Final answer:
The technique that attaches electrodes to the scalp to measure brain electrical waves is Electroencephalography (EEG), which is used to study brain activity patterns, such as in sleep research.
Step-by-step explanation:
The technique that attaches electrodes to the scalp to measure the changes in electrical waves across the surface of the brain is known as Electroencephalography (EEG). This method is particularly useful for researchers studying sleep patterns and identifying sleep disorders. The EEG captures electrical activity, or brainwaves, including both their frequency and amplitude with millisecond accuracy, providing a measure of a brain's overall electrical activity without pinpointing the exact location.
Other techniques mentioned but not matching this description include functional magnetic resonance imaging (fMRI), which maps the most active areas of the brain in 3D by measuring changes in blood flow in relation to brain activity, and positron emission tomography (PET) scans, which involve the monitoring of a tracer substance to create a rough map of active brain regions. Transcranial magnetic stimulation (TMS) is a different diagnostic technique that uses a localized magnetic field to influence brain activity, but it does not measure electrical waves through the scalp like EEG does.