Effect of low or high frequency stimuli to the dorsal root on the motility of microglia in spinal dorsal horn. (A). Sample images showing the extension and retraction of microglia in control (top), low frequency stimulation (LFS) (middle) and high frequency stimulation (HFS) induction groups (bottom). Right image is showing the microglia at 10 min and 30 min after imaging. LTP induction was delivered at time 10 min. (B). Extension (top) and retraction (bottom) of microglia in LTP induction groups is similar to that in control group. The number, distance, and percentage of volume of extension or retraction processes were measured. Note that the "rundown" of microglial extension was found in the three groups.