Magnetoencephalography in studies of human cognitive brain function.

Magnetoencephalography provides a new dimension to the functional imaging of the brain. The cerebral magnetic fields recorded noninvasively enable the accurate determination of locations of cerebral activity with an uncompromized time resolution. The first whole-scalp sensor arrays have just recently come into operation, and significant advances are to be expected in both neurophysiological and cognitive studies, as well as in clinical practice. However, although the accuracy of locating isolated sources of brain activity has improved, identification of multiple simultaneous sources can still be a problem. Therefore, attempts are being made to combine magnetoencephalography with other brain-imaging methods to improve spatial localization of multiple sources and, simultaneously, to achieve a more complete characterization of different aspects of brain activity during cognitive processing. Owing to its good time resolution and considerably better spatial accuracy than that provided by EEG, magnetoencephalography holds great promise as a tool for revealing information-processing sequences of the human brain.