A train of impulses simply travelling on a long fiber may, for
example, be regarded as a short-term memory much in the same way as
a delay line acts as a transient memory in a computer. A similar
but slightly longer term memory may also be thought of to exist in
the form of waves circulating in closed loops (23). In fact, it is
almost universally held today that most significant memory occurs
in two basic interrelated ways. First of all, such a short-term
circulating, reverberatory or regenerative memory which, however, could
not conceivably persist through such things as coma, anesthesia,
concussion, extreme cold, deep sleep and convulsive seizures and
thus, secondly, a long-term memory trace which must somehow reside
in a semipermanent fine-structural change. As Hebb (9) stated, “A
reverbratory trace might cooperate with a structural change and carry
the memory until the growth change is made.”