Techniques

Question 1

fMRI - positives and negatives

Answer 1

Heavily dominates human research cos:
Whole brain awake imaging in humans and animals
Non-invasive
Limitations:
Low spatial resolution
Moderate temporal resolution
Expensive

Question 2

Limitations to vascular events

Answer 2

Blood based changes are delayed and extended
Even if we know everything about the neurovascular unit, haemodynamics aren’t perfect
So never fully capture what’s happening at the neural level

Question 3

Calcium signalling

Answer 3

Happens in:
Exocytosis of synaptic vesicles
Backpropogation of APs
Gene transcription
Synaptic plasticity
Vasodilation
Does this always reflect neural activity?
No but if can image changes in calcium levels we can have an idea of what’s happening which can strongly be linked to specific neural events

Question 4

What are GECIs?

Answer 4

Opsins genetically inserted into certain neural populations which fluoresce when light is shined on them and can change the intensity of the colour which fluoresces depending on the amount of free calcium in there
Stand for genetically encoded calcium indicated
Can be:
FRET-based = calcium binding causes them to fluoresce yellow from blue
GCaMP = calcium binding causes photon emission = increase in fluorescence

Question 5

Limitation of GECIs

Answer 5

Not measuring calcium levels just light and the interaction between light and calcium ions

Question 6

Current trend moving towards multimodal imaging - why?

Answer 6

It covers weaknesses in a single technique and increases certainty in results
Allows for illumination of relations between modalities

Question 7

What is multimodality?

Answer 7

Combination of techniques that make up for limitations of individual techniques

Question 8

What is neuroimaging?

Answer 8

Any technique used to obtain and integrate single or multiple measures of brain structure or function into a picture (or series of pictures) of the brain. The imaging technique used defines the inferences we can make from the data.