Functional Brain Imaging Techniques

Functional Techniques

measures the activity inside a tissue or region, or an organ.
monitors the changes in blood flow, metabolism, an area’s chemcials components

Temporal resolution (functional)

how fast functional techniques pick up on changes

PET

Positron Emmison Tomography (colourful)

injects a radio active tracer like glucose  into blood stream where it goes to most active brain regions. get someone to perform a task during and get the patterns of activity. this shows which area uses more glucose (more active)
then reconstructed into computer generated images that are colour coded
can be combined with CT or MRI to make it more clear

fMRI (bold)

function MRI
the use of an MRI machine, while detecting which areas have the most oxygen (BOLD) blood oxygen dependent signal. areas with more oxygenated blood are higher activity
can show networks of activity in the brain but its not a direct measurement. were inferring based off of BOLD

dfMRI

two people are put into an MRI machine so you can study peoples interactions while in MRI machine

Temporal resolution for PET

it will captsure slow movment of metabolism but not fast activities

Spatial Res for PET

Moderate

Invassiveness of PET

Yes, because there is an injection of a radioactive tracer, and if you repeat it you risk too much radiaiton exposure

What are PETs better for studying

Metabolic changes
receptor binding
disease processes (oncology)

Temporal Resolution for fMRI

high she fast af (1-3 per scan) so fast tis good at mapping rapid changes in dynamic activity

Spatial Resolution for fMRI

High it can differentiate different area of the brain well (localizing them)

Invassiveness of MRI

Non invassive no radiation

fMRIs are Better at

mapping brain activity, function networks, and cognitive tasks

FNIRS

Functional near infrared Spectroscopy
uses an infared light to move through skin, skull and cortex, the reflection of this light is used to measure activity

FNIRS (pros and cons)

fast, non invasive, has compact apparatus

cons: only measures surface cortical regions, and has a lower spatial resolution

Speed accruacy trade off

Interpretation of brain imaging

to interpret brain imaging, you have a control and experimental condition. comparing the two show the difference image.

you then layer the difference images from multiple people to get an average/mean difference image

also just becuase an area of the brain is active doesn’t mean we know what they’re thinking about / whats causing the activation so techniques are correlational. this object related to the activation of hippocampus area, no conclusion

the dead salmon example

a dead salmon was put in an mri machine and when they presented a task to the fish, brain activity lit up, but since its literally dead it means false activity can occur. (random noise in MRI time series)
so we need to control for it by using multiple comaprisons

MEG

Magnetoencephalography
measures magnetic field giving off by neurons using SQUIDS
so it measures fast, has good spatial resolution (not for deep dtrucutres as much)
non invasive

no imaging