Behaviour-Induced Neural Events after Brain Injury

Kathleen Friel
kfriel@kumc.edu

Dr. Grover,
Thanks very much for your questions!  

You are right that the purpose of the restrictive jacket in this study was to encourage the animals to use their impaired arm after the lesion.  The goal of training, in the "jacket/rehabilitative training" group presented, was to have monkeys to use their impaired arm after the lesion.  After a lesion, if neither arm of the monkey is restrained, they will often use their unimpaired hand to retrieve pellets.  However, the experiments required the animals to use their impaired hand during training.  Since we could not verbally encourage the monkeys to use only their impaired hand during training, we fitted them with jackets that restricted use of the unimpaired hand.  This forced the animals to use the impaired hand during training.  

I do believe that recovery occurs through compensatory mechanisms, as you suggest.  There are many different ways to look at recovery, and at compensation, after lesion.  Behaviorally, it has been  shown by many researchers (some of whom have posters in this session!) that animals and humans will favor using unimpaired body parts to complete motor tasks after a lesion.  Thus, they often compensate by using other limbs.  In our studies, we have been interested in looking at how animals use their impaired limb after lesion.  Therefore, we force them to use their impaired hand after the lesion to retrieve pellets.  In a previous study (Friel and Nudo, 1998) we found that some animals use different movements to retrieve pellets after a lesion with their impaired hand.   This shows another way animals can compensate after injuryÑusing the impaired limb in a different way.  Reorganization of primary motor cortex and/or other motor areas both ipsilateral and contralateral to a lesion surely play a critical role in functional recovery.  Many different labs have shown changes in many different areas of the brain following a lesion, and it is expected that at least some (if not many) of these changes are adaptive events that promote recovery of function.

Thank you very much for your interest in our work, and feel free to contact me if you have any more questions about our poster (or these answers!).  Enjoy the rest of the meeting!!

Kathleen Friel, M.S.  (not Dr. Friel yet!)
Department of Molecular and Integrative Physiology
University of Kansas Medical Center
kfriel@kumc.edu