Conciousness Flashcards
What is conciouness?
Very hard to define:
- experience and awareness of the self and world around us
- Something that is like a “first-person narrative”
What are the different elements of conciousnes?
- Level of conciouness
- awake?
- Asleep
- Content of conciousness
- Happens when eyes are open
- can be nothing
- but can also be highly intlectual content
- Self
- seperate experience from external world
What is the differenc between brain death, coma and persistent vegitative state?
All three have no levels of awareness but
- Brain death
- total absence of brain function
- absent relflexes etc.
- Coma
- eyes-closed, depressed consciousness from which they cannot be aroused
- but brain stem reflexes are present, spontaneous breathing + motor function possible
- Vegetative state (e.g. end state dementia)
- eyes might be open
- non-purposeful movements might be present
What are the main structural components of the Reticular formation (RF)?
Mainy located in the
- Ventral tegmental area (dopaminergic neurones) (midbrain)
- Locus coeruleus (noradrenergic neurones) (pons)
but projects into
- RF projects to the hypothalamus, thalamus and the cortex –> basically everywhere
What is the main function of the Reticular formation?
The degree of activity in the reticular system is associated with alertness/levels of consciousness
What is the neurological mechanism of conciousness?
- There is no single brain region for conciousness
- the interaction of many regions determines the level of conciouness
–> normally way the neurons are interactiong and interaction of neurons over time
Need a mixutre of integration of different regiona but also Differentiation in brain regions (if everything the same–> seizure)
What is TMS?
Transcranial magnetic stimmulation
–> stimmulates different regions of the brain externally
How is TMS used in determination of level of conciousness?
- TMS stimulus is induced
- Measuring brain activity straight after stimmulation
- The more complex–> the more concious the person is
–> Compexity measures variation (not seizrous) and is used as diversity of brain activity = high conciousness
What is PCI?
Pertubational complexity index–> Quantifyingbrain complexity using transcranial magnetic stimulation and EEG
- The more complex the EEG response after a stimmulation (TMS) is, the more concious is the person
What is coma?
absent wakefulness and absent awareness
–> unarousable unresponsiveness
failure to respond normally to light, pain, or sound stimmuli
What is the vegetative stateß
State of wakefullness without awareness with
- spontaneous stimmulus induced arousal
- sleep-wake cycle
- reflexive and spontaneous behaviours
What is the minimally concious state?
State of wakefullness with minimally but clear evidence of awareness (destruction of cortex and heminspheres)
- inconsistend but reproducibel responses to stimmuli above reflex behavior
What is the Neural correlates of consciousness (NCC)?
Neural pathways that indicate/ are responsible for conciousness
- The minimum neuronal mechanisms jointly sufficient for any one specific conscious experience.
- Primarily localized to a posterior cortical hot zone that includes sensory areas
–> not known yet
Inwhich states of wakefullness can you see which EEG waves?
What are delta EEG waves?
When are teex seen?
slow EEG waves (up to 4Hz) seen in sleep
What are Theta EEG waves?
When can they be oserved?
WAves 4-8Hz
–> slowing is bad
What is a EEG alpha rythym
Syncronised waves in, conciousness when relaxed and eyes are closed –> healthy (mainly in posterior electrodes)
What is a EEG beta rythm?
When is it observed?
Normally observed in normal wakefulness with eyes open 13-30Hz
Sort the following EEG waves from slow to fast
- Alpha
- beta
- delta
- theta
- Beta
- Alpha
- Theta
- Delta
What are the metabolic causes of coma?
- Drug overdose
- hypoglycaemia
- diabetes
- “the failures” (liver, kidney etc.)
- hypercalcaemia
What is non-metabolic coma?
What are possible reasons?
Not linked to metabolic disfunction, mostly traumatic or injury
- epilepsy, hypoxia, meningitis, stroke, infections, haemorrhages, tumors etc.
What is the typicall presentation of tan eytradural haemorrhage
Trauma to head
concussion –> loss of conciousness (often fracture+ rupture of middle meningeal artery)
lucit interval (awake+ concious)
loose conciousness again
What are diffuse axonal injuries?
White matter tract injury
–> When brain moves in trauma –> interruption + damage to tracts can occuer (e.g. in corpus calossum) (dificult to image)
What is the problem with posterior fossa lesions?
They can compress the brainstem –> bad
What is a bilateral medial thalamic infarct?
What are the consequences?
Stroke causing damage to the thalamo-cortical system –> loss of conciousness
