L10 - Reticular Formation

Question 1

Arousal

Answer 1

Emotional state associated with a goal of avoidance of something noxious

Question 2

Consciousness

Answer 2

Awareness of internal and external states

Involves the cerebral cortex and reticular formation

Question 3

Reticular formations

Answer 3

Diffuse network of neurones in the brainstem

Question 4

Positive feedback loop

Answer 4

Monominergic projections ascend from the reticular formation to the cerebral cortex and activate the cortex

Pyramidal cells descend from the cerebral cortex to the reticular formation and activate the reticular formation

Question 5

Inputs to the reticular formation

Answer 5

Somatosensory system - sensory neurones

Cortex

Question 6

Outputs of the reticular formation

Answer 6

Basal forebrain nuclei
Hypothalamus
Thalamus

Question 7

Basal forebrain nuclei

Answer 7

Send projection to the cortex
Stimulate the release of acetylcholine
Excitatory

Question 8

Hypothalamus

Answer 8

Project to the cerebral cortex
Stimulate the real ease of histamine
Excitatory

Question 9

Thalamus

Answer 9

Projections to the cerebral cortex
Stimulates the release of glutamate
Excitatory

Question 10

Reticular activating system

Answer 10

Ascending projections to the basal forebrain nuclei, hypothalamus and thalamus

Question 11

Glasgow coma scale

Answer 11

Highest score - 15
Lowest score - 3

Eye opening
Motor response
Verbal response

Question 12

EEG

Answer 12

Electroencephalogram
Measures activity in groups of 1000s of neurones

• high temporal resolution - fast
• low special resolution - hard to localise neurones as electrodes spaced out

Question 13

EEG when awake

Answer 13

50 Hz
A lot of external sensory input prevents neurones from synchronising therefore irregular
Beta waves

• also seen in REM

Question 14

Stage I - closed eyes

Answer 14

10Hz
Decreased external sensory input
Neurones firing more in synch
Alpha waves

Question 15

Stage II/III

Answer 15

Background alpha waves
Sleep spindle - caused by thalamus
K complex

Question 16

Sleep spindle

Answer 16

When sleeping there is negative feedback on the thalamus but there can be sudden, unpredictable excitability of thalamus that causes sleep spindles

Question 17

K complexes

Answer 17

Insight into intrinsic rate of cerebral cortex

Question 18

Stage IV

Answer 18

K complexes
Delta waves
Decreased frequency and high amplitude as neurones are in synch

Question 19

Sleeping

Answer 19

Pass around 6 cycles of sleep from stage 4 to REM
Inhibit the reticular activating system, thalamus and positive feedback loop
Removal of sensory inputs

Question 20

REM

Answer 20

Dreaming

• Cortex provides the sensory input
• Paralysed except for the occulomotor muscles of the eyes as inhibitory projections inhibit LMNs (glycinergic)
• EEG similar to person that is awake but difficult to arouse due to inhibition of thalamus
• essential for life
• autonomic effects are seen e.g. penile erection and loss thermoregulation

Question 21

Pons

Answer 21

Neurones in the pons activate REM sleep

Question 22

Nocturnal bruxism

Answer 22

Grinding of teeth during sleep

Question 23

Functions of sleep

Answer 23

Energy conservation
Muscle repair
Memory consolidation
Clear neck of extracellular debris

Question 24

Sleep disorders

Answer 24

Insomnia - symptom
Narcolepsy
Sleep apnoea

Question 25

Cause of insomnia

Answer 25

Anxiety
Stress
Depression
Caffeine

Question 26

Narcolepsy

Answer 26

Neurones releasing less orexin

Genetic defect in the orexin gene

Question 27

Obstructive sleep apnoea

Answer 27

Neck tissue compressed the trachea and pharynx
Narrowing the airways
Wake up several times during the night

Question 28

Coma

Answer 28

Widespread cortical and brain stem damage with various EEG patterns
Unarousable
Unresponsive to stimuli
No sleep wake cycle detected

Question 29

Persistent Vegetative state (PVS)

Answer 29

Like coma but with spontaneous eye opening

Sleep - wake cycle detectable