fMRI (functional magnetic resonance imaging) measures brain activity by detecting changes in blood oxygenation levels, which are associated with neural activity.

EEG (electroencephalography) measures brain activity by detecting electrical activity on the scalp, which is generated by the synchronized firing of neurons.

MEG (magnetoencephalography) measures brain activity by detecting magnetic fields generated by neural currents, which are associated with neural activity.

PET (positron emission tomography) measures brain activity by detecting the distribution of radioactive tracers, which are taken up by neurons and reflect glucose metabolism, an indicator of neural activity.

fMRI has the highest spatial resolution among the mentioned techniques, allowing for the visualization of brain activity in specific brain regions.

EEG has the highest temporal resolution among the mentioned techniques, allowing for the measurement of brain activity on a millisecond timescale.

fMRI offers higher spatial resolution compared to EEG and MEG, allowing for the visualization of brain activity in specific brain regions.

EEG and MEG offer higher temporal resolution compared to fMRI, allowing for the measurement of brain activity on a millisecond timescale.

fMRI is commonly used to study brain connectivity by measuring the correlations in brain activity between different brain regions.

PET is commonly used to study neurotransmitter systems in the brain by using radioactive tracers that bind to specific neurotransmitter receptors or transporters.

The main limitation of fMRI is its low temporal resolution, which limits its ability to capture fast-changing brain activity.

The main limitation of EEG and MEG is their low spatial resolution, which limits their ability to precisely localize brain activity.

PET is considered to be invasive because it involves the injection of radioactive tracers into the bloodstream.

PET is typically the most expensive neuroimaging technique due to the cost of the radioactive tracers and the specialized equipment required.

The primary application of neuroimaging techniques in clinical settings is the diagnosis of brain disorders, such as stroke, epilepsy, and neurodegenerative diseases.