FIG. 2.

The impact procedure on the mouse spinal cord is shown, along with a plot of the position of the impactor tip versus time. The bold, solid line represents the command pulse, in voltage (the amplitude is not to scale), and the displacement for 0.1 m/s (□), 0.2 m/s (△), and 0.4 m/s (◯) are presented as mean ± standard deviation (n = 6 for each group). Negative displacements represent the upward motion (from ventral to dorsal). Prior to phase I, the impactor tip was placed directly on top of the exposed cord by the XYZ translator. With the initiation of impact procedure via a computer command, the impactor tip was moved up (phase II) and rapidly down (impact occurs, phase III). The impactor tip was immediately moved up to avoid secondary impact.