Fictive motor programs.
Fundamental to our design of a brain that thinks is the halting of a
motor program at the ventral anterior-ventral lateral complex of the
thalamus. What shall we call such a halted and rejected motor program?
Some have bridled at calling it any kind of a motor program. They say
that if it isn't connected to motor neurons it isn't a motor program
period.
This awkwardness is apparent in the study of central pattern
generators. The preparation is usually a small neural circuit
maintained in vitro. After studying the output of the neurons, the
investigator says that if this circuit were re-connected to the body
(a leech, say), the organism would swim. The re-connection remains
hypothetical and this is unsatisfactory to some. No matter how
sophisticated the argument may be that the circuit would work, people
ask for a demonstration. In only a few cases, has this been possible.
We believe wholeheartedly that it would, but doubts persist. The motor
pattern produced by the circuit is called a fictive motor pattern.
I argue that we should call the motor programs that are halted and
rejected at the thalamus "fictive", fictive motor programs. There
should be no element of implied falsity. I feel that the motor
program, although it disappear into thin air, is real, and if it were
to continue to the motor cortex, the animal would behave.
ray