Postscript - Brain Theory from a Circuits and Systems Perspective - page 176

a path to appropriate parts of the overall system, and timing applies, meaning that
brain events must occur within appropriate time frames.
Circuits and systems are not vague concepts; they use realistic elements; and
they either function correctly or they do not. Unlike dreamy concepts, circuitry has
the advantage that it may be simulated in a computer, or physically constructed by
clever engineers. There are only so many ways a functioning system can be
synthesized, given what is known about how neurons pulsate and perform Boolean
logic. Based on what is known of neural logic, this topic presents a particular circuit
for stream of consciousness. This topic's system is not the only possible system, just
one of many that could be proposed.
This topic does not pursue reverse engineering based on physical dissection of
the brains of lower life forms. To arrive at a fitting hypothesis, this topic applies
logic theory using realistic circuit elements to develop a system, and then analyzes
the resulting interconnection to verify its correctness. Neural circuits and neural
systems (NCANS) is a form of circuit science, but is definitely not the bailiwick of
circuit engineers, since engineering is mainly a for-profit activity mostly limited to
hardware. So unless practical medical or robotic devices are involved, engineering
interest is likely to be lukewarm. Consequently owing to the hardware bias of
circuit theory, the subject of NCANS has been neglected for many decades.
The good news is, there remains an opportunity for young scientists to realize its
importance, and to revive it.
Novel Circuit Elements for an Efficient System
Certain elements are necessary to a neural system but these novel elements might
not be universally expected, at least not by circuit engineers. For example, an
interesting circuit element has been described as a weak synapse, meaning it
triggers and transmits only one dendritic pulse, a sort of pulsed mono stable
multivibrator. Particular subcircuits also select and transmit only the first pulse of
a burst, effectively accomplishing the same function as a weak synapse. Single
pulses have been observed in brain cells, and their purpose has long been a topic of
speculation. This topic proposes that single pulses are extremely important to
system timing.
Single pulses are needed for an accurate sequencing of subcircuits, which would
not be efficient otherwise. For example, multiple returns from long-term memory
need to be individually catalogued for a priority determination, which is best done
with a single pulse moving along a delay line, as in this topic's recall referee.This
process could be accomplished with neural equivalents of a pulse counter and
binary decoder, but this would require many more neurons and a complex logic
network. Taking advantage of single pulses is considerably more efficient.
Single pulses are key to recursive neurons that recycle a single pulse, thus
establishing an element of memory of a certain type. But such neurons, termed
multivibrators, are far more than elements of memory. By varying the frequency of