conciousness Flashcards
define conciousness
the person’s experience of the mind and his environment
features of conciousness
level- asleep to awake content- the richness of the content, how much are we aware of- in a lecture hall, lots of things going on, so lots of content self- idea that we remember we are us, not to do with our surroundings, but rather us
DIAGRAMgraph of wakefulness and awareness including conciousness DISORDER
wakefulness in whether eyes are open, awareness is essentially content, how much are we aware of coma- eyes not open and no awareness vegetative state (far low right)- eyes open but no awareness minimally conscious- eyes open, can recognise simple things like family ie little awareness, thus different from vegetative slate locked in syndrome- eyes open, aware of things, but paralysed REM sleep- eyes flickering, and a bit of awareness (dreams), so in middle
conciousness- what controls it and where is it
reticular activating system- controls it, but it is NOT the location of conciousness conciousness is not present in one area, present in multiple areas in thalamo-cortical system ie interaction between thalamus and cortex- without RAS this cannot happen
how conciousness works
not to do with location of neurones (ie one area of brain), or number of neurones (the more neurones fire, the more awake you are), but rather dynamics of neurones, both INTEGRATION (neurones working together over a period of time) and DIFFERENTIATION (neurones specialising in different things) to achieve conciousness- need both, if ONLY integration, then would be like seizure
DIAGRAM method to test conciousness
transcranial magnetic stimulation- an impulse fired to a certain part of brain, and reaction of that area of brain measured using EEG- the more compex it is (ie more differentiation and integration), the more awake you may be, thus the complexity can differentiate between being awake or asleep- PCI (pertubational complexity index) then measures this- patients with low levels of conciousness in day to day life have lower PCI score, patients with locked in syndrome have same PCI as healthy subjects
DIAGRAM covert awareness if disorders of conciousness
idea that there is still some awareness in patients whose eyes are open but can’t respond- when asked to thing about something eg think about tennis, the same area of brain is triggered as a healthy subject, suggesting they are thinking about it, but cannot answer
focial injury to brain- neglect
where they are not conscious of one side of their body/visual field etc. eg if they draw a clock, may just draw half of it, if they draw a face, may only draw half of it visual neglect different to hemianopia (loss of vision in one eye), as in neglect, you are not aware of one side
EEG rhythms
there are different types of waves- delta waves (slowest-below 4 HZ), then theta (4-8), then alpha (8-13), then beta (13-30) delta and theta waves occur when sleeping (as slower when asleep), but if present when awake, it is bad. beta should be present when awake NB- delta and theta waves don’t occur in REM SLEEP
beta becomes thetha in stage 1-2 (light)- theta goes to delta in stage 3-4
DIAGRAM glasgow coma scale+ lowest score
E 4, V 5, M 6 Eyes open- no, in response to pain, in response to speech, spontaneous 1-4 verbal- no, incomprehensible sounds, inappropriate words, disoriented speech, oriented speech 1-5 motor responses- no, extensor response to pain, flexor response to pain, withdrawal to pain, localisation of pain, follows commands 1-6
lowest score 3 ie dead
causes of coma
metabolic causes- drugs, hypoglycaemia, diabetes intracranial- head trauma, meningitis, epilepsy, encephalitis hemisphere lesion- infarct/haemorrhage, tumour brainstem- infarct, tumour
DIAGRAM extradural haemorrhage
above the dura
DIAGRAM subdural haemorrhage
underneath the dura
diffuse axonal injury
white matter tract eg corpus callosum damaged, impairing communication between different parts of brain
DIAGRAM posterior fossa lesion
compress brainstem
DIAGRAM bilateral medial thalamic infarcts
affects thalamo-cortical system, causing coma
