Brain Architecture for an Intelligent Stream of Consciousness - Brain Theory from a Circuits and Systems Perspective - page 19

Fig. 2.1 Basic neural signaling (ms milliseconds, STM short-term memory, LTM long-term
memory)

Inputs are thought of as pulses propagated along dendrites which have been
triggered by receptors. Two major types of neural logic are identified in a later
chapter: (1) dendritic logic, of which there may be thousands of gates per neuron,
but in a gate of this type, pulses must arrive concurrently, and (2) enabled logic,
which is limited to charge accumulation and subsequent triggering at a capacitive
body such as a soma. Engineers are familiar with enabled logic in that it pertains to
the activation functions used in artificial neural networks.
STM elements have an output burst that can be much longer than ten pulses,
depending on ionic conditions within the dendrites, as discussed below. Bursts
range in duration from a few milliseconds to several seconds. STM neurons produce
regular pulses, that is, between about 70 and +40 mV, with pulse width about

2 ms, so that they are able to signal other neurons.
LTM elements ideally are instantly programmable, and last indefinitely, many
decades. They may involve long-term potentiation (LTP) (trapped charge) and
recursive neurons (that feed back on themselves); these may be organized to emit
regular pulses only when called upon. Mechanisms and purposes of short- and
long-term memory elements are going to be discussed in later chapters.

Introduction to Human Memory

The focus in this topic is on explicit memory, as perceived in a brain, and not on
implicit memory, such as automatic reflexes without direct mental involvement.
Human explicit memory may be divided into two types, conscious STM and
subconscious LTM. Signals that activate STM neurons are assumed in this topic
to flow from the five senses and also from recalls emanating from LTM.