What does Magnetoencephalography (MEG) primarily measure?

Magnetoencephalography (MEG) primarily measures magnetic fields produced by brain activity. This technique is based on the principle that when neurons in the brain are active, they generate tiny magnetic fields as a byproduct of their electrical activity. MEG provides a non-invasive way to map brain functions in real-time, allowing researchers and clinicians to observe the dynamics of brain activity as it occurs.

The measurement of magnetic fields offers several advantages, including high temporal resolution, which allows for the detection of changes in brain activity within milliseconds. This is particularly useful for understanding the timing and sequence of neural processes. Additionally, MEG can provide spatial localization of brain activity with considerable precision, helping to identify which areas of the brain are involved in specific tasks or cognitive functions.

While electrical activity of neurons is related and can indeed be measured through techniques like EEG, MEG focuses specifically on the magnetic fields, providing a different perspective on brain function. The other options, such as blood flow in the brain and neurotransmitter release, are measured using different methods like functional magnetic resonance imaging (fMRI) or other types of imaging and biochemical assays, respectively, and do not pertain directly to what MEG measures.