Neuroquantology, the Ultimate Quest - Brain Theory from a Circuits and Systems Perspective - page 150

have not yet been observed directly. However, the probabilities they predict are
accurate and supported experimentally.
The Heisenberg interpretation has been further developed [ 3 ] since it seemed
that classical physics, taken from the bottom up, could not fully describe brain
functioning. The nonlinearity of the synaptic system and the large number of states
into which the brain can evolve, it was argued, point to a (top down) quantum
mechanical system as the appropriate way to describe brain functioning. But if one
proposes large-scale excitation of a brain in which conscious events are spontane-
ous selections (collapses) among possibilities (basic states), then fundamental
questions arise. For instance, what computational power, exactly, creates the
possibilities? And what are the possibilities? Such questions remain open.
Returning to tunneling, electrons in particular seem to have a role.

Electrons in Ionic Solutions

Electrons are easily captured by positive charge. Within ionic solutions they are
routinely quasi-free but only for nanoseconds; because of their small mass, 1/1,836
of a proton, they achieve high velocities [ 4 ]; so they permeate a given region.
Electrons tunnel through barriers where classically they cannot go, so in fact they
permeate beyond any given region.
Electrons are plentiful in nature. The water molecule, for instance, has exposed
eccentric electron orbitals from which electrons are easily freed. Stray electrons,
knocked free by thermal agitation, are extremely mobile. Therefore it is reasonable
to consider electrons when investigating some of the mysteries of neural electricity.
Clearly electrons have a major role in metals and semiconductors. At high
electric fields, even insulators break down and conduct electrons. In contrast, neural
membranes are surrounded by ionic solutions that mostly use ions to pass electrical
charge, not electrons.
Even though ions pass nearly all of the electrical current for lower current
densities, it is known that electrons in ionic solutions carry some of the current at
higher current densities. The evidence is from the field of electroplating, where
there is a decrease in electroplating efficiency as currents are increased. This is
because some of the current is due to electron flow, which does not plate an
electrode. Likewise in ion channels current densities are high, so ions may block
the channel. Under such conditions electron tunneling may be important. Stray
electron tunneling, aided by local electric fields, can be used to explain significant
components of ion channel current.

Electrons in Ion Channels of Neurons

What makes the electron especially potent for its size is that it carries a unit of
negative electrical charge ( 10 19 C, or coulomb). An interesting

proposal is that electron tunneling into ion channels and subsequent capture by ions
are important to the formation of the peak of a neural pulse [ 5 ].

q ¼ 1.6