Consciousness Flashcards
What is consciousness?
The subject experience of the mind and the world around us
That there is ‘something it is like’ to be in the state of the subjective or first-person point of view
The state of being aware of and responsive to one’s surroundings
What are the different elements of consciousness?
Level
Content
Self
What is the role of the reticular activating system in consciousness?
The reticular formation (RF) regulates many vital functions
The degree of activity in the reticular system is associated with alertness/levels of consciousness
RF projects to the thalamus and the cortex, allowing that sensory signals to reach cortical sites of conscious awareness such frontoparietal cortex
Ventral tegmental area (dopaminergic neurones)
Locus coeruleus (noradrenergic neurones)
Give examples of disorders of consciousness.
Coma
Vegetative state
Minimally conscious state
What is coma?
Absent wakefulness and absent awareness.
A state of unrousable unresponsiveness, lasting more than 6 hours in which a person:
- cannot be awakened
- fails to respond normally to painful stimuli, light or sound
- lacks a normal sleep-wake cycle
- does not initiate voluntary actions
What is a vegetative state?
Wakefulness with absent awareness.
A state of wakefulness without awareness in which there is preserve capacity for spontaneous or stimulus-induced arousal, evidenced by sleep-wake cycles and a range of reflexive and spontaneous behaviours.
Characterised by complete absence of behavioural evidence for self- or environmental awareness.
What is a minimally conscious state (MCS)?
Wakefulness with minimal awareness.
A state of severely altered consciousness in which minimal but clearly discernible behavioural evidence of self- or environmental awareness is demonstrated.
Characterised by inconsistent, but reproducible, responses above the level of spontaneous or reflexive behaviour, which indicate some degree of interaction with their surroundings.
What is the frequency of delta waves in EEG?
Up to 4Hz
What is the frequency of theta waves in EEG?
4-8Hz
What is the frequency of alpha waves in EEG?
8-13Hz
What is the frequency of beta waves in EEG?
13-30Hz
What types of waveforms are seen in different levels of consciousness on the EEG?
Awake- beta waves
Drowsy, relaxed- alpha waves
Stage N1 sleep- theta waves
Stage N2 sleep- sleep spindles
Stage N3 sleep- delta waves
REM sleep- fast, random
How is the Glasgow Coma Scale scored?
Eyes open:
- none = 1
- in response to pain = 2
- in response to speech = 3
- spontaneous = 4
Verbal responses:
- none = 1
- incomprehensible sounds = 2
- inappropriate words = 3
- disoriented speech = 4
- oriented speech = 5
Motor responses:
- none = 1
- extensor response to pain = 2
- flexor response to pain = 3
- withdrawal to pain = 4
- localisation of pain = 5
- obeys commands = 6
What is the lowest score possible on the Glasgow Coma Scale?
3: severe brain injury and brain death
What are the metabolic causes of coma?
Drug overdose
Hypoglycaemia
Diabetes
‘the failures’
Hypercalcaemia
