Variations in compensation may explain why, with acute manipulations including intrathecal application of BDNF and activated microglia, reduction in Eanion to around -62 mV caused almost an equivalent decrease in withdrawal threshold as that associated with reduction of Eanion to -49 mV following peripheral nerve injury [42]: compensation that could have developed in the latter case, may not have had time to develop in the former case; it is also possible, however, that BDNF has other effects [64] that are unaccounted for in this argument. This evidence concerns the gene BDNF and peripheral nerve injury.