Amygdala

Question 1

Name the six neuronal oscillations from lowest to highest frequency.

Answer 1

Delta.
Theta.
Alpha.
Mu.
Beta.
Gamma.

Question 2

When are delta waves seen?

Answer 2

<4 Hz.
Deep sleep.

Question 3

When are theta waves seen?

Answer 3

4-7 Hz.
Sleep and wakefulness.

Question 4

When are alpha waves seen?

Answer 4

8-13 Hz.
Largest over occipital cortex during quiet wakeful states.

Question 5

When are mu waves seen?

Answer 5

8-13 Hz.
Cortical specific, largest over motor and somatosensory cortices, similar to alpha waves.

Question 6

When are beta waves seen?

Answer 6

15-30 Hz.

Question 7

When are gamma waves seen?

Answer 7

30-90 Hz.
Attentiveness or highly active cortex, underpin attentional processes like working memory, intrinsically generated.

Question 8

What are spindles?

Answer 8

8-14 Hz.
Seen during sleep.

Question 9

What are ripples?

Answer 9

8-200 Hz.
Brief bursts of high neural activity.

Question 10

Describe the first stage of sleep.

Answer 10

Theta waves.
4-8 Hz.
Large amplitudes of 50-100 uV.

Question 11

Describe the second stage of sleep.

Answer 11

Sleep spindles.
10-12 Hz.
Occur periodically in bursts that last for a few seconds.

Spontaneously occurring K complexes.
Sharp, high voltage, bi-phasic wave that lasts for more than 0.5 seconds.

Question 12

Describe the third and fourth stages of sleep.

Answer 12

Delta waves.
0.5-4 Hz.

Question 13

Describe REM sleep.

Answer 13

High frequency brain rhythms similar to those seen in the awake state (alpha, beta and gamma).
Body is immobilised except eyes and respiratory muscles.

Question 14

Why is non-REM sleep sometimes referred to as slow-wave sleep?

Answer 14

Due to the large, slow, high amplitude theta and delta rhythms generated during this time.

Question 15

Non-REM sleep involves increased activity of the parasympathetic ANS, which results in what?

Answer 15

Reduced muscle tension.
Reduced temperature and energy consumption.
Reduced heart rate, respiration and kidney function.
Minimal movement.
Increased digestive processes.

Question 16

Why are K complexes thought to exist?

Answer 16

They are thought to be responses to internal or external stimuli, e.g. respiratory interruption or touch on the skin.

Question 17

Where are K complexes mostly localised?

Answer 17

Frontal and superior frontal cortices.

Question 18

REM sleep involves increased activity of the sympathetic ANS, which results in what?

Answer 18

Reduced core temperature.
Increased, irregular heart and breathing rates.

Question 19

What are the suprachiasmatic nuclei (SCN)?

Answer 19

Bilateral structure found in the anterior hypothalamus. Regulates circadian rhythms in the body.

Question 20

Name the three neuropeptides expressed by the SCN.

Answer 20

Vasoactive-intestinal peptide (VIP).
Gastrin-releasing peptide (GRP).
Arginine-vasopressin (AVP).

Question 21

When is VIP expressed and what is its function?

Answer 21

Increases during dark period/night time.
Controls daily circadian rhythms and maintains internal synchronisation of the SCN.

Question 22

When is GRP expressed?

Answer 22

Activated by direct light input.
Increases in the morning and peaks around midday.

Question 23

What is the function of AVP?

Answer 23

Coordinates circadian feeding rhythms and thirst controlling neurons.

Question 24

How does light reset the oscillations in the SCN?

Answer 24

Melanopsin-containing retinal ganglion cells project directly to the SCN via the retino-hypothalamic tract.

Question 25

Describe the indirect pathway that the SCN projects circadian information down.

Answer 25

Projects down into the cord and back up into the pineal gland where melatonin is produced.

Question 26

Name the five key NTs of the sleep-wake cycle.

Answer 26

Noradrenaline. Serotonin. Acetylcholine. Hypocretin. Histamine.

Question 27

What is the function of melatonin?

Answer 27

It is released as the environment darkens. It promotes and maintains sleep.

Question 28

Brain levels of nitric oxide are at their highest during wakefulness and rise rapidly as we become more sleep deprived. What is the result of this?

Answer 28

It triggers the release of adenosine.

Question 29

What does the release of adenosine result in?

Answer 29

Inhibits the acetylcholine, noradrenaline and serotonin modulatory systems, causing the brain to fall into the slow-wave synchronous theta and delta activity of non-REM sleep.

Question 30

What causes the synchronous activity during delta rhythms?

Answer 30

Neural interconnections within the thalamus, and between the thalamus and cortex.

Question 31

How does the thalamus project to the cerebral cortex?

Answer 31

In a bi-directional thalamo-cortical network which modulates the flow of sensory and motor information to and from the cortex.

Question 32

What neurons make up the bi-directional thalamo-cortical tract?

Answer 32

Excitatory relay neurons. Inhibitory neurons. GABAergic inhibitory reticular neurons. Interneurons.

Question 33

Which neurons generate sleep spindles and K complexes, and what do this represent?

Answer 33

GABAergic inhibitory reticular neurons. Represents synchronised oscillatory electrical activity between these neurons and the thalamo-cortical relay neurons.

Question 34

Where are GABAergic inhibitory reticular neurons located?

Answer 34

In a sheet-like nucleus that covers most of the rostral, lateral and ventral parts of the thalamus.

Question 35

Adenosine levels decrease while we sleep, which results in what?

Answer 35

Increased activity in the acetylcholine, noradrenaline, serotonin and histamine systems.

Question 36

Where is noradrenaline expressed from?

Answer 36

The locus coeruleus in the pons.

Question 37

The locus coeruleus has one axon branch in where and the other in where?

Answer 37

Cerebral cortex and cerebellar cortex.

Question 38

How does noradrenaline affect the neurons of the locus coeruleus?

Answer 38

Makes them more responsive to sensory stimuli and increases the brain's responsiveness - an important feature as you wake up.

Question 39

Where is serotonin expressed from?

Answer 39

Raphe nuclei.

Question 40

When do raphe nuclei neurons fire most rapidly?

Answer 40

When you are awake and active.

Question 41

What are the key components of the reticular activating system, and what is its purpose?

Answer 41

Locus coeruleus and raphe nuclei. Arouse and awaken the forebrain.

Question 42

Acetylcholine is expressed within the basal forebrain for what purpose?

Answer 42

To regulate general brain excitability during arousal and sleep-wake cycles.

Question 43

Acetylcholine is expressed within the midbrain and pons for what purpose?

Answer 43

Projects to the thalamus to regulate the excitability of sensory relay nuclei.

Question 44

Describe the cholinergic pathway and its function.

Answer 44

Sensory relay nuclei project up to the telencephalon to provide a cholinergic link between the brainstem and basal forebrain. This pathway is key to activation and wakefulness.

Question 45

Which neurons express histamine?

Answer 45

Midbrain neurons.

Question 46

Which neurons express hypocretin?

Answer 46

Neurons of the lateral hypothalamus.

Question 47

What is the function of hypocretin?

Answer 47

Excite neurons of the cholinergic, noradrenergic, serotonergic, dopaminergic and histaminergic systems. Inhibits REM sleep by promoting wakefulness and facilitating neurons that enhance motor behaviours. Regulates neuroendocrine and autonomic systems.

Question 48

Just before we wake, which hormones are released and why?

Answer 48

Glucocorticoids, e.g. cortisol. To prepare the brain and body for physical and cognitive activity.