A novel videographic method for quantitatively tracking vibrissal motor recovery following facial nerve injuries in rats

Background: Previous studies of vibrissal movements employ either optoelectronic recording techniques in the head fixed rodent, or videographic recordings in freely moving animals. However, both approaches have shortcomings for quantitatively tracking the process of vibrissal motor recovery.

New method: A critical feature of our videographic method is to measure tagged vibrissae movements while leaving all others intact in body restrained rats without head fixation. Thirty two adult rats underwent facial nerve manipulation and testing. All animals underwent baseline preoperative whisking testing. In the experimental groups, the right facial nerve was either crushed, or transected and sutured. In the control groups, the left facial nerve underwent either sham surgery, or transection denervation. Whisking function was measured for the ensuing 2 to 12 weeks. Data were analyzed for whisking recovery.

Results: Baseline preoperative whisking testing showed that majority of free whisking on the both sides is synchronous and symmetric, which allows us to compare vibrissal motor data between intact and manipulated side after facial nerve injury. As expected, the recovery of whisking function following crush is better and earlier than that with transection and suture.

Comparison with existing method(s): To our knowledge, this novel videographic method is a significant simplification over currently employed optoelectronic recording techniques and videographic methods.

Conclusions: Our novel videographic method may be a powerful tool to investigate motor recovery from facial nerve manipulation in the rat model.