Sleep physiology, Hypothalamus, Thalamus, Limbic system Flashcards
What structure in the hypothalamus regulates the sleep cycle via circadian rhythm
Suprachiasmatic nucleus (SCN)
What hormones does the circadian rhythm control the nocturnal release of?
- ACTH
- Prolactin
- Melatonin
- NE
The pineal gland releases melatonin, how is this initiated - what structure initiates it?
SCN releases NE
- NE influences the pineal gland to release melatonin
What is SCN regulated by?
Environment (light)
What drugs will decrease N3 sleep and REM sleep?
- Alcohol
- Barbiturates
- Benzodiazepines
What EEG waves dominate the N1 stage of sleep?
Theta
What waves have the highest frequency and lowest amplitude?
Beta (awake, eyes open)
What waves have the lowest frequency and highest amplitude?
Delta (stage N3)
During what stage of sleep does bruxism occur?
Stage N2
How are benzos useful for night terrors and sleepwalking?
Occur during stage N3 of sleep cycle and benzodiazepines reduce N3 and REM sleep
What are the 4 stages of sleep?
- Stage N1 (theta)
- Stage N2 (sleep spindles and K complexes)
- Stage N3 (delta)
- REM sleep (Beta waves)
During what stage of sleep do sleep spindles and K complexes form on EEG?
Stage N2
What percetage of sleep does each stage take up?
- Stage N1 (5%)
- Stage N2 (45%)
- Stage N3 (25%)
- REM sleep (25%)
How often does REM sleep occur?
Every 90 minutes, duration of REM increases through the night
The activity of what causes eye movements during REM sleep?
PPRF (Paramedian pontine reticular formation / conjugate gaze centre)
What wave forms will be seen on EEG during REM sleep?
Beta waves
Sleepwalking, night terrrors and bedwetting occur during what stage of sleep?
Stage N3
What stage of sleep has sexual arousal and possibly serves as a memory processing function?
REM sleep
Describe the physiological changes which occur during the REM stage of sleep?
- Loss of motor tone
- Increased brain O2 use
- Variable HR/BP
- Increased ACh
What changes occur in sleep in the elderly?
- Decreased REM
- Decreased N3
- Increased sleep latency
- Increased early awakenings
What changes occur in sleep in depression?
- Increased REM
- Decreased REM latency
- Decreased N3
- Repeated nightime awakenings
- Early morning awakening (terminal insomnia)
What stage of sleep is effected in narcolepsy?
Decreased REM latency
What part of the hypothalamus controls hunger?
Lateral nucleus
What is the lateral nucleus stimulated by and inhibited by?
- Stimulated by ghrelin
- Inhibited by leptin
What does the Anterior nucleus (hypothalamus) control?
Cooling (Air Con), paraympathetic
What does the posterior nucleus control (hypothalamus)?
Heating, sympathetic
What do the supraoptic and paraventricular nuclei synthesise?
ADH and oxytocin
What does the Preoptic nucleus release?
GnRH
What does the Preoptic nucleus control?
- Thermoregulation
- Sexual behaviour
What condition is a result of a failure of GnRH-producing neurons to migrate from olfactory pit?
Kallman’s syndrome
What is the main function of the thalamus?
Major relay for all ascending sensory information except olfaction
What inputs does the Ventral postero-lateral nucleus (thalamus) receive?
- Spinothalamic
- DCML
Where do the inputs from the Ventral postero-lateral nucleus (thalamus) go to?
Primary somatosensory cortex (parietal lobe)
What inputs go to the Ventral postero-medial nucleus (in thalamus)?
- Trigeminal (face sensation)
- Gustatory pathway (taste)
Very Pretty Makeup goes on the face
Where do inputs go to from the Ventral postero-medial nucleus (thalamus) go to?
Primary somatosensory cortex
What inputs does the Lateral geniculate nucleus (thalamus) receive?
Vision
- CN II
- Optic chiasm
- Optic tract
Lateral = Light
Where do inputs from the Lateral geniculate nucleus (thalamus) go to?
Primary visual cortex
Where does the Medial geniculate nucleus (thalamus) receive inputs from?
Superior olive and inferior colliculus of tectum (hearing)
Medial = Music
Where do inputs from the Medial geniculate nucleus (thalamus) go to?
Primary auditory complex (temporal lobe)
Where does the Ventral anterior and lateral nuclei (thalamus) receive inputs from?
- Basal ganglia
- Cerebellum
(motor)
Venus astronauts love to move
Where do inputs from the Ventral anterior and lateral nuclei (thalamus) go to?
Motor cortices (frontal lobe)
What is the function of the limbic system?
- Emotion
- Olfaction
- Behaviour modulation
- ANS function
Feeding, Feeling, Fighting, Feeling, Fucking (sex) (5Fs)
What structures does the limbic system consist of?
- Hippocampus (memory)
- Amygdalae (processing emotions associated w. fear)
- Mammilary bodies (recollective memory)
- Anterior thalamic nuclei (episodic memory)
- Cingulate gyrus (processing emotions, behaviour regulation, regulate motor function)
- Entorhinal cortex (memory formation, navigation, perception of time)
What can damage or decreased activity to the mesocortical pathway result in?
Negative symptoms, anergia, apathy, lack of spontaneity (connects to frontal lobe)
What does the mesocortical pathway connect?
Ventral Tegmental Area (VTA) (dopamine producing) to the frontal cortex
What does the Mesolimbic pathway connect
VTA (dopamine producing) to Nucleus accumbens (ventral striatum, part of BG), Prefrontal cortex and Amygdala
An increase in activity of the Mesolimbic system is associated with what condition?
Schizophrenia (delusions, hallucinations)
A decrease in activity of the nigrostriatal pathway will result in what symptoms?
Extrapyramidal symptoms (dystonia, akathisia, parkinsonism, tardive dyskinesia)
What dopamenergic pathway is targeted by antipsychotics?
Mesolimbic (can affect nigrostriatal leading to tardive dyskinesia OR Tuberoinfundibular -> hyperprolactinemia)
What dopamenergic pathway is affected by movement disorders?
Nigrostriatal pathway
The tuberoinfundibular pathway connects what?
Hypothalamus to anterior pituitary
A decrease in activity of the tuberoinfundibular pathway can result in what side effect?
- Galactorrhea (hyperprolactinemia), decr libido, gynaecomastia
What are the 2 primary dopamine producing areas of the brain?
- Ventral Tegmental Area (VTA)
- Substantia Nigra (2 of them)
Located in midbrain