Spatial Coding in the Subiculum Requires Anterior Thalamic Inputs

Summary Hippocampal function relies on the anterior thalamic nuclei, yet the reasons remain poorly understood. While anterior thalamic lesions disrupt parahippocampal spatial signalling, their impact on the subiculum is unknown, despite the importance of this area for hippocampal networks. We recorded subiculum cells in rats with either permanent ( N -methyl-D-aspartic acid) or reversible (muscimol) anterior thalamic lesions. The diverse spatial signals normally found in the subiculum, including place cells, disappeared following permanent thalamic lesions and showed marked disruption during transient lesions. Meanwhile, permanent anterior thalamic lesions had no discernible impact on CA1 place fields. Thalamic lesions reduced spatial alternation performance (permanently or reversibly) to chance levels, while leaving a non-spatial recognition memory task unaffected. These findings, which help to explain why anterior thalamic damage is so deleterious for spatial memory, cast a new spotlight on the importance of subiculum function, and reveal its dependence on anterior thalamic signalling.