Answer:
Electroencephalography (EEG): The electrodes are placed on the scalp to measure the electrical activity of the brain. EEG may be used to investigate brain activity related to various cognitive and motor activities.
Functional Magnetic Resonance Imaging (fMRI): Magnetic fields and radio waves are used in this approach to create pictures of brain activity. fMRI is a non-invasive method of studying brain function that is often used to investigate variations in brain activity during cognitive activities.
Positron Emission Tomography (PET): A radioactive tracer is injected into the circulation and its distribution in the brain is measured using a scanner. PET imaging can be used to investigate brain activity related with various mental states, such as emotions or cognition.