Fig. 1.

SHR exhibit similar working memory deficits to hippocampal-lesioned rats, particularly in long delay trials of the DA task. Tukey's multiple comparison test: *p < 0.05, ***p < 0.001. (a) Experimental apparatus and paradigm for the delayed alternation task. This task was run on an elevated figure-eight maze. Animals received a food reward for correctly alternating between left and right arms of the maze. (b) Average percentage of correct choices for female and male SHR (n = 12), WKY (n = 12), hippocampal-lesioned (n = 6), and sham-lesioned (n = 6) rats in each delay condition (no delay, 10 s, and 60 s). All groups performed similarly in the 0-s delay condition, but hippocampal-lesioned rats performed significantly worse than sham-lesioned, SHR, and WKY rats in the 10-s delay trials. In the 60-s delay condition, hippocampus-lesioned rats once again performed worse than all groups, but SHR also performed worse than sham-lesioned and WKY rats. (c) Average proportion of trials with strings of four or more errors for SHR, WKY, hippocampal lesion, and sham-lesioned rats in each delay condition (no delay, 10 s, and 60 s). No groups made error strings of four or more errors in the no delay condition. In the 10-s delay condition, there was a trend for hippocampal-lesioned rats to make more errors than the other groups. In the 60-s delay condition, SHR and hippocampus-lesioned rats performed similarly, with both SHR and hippocampus-lesioned rats making a higher number of error strings of four or more errors than WKY and sham-lesioned rats.