Figure 1.

SNI impairs spatial working memory and short-term memory (STM), but not spatial reference memory or long-term memory (LTM) in rats. (a) The mechanical allodynia was verified by lasting decrease in paw withdrawal thresholds on ipsilateral side in SNI group, compared with those in sham group (n=15 in SNI group and n=20 in sham group). (b and c) In the same rats working memory and reference memory were evaluated with radial eight-arm maze at 11–20 days after operation. (d–f) In the five rats that did not exhibit significant decrease in paw withdrawal thresholds following SNI, working memory errors but not reference memory errors were also significantly higher, compared with sham group (n=20 in sham group). (g–i) Paw withdrawal thresholds, working memory and reference memory in the rats at 31–40 days after SNI and sham operation are shown (n=10 in each group). (j–l) Paw withdrawal thresholds were tested in SNI and sham groups, and the recognition index for STM and for LTM were determined by novel object recognition test at 19 days and at 20 days after operation. ^**P<0.01 compared with sham groups (n=8 in each group). Data are presented as means±SEM.