dynamic activity of large numbers of neurons, and the language of
mathematics is used to model and describe the complexities of how
activity in millions and billions of cells creates large-scale coherent
electrical oscillation in the brain—global activity that in turn impacts
the local activity of individual neurons. One of the founders of neuro-
dynamics, Walter J. Freeman (b. 1927), has put it this way:
For centuries brains have been described as dynamic systems, beginning
with Descartes, who conceived the pineal as a kind of valve used by the
soul to regulate the pumping of spiritual fluid into the muscles. ... This
was followed by metaphors of clocks, telegraph and telephone systems,
thermodynamics (which underlay Darwinian “nerve energy” and the
Freudian “Id”), digital computers, and holographs. Yet brains are not
“like” any artificial machine. If anything, they are “like” natural self-
organizing processes such as stars and hurricanes. With the guidance
and constraint of genes, they create and maintain their structures while
exchanging matter and energy with their surrounds. They are unique in
the way they move themselves through their personal spaces and incor-
porate facets of their environments for their own purposes, to flourish
and reproduce their kind.In his work—more than sixty years of focusing on the question of how
brains operate—Freeman has kept their unfathomable complexity
front and center.
Here’s a plausible neurodynamic scenario of what happens during
sensory perception and action: Sensory information coded as se-
quences of action potentials in specific neural fibers enters the brain
via the spinal cord and cranial nerves and soon reaches the olfactory
bulbs, brainstem, thalamus, and cerebral cortex. Once in the corti-
cal neuropil things get wild and crazy, with sensory-evoked action
potentials having widespread impact on the global activity of the
cerebral cortex. The ongoing cortical activity may reside at the edges