Functional assessments of the rodent facial nerve: A synkinesis model

Tessa Hadlock, Jeffrey Kowaleski, David Lo, Roberto Bermejo, H. Philip Zeigler, Susan Mackinnon, James T. Heaton

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Objectives/Hypothesis: Rodent whisker movement has been used as a tool, after facial nerve manipulation, to quantify functional recovery. We have recently established a method to study functional correlates of aberrant regeneration of the facial nerve. Our objective was to establish normative parameters for both spontaneous and induced whisking and blinking behavior in a large group of normal rats. Study Design: Prospective animal study. Methods: Eighty animals underwent quantitative facial movement testing to measure simultaneous vibrissal movement and ocular closure for each side independently. Right and left C-l whisker positions were continuously recorded for 5-minute sessions, and changes in infrared detection corresponding to eye closure were continuously recorded. Whisking and blinking were elicited by delivery of olfactory stimuli (10 s scented airflows) and corneal air puffs. Whisks were counted and analyzed, and eye closures were counted. Results: Whisking amplitude, velocity, and acceleration were consistent with literature values. Air puff delivery elicited an ipsilateral blink 99% of the time, a contralateral blink 18% of the time, and changes in or initiation of bilateral whisking 70% of the time. Olfactory stimulus delivery prompted a change in whisking behavior 83% of the time, and eye closure 20% of the time. Conclusions: This study establishes normative data for assessing cranial nerve VII-controlled facial movement in four separate facial regions. We demonstrate the capability and tendency of animals to move their orbicularis oculi muscles independently of and simulta-neously with their midfacial muscles. This model pro-v des an excellent tool for the study of aberrant regen-eration after facial nerve injury in the rodent.

Original languageEnglish
Pages (from-to)1744-1749
Number of pages6
Issue number10
StatePublished - Oct 2008


  • Kinematics
  • Rodent facial nerve
  • Synkinesis
  • Whisking


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