MOTOR CONTROL FOR SPEECH
-based on D. Rosenbaum Human Motor
Control, Chapter 1.
A. Skilled movement vs. unskilled
reaches: 2 phases -
motion + refined end
B. Efficiency problem: how to minimize effort to achieve a goal
-synergies: special-purpose combination
of constraints on muscles
C. Serial order problem (Karl Lashley, 1951 `The problem
of serial order in behavior', PsyRev)
1. response chain model:
a) Each item excites the next item: n->n+1->n+2
or, for greater speed, each might excite the next but one:
n -> n+2
n+1 -> n+3 ...
The first item ihibits the second and the second inhibits
the 3d, etc.
Thus, making the first one fire, releases the inhibition
on the 2d, which releases the 3d, etc.
eg, comb model, schemas
D. Degrees of freedom problem : How to control all the
thousands of possible variables in a manageable way.
(kinematics vs dynamics) and motor equivalence
inverse kinematics: find
a path given a goal
coordinates vs. spatial coordinates
inverse dynamics problem:
find muscle activtn pattern given a path
E. Feedback (perceptual-motor integration)
1. closed loop
control (eg, a thermostat or the Watt steam governor
but: a) What
is the right correction when there are many possible reasons for an
The problem of a multidimensional system
b) Sherrington's `spinal cat' (which spine severed) could still walk
(if its body was suspended over a treadmill).
2. open loop
- actions are performed without feedback. Especially
for skilled action
F. Mass-Spring model:
a) helps greatly to solve
the degrees-of-freedom problem
b) sets a target, not a
movement - so no start/stop control is needed.
c) thus it is open loop
d) rate of motion,
peak velocity location, etc require no explicit control
G. Multiple Coordinated Movements
1. Two limbs: Haken-Kelso-Bunz (1985) model for
2. . Jaw + Lower Lip + Upper Lip
neural model of David