Final answer:
The EEG is the device that tracked a mental impulse by measuring the brain's electrical activity, and it is crucial in research areas such as sleep disorders and the study of brain processing power. Other techniques like transcranial magnetic stimulation facilitate diagnostic and therapeutic measures by targeting specific brain activity.
Step-by-step explanation:
The device that tracks a mental impulse, serving as a precursor for electroencephalography (EEG), is the EEG itself. This diagnostic tool is essential in measuring the electrical activity of the brain. By placing an array of electrodes around a person's head, the EEG captures brainwave frequencies and amplitudes with millisecond accuracy. This brain activity monitoring is particularly useful for research in areas like sleep disorders, as well as for understanding the brain's processing capabilities, such as catching an object which involves calculation of trajectory and coordination of movement in space.
Moreover, transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG), which employs the SQUID sensor, are other advanced techniques that target electrical activity in the brain for diagnostic and therapeutic purposes. TMS, which induces weak electric currents through a localized magnetic field for recovery of brain electrical functioning, is a notable example of electromagnetic induction applied to brain research.