Abstracts

Rationale: Place representation in the hippocampus is disrupted in animal models of TLE. Much of the research on the hippocampus in epilepsy has focused on CA1, and little is known about how the function of upstream regions such as CA3 and DG may be altered in epilepsy.

Methods: We performed high density single-unit recordings from all subregions in epileptic and saline control mice. Mice were trained to forage in a familiar environment while tetrodes were slowly advanced towards all subregions. Once tetrodes reached their target, we recorded hippocampal neural activity while mice explored both familiar and novel environments (N = 9, 4 control, 5 epileptic).

Results: In control mice, we observe a trend toward spatial remapping of CA3 fields between a familiar and novel environment (p = 0.058), which was accompanied by a rate change (p = 0.0571). In epileptic mice, we also observed remapping of CA3 place fields (p = 0.0280), however, we observed no rate change, indicating impaired rate mapping in new environments (n.s., p = 0.421). The rate change in control mice was significantly larger than in mice with epilepsy (p = 0.032).

Conclusions: Current analyses are underway to assess additional features of spatial coding, such as spatial information and field size, as well as place field development and stabilization with experience in novel environments. By better understanding CA3 dynamics and how they change with epilepsy we can gain insight into impaired memory processing in epilepsy.


Funding: NIH R01 (R01FG25962) to Dr. Laura A. Ewell
NIH T32 Epilepsy Research Grant to Dr. Brittney L. Boublil