Final answer:
The placement of electrodes around a person's head measures brain electrical activity through a procedure called EEG, which shows brainwave frequency and amplitude. Techniques like fMRI and MEG also measure brain activity, useful for neurological research. Transcranial magnetic stimulation is another technique to treat brain function disorders.
Step-by-step explanation:
Placing electrodes around a person's head to measure the brain's electrical activity refers to a procedure known as electroencephalography (EEG). EEG is a technique that measures the electrical activity of the brain by using an array of electrodes placed on the scalp. The signals received by the electrodes result in a printout of the brainwaves, which indicates both the frequency and amplitude of the electrical activity in the brain with very accurate timing, useful for research in various neurological conditions including sleep disorders.
Other brain activity measurement techniques include functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). fMRI measures changes in blood flow in the brain, which correlates with neural activity and can generate a three-dimensional map of the most active brain regions during tasks. MEG measures weak magnetic signals produced by electrical discharges in the brain with the help of a SQUID sensor and provides information on brain function, which can contribute to studies of diseases like Alzheimer's and epilepsy.
Transcranial magnetic stimulation is another application that makes use of electromagnetic fields to manipulate electrical activity in certain areas of the brain to potentially treat conditions like depression and hallucinations.