
- patient are unable to reach Stage III and IV to get restorative sleep
What happens in REM behavior disorder?
- Loss of REM atonia = muscle tone during REM
- Ranges from talking/small movements to acting out dream
- 80% later develop alpha-synucleinopathies (parkinson’s/lewy bodies)
(may be first symptom of parkinson’s)
