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Introduction to neurotechniques (Pre-neuroimaging (structural) (lesion…
Introduction to neurotechniques
structural and functional co-evolved
structural = brain anatomy
functional = investigate living dynamic brain
Pre-neuroimaging (structural)
lesion studies
study functional brain damage; relshp bet brain & beh
drawback: precise location of lesion only available after they died
X-rays: wilhelm rontgen
doesn't work because of the lack of contrast
ventriculography/pneumoence...walter dandy: adverse side effects including death (drill hole in brain)
Commercial CT scan (Computed tomography); Godfrey Hounsfield. Also know as X-ray CT or CAT scan.
combine x-rays from many directions to reconstruct the volume or interest in slices
MRI
study brain structures 1.(high-res anatomical scanning)
look at microstructural changes with diffusion tensor imaging (DTI)
map white matter tracks in brain (distinguish gray matter (neuronal cell bodies) from white matter (myelinated tracts)
little hardware/software mods can be used for research
used to track normal/abnormal dev of neural
pathways in childhood
Pre-neuroimaging (functional)
Angelo Mosso (pioneer of functional brain imaging)
link cerebral blood flow and cognition
studied using brain weight (apparatus), brain pulsations in newborns, exposed brains of skull defect patients
EEG: electroencephalography (Hans Berger)
1.measure brain function in real time 2. first measure of epileptic spikes 3. char of several stages of sleep
main use now: detect & char epileptic seizures +fMRI: which brain regions are involved
PET (most expensive) positron emission tomography
nuclear medicine technique > tag active mol of short lived tracer > injected into body
tissue tracer conc & location: computed by detecting gamma rays emitted as byproduct of decay of radioactive tracer.
tracers decay quickly (short half life), need to be produce onsite in cyclotron (expensive)
fMRI*
1.measure dynamc changes every couple of secs in whole bbrain during experimental tasks (task-based fMRI) 2. at rest (resting state fMRI)
modern-day phrenology: find discrete location of specific brain functions
spatial vs temporal resolution
3D structural: takes mins to acquire: Low temporal res.
High amt of details: high spatial res
fMRI: dynamic imaging. few secs to scan: high temporal res
poor amt of details in images: low spatial res