12) Reticular Formation and Consciousness

Question 1

What is arousal?

Answer 1

Emotional state associated with some kind of goal or avoidance of something noxious

Question 2

What is consciousness?

Answer 2

Awareness of both external world and internal states

Question 3

What is the reticular formation?

Answer 3

Diffuse population of specialised interneurones in brainstem

Question 4

What are the outputs of the reticular formation?

Answer 4

Thalamus
Hypothalamus
Basal forebrain nuclei
Spinal cord

Question 5

What are the components of the Glasgow Coma Scale?

Answer 5

Eye opening (1-4)
Motor response (1-6)
Verbal response (1-5)

Question 6

What does an EEG measure?

Answer 6

Combined activity of neurones in a given part of the cortex, high temporal resolution

Question 7

What are the 6 stages of sleep?

Answer 7

Awake
Stages 1-4
R.E.M. sleep

Question 8

Describe an awake EEG:

Answer 8

Irregular, beta waves, 50Hz

Question 9

Describe a drowsy EEG:

Answer 9

Alpha waves, 10Hz, amplitude increasing

Question 10

Describe a stage 1 sleep EEG:

Answer 10

Background of alpha waves with slow waves (theta waves, 5Hz)

Question 11

Describe a stage 2/3 sleep EEG:

Answer 11

Background of theta waves with occasional bursts of activity and big waves (K complexes)

Question 12

Describe a stage 4 sleep EEG:

Answer 12

Delta waves, 1Hz, cortex acting independently of RF

Question 13

Describe a REM sleep EEG:

Answer 13

Sawtooth waves (like beta waves)

Question 14

What is the mechanism behind sleep?

Answer 14

Deactivating the reticular activating system and inhibiting the thalamus - decreased cortical activity

Question 15

What initiates REM sleep?

Answer 15

Group of neurones in the pons

Question 16

Why is muscle tone in most of the body lost during REM sleep?

Answer 16

Descending inhibition of LMNs by glycinergic fibres arising from reticular formation and running down reticulospinal tracts

Question 17

What are some autonomic effects of REM sleep?

Answer 17

Penile erection

Loss of thermo-regulation

Question 18

What are the functions of sleep?

Answer 18

Bodily repair
Memory consolidation
Clearance of extra-cellular debris

Question 19

What are some disorders of sleep?

Answer 19

Insomnia
Narcolepsy: excessive sleepiness triggered by extreme emotion
Sleep apnoea

Question 20

What is brain death and how does it appear on EEG?

Answer 20

Widespread cortical and brainstem damage, flat EEG

Question 21

What is a coma and how does it appear on EEG?

Answer 21

Widespread brainstem and cortical damage with various EEG patterns detectable, unarousable and unresponsive to stimuli

Question 22

What is a persistent vegetive state and how does it appear on EEG?

Answer 22

Widespread cortical damage with various EEG patterns Spontaneous eye opening and can localise to stimuli by brainstem reflex

Question 23

What is locked in syndrome?

Answer 23

Basilar/pontine artery occlusion

Eye movements preserved but all other somatic functions lost from pons down

Question 24

What are sleep spindles (stage 2/3 sleep)?

Answer 24

Thalamic activity to wake the cortex