Consciousness

Question 1

What are the 3 components required for normal consciousness?

Answer 1

level of consciousness
state of consciousness
content of consciousness

Question 2

What do the anatomical structures of consciousness components have together?

Answer 2

reciprocal connections and prolific communication

Question 3

What is level of consciousness?

What is the anatomical component of level of consciousness?

Answer 3

a continuum – asleep/minimal arousal to awake/aroused

anatomical component: diffuse brainstem structures

Question 4

What is state of consciousness?

What is the anatomical component of state of consciousness?

Answer 4

responsiveness to stimuli (verbal, pain, etc.)

anatomical component: multiple regions of thalamus

Question 5

What is content of consciousness?

What is the anatomical component of content of consciousness?

Answer 5

perception, emotion, meaning, memories

anatomical component: widespread regions of cerebral cortex

Question 6

Level of Consciousness: Reticular Formation

What is the function of reticular formation in consciousness?

Answer 6

required for establishing level of consciousness (asleep to awake)

Question 7

Level of Consciousness: Reticular Formation

What is the reticular formation

Answer 7

numerous nuclei within brainstem that form a diffuse network of interconnected neurons with ascending and descending projections

Question 8

Level of Consciousness: Reticular Formation

What type of input does reticular formation receive?

Answer 8

receives and modifies afferent input from all sensory modalities

Question 9

What is the ascending reticular activating system (ARAS)?

Answer 9

subsystem of reticular formation – ascending pathways to cortex

set of connected nuclei in the brain responsible for regulating wakefulness and sleep-wake transitions

Question 10

Ascending Reticular Activating System (ARAS)

What does ARAS reticular formation do?

Answer 10

processes afferent sensory info from spinoreticular tract afferents from spinal cord to…

thalamus
aminergic and cholinergic nuclei
medial zone of reticular formation
hypothalamus

Question 11

Ascending Reticular Activating System (ARAS)

What is afferent sensory info sent to thalamus?

Answer 11

to influence cortical input

Question 12

Ascending Reticular Activating System (ARAS)

What is afferent sensory info sent to aminergic and cholinergic nuclei?

Answer 12

to influence level of consciousness

Question 13

Ascending Reticular Activating System (ARAS)

What is afferent sensory info sent to medial zone of reticular formation?

Answer 13

to influence output to spinal cord through medial zone

Question 14

Ascending Reticular Activating System (ARAS)

What is afferent sensory info sent to hypothalamus?

Answer 14

to influence autonomic output

Question 15

Ascending Reticular Activating System (ARAS)

What are the neurotransmitters?

Answer 15

norepinephrine, dopamine serotonin, histamine, acetylcholine

Question 16

Ascending Reticular Activating System (ARAS)

What does the neurotransmitter system do?

Answer 16

modify neuronal processing in widespread CNS areas

Question 17

What does norepinephrine (NE) do?

Answer 17

allows focus on specific task or sensory input, helps suppress less salient inputs

affects arousal, attention, sleep/wake state

Question 18

What is norepinephrine (NE) produced by?

Answer 18

locus ceruleus

Question 19

Where is the locus ceruleus?

Answer 19

located within pons, projecting to thalamus and forebrain

Question 20

What happens if there’s a lesion in the locus ceruleus?

Answer 20

lesion in locus ceruleus = low level of NE = low level of arousal

Question 21

What does dopamine do?

Answer 21

responsible for behavioural arousal and waking, promoting locomotor and exploratory behaviours toward positively rewarding stimuli

affects motivation, reward

Question 22

What are dopaminergic neurons?

Answer 22

collections of neurons in CNS that synthesize the neurotransmitter dopamine

Question 23

Where are dopaminergic neurons?

Answer 23

in ventral tegmental area (VTA), projecting to prefrontal cortex and limbic structures

Question 24

What happens if there’s a lesion in the ventral tegmental area (VTA)?

Answer 24

lesion in VTA = less attentive, and indecisive

Question 25

What does serotonin do?

Answer 25

regulates quiet wakeful state in consciousness affects aggression, mood, sleep/wake state - mood – sense of well-being - sleep – lack of serotonin = insomnia - anxiety/aggression controlled

Question 26

Where are serotonin-releasing neurons?

Answer 26

in Raphe nuclei, projecting to thalamus, cortex, and other NT systems in brainstem

Question 27

What does histamine do?

Answer 27

stimulates wakefulness

Question 28

What does antihistamine do?

Answer 28

induce drowsiness

Question 29

Where are histamine-releasing neurons?

Answer 29

from midbrain, projecting to thalamus and cortex

Question 30

What does acetylcholine do?

Answer 30

increase thalamocortical activation and arousal

Question 31

Where is acetylcholine?

Answer 31

from neurons in pons, projecting to thalamus and cortex

Question 32

What does the thalamus do?

Answer 32

determines how responsive you are to your environment

Question 33

What type of nuclei does the thalamus have?

Answer 33

anatomically and functionally distinct nuclei: - relay nuclei - association nuclei ‘other nuclei’ – play critical roles in alertness and attention - intralaminar nuclei - thalamic reticular nucleus (TRN)

Question 34

What is the thalamic reticular nucleus (TRN)?

Answer 34

thin mesh of neurons immediately outside of thalamus is an interconnected network of GABAergic neurons

Question 35

What are GABAergic neurons?

Answer 35

produce gamma-Aminobutyric acid (GABA), which is the main inhibitory neurotransmitter in CNS

Question 36

What does the thalamic reticular nucleus (TRN) have dense reciprocal connections with?

Answer 36

- ARAS - other thalamic nuclei - cerebral cortical structures

Question 37

What does the thalamic reticular nucleus (TRN) do?

Answer 37

'gatekeeper of consciousness' coordinates synchronous firing (40 Hz) between cortex and thalamus necessary for consciousness

Question 38

Content of Consciousness: Cortex What is the cortex required for?

Answer 38

to establish significance and meaning of consciousness experience

Question 39

Content of Consciousness: Cortex What connections does the cortex have with other structures? What structures are they?

Answer 39

synchronous and reciprocal connections with thalamus and other cortical areas

Question 40

Content of Consciousness: Cortex What are the important areas of the cortex?

Answer 40

prefrontal and parietal cortical areas

Question 41

What is the prefrontal cortex?

Answer 41

important association area

Question 42

What is the function of the prefrontal cortex?

Answer 42

considered to have executive function over consciousness

Question 43

Why is the prefrontal cortex much more complex than other association areas?

Answer 43

it is involved in our ability to associate self with society and society’s expectations: - to plan future actions - to predict - to be attentive - to concentration on task - to discriminate between trivial and important - to behave appropriately * these executive mental functions are disrupted in frontal lobe disease