The brains selection of a course in the sequencing of individual thought phases in time
Thought progresses endlessly through sequences of visualizations (visual images, sound images, fragrance or tactile visualizations, with language and numbers being combinations of these). Such visualizations are occasionally interrupted and sequences derailed by the occurrence of actual sensory perceptions, including the communication of other peoples thoughts. Individual visualizations in the mind are simultaneous activations (increased firing rate) of large groups of neurons with preestablished synaptic interconnections (memorization). See, for example, Edelmans work at Scripps.
Neurons generally do not endlessly sustain their firing rate, even when continuously excited by synaptic or sensory inputs. In general, activation fades after a short time. This may be explained by fatigue. More likely, fading evolved in evolution because it provides specific benefits in neural signal processing. In sensory perception, fading under constant excitement allows for improved detection of variations, as in the detection of moving objects. In thought processes, fading of momentary visualizations is necessary to allow thought progression through sequencing to subsequent visualizations. As the neural group activation of one momentary visualization fades, another visualization is activated and can gain prevalence. Signal transmissions in the brain are in the range below 10 msec, indicating the possible high rate of thought (visualization) sequencing.
It is important to note that frontal lobe thought progression (uninfluenced by sensory perception) is one-dimensional. Thought does not divert in many directions simultaneously; only one visualization follows a given one at any one time. This is true specifically for conscious thought. There is some indication that some additional thought progression may occur subconsciously (multi-tasking), some not in the forebrain but in the cerebellum. These side progressions are in themselves linear. Examples are driving or other routine occupations while simultaneously pursuing a discussion with somebody else. Other multi-tasking may be time-sharing of awareness under alternating focus (as in driving a car while carrying on a conversation and simultaneously following directions). Thought does not jump arbitrarily between unrelated visualizations. Undisturbed thought sequences follow associated visualizations, most likely also when in the subconscious.
The connections of sequential thought phases are commonly called thought associations. For example, the visualization of a car is associated with all its components, functions, and uses. Physiologically, associations between visualizations are accomplished through common usage (sharing) of neurons between groups that form related visualizations or through synaptic connections to neuron groups producing other visualization in the mind. Most visualizations in the brain are synaptically associated with several other visualizations, as memorized through prior experience or thought. Since the thought sequences in the brain never stand still, which of the synaptic connections will be pursued to present the next visualization in the mind?
First premise or hypothesis: The synaptic couplings of visualizations (thought associations) have different strength (resulting in different strength of the secondary firing rate) as a function of three factors:
Any combination of these causes can lead to specific synaptic signal strength that is memorized with or physically expressed in the formation of most synaptic connections (associative links)."
It is important to note that the evaluation of experience and perceived consequences, often related to positive or negative emotions, requires connections between the forebrain and the amygdala and other parts of the limbic system of the brain where such signals are being processed. The effect of the amygdala connections were recently confirmed (bibliography #7) and their accidental or clinical disruption has shown the results expected from the above hypothesis. With personal "valuation" and perceived consequences being so important in synaptic coupling, psychological factors and temperament significantly influence the thought process and, consequently, creativity.
It seems easier to add new valuation (as through strong experiences or significant thought) than to dissolve old valuations (as in trying to undo aversions or prejudices, especially when even sparse selective observation allows ongoing confirmation).
Second premise or hypothesis: "It is postulated that, from among all the synaptic associations to other visualizations, the strongest synaptic connection to another association is selected for visualization sequencing (thought association) with lesser associations being actually suppressed from activation."
Even if several next associations are receiving activation signals, only the
one with the strongest synaptic excitation will be activated. All indications
are that a newly activated, preferred association has a dampening effect on
competitively possible alternative visualizations, keeping those at rest. This
can be accomplished in the brain by nerval connections producing signal inhibition
(as commonly observed), or by cross-connecting neurons such as those that can
be found in retinal networks, or through brain-chemical processes on the neurotransmitter
The fact that the strongest signal transmission prevails (or is "selected") in associative linkages alludes to biological evolution. This is truly significant. One can find a number of parallels between thought evolution and biological evolution. However, an exploration of this facet of practical creative thought leads beyond the scope of this paper.
The hypothesis presented above, regarding the selective continuity of associative thought, leads to the question whether all thought sequences are predetermined. This is not necessarily so. First, sensory perception can interrupt thought sequences, start new ones, and influence their course. Second, as with all the phenomena of nature, there is always an area of statistical distribution somewhere. If two possible associative linkages are of equal synaptic strength, statistical signal strength variation will lead to a temporary inequality and an unpredictable selection of one progression of thought sequences over the other. There could be some Heisenberg uncertainty principle in thought sequencing somewhere. Thus, minute momentary differences can lead to enormous consequences (chaos theory), which, taken together with the probabilistic occurrence of interrupting perceptions, leave room for transcendental considerations. Third, ones own thought can impact synaptic valuation and consequent associative linkage, thereby influencing future thought patterns which, in turn, influence synaptic connections from then on. Systems with such feedback characteristics can become undetermined. In practical terms, this is the basis base for "freedom of will."