The grasping test: a simple behavioral method for objective quantitative assessment of peripheral nerve regeneration in the rat

Behavioral recovery is the major goal of neuroscience research on the peripheral nervous system. However, behavioral methods of assessing peripheral nerve regeneration are still lacking. In the present work we used the median nerve and finger flexors as the experimental model. After resection or crush injury of the median nerve, rats were submitted daily to the grasping test. For this, they were gently lifted by the tail and allowed to grasp a grid connected to an ordinary electronic balance. While grasping the animal continued to be lifted by the tail with increasing firmeness until it lost its grip. At this precise moment the value shown by the balance was recorded. In the crushed median nerve, recovery of function was clearly demonstrated by the grasping test. The test also indicated the exact day on which recovery began and its improvement with time. This very simple objective behavioral method provides a sensitive quantitative technique for assessing recovery. The experimental model using the median nerve seems to be better than the sciatic nerve model, as no articular contractures or autotomies were noted in the present experimental animals.