Rl. Segal et Sl. Wolf, OPERANT-CONDITIONING OF SPINAL STRETCH REFLEXES IN PATIENTS WITH SPINAL-CORD INJURIES, Experimental neurology, 130(2), 1994, pp. 202-213
Hyperactive spinal stretch reflexes (SSRs) often occur with spinal cor
d injuries (SCI). These altered SSRs may impair movement. Recent studi
es in monkeys and human subjects have indicated that the magnitude of
SSRs can be modulated using operant conditioning. The purpose of this
study was to determine whether hyperactive biceps brachii SSRs could b
e operantly conditioned downward. Seventeen chronic (> 1 year postlesi
on) spinal cord-injured patients participated. Subjects were trained t
o keep biceps background (prestretch) electromyographic (EMG) activity
and elbow angle at predetermined levels prior to having the elbow rap
idly extended by a torque motor to elicit the biceps SSR. All subjects
participated in six baseline sessions over a 2 week period. Then, sub
jects were randomly assigned to either control or training groups for
the next 24 sessions over an 8-week period. By the end of the study, t
raining subjects had significantly reduced biceps SSRs (t test, P < 0.
001), while control subjects SSRs were not significantly reduced (t te
st, P > 0.05). The reduced SSRs persisted for up to 4 months following
cessation of training. The results of this study support the hypothes
is that hyperactive SSRs can be operantly conditioned downward in SCI
patients. (C) 1994 Academic Press, Inc.