Systemic Injection of Kainic Acid Differently Affects LTP Magnitude Depending on its Epileptogenic Efficiency
(A) Animals were tested in five sessions (3 min each) separated by 5 min interval and grouped in three different phases: familiarization, spatial change and novel object recognition. During the familiarization phase (two trials) five objects were simultaneously placed in the open field. In the spatial change phase (two trials) two objects were displaced (arrows). In the novel object recognition phase (1 trial), a new object was substituted for the upper-left object (arrow). (B) Discrimination ratios for the spatial change tasks for Wistar (W) and Sprague-Dawley (SD) rats. * P<0.05 for pair-wise comparisons between groups; ## P<0.01; ### P<0.001 for comparisons with chance level. Note poor performance of epileptic rats in Sprague-Dawley (n = 12) but not in Wistar animals (n = 13). The control grop is composed of n = 11 Wistar and n = 12 Spague-Dawley rats. Resistant rats are n = 4 Wistar and n = 5 Spraque-Dawley. (C) Discrimination ratios for the novel object recognition. Note that deficits specifically affect hippocampal-dependent spatial memory and not recognition memory. (D) Positive correlation between LTP magnitude and discrimination ratios in the spatial memory task (r2 = 0.14, P = 0.017). (E) No correlation was found between LTP magnitude and discrimination ratios in the novel object recognition task.