Hippocampal function and behavior: Spatial discrimination and response inhibition

Discriminative avoidance learning in hippocampal and cortical rats: Acquisition rate, behavioral strategies, and long-term retention

“…The perseveration in maze situations might be explained by the fact that hippocampal animals do not process the information concerning the alternative place and that it is only when they start focusing on the visual cues that they remember from one trial to the next that there is a binary choice. As suggested by Olton, the reliance on exclusively ballistic cues early in the learning session results in perseveration (Olton & Werz, 1978). In our experimental setup, which does nol promote the use of response-produced cues, the HL rats learn faster, because they do not have the initial place cues upon which to fixate and because, for these animals, the most salient cues in the Thompson apparatus are the visual ones.…”

The hippocampus and cue utilization

“…The impairment of braindamaged animals would thus be attributed to their having adopted less efficient response sequence strategies, resulting in greater numbers of tracings (Note 1). If this is so, then hippocampal and normal rats should display different response patterns in solving the task and, in fact, Olton and Werz (1978) HIPPOCAMPUS AND CUE UTILIZATION 283 have provided some evidence that this is, in fact, the case, at least for a 17 -arm version of the maze. Accordingly, we analyzed response patterns by quantifying, for each response, the arm selected as a function of the arm just chosen.…”

“…This possibility is being assessed in an ongoing study in which animals are prevented from using response-produced cues in either pre-or postoperative learning of the maze. Using a procedure similar to that described by Olton and Werz (1978), the animal is restricted to the center of the apparatus for 15 sec after returning from the previously selected arm and before the next response. This is accomplished by lowering a cylinder so as to block access to any of the goal arms.…”

Spatial and temporal response patterns on the eight-arm radial maze

“…Determining the relationship between response stereotypy and response algorithms may be particularly important for subjects given brain lesions [9,14,23] or treated with drugs [15,21,24] for the express purpose of disrupting memory systems. Such manipulations may selectively eliminate one of several strategies available to an intact, untreated animal.…”

“…Such manipulations may selectively eliminate one of several strategies available to an intact, untreated animal. For these subjects, any inference that the manipulation has caused a strange in strategy must be made cautiously [9,14,21]. Several procedures [12,27] allow one to determine whether subjects perform effectively after the use of response algorithms has been eliminated.…”