University of Connecticut, Storrs, CT, United States.
Behav Brain Res. 2012 Jan 1;226(1):56-65. doi: 10.1016/j.bbr.2011.08.039. Epub 2011 Sep 2.
The human hippocampus supports the formation of episodic memory without confusing new memories with old ones. To accomplish this, the brain must disambiguate memories (i.e., accentuate the differences between experiences). There is convergent evidence linking pattern separation to the dentate gyrus. Damage to the dentate gyrus reduces an organism's ability to differentiate between similar objects. The dentate gyrus has tenfold more principle cells than its cortical input, allowing for a divergence in information flow. Dentate gyrus granule neurons also show a very different pattern of representing the environment than "classic" place cells in CA1 and CA3, or grid cells in the entorhinal cortex. More recently immediate early genes have been used to "timestamp" activity of individual cells throughout the dentate gyrus. These data indicate that the dentate gyrus robustly differentiates similar situations. The degree of differentiation is non-linear, with even small changes in input inducing a near maximal response in the dentate. Furthermore this differentiation occurs throughout the dentate gyrus longitudinal (dorsal-ventral) axis. Conversely, the data point to a divergence in information processing between the dentate gyrus suprapyramidal and infrapyramidal blades possibly related to differences in organization within these regions. The accumulated evidence from different approaches converges to support a role for the dentate gyrus in pattern separation. There are however inconsistencies that may require incorporation of neurogenesis and hippocampal microcircuits into the currents models. They also suggest different roles for the dentate gyrus suprapyramidal and infrapyramidal blades, and the responsiveness of CA3 to dentate input.
人类海马体支持情景记忆的形成，而不会将新记忆与旧记忆混淆。为了实现这一点，大脑必须消除记忆的歧义（即，强调经验之间的差异）。有一致的证据表明模式分离与齿状回有关。齿状回的损伤会降低生物体区分相似物体的能力。齿状回的主细胞比其皮质输入多十倍，从而允许信息流的发散。齿状回颗粒神经元在表示环境方面也表现出与 CA1 和 CA3 中的“经典”位置细胞或内嗅皮层中的网格细胞非常不同的模式。最近，早期基因已被用于“标记”整个齿状回中单个细胞的活动。这些数据表明齿状回能够强烈地区分相似的情况。这种分化是非线性的，即使输入的微小变化也会导致齿状回的响应接近最大值。此外，这种分化发生在齿状回的整个纵向（背腹）轴上。相反，这些数据表明齿状回的上、下棘突刀片之间的信息处理存在分歧，这可能与这些区域内的组织差异有关。来自不同方法的累积证据一致支持齿状回在模式分离中的作用。然而，也存在不一致之处，可能需要将神经发生和海马微电路纳入当前模型中。它们还表明齿状回的上、下棘突刀片以及 CA3 对齿状回输入的反应具有不同的作用。
