Table 1.

Mean number of errors during preinjection (1–16) and postinjection (17–56) training trials

Group	T 1–4 (day 1)	T 5–8 (day 2)	T 9–12 (day 3)	T 13–16 (day 4)	T 17–56 (days 5–14)
C-Sal	1.73	1.64	1.27	1.27	.636
C-Glu	1.64	1.54	1.09	1.09	.673
H-Sal	1.90	1.63	1.54	1.18	.655
H-Glu	1.64	1.54	1.45	1.09	.591

Rats received four daily training trials and were given posttraining injections of glutamate or saline on days 4, 5, and 6. The high level of performance reached by all groups by day 4 may have precluded observation of memory enhancing effects of glutamate when the number of errors is used as a measure of memory. However, an influence of posttraining glutamate infusion on memory was revealed via an influence on the later use of place or response learning on the probe trials (see Fig. 2). T, trial; C, caudate; Sal, saline; H, hippocampus; Glu, glutamate.