Tone of Voice and Mind : The Connections between Intonation ...

Synapses and action potentials 175
ism biochemical imbalances have occurred and (ii) make cognitive deductions
about appropriate behavior. For both of these functions, neurons are essential.
In other words, the neuron is the functional unit for both sensing the external
world (ion exchange) and initiating motor behavior that will lead to changes
in that external world (neurotransmitter release).
In this view, the release of neurotransmitters – which is the end result of
impulse conduction – is only one half of the neuron’s interaction with its external
world. In an informational sense, the release of inhibitory or excitatory
molecules and the subsequent effect on other neurons is all-important, but
for the individual neuron, the ion-exchanges occurring down the length of the
axonal processes are more drastic, more energetically-demanding, and more
direct interactions with the environment (Figure 6-8).
It is not for us to make anthropomorphic guesses about what the release of
neurotransmitters or the action potential itself “feels like” for the neuron, but it
is a fact that the neuron periodically opens up to its local environment and allows
the thermodynamic flow of ions into and out of the cell. It is of course true
that the “opening up” of the neuron to environmental molecules is restricted to
Figure 6-8. The two modes of contact between a neuron and its extracellular environment.
Synaptic communications (A) are central to the phenomena of cognition,
whereas the deluge of ions from the extracellular fluid into the cell during the action
potential is arguably the single-cell protophenomenon of subjectivity – i.e., directly
“feeling” the (ionic state of the) external world (Cook 1999c, 2000a, 2002a, b).