Observing the Brain Flashcards
5 methods to observe the brain
- Lesion deficit model
- CT scans (computerised tomography)
- PET scans (positron emission tomography)
- fMRI (functional magnetic resonance imaging)
- EEG (electroencephalography)
what is the lesion deficit model
- Oldest method
- Brain damage linked to brain behaviour change
- Phineas Gage (1848) railroad incident
strengths of the lesion deficit model
o Direct
o Real and natural data
o Pre and posy behaviour measurement (HM)
weaknesses of the lesion deficit model
o Variability (between patients and injuries)
o Temporal challenges (brain improvement differs)
o Ethics
what are CT scans
series of x-rays
strengths of CT scans
o Quick (good for acute trauma)
o High resolution - Great visualisation of bone and blood
o 3D reconstruction (combine images)
weaknesses of CT
o Uses ionising radiation which is harmful
o Not great for soft tissue (the brain!)
o Snapshot
What are PET scans
- Monitoring radioactive (radiolabelled) tracer
- E.g. glucose in AD, Pittsburgh compound B (binds fibrillar beta-amyloid)
PET scans and AD
- Monitoring radioactive (radiolabelled) tracer - glucose in AD, Pittsburgh compound B (binds fibrillar beta-amyloid)
strengths of PET
o Very specific depending on tracer
o Measures absolute (exact) levels of activity
o Combine with CT
weaknesses of PET
o Uses ionising radiation
o Expensive (including the tracer itself)
o Modest spatial resolution
o Snapshot
what is fMRI
- BOLD (blood-oxygen-level dependent) signal
- Different levels of oxygenated haemoglobin
- Voxel measurement (3D pixel)
how many neurons and glia in 3mm voxel?
2 million neurons and 2 million glia
how many neurons and glia in 1mm voxel?
72000 neurons and 72000 glia
strengths of fMRI
o Functional, in real-time
o Good spatial resolution
o No radiation
