Which experimental methods measure neural activity and what does each assess?

• A. EEG measures cortical electrical activity; EMG measures muscle activity; nerve conduction studies assess peripheral nerve conduction velocity and amplitude.
• B. EEG measures muscle activity; EMG measures brain signals; nerve conduction studies measure spinal reflexes.
• C. EEG measures neurotransmitter levels; EMG measures blood flow; nerve conduction studies measure synaptic efficiency.
• D. EEG measures heart rate; EMG measures respiration; nerve conduction studies measure cortical maps.

Answer: (A)

Measuring neural activity can be done at different levels with distinct tools, each asking a different question about the nervous system. EEG records the brain’s electrical activity from the cortex through scalp electrodes, reflecting synchronized activity of cortical neurons and giving a picture of brain states, oscillations, or abnormalities. EMG captures electrical activity from muscles, reflecting motor unit action potentials and the influence of motor neurons on muscle fibers, which is useful for assessing muscle and motor-nerve function. Nerve conduction studies test peripheral nerves by delivering a small electrical stimulus and recording the response downstream, yielding conduction velocity and amplitude that indicate how well the nerve and myelin are functioning.

So, EEG measures cortical electrical activity, EMG measures muscle activity, and nerve conduction studies measure peripheral nerve conduction velocity and amplitude.