Page 107 - Artificial Intelligence in the Age of Neural Networks and Brain Computing

2. Ephapsis 95

is placed into spatiotemporal context by the theta oscillation mechanism. There is a
relation between gamma activity and slower theta oscillations. The slow carrier
wave can serve to combine and segregate cell assemblies, nested within gamma
waves. Buzsaki postulates that it is the brain’s interaction with the body and the
physical-social environment that provides the meaning to subset of spontaneous
states of brain. Echoing philosopher George Mead, he wrote: “The brain gradually
acquires self-awareness by learning to predict neural performance of other brains.
Acquisition of self-consciousness requires feedback from other brains.”
Despite his profound insight into oscillatory nature of workings of brain, Buzsaki
remains, like most scientists, a dualist, sending “information” between neuronal
groups, using oscillations as a novel way to explain “binding problem” and finding
cognitive maps in hippocampus. Howard Eichenbaum [5] interpreted the same ob-
servations differently; for him hippocampus does not create a cognitive map, that is,
a representation, rather it integrates temporal events in any modality, not just a loco-
motion, and converts them into a spatially organized “personal story book” via path
integration. Similarly, McNaughton concluded that place cells are formed by dead
reckoning and distance is calculated on the basis of self-motion clues.

2. EPHAPSIS
In 1975, Freeman did not yet have a clear understanding of the mechanism which
could bring the billions of neurons that make up each human cerebral hemisphere
into global order within a few thousandths of a second. In 2006 however, he pub-
lished with Vitiello a seminal paper [6] which offers an answer. Freeman and Vitiello
start with an observation:

The dominant mechanism for neural interactions by axodendritic synaptic trans-
mission should impose distance-dependent delays on the EEG oscillations owing
to finite propagation velocities and sequential synaptic delays. It does not. Neural
populations have a low velocity information and energy transfers and high veloc-
ity of spread of phase transitions.
The answer to this puzzle may be provided by Carver Mead’s Collective Electro-
dynamics [7] or Giuseppe Vitiello’s Quantum Field Theory (QFT) [8], both of which
differ drastically from Quantum Mechanics. Freeman speculates that wave packets
he observed act as a bridge from quantum dynamics at the atomic level through the
microscopic pulse trains of neurons to macroscopic properties of large populations
of neurons. Field theory of many-body systems allows for phase transition by spon-
taneous break of symmetry (SBS) or event-related potential (ERP). SBS is always
accompanied by the dynamical formation of collective waves (NambudGoldstone
modes or bosons) that span the whole system. These ordering waves (bosons)
condense in the system ground state and ordering is a result of this boson conden-
sation. Examples of macroscopically observed patterns are phonons (elastic waves)
in crystals and the magnons (spin waves) in magnets.