8.2.1 Consciousness

Question 1

What is consciousness?

Answer 1

Awareness of both external world and internal states

Question 2

What is arousal?

Answer 2

Emotional state associated with a goal or avoidance of something noxious

Question 3

What neural components are required for consciousness?

Answer 3

Cerebral cortex

Reticular formation

Question 4

What is the function of the cerebral cortex in conciousness?

Answer 4

Site where conscious thoughts arise, receives many inputs, including from reticular formation

Question 5

What is the function of the reticular formation?

Answer 5

Keeps the cortex awake, receives many inputs, including from the cortex and sensory systems

Question 6

How are the cerebral cortex and reticular formation connected?

Answer 6

Connected by reciprocal excitatory projections

Forms a positive feedback loop, seen when there is a binary outcome e.g. sleep/awake, ovulating/not ovulating

Question 7

What are the 3 major relay nuclei from the reticular formation to the cortex?

Answer 7

Basal forebrain nuclei

Hypothalamus

Thalamus

Question 8

What type of projections does the reticular formation send to the cerebral cortex?

Answer 8

Cholinergic, excitatory projections

Question 9

Outline the Basal forebrain nuclei projections

Answer 9

First order sensory neurones synapse with second order

Second order decussate and arise to the reticular formation

Reticular formation sends projections to the basal forebrain nuclei

Basal forebrain nuclei send ACh excitatory projections to the cortex

Question 10

Outline the Hypothalamus excitatory fibre projection to the cortex

Answer 10

First order sensory neurones synapse with second order

Second order decussate and arise to the reticular formation

Reticular formation sends projections to the Hypothalamus

Hypothalamus sends histaminergic excitatory projections to the cortex

Hence why anti-histamines have a sedative effect

Question 11

Outline the Thalamus excitatory fibre projection to the cortex

Answer 11

First order sensory neurones synapse with second order

Second order decussate and arise to the reticular formation

Reticular formation sends projections to the Thalamus

Thalamus sends glutamatergic excitatory projections to the cortex

Question 12

Where else does the reticular formation also send projections?

Answer 12

Down the cord, responsible for maintaining muscle tone

Question 13

What is the reticular activating system?

Answer 13

Large part of the reticular formation devoted to arousal

Contains the fibre projections from the reticular formation to the basal forebrain, hypothalamus and thalamus

Question 14

How is consciousness assessed?

Answer 14

Glasgow coma scale

Question 15

What are the 3 parts used by the GCS to assess conciousness?

Answer 15

Eyes- 4(eyes 4 letters so 4)
Motor response- 6(muscle 6 letters so 6)
Verbal response- 5 (voice 5 letters so 5)

Score out of 15 (higher the better)

Question 16

What is an electroencephelogram?

Answer 16

Used to measure the activity of neurones in a particular region of the cortex

High temporal resolution as EEG works very fast

Poor spatial resolution as limited by the number of electrodes

Question 17

What is an electroencephalogram used for?

Answer 17

Detecting neuronal synchrony and evidence of normal cerebral function

Question 18

When does neuronal synchrony occur?

Answer 18

Occurs commonly in the brain during both physiological and pathological processes e.g. sleep and epilepsy