Anatomical and Physiological Basis of Consciousness

Question 1

3 anatomical areas responsible for consciousness

Answer 1

Brainstem
Thalamus
Cerebral cortex

Question 2

5 NTs in the ARAS

Answer 2

NE
DA
Serotonin
Histamine
Acetylcholine

Question 3

What role does the
1. Brainstem
2. Thalamus
3. Cortex
play in consciousness?

Answer 3

1. Level of consciousness
2. State of consciousness
3. Content of consciousness
   All 3 components are required

Question 4

Reticular formation

Answer 4

Numerous nuclei within the brainstem
Required for establishing level of consciousness
Forms diffuse network of interconnected neurons with ascending and descending projections
Receives and modifies afferent input from all sensory modalities

Question 5

Role of NE

Answer 5

Generated from locus ceruleus within pons projecting to thalamus and forebrain
Allows a focus on a specific task or sensory input
Helps suppress less salient inputs
*Attentional wakefulness

Question 6

Role of DA

Answer 6

Dopaminergic neurons in the VTA project to prefrontal cortex and limbic structures
Responsible for *behavioural arousal and waking
Promotes locomotor and exploratory behaviours toward positively rewarding stimuli
Also involved in attentive arousal

Question 7

Role of serotonin

Answer 7

Serotonergic neurons in raphe nuclei project to thalamus, cortex and brainstem
In consciousness, serotonin regulates a quiet, wakeful state
Lack of it can cause insomnia, anxiety and aggression, low mood

Question 8

Role of histamine

Answer 8

Released from midbrain and project to thalamus and cortex
Stimulates wakefulness (antihistamines cause drowsiness)
Gets the cortex involved in wakefulness

Question 9

Role of acetylcholine

Answer 9

From neurons in the pons and projects to thalamus and cortex
Increases thalamocortical activation (talking between the two) and arousal
Dominant waker upper!

Question 10

2 nuclei of the thalamus that are important in alertness and attention

Answer 10

Intralaminar nuclei

Thalamic reticular nucleus

Question 11

Thalamic reticular nucleus (TRN)

Answer 11

Thin mesh of neurons right outside the thalamus
Interconnected network of GABAergic neurons
Coordinates the synchronous firing (40 Hz) between cortex and thalamus necessary for consciousness

Question 12

Role of the cerebral cortex in consciousness

Answer 12

Required to establish significance and meaning of consciousness
Synchronous and reciprocal connections with thalamus and other cortical areas
Prefrontal and parietal cortical areas important

Question 13

Top down attention

Answer 13

Volitional control over the focus of attention
Something you are thinking about and deciding to pay attention to
Frontal lobe and cortical structures modulate the streams of what you are attending to

Question 14

Bottom up attention

Answer 14

Rapid and automatic form of selective attention
The more salient a location or object in the image, the more likely it will be noticed
Bit more protective and basal