Figure 1.

In vitro LTP recording from the CA1 hippocampal region of NCAM deficient (NCAM−/−) and wild-type (NCAM+/+) mice. A, Injection of PSA-NCAM-Fc (100 μg/ml) into slice from NCAM−/− mice before first theta-bust stimulation (TBS-1) significantly increased LTP at the recording site adjacent to the injection site as compared with LTP recorded at the control site in the same slice. LTP induced by a second theta-bust stimulation (TBS-2) after PSA-NCAM-Fc injection was also higher at the injected than at the control site. B, Injection of NCAM-Fc (100 μg/ml) failed to rescue LTP induced by either TBS-1 or TBS-2 in NCAM−/− mice. C, Injection of PSA (100 μg/ml) restored LTP in NCAM−/− mice. D, Injection of PSA (100 μg/ml) impaired LTP in NCAM+/+ mice. E, PSA injected at a concentration of 300 μg/ml did not rescue LTP in NCAM−/− mice. F, Injection of PSA (100 μg/ml) starting 10 min after TBS-2 rather than 20 min before TBS-1 as in A–E did not affect LTP in NCAM−/− mice. All data are represented as mean slope + SEM of fEPSPs normalized to the baseline values. *p ≤ 0.05 (paired t test). Time intervals of injection are indicated by horizontal bars.