Circuit Elements Required for Neural Systems - Brain Theory from a Circuits and Systems Perspective - page 30

Chapter 3
Circuit Elements Required for Neural Systems
Introduction
Circuit elements introduced in this chapter are (1) short-term memory (STM)
neuron, (2) regular synaptic contact, (3) weak synaptic contact, (4) postsynaptic
capacitor with initial charge representing long-term potentiation (LTP), (5) capaci-
tive termination for dendrites, (6) dendritic AND, OR logic, (7) dendritic XOR,
NOT logic, (8) enabled, or soma AND, OR logic, and (9) enabled, or soma NOT
logic. Also available are delay and sundry other elements. Some of these are novel
in traditional circuits and systems, which has always been aimed at solid-state
circuitry, but these nine elements are essential when modeling pulsating neurons.
The functions of these nine elements are demonstrated by a set of simulation
experiments in the appendix.
Classical elements are also useful, such as capacitance, resistance, independent
voltage sources and current sources, and controlled sources controlled by circuit
variables (voltages and currents). Circuit elements as above are required to
(1) serve to model neural behavior in an accurate way and (2) satisfy the needs of
a functioning brain system.
Models as in this chapter summarize experimental data; they serve to inspire
future experiments, and hopefully encourage understanding. Models, of course,
must be routinely updated to reflect new experimental data. Models sometimes lead
to practical versions of the modeled system, as they have done for artificial neural
networks, but students are well advised to seek full comprehension before
attempting engineering applications.