Sleep and consciousness Flashcards
Describe the organisation of neurons in the brain cortex [1]
Organized in layers, or laminas, parallel to the surface of the brain
Which lamina layer predominately generates the current that EEGs detect
Layer 1
Layer 2
Layer 3
Layer 4
Layer 5
Which lamina layer predominately generates the current that EEGs detect
Layer 1
Layer 2
Layer 3
Layer 4
Layer 5
What are EEG recordings detecting when placed on the head? [1]
EEGs detect the summated post synaptic potentials create a field with positive and negative poles (dipole). The dipole vector, or direction of energy flow, is parallel to the orientation of the pyramidal cells generating the activity
EPSP (Excitatory postsynaptic potential; Na+ & K+ entering cell and source of current into extracellular medium)
Versus
IPSP (inhibitory postsynaptic potential; flow of negatively charged chloride ions entering the cell and source of current in the extracellular medium)
Most of the electrical activity recorded in the EEG is generated by pyramidal neurons similarly oriented in space with synchronous firing created from which areas? [2]
created by thalamo-cortical oscillations:
- thalamic input from the sensory systems
- non-specific thalamic input generates rhythmic oscillations
In wakefulness EEG is more [desynchronized / synchronized]?
In sleep the EEG is more [desynchronized / synchronized]?.
In wakefulness EEG is more desynchronized.
In sleep the EEG is more synchronized.
Which area of the brain alters the frequency / desynchronizes the of EEG during wakefulness? [1]
Reticular activating system
Which of the following EEG frequencies are responsbile for ‘active wakefullness & REM sleep’?
Gamma
Beta
Alpha
Theta
Delta
Which of the following EEG frequencies are responsbile for ‘active wakefullness & REM sleep’?
Gamma
Beta
Alpha
Theta
Delta
Which of the following EEG frequencies are active during for ‘sleep & meditation’?
Gamma
Beta
Alpha
Theta
Delta
Which of the following EEG frequencies are active during for ‘sleep & meditation’?
Gamma
Beta
Alpha
Theta
Delta
Which of the following EEG frequencies are active during ‘active information processing’’?
Gamma
Beta
Alpha
Theta
Delta
Which of the following EEG frequencies are active during ‘active information processing’’?
Gamma
Beta
Alpha
Theta
Delta
Which of the following EEG frequencies are occur while resting with the eyes closed’?
Gamma
Beta
Alpha
Theta
Delta
Which of the following EEG frequencies are occur while resting with the eyes closed’?
Gamma
Beta
Alpha
Theta
Delta
Which are the following EEG frequencies?
EEG
Which of the following is eyes closed and eyes open?
A: eyes closed
B: eyes opened
What does it mean physiologically if the EEG shows a ‘desynchronised’ appearance versus ‘synchronised’ appearance? [1]
Desynchronised:
* If individual neurons (eg A,B, C) are firing out of phase with each other
Synchronised:
* If individual neurons (eg A,B, C) are firing in phase with each other
* EEG shows high amplitude ‘slow wave’ appearance
Describe how EEG recordings change from awakefullness to sleep and how these change during sleep. [4]
Awake: high frequency, unsynchronised EEGs
Stage 1: theta waves
Stage 2: sleep spindles
Stage 3 - 4: delta waves
REM: low voltage, random fast sawtooth waves
Then repeats 4 or 5 times per night
Describe EEGs in epilepsy patients during an epileptic attack [1]
Epilepsy – waves are hypersynchronized: very high amplitude: causes patients to lose consciousness.
Label A & B
A: alpha waves
B: beta waves
Very large ‘theta’ and ‘delta’ slow waves can occur in which populations [2]
Very large ‘theta’ and ‘delta’ slow waves can occur in** young children and in sleeping adults**
Label A & B
A: Awake normal
B: epileptic seizure
Spindle waves are present in EEG waves in which stage of sleep:
Stage 1
Stage 2
Stage 3
Stage 4
Spindle waves are present in EEG waves in which stage of sleep:
Stage 1
Stage 2
Stage 3
Stage 4
What is the function of slow wave sleep? [5]
Increased growth and maintenance of the immune, nervous, skeletal and muscular systems:
- Growth hormone is secreted mostly during slow wave sleep
- Wound repair and regrowth of injured tissue
- Glycogen stores in the brain also increase during slow wave sleep.
- Declarative and emotional memory consolidation
- Waste products removed from CSF
Which hormone is released by the pineal gland? [1]
melatonin is released from the pineal gland into the blood and CSF
Describe the role of melatonin during sleep [2]
Powerful free radical scavenger: neutralises the free radicals that have accumulated during waking, especially in neurons
(Maintaining GABA function
Preventing seizures in the brain)
What is the function of REM sleep ? [3]
- Consolidate long-term memory (LTM)
- Removes unwanted memories or connections from the brain during sleep, “defragmenting” memories, strengthening wanted and deleting unwanted connections in long term memory
- Helps to cope with lifes stresses: increases during periods of stressful experiences
Which area of the brain is key for controlling sleep and wakefulness [1].
Reticular formation
The action of the reticular formation is controlled by signals from which organ? [1]
How does the RFs structure help with its function? [1]
hypothalamus
The reticular neurons have long and widely branching axons that project diffusely to most of the cerebral cortex Their activity keeps us awake and alert; when these neurons are switched off we sleep.
In which part of the hypothalamus is the BBB ‘leaky’? [1]
preoptic area
Pre-optic system
State and explain three molecules that are stimuli for sleep [3]
- Adenosine: high levels increase sleep
- Ghrelin: reduces desire for sleep
- Leptin: increase sleepiness
Describe the pathway of the suprachiasmatic nucleus (SCN) involved in circadian rhythm [4]
Inputs from branches of optic nerve fibres leaving the retina synapse at suprachiasmatc nucleus
Goes via superior cervical ganglion
SVG synapses onto the pineal gland
Pineal gland increases melatonin during the night
Which of the following EEG frequencies are active during ‘active information processing’’?
Gamma
Beta
Alpha
Theta
Delta
Which of the following EEG frequencies are active during ‘active information processing’’?
Gamma
Beta
Alpha
Theta
Delta
How does melatonin synchronise all the clocks of the body? [2]
All cells have own individual clocks
Causes increase in BMAL andCLOCKtranscription products in cytoplasm of cells that controls each cell clock
State two systems that maintain wakefulness [2]
1. The Orexin system:
* orexin neurons excite the monoamine neurons in the brainstem, especially the locus coeruleus and raphe nuclei.
2. Tuberomamillary (TMN) system:
* release histamine at their synapses. Are tonically active during wakefulness
State the effect of the following on sleep / wakefulness during wakefulness, slow wave sleep (SWS) and REM sleep.
- Noradrenaline neurons
- Serotonin neurons
- Cholinergic neurons
Noradrenaline neurons:
* they are most active when the individual is aroused for ‘fight or flight’
* During both slow wave (SWS) and REM sleep their activity drops to a low level
Serotonin neurons:
* wakefulness: serotonin neurons fire spontaneously at at steady level that seems independent of the level of alertness.
* Slow wave sleep: spontaneous activity in the serotonin neurons is decreased
* REM sleep seratonin activity ceases completely
Cholinergic neurons:
* Awake: neurons are spontaneously active.
* SWS: decreases to a low level
* REM: increase their activity to the same rate as during alert waking
What does EEG like look during REM sleep?
motor cortex EEG is desynchonised and just as active as during waking: sends motor commands down the corticospinal tract. Somehow these commands do not activate the lower motor neurons. The only two exceptions are the extraocular muscles and the muscles of the diaphragm
What is sleep apnea? [1]
What pathologies does this lead to? [3]
Motor muscle paralysis starts to affect respiratory system: causes massive rush of adrenaline and person to wake up
Leads to chronic fatigue and depression
Surge in sympathetic activity causes increase in BP: strokes due to ruptured BV
