Figure 6.

Rearrangement of object-place configuration in controls and second exposure in test animals facilitates LTD. Roughly 1 week after attempting to induce learning-facilitated LTD in vehicle- or MPEP-treated animals, treatment with sub-LFS (1Hz, 600 pulses) was repeated in the presence of the now familiar object-place configuration (3 control and 3 test: see Fig. 4 for experimental schema). No drug treatment was given. Under these conditions, animals that were previously treated with vehicle did not express LTD (3 control; n = 9), whereas animals that had been treated with MPEP (1.8 μg) before novel exposure to the object-place configuration now expressed robust LTD (3 test; n = 7). On next exposure, control animals responded to a rearranged object-place configuration with LTD facilitation (4 control; n = 8). Test group animals were presented with the same configuration once more and did not express LTD (4 test; n = 7). Analog traces show the field potentials preinjection, 5 min, 4 h, and 24 h following sub-LFS. Vertical scale bar corresponds to 3 mV, and horizontal bar corresponds to 3 ms.