The ability to associate events that are temporally apart, requires an intact hippocampus. Our current major focus is on the roles of transient receptor potential cation (TRPC) channels in temporal association memory. TRPC channels are abundant in hippocampal principal cells (Fig. 1A). We have recently shown that TRPC channels modulate dynamical properties of hippocampal pyramidal cells known as persistent firing (Fig. 1B). Computational simulations have indicated that TRPC channels play crucial roles in shaping neural network activity, allowing persistent firing to co-exist with the theta oscillations. We plan to further our understandings of the contributions of TRPC channels on behavioral levels using TRPC channel manipulations in vivo.

Grid cells in the medial entorhinal cortex (MEC) are believed to support spatial navigation. It has been proposed that grid cell firing emerges through path integration, which is the ability to update spatial representation by using idiothetic cues. MEC layer II has mainly two different types of cells: pyramidal and stellate cells. However, the cellular mechanisms supporting path integration and grid cell formation remain unknown. Oscillatory properties of MEC layer II neurons and persistent firing may support path integration (Fig. 2). We have recently shown that properties of MEC layer II neurons such as the spike adaptation ratio are different along the dorso-ventral axis, indicating these cellular properties may underlie differences in grid cell spacing.