Lecture 6 - Neuroscientific methods and brain injury Flashcards
(36 cards)
which type of brain scan requires a magnetic field
MRI
what are the magnetic signal s picked up by
radio frequency coil
what does diffusion tensor imaging (DTI) measure
quantifies the relative diffusivity of water molecules in bundles of axons in white matter to determine their location and orientation
advantages of MRI VS CAT
no radiation exposure
better spatial resolution
better distinction between white and grey matter
3D images
disadvantages of MRI VS CAT
cost
no ferrous material
what is functional imaging
computerised methods of detecting metabolic or chemical changes within the living brain
what is a PET scan
positron emission tomography
reveals the localisation of a radioactive tracer in a living brain
what does an MRI measure
blood oxygen level dependant signal
BOLD
variations in hydrogen concentrations in brain tissue
how does an fMRI work
detects increases in oxygen levels during neural activity
how does TMS work
transcranial magnetic stimulation
a current is passed into the coil which is rapidly changing, generates a magnetic field which induces an electrical field in the underlying cortex and the tissue current alters normal pattern of neural activity
lesion method
infers brain function by observing consequences of brain injury
limitations of the lesion method
the brain is not modular
poor spatial precision
poor temporal precision
individual variability
diaschicis
diaschicis
other areas of the brain that are not damaged may also be functioning abnormally
what are misleading lesion overlays
some brain areas are more vulnerable, overlay plots highlight these areas of common damage
what is the solution to lesion overlays
subtraction - regions that are damaged in experimental group only, as damage to unrelated areas should be the same in both groups
CT
forms 3D image by combining X-rays of cross-sections of the brain
EEG
sums the electrical activity of neurones between 2 electrodes detects activity but is poor at localising it
what is a TBI
traumatic brain injury
impairment of brain function as a result of mechanical force
what are the 2 types of head injuries
penetrating (open)
blunt (closed)
focal injury
occurs in a specific area
contusions, laceration, inter cranial haemorrhage
what are the 2 stages of TBI
primary injury and secondary injury
what is used to initially assess head injury
glasgow coma scale (GCS)
3-15
before medication
mild = 14-15
moderate = 9-13
severe = 3-8
signs of mild TBI
confusion
LOC (<30mins)
amnesia near injury time
MMSE
mini mental state exam
0-30
questions asked on orientation, immediate recall, attention and calculation and language
