Sleep, EEG

Question 1

Define sleep

Answer 1

Easily reversible state of inactivity with a lack of interaction with the environment

Question 2

What is consciousness?

Answer 2

Having awareness, with perceptions, thoughts and feelings

Question 3

What are the two main forms of externally discernible sleep?

Answer 3

• When the eyes move rapidly side to side (REM)

* When they do not (non-REM/ slow wave/ deep sleep)

Question 4

How does the EEG work?

Answer 4

• Picks up post synaptic activity of synchronised dendritic activity
• The more neurones that are synchronised, the bigger the peaks on the EEG

Question 5

Describe stage 1 of sleep

Answer 5

• Stage 1: duration of 1-5 minutes, easily aroused, slow rolling eye movements
• Some theta waves and higher amplitude waves

Question 6

Describe stage 2 of sleep

Answer 6

• 10-15 minutes
• K complexes
• Sleep spindles
• No eye movement
• Body movement remains possible

Question 7

Describe stage 3 of sleep

Answer 7

• Few mins duration
• Slower frequency
• Delta waves appear
• harder to rouse
• Few spindles

Question 8

Describe stage 4 of sleep

Answer 8

• Deepest sleep
• Hardest to rouse
• EEG waves at 2Hz and high amplitude - delta waves
• Lower heart rate and BP
• 15-30 minutes

Question 9

Describe REM sleep

Answer 9

• Fast beta waves
• Rapid eye movement
• Subject easier to rouse than in stage 4
• Dreaming recalled
• Low muscle tone

Question 10

Typical night sleep

Answer 10

• Several cycles through the 5 stages of sleep
• Stage 4 is only reached in the initial cycles
• deepest sleep attained after is stage 3

Question 11

What is REM characterised by?

Answer 11

• Rapid eye movement
• Increases in heart rate
• Increased neuronal activity
• Increased respiration and oxygen consumption
• Penile erection

Question 12

What is the reticular formation?

Answer 12

• Diffuse collection of at least 100 networks of neuromodulatory neurones spanning all three divisions of the brainstem

Question 13

Where do the projections of the reticular formation go to?

Answer 13

• Thalamus
• Hypothalamus
• Some brainstem nuclei
• The cerebellum
• Spinal cord
• Cerebral cortex

Question 14

Where does the reticular formation receive input from ?

Answer 14

• The cerebra (collaterals from the corticospinal pathway)
• visual and auditory systems
• Sensory spinal system
• Cerebellum
• Certain brainstem nuclei

Question 15

Describe the neural control of non-REM sleep

Answer 15

• Cortical slow waves caused by hyper polarised thalamus
• Decreased activity in the arousal centres of the reticulum
• Sleep spindles and L complexes are caused in part when the thalamic neurones hyperpolarise (due to reduced ascending reticular formation input)
• Slow wave rhythmicity blocks ascending sensory input

Question 16

Where are orexinergic neurones

Answer 16

In the lateral hypothalamus, they project to the cerebra, arousla nuclei, vneterolateral pre optic nuclei in the anterior hypothalamus

Question 17

VLPO lesion

Answer 17

insomnia

Question 18

What is the effect of orexin?

Answer 18

Enhance the arousal nuclei and cause indirect inhibition of the VLPO via reciprocal inhibition pathways

Question 19

What is the centre of non REM sleep?

Answer 19

Ventrolateral pre-optic nucleus

Question 20

What is the role of the suprachiastmatic nucleus?

Answer 20

• Controls circadian cycle s

* Influences physiological and behavioural rhythms occurring over a 24 hour period including the sleep/wake cycle

Question 21

What resets the clock gene?

Answer 21

Receptors in the retina containing melanopsin react to light and synapse directly onto the SCN

Question 22

What causes narcolepsy?

Answer 22

• Onset due to specific loss of the orexin containing neurones in the lateral hypothalamus
• Thought to be an inherited auto-immune condition linked to chromosome 6

Question 23

How does narcolepsy present?

Answer 23

• Repeatedly falling asleep during the day, regardless of current activity - go straight to REM sleep
• Limb weakness during emotional episodes
• Night time or morning wakening accompanied by muscular paralysis
• Vivid dream recollection just prior to wakening

Question 24

Wha tis the treatment of narcolepsy?

Answer 24

• Modafanil
• Amphetamines
• Methylphenidate
• Sodium oxybate
• SSRIs and tricyclic antidepressants suppress REM sleep
• Venlafaxine may help cataplexy

Question 25

Simple partial seizure

Answer 25

* Focal with minimal spread of abnormal discharge | * Normal consciousness and awareness maintained

Question 26

Complex partial seizure

Answer 26

* Local onset then spreads * Impaired consciousness * Clinical manifestation varies with site of origin and degree of spread * Temporal lobe epilepsy most common

Question 27

Secondarily generalised seizures

Answer 27

* Begins focally, with or without focal neurological symptoms * Variable symmetry, intensity and duration of tonic (stiffening) and clonic (jerking) phases * Typical duration up to 1-2 minutes * Postictal confusion and somnolence

Question 28

Generalised seizures

Answer 28

* Noth hemispheres * present in 40% of all epileptic syndromes * Manifestation of the seizure determine by cortical site at which the seizure arises

Question 29

What are the generalised seizures?

Answer 29

* Absence * Myoclonic * Clonic * Tonic * Tonic-clonic * Atonic

Question 30

Absence seizure

Answer 30

* Petit-mal * Sudden onset and abrupt cessation * Consciousness is altered * Mild clonic jerking, postural tone changes, autonomic phenomena

Question 31

atonic seizure

Answer 31

* sudden loss of postural tone | * Most often in children

Question 32

Tonic-clonic seizure

Answer 32

* Grand mal * Major convulsions with rigidity (tonic) and jerking (clonic) * Slows over 60-120 seconds followed by stuporous state

Question 33

Which seizures are non-convulsive?

Answer 33

Atonic and absence

Question 34

What is status epilepticus?

Answer 34

* More than 30 minutes of continuous seizure activity * Two or more sequential seizures spanning this period without full recovery between seizures * Medical emergency

Question 35

What are the targets for AEDs?

Answer 35

* Increase inhibitory neurotransmitter system - GABA * Decreased excitatory neurotransmitter system * Block voltage gated inward positive currents * Increase outward positive current * Many AEDs pleiotropic - act via multiple mechanisms