Consciousness: Confessions of a Romantic Reductionist (The MIT Press)

by Christof Koch

The brain is a highly evolved organ, yet it is also a physical system that obeys ironclad laws of conservation of energy and of electrical charge. Gauss’s and Ohm’s laws regulate the distribution of charges inside and outside of nerve cells and their associated electric fields. All the synaptic and spiking processes described above contribute to the electrical potential that is picked up by electrodes stuck into the brain’s gray matter. If tens of thousands of neurons and their millions of synapses are active, their contributions add up to something called the local field potential. The distant echo of this electrical activity is visible in the never-ceasing peaks and troughs recorded outside the skull by an electroencephalograph (EEG). The local field potential, in turn, feeds back onto individual neurons. We are now learning that this feedback forces neurons to synchronize their activity.