Consciousness

Question 1

Level of consciousness

Answer 1

continuum between being asleep/minimal arousal to awake/aroused
Diffuse brainstem structures

Question 2

State of consciousness

Answer 2

responsiveness to stimuli

thalamus

Question 3

Content of consciousness

Answer 3

preception, emotion, meaning, memories

widespread regions of cerebral cortex

Question 4

Consciousness components

Answer 4

level
state
content

all 3 needed for normal consciousness

Question 5

Reticular formation

Answer 5

required for establishing LOC
numerous nuclei within tegmentum of brainstem
diffuse network of interconnected neurons with ascending and descending projections
Receives and modifies afferent input from all sensory modalities

Question 6

Ascending reticular activating system

Answer 6

Lateral zone: processes afferent sensory information
NT systems: modify neuronal processing in widespread CNS areas
- norepi
- dopamine
- serotonin
- histamine
- ACh

Question 7

NorEpi location (consciousness)

Answer 7

locus ceruleus in tegmentum of pons

projects to thalamus and forebrain

Question 8

NorEpi function (consciousness)

Answer 8

allows focus on specific task or sensory input
helps suppress less salient inputs
cognitive function
arousal
mood
attention
sleep/wake state
pain

Question 9

Locus ceruleus lesion (consciousness)

Answer 9

low level of NE –> low level of arousal

Question 10

Dopamine location (consciousness)

Answer 10

ventral tegmental area

projects to prefrontal cortex, limbic structures

Question 11

Dopamine fxn (consciousness)

Answer 11

behavioural arousal/waking
promotes locomotor and explatory behaviour towards positively rewarding stimuli
motivation
reward
emotion
drug-seeking
executive function

Question 12

VTA lesion (consciousness)

Answer 12

affect attentive arousal –> less attentive, indecisive

Question 13

Serotonin location (consciousness)

Answer 13

Raphe nuclei

project to thalamus, cortex, other NT systems in the brainstem

Question 14

Serotonin function (consciousness)

Answer 14

in consciousness: quiet, wakeful state

• mood, sense of well-being
• sleep
• anxiety/aggression controlled
• Neurotrophic actions –> CNS development
• mood
• appetite
• sleep/wake state
• pain
• aggression
• cognitive fxn

Question 15

Serotonin deficiency (consciousness)

Answer 15

insomnia

anti-depressants increase serotonin

Question 16

Histamine location (consciousness)

Answer 16

tegmentum of midbrain

projects to thalamus, cortex

Question 17

Histamine fxn (consciousness)

Answer 17

stimulates wakefulness

Question 18

ACh location (consciousness)

Answer 18

tegmentum of pons

project to thalamus, cortex

Question 19

ACh fxn (consciousness)

Answer 19

increase thalamocortical activation and arousal

Question 20

Types of nuclei in the thalamus

Answer 20

relay nuclei
association nuclei
others: --> alertness and attn
 - intralaminar nuclei
 - thalamic reticular nucleus (TRN)

Question 21

Thalamic reticular nucleus

Answer 21

Gatekeeper of consciousness
thin mesh of neurons immediated outside of thalamus
Dense reciprocal connection with:
- ARAS
- other thalamic nuclei
 - cerebral cortical structures

Interconnected network of GABAergic neurons
Coordinates synchronous firing (40 Hz) between cortex and thalamus necessary for consciousness ( = carrying freq of consciousness)

Question 22

Cortex - fxn in consciousness

Answer 22

establish significance and meaning
synchronous and reciprocal connections with thalamus and other cortical areas
Prefrontal and parietal cortical areas are important

Question 23

Parietal area (consciousness)

Answer 23

attention
awareness of self
awareness of extrapersonal space

Question 24

Prefrontal cortex (consciousness)

Answer 24

association area
executive fxn over consciousness
society/societal expectations

direction and maintaining attention
morality
problem-solving
adjusting behaviour to social norms
planning
working memory
deliberate decisions

Question 25

Top-down attention

Answer 25

Volitional control over focus of attention

e.g. visual attention - illuminates objects in field of view, enhances processing

Question 26

Bottoms-up attention

Answer 26

rapid and automatic form of selective attention

the more salient a location/object in the image, the more likely it will be noticed

Question 27

Coalition of neurons

Answer 27

a group of synaptically coupled forebrain neurons that encode one percept, event or concept
Labile
members of a coalition reinforce each other and suppress members of competing coalitions
attention biases these competing interactions
Synchronized reciprocal firing (40Hz) with thalamus plays a role in strengthening one coalition at expense of others