What outcome does an EEG measure primarily reflect?

The primary outcome that an EEG measures is the electrical activity of the brain. EEG, or electroencephalography, involves placing electrodes on the scalp to detect and record the electrical impulses produced by neuron activity. These measurements provide valuable insights into the brain's functional state, as they capture real-time fluctuations in electrical potential resulting from synaptic activity among nerve cells.

Understanding brain electrical activity is crucial for diagnosing conditions such as epilepsy, sleep disorders, and other neurological conditions. In contrast, blood flow measurements pertain to hemodynamics and are typically assessed using techniques like fMRI or PET scans, necessitating different methodologies. Nerve conduction speed is related to how fast impulses travel along nerves, which does not directly reflect the brain's electrical state. Lastly, brain cell density refers to the number of neurons in a certain volume of brain tissue and does not provide direct information about the brain's dynamic electrical activity. Thus, the EEG's focus on electrical activity effectively distinguishes it from these other physiological measurements.