consciousness

Question 1

Level of consciousness

Answer 1

Continuum: asleep (minimal arousal) to awake (aroused)
- Brainstem structures - reticular formation

Question 2

Reticular formation

Answer 2

• Numerous nuclei w/i brainstem
• Network of interconnected neurons, ascending and descending
• Receives + modifies input from all sensory modalities

Question 3

Ascending reticular activating system

Answer 3

Gets info from spinoreticular tract, sends to:
- Hypothalamus: autonomic output
- Thalamus: cortical output
- Aminergic + cholinergic nuclei: level of consciousness
- Medial zone of reticular formation: output to spinal cord thru medial zone
- Many NTs involved

Question 4

Norepinephrine

Answer 4

Locus cereleus in pons
- Projects to thalamus and forebrain
- Allows focus on task or sensory input
- Suppresses less important input
Lesion in locus cereleus = low NE = low arousal

Question 5

Dopamine

Answer 5

Ventral tegmental area (floor of midbrain)
- Projects to prefrontal cortex + limbic structures
- Behavioural arousal and waking
- Promotes locomotor and exploratory behaviours t/w psoitively reqarding stimuli
Lesion in VTA = less attentive arousal = less attentive, indecisive

Question 6

Serotonin

Answer 6

Raphe nuclei (brainstem)
- Projects to thalamus, cortex, other NT systems in brainstem
- Regulates quiet wakeful state
- Mood, sense of well-being, control of anxiety/aggression
- Sleep (lack of serotonin = insomnia)

Question 7

Histamine

Answer 7

Midbrain
- Projects to thalamus and cortex
- Wakefulness

Question 8

Acetylcholine

Answer 8

Pons
- Projects to thalamus and cortex
- Incr thalamocortical activation and arousal

Question 9

State of consciousness

Answer 9

Responsiveness to stimuli
- Multiple regions of thalamus

Question 10

Thalamic reticular nucleus

Answer 10

Most important in alertness and attention
- Immediately outside thalamus
- Reciprocal connections w ARAS, other thalamic nuclei, cerebral cortical structures
- Network of GABAergic neruons
- Coordinates synchronous firing b/w cortex and thalamus necessary for consciousness (40Hz)

Question 11

Content of consciousness

Answer 11

Perception, emotion, meaning, memories
- Many regions of cerebral cortex

Question 12

Cortex

Answer 12

Establishes significance and meaning of consciousness
- Synchr and reciprocal connections w thalamus + other cortical areas
- Prefrontal and parietal imp

Question 13

Top-down attention

Answer 13

Form of selective attention
- Voluntary control over focus of attention

Question 14

Bottom-up attention

Answer 14

Rapid and autonomic selective attention
- The more important a location or object in image, the more likely it will be noticed

Question 15

Attention

Answer 15

selects subset of info from constant stream of information
- Synaptically coupled forebrain neurons that encode one event or concept
- Coalitions labile (born and die w/i seconds)
- Reinforce e/o and suppress competing coalitions
- Attention biases certain ones
- Synch reciprocal firing (40Hz) w thalamus strengthens coalitions

Question 16

Prefrontal cortex

Answer 16

Important association area
- Executive function over consciousness
- Involved in ability to associate self w society (complex)
- Disrupted in frontal lobe disease