Topic 3 - functional imaging Flashcards
how does fMRI work
creates maps of cerebral activity based on increased neuronal activity and compensatory changes in vascular perfusion
what is the response for an activated neuron
activated neuron = increased O2 extraction = overcompensating vasodilatory response = elevated oxyhemoglobin and decreased deoxyhemoglobin
what does BOLD (blood oxygen level dependent) imaging measure
relative decrease in deoxyhemoglobin
what are the disadvs of fMRI
low temporal resolution (very slow)
not always going to show the same thing (consistently different results)
what does fNIRS (functional near infrared spectroscopy) measure
relationship between oxy and deoxyhemoglobin
- provides info of cortical blood O2 changes
what are the disadvs of fNIRS
only on the outside of the brain
can differ with each individual based on anatomy (CSF, thickness, etc)
what does fNIRS show following concussion
can show physiological disruption
suggests a reduction in connectivity indicates a disruption in brain region communication and may be present in mTBI patients
what is shown about M1 from fNIRS
disruption in metabolism
may be result of high content of pyramidal cells (more susecptible to energy crisis)
what is different about EEG from all other imaging
only one that directly measures electrical activity (all others infer)
what does EEG do
makes a record of electrical activity in pyramidal neurons in the superficial layer of the cortex using electrodes
- electric signals form APs across 1000s of neurons can be detected and recorded through the dipoles they create
how long do EEGs show disruptions
up to 6-12 months after initial injury
