Figure 3.

Diverse research methodologies and multiple analytical levels

This graph presents functional measures of brain activity. It also includes statistical analyses that consider multiple variables simultaneously, known as multivariate analyses, as well as approaches tailored to individual subjects. These methods build on earlier techniques that relied solely on anatomical matrices or single measurements, known as univariate methods. Both tailored and group-based approaches combine multiple brain-scanning methods. fMRI measures brain activity by detecting changes in blood flow. EEG records electrical signals from the scalp. These are used alongside brain stimulation techniques. These include noninvasive methods such as tDCS, which uses weak electrical currents on the scalp. Invasive techniques such as TMS use magnetic fields to stimulate neurons. Often, these techniques are used together. PET is also used; it measures dopamine activity by tracking a radioactive tracer in the brain, complementing the other methods. The acronyms used here are fMRI (functional magnetic resonance imaging), EEG (electroencephalography), tDCS (transcranial direct current stimulation), TMS (transcranial magnetic stimulation), and PET (positron emission tomography).