Magnetoencephalography and Physics

The most enthralling development in Neuroscience to me, is that of using an understanding of

electromagnetism to engineer a device which, when coupled with a powerful computer can non-invasively and comfortably show a simulation of the brain in action, in real time.

The skull is a resistive plate, protecting the electrically active brain from the elements, accidents and electrical interference. Resistors like bone and plastic don't allow electrons to pass freely through them. This makes it difficult to detect the electrical activity in the brain, or "see the brain" non-invasively. Techniques like Magnetoencephalography, MEGs have been built and developed by engineers and physicists. MEG allows us to look inside the brain based on an understanding of the fundamental relationship between electric and magnetic fields, which are produced by currents of moving charges. Consider the neuron like a circuit and if you are interested look up the Hodgkins Huxley model of the cell, and more on that later.

Superconductive materials give no resistance to moving charges at a cost, they must be cooled to extremely low temperatures, an expensive and space consuming process. (Responsible for the bulk of the device.) In MEGs Helium is used to cool the superconducting quantum interference devices, SQUIDs to extremely cold temperatures allowing changes detected near the head to be sent to the computer faster than any detector has ever done before. The brain’s electrical activity can be visualized from the magnetic dipole activity created by "Big Boy" Cortical neurons. the resistive skull plate does not interrupt or change the magnetic fields as opposed to Electric fields which can only be directly measured by EEG through tiny gaps in the skull. Source of electromagnetic activity can be localized accurately and quickly, allowing new experimental methods in cognitive science to be developed with real time imaging capability.