Figure 5. DNMT inhibition disrupts hippocampal place field stability in vivo. Top panels.

illustrate data obtained using in vivo multi-electrode recording techniques to quantitate place cell firing patterns, and to evaluate consistency of firing of a single hippocampal (dorsal CA1/CA3) place cell. For illustrative purposes data from a single control animal (and a single place cell) are shown. Pseudo-color images illustrate firing rates (blue = low, red = high). In this experiment the animal was placed sequentially onto a round circular maze, with each session separated by 10 minutes. As shown, there is a strong correlation of place cell firing between session 1 and session 2, when the animal is simply re-placed into the same familiar environment. However, when the same animal is placed into a new different environment (session 3), the place cell shows a different place field firing pattern. The dissimilarities in place cell firing can be quantitated using a Pearson correlation coefficient. The bar graph in the Bottom Panel presents Pearson correlation coefficient data testing the effects of the DNMT inhibitor zebularine on place cell firing pattern consistency in this type of place cell experiment (n=5 Long-Evans rats, p<0.05). Zebularine infusion ICV leads to a significant decrease in Pearson correlation coefficients for animals when they are re-placed into the familiar environment. These data are consistent with the idea that DNMT inhibition leads to a destabilization of place cell firing patterns. For a more complete description of these results please see (Roth et al. 2015).