MEGsignaaleilla

MEGsignaaleilla is a term used in neuroscience to denote the signals detected by magnetoencephalography (MEG). The word appears in Finnish-language literature and refers to the magnetic fields produced by synchronized neural activity, mainly in the cerebral cortex. MEG signals offer high temporal resolution, capturing brain activity on a millisecond timescale while remaining non-invasive.

Measurement relies on sensors that detect tiny magnetic fields. Traditional MEG uses superconducting quantum interference devices (SQUIDs) in a helmet-like dewar, while newer systems use optically pumped magnetometers. The sensor array surrounds the head, and data are recorded at kilohertz sampling rates in magnetically shielded rooms to reduce noise.

MEG data are analyzed to determine when and where neural activity occurs. Common analyses include event-related fields, time–frequency representations, and functional connectivity. Source localization estimates cortical sources with inverse modeling methods such as beamforming or minimum-norm estimates; the inverse problem is ill-posed, so results depend on modeling assumptions.

Applications include mapping sensory and cognitive processes, language and auditory research, localizing epileptic foci for surgery, and studying brain dynamics in health and disease. MEGsignaaleilla complements EEG and functional MRI in multimodal studies.

Limitations include focus on cortex with limited depth sensitivity, reliance on shielding and artifact rejection, and the need for specialized facilities. The technique is expensive and requires careful experimental design, but its high temporal resolution makes it valuable for studying rapid brain processes.