Following the intertrial interval, the rat was returned to the maze for a 3 min test phase, during which the time spent exploring the displaced and nondisplaced objects was recorded (see Figure 1C).
Following the intertrial interval, the rat was returned to the arena for a 3 min test phase, during which the time spent exploring the familiar and novel objects was recorded.
After 5 days habituation to the boxes, rats received 2 trials (one/day) on each of the four tasks (OR, OP, OC, OPC, OPC, OC, OP, OR), with 3 min sample phases, a 2 min retention interval and a 3 min test phase.
After a 90 min delay, during which mice returned to their home cage, they were reintroduced into the arena for 10 min (test phase) and exposed to two objects, a familiar object and a novel object, placed at the same locations as during the training phase.
This observation phase was followed by a 10-min test phase, for which we introduced an opaque divider in the upper female compartment that prevented the female from looking into the right male compartment when she was sitting on the perch in front of the left male compartment and vice versa (Figure 2A).
Intra-BLA microinjection of different doses of a non-selective muscarinic receptor antagonist, scopolamine (0.5 1 μg/rat, intra-BLA), 5 min before the testing phase dose-dependently induced amnesia.
In experiments 3 and 5, the same doses were administered 15 min before the NOR testing phase and immediately prior to exposure to the locomotor activity boxes respectively.
24 hr after the acquisition phase, each mouse was reintroduced to the test arena for 8 min. During this phase (retention testing phase) the mouse was presented with one copy of the object that it was exposed to during the acquisition phase (familiar object) and one novel object (either silver or black objects, depending on which was presented during the acquisition phase).
The sessions lasted ∼120 min each (including electrode placement, a learning phase, and a testing phase) and were distributed over a 7 day period.
"The next phase is a testing phase," Dr. Howard said.
