GABAergic CA1 neurons are more stable following context changes than glutamatergic cells

Abstract

The CA1 region of the hippocampus contains both glutamatergic pyramidal cells and GABAergic interneurons. Numerous reports have characterized glutamatergic CAMK2A cell activity, showing how these cells respond to environmental changes such as local cue rotation and context re-sizing. Additionally, the long-term stability of spatial encoding and turnover of these cells across days is also well-characterized. In contrast, these classic hippocampal experiments have never been conducted with CA1 GABAergic cells. Here, we use chronic calcium imaging of male and female mice to compare the neural activity of VGAT and CAMK2A cells during exploration of unaltered environments and also during exposure to contexts before and after rotating and changing the length of the context across multiple recording days. Intriguingly, compared to CAMK2A cells, VGAT cells showed decreased remapping induced by environmental changes, such as context rotations and contextual length resizing. However, GABAergic neurons were also less likely than glutamatergic neurons to remain active and exhibit consistent place coding across recording days. Interestingly, despite showing significant spatial remapping across days, GABAergic cells had stable speed encoding between days. Thus, compared to glutamatergic cells, spatial encoding of GABAergic cells is more stable during within-session environmental perturbations, but is less stable across days. These insights may be crucial in accurately modeling the features and constraints of hippocampal dynamics in spatial coding.

Distinct spatial maps and multiple object codes in the lateral entorhinal cortex

“…Here, we demonstrated that spatial FS neurons in LEC and CA1 remapped in different spatial contexts. This further substantiates the notion that FS neurons contribute to feature coding in the networks that they are embedded in 18,43,44,47,62 .…”

The temporal and contextual stability of activity levels in hippocampal CA1 cells

“…To drive GCaMP expression, we used human synapsin I gene promoter, which promotes transgene expression in both excitatory and inhibitory cells. Recent studies have reported that a subset of inhibitory cells in the CA1 show spatial and environmental modulation in activity (Geiller et al, 2020; Schuette et al, 2022). Therefore, it will be of interest and value to study the relationship between gA/gPC indices and subtypes of neurons.…”