Multielectrode intrafascicular and extraneural stimulation. 
The relationship between nerve stimulation, pulse amplitude and isometric muscle force was measured to investigate recruitment of motor units.  Force addition experiments were performed to obtain insight in the intersection of motor unit groups recruited by different electrodes.  Intrafascicular and extraneural multielectrode configurations were used for nerve stimulation.  Experiments were performed on rats.  The common peroneal nerve was stimulated and the forces of the tibial anterior and extensor digitorum longus muscles were measured isometrically.  Recruitment was more stable for intrafascicular electrodes than for extraneural electrodes.  Especially for intrafascicular electrodes no strict inverse recruitment was observed.  Force addition experiments indicated that small overlap of recruited motor unit groups occurred more often for intrafascicular than for extraneural electrodes.