Journal: bioRxiv
Article Title: UNIQUE DEFICITS IN PLACE CODING ACROSS SUBFIELDS OF THE HIPPOCAMPUS IN A MOUSE MODEL OF TEMPORAL LOBE EPILEPSY
doi: 10.64898/2025.12.17.694941
Figure Lengend Snippet: Experimental timeline and classification of place cells. A, Experimental timeline. At 12 weeks of age, mice were induced with a supra-hippocampal injection (AP: -2.00 mm from bregma, ML: +1.50 mm, DV: -0.8 mm, from dura) of kainic acid. Four weeks later, mice were implanted with an Open Ephys ShuttleDrive and hippocampal recordings were performed. B, Coronal sections through the hippocampus with tetrode tracks from control (black) and KA (pink) mice. The tetrode positions for recordings are indicated with a white circle for hippocampal CA1, CA3, and DG subregions. Scale bar, 870 µm. C, Cumulative distribution functions for peak firing rates in CA1, CA3, and DG of control and KA mice. There was no significant difference in peak firing rate between control and KA mice for CA1 ( z = 0.40, p = 0.69), CA3 ( z = 1.89, p = 0.06), and DG ( z = 0.86, p = 0.39). Putative principal neurons were categorized as active if they had a peak firing rate ≥ 2 Hz. There was a significant difference in the percentage of active versus inactive principal neurons for CA3 (𝝌 2 = 3.87, p ≤ 0.05). There was no significant difference in the percentage of active versus inactive principal neurons for CA1 (𝝌 2 = 0.49, p = 0.48) and DG (𝝌 2 = 0.69, p = 0.40). D, Hippocampal single units recorded from CA1, CA3, and DG organized by spatial information for control and KA mice. Single units were detected using KiloSort and curated in Phy2. Putative principal neurons were distinguished from interneurons using a ≤ 10 Hz average firing rate cutoff. Spatial information was calculated for putative principal neurons and example rate maps are shown, organized from low to high spatial information. Spatial information (black) is indicated to the right of each example map. E, Proportion of place and non-place cells in CA1, CA3, and DG for control (dark/light grey) and KA (dark/light pink) mice. Place cells were distinguished from non-place cells using a shuffling procedure of spatial information. Single units were categorized as place cells if their spatial information was greater than the 95th percentile of the shuffled distribution and the peak rate was ≥ 2 Hz. Percentages of place and non-place cells are represented for each subregion in a pie chart, along with the number of place cells over the total number of cells recorded. There was a significant decrease in the proportion of place cells in CA1 of KA mice compared to controls (𝝌 2 = 12.01, p ≤ 0.001). There was no significant difference in the proportion of place cells between control and KA mice for CA3 (𝝌 2 = 0.20, p = 0.66) and DG (𝝌 2 = 0.13, p = 0.72). Wilcoxon rank sum test and Chi-squared test. Significance denoted with asterisks: ***p ≤ 0.001.
Article Snippet: Kainic acid (KA) (Tocris) was dissolved in saline to provide a solution with a concentration of 20 mM ( , , , ).
Techniques: Injection, Control