Affiliations: Division of Physical Therapy, Department of
Rehabilitation Medicine, Emory University School of Medicine, Atlanta, GA,
US,4 | Department of Cell Biology, Emory University School of
Medicine, and Neuroscience Program, Graduate Division of Biological and
Biomedical Sciences, Graduate School of Arts and Sciences, Emory University,
Atlanta, GA, USA
Note: [] Correspondence to: Richard L. Segal, Room 228, Center for
Rehabilitation Medicine, Emory University, 1441 Clifton Road NE, Atlanta, GA
30322, USA. Tel.: +1 404.712.5654; Fax: +1 404.712.4809; E-mail:
[email protected]
Abstract: Purpose: Successful operant conditioning of the biceps brachii
spinal stretch reflex (SSR) has resulted in concurrent changes in the magnitude
of long latency reflex responses (LLRRs). This finding suggests a coupling of
the SSR and LLRR. The purpose of the present study was to downtrain the LLRR
using operant conditioning and to observe any concurrent change in the SSR.
Methods: Fourteen, able-bodied, human subjects were randomly assigned to either
the control group or the training group. The LLRR and SSR responses were
measured as magnitude of electromyographic response to a quick stretch of the
elbow flexors, delivered by a torque motor. All the subjects attended fourteen
sessions. The first six sessions were baseline sessions during which no
conditioning or feedback occurred. The next eight sessions were the same as the
baseline sessions (extended baseline sessions) for the control group; no
feedback or operant conditioning of the LLRR occurred. The next eight sessions
for the training group comprised the operant conditioning. Results: Operant
conditioning of the LLRR resulted in a statistically significant reduction of
that response within the training group and between the two groups. Also,
operant conditioning of the biceps brachii LLRR did not result in concurrent
changes in the magnitude of the SSR suggesting an uncoupling of these
responses. Conclusions: The LLRR of the biceps brachii could be operantly
conditioned without significant changes in the SSR which suggests that these
two responses can be volitionally uncoupled.
