We propose that a major contribution of juvenile and adult hippocampal neurogenesis is to allow behavioral experience to sculpt dentate gyrus connectivity such that sensory attributes that are relevant to the animal’s environment are more strongly represented. This “specialized” dentate is then able to store a larger number of discriminable memory representations. Our hypothesis builds on accumulating evidence that neurogenesis declines to low levels prior to adulthood in many species. Rather than being necessary for ongoing hippocampal function, as several current theories posit, we argue that neurogenesis has primarily a prospective function, in that it allows experience to shape hippocampal circuits and optimize them for future learning in the particular environment in which the animal lives. Using an anatomically-based simulation of the hippocampus (BACON), we demonstrate that environmental sculpting of this kind would reduce overlap among hippocampal memory representations and provide representation cells with more information about an animal's current situation; consequently, it would allow more memories to be stored and accurately recalled without significant interference. We describe several new, testable predictions generated by the sculpting hypothesis and evaluate the hypothesis with respect to existing evidence. We argue that the sculpting hypothesis provides a strong rationale for why juvenile and adult neurogenesis occurs specifically in the dentate gyrus and why it declines significantly prior to adulthood.

我们提出，少年和成年海马神经发生的一个主要贡献是允许行为经验来塑造齿状回的连接性，从而更强烈地代表与动物环境相关的感觉属性。然后，这个“专门的”齿状体能够存储大量可区分的记忆表示。我们的假设建立在越来越多的证据之上，即许多物种的神经发生在成年前下降到低水平。正如一些当前的理论所假设的那样，我们认为神经发生主要具有前瞻性，而不是持续的海马功能所必需的功能，因为它允许经验塑造海马回路并优化它们以供将来在动物生活的特定环境中学习。使用基于解剖学的海马体模拟 (BACON)，我们证明了这种环境雕刻将减少海马记忆表征之间的重叠，并为表征细胞提供有关动物当前状况的更多信息；因此，它将允许存储和准确调用更多的记忆，而不会受到重大干扰。我们描述了由雕刻假设产生的几个新的、可测试的预测，并根据现有证据评估假设。