CA1alueen

The CA1 area, or CA1 region, is a subdivision of the hippocampus proper, forming part of the Cornu Ammonis. It lies between CA2/CA3 and the subiculum and is a core component of the hippocampal circuitry involved in memory processing.

Histologically, CA1 is dominated by pyramidal neurons whose cell bodies reside in the stratum pyramidale, with apical dendrites extending into the stratum radiatum and distal tufts in the stratum lacunosum-moleculare. The main inputs come from CA3 via the Schaffer collateral pathway and directly from the entorhinal cortex layer III through the temporoammonic pathway. The major output projections travel to the subiculum and back toward the entorhinal cortex, forming a key relay within the hippocampal formation.

Functionally, CA1 integrates information from its inputs and contributes to the encoding and retrieval of episodic and spatial memories. The region contains place cells and participates in temporal coding, including theta phase relationships during navigation and learning. Synaptic plasticity in CA1, notably NMDA receptor–dependent long-term potentiation, is a prominent substrate studied in memory formation.

Clinically, CA1 is particularly vulnerable to ischemic and hypoxic injury and is often affected early in neurodegenerative disorders such as Alzheimer's disease. Changes in CA1 circuitry are associated with memory impairment and cognitive decline, and the region is frequently examined in studies of epilepsy and hippocampal function.

The name CA1 derives from Cornu Ammonis, the historical term for the hippocampal subfields.