Indirect Measures Flashcards
List the indirect measures discussed in the lecture
- xrays
- CT scans
- fMRI (blood O2)
- Optical imaging (blood O2)
- PET (metabolic activity via radioactive tracers)
- Concussions and lesions (anatomy)
- TMS (neural disruption)
Historically, brain ______ could be used to match ______ to function. These include, stroke, _______ or _______. However, it is a slow process, and the technique is ______.
injury structure surgery accidents indirect
Many indirect measures are now based on ______. An x-ray provides an _______ across the entire brain and, along with a CT, are both safe, _________ procedures. However, a CT allows you to obtain _____ of the brain and can provide a ____ structure. CTs also provide _____ resolution images.
imaging average non-invasive slices 3D high
Similar to a CT scan is a ____. The works by using a ____ field and measuring the amount of ________ energy released by ______. This varies across _____ types, allowing you to see different tissues. It provides _____ resolution images, is non-invasive and _____.
MRI magnetic electromagnetic protons tissue high safe
Diffusion tensor imaging (DTI) tells us more about the ______ of brain areas and is commonly used with ____. It works by measuring the _____ of ____ molecules. They form different ____ which can tell us the structures being observed
connectivity MRI movement water shapes
Metabolic methods are also safe for humans and include _____ scans and ____. They are based on the idea that the brain uses a lot of ______, and hence has to use it wisely. We can measure the ______ _____ in and out of certain brain regions while the subject completes a ____, look at the activity and infer a ______ of that region. Previously, _______ tracers were used in animals in this way.
PET fMRI energy blood flow task function radioactive
Describe how PET scans work and how measures are obtained.
- combination of MRI and radioactive tracer
- measure the resting response, compare it to different images obtained when patient is completing a task.
Optical imaging is another technique that relies on _____ function. Participants are given _____ while a camera points to a particular brain area. If the blood changes from ____ to ____ it signifies that ________ are being consumed in that area. It can be used to measure _____ networks, brain ______ or brain ______.
metabolic tasks red to blue resources neural areas networks
fMRI is probably the most popular technique for human _______ neuroscience research. It captures the ____ of O2. The pictures obtained are compared to ________ models, and if there’s a fit, it’s statistically significant. You can also obtain a trace of _____ response over time (%). It is best for measuring _____ networks and ______ areas.
cognitive captures standardised BOLD (Blood-oxygen-level dependent) brain brain
Describe the BOLD response in an fMRI
The brain starts using an area so there’s an initial dip in the O2. The brain realises it’s using that area, so the metabolic processes sends a lot of resources to that area, and sends a rush of new blood to that region.
TMS, or _______ ______ _______ introduces a _______ into a brain region which _______ or ______ brain activity. The current is generated by a coil, which in turn creates a ______ current in the brain.
However, it is non-invasive and _____ for humans. The best thing about this technique is that it is a _____ measure, as you are intervening/altering with a brain region and measuring the response.
transcranial magnetic stimulation current stimulates disrupts magnetic
safe
causal
Describe the adv and disadv of fMRI
Adv
- non-invasive
- real-time - see effects over time (but it’s 6 secs behind) - replaced PET which had almost no temporal resolution
- relatively cheap/
Disadv
- temporal resolution is good, but not compared to EEG
- dependent on vasculature of the brain
Describe the adv and disadv of PET
Adv - safe/non-invasive - you can look at lots of different metabolic functions Disadv - correlational - poor temporal resolution - radioactive compounds have short-half-lives, hence limited time availlable - poor spatial resolution - expensive - invasive with radioactive chemicals
Describe the adv and disadv of TMS
Adv
- modulation to brain is reversible
- causal
- great temporal resolution - brain doesn’t have time to compensate for loss of function
- cheap
Disadv
- cortical restriction - can’t go into deep brain structures - dodgy targeting
Describe the adv and disadv of brain lesions
Adv
- causal, yet indirect
Disadv
- untargeted
- have to wait for a case to occur
- no control groups
