The genetic signature of memory encoding along the human hippocampal axis

Episodic memory formation engages hippocampal oscillations that vary along the anterior-posterior axis, but the molecular programs supporting this physiological specialization remain unclear. Here, we leveraged a rare neurosurgical dataset in which patients performed verbal episodic memory tasks during intrahippocampal intracranial EEG recordings prior to en bloc hippocampal resection, enabling integration of encoding-related oscillatory signatures with matched cell-type-resolved transcriptomics from the same individuals. Subsequent memory effects (SMEs) spanned delta/theta, gamma, and hippocampal ripple activity across anterior and posterior hippocampus. Single-nucleus RNA sequencing from anatomically matched anterior and posterior tissue revealed longitudinal transcriptional gradients, most prominent in excitatory neurons. Spatial transcriptomic maps validated axis-enriched transcripts and their localization. Linking subject-specific SMEs to gene expression identified distinct molecular programs: anterior low frequency SMEs associated with synaptic and chromatin-regulatory pathways, and posterior high-frequency SMEs associated with metabolic and protein synthesis processes. Gene regulatory network inference further revealed axis-specific hub architectures. Together, these results define a cell-type-specific genetic architecture linking longitudinal molecular specialization to the human hippocampal encoding dynamics.