The lack of effect of hippocampal lesions on these probe trials is striking given that hippocampal lesions significantly enhanced the initial learning of the task.
The ability to learn initially a reward rule for a T-maze discrimination task (initial learning) was examined in young control (4-month-old), aged control (24-month-old) and YKS-treated aged (24-month-old) rats.
Singer, A.C., Carr, M.F., Karlsson, M.P. & Frank, L.M. Hippocampal SWR activity predicts correct decisions during the initial learning of an alternation task.
Consistent with the findings of the present study Muellbacher et al. [5] found that 4 hours after initial learning of the ballistic task, rTMS did not cause interference.
In this task, an initial learning event on day 1 (context A; 'upstairs') is NMDAR-dependent, while a subsequent learning event the next day (context B; 'downstairs') is NMDAR-independent [5], [6], [7], [8].
Figure 3b shows that after a break of 4 hours between FT training sets there was retention of the learning in Group 4. Contrary to what was observed in Experiment I, where learning of a competing task immediately after initial learning caused interference, no interference was observed for Group 3, in which subjects engaged in AT learning 3 hours and 40 minutes after initial FT practice.
As mice had completed the initial learning phase of the visual discrimination task before commencing rTMS they were accustomed to handling and remained relatively still without restraint.
In humans, the consolidation or stabilization of motor memory (in this case, a finger pattern tapping task) has been demonstrated to occur in the first 6-hours following initial learning: learning a new variation on the motor task after reactivation of the previously learned motor task can block the reconsolidation of memory for the original task [15].
The duration of the intermediate task-free break was about 20 minutes and corresponded to the overall duration of initial learning and the consecutive selective reminding (SR) tasks (see below).
