A Unified Mathematical Framework for Coding Time, Space, and Sequences in the Hippocampal Region
A Unified Mathematical Framework for Coding Time, Space, and Sequences in the Hippocampal Region
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DOI：
10.1523/jneurosci.5808-12.2014
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发表时间：
2014-03-26
影响因子：
5.3
通讯作者：
Eichenbaum, Howard
中科院分区：
文献类型：
--
作者：
Howard, Marc W.;MacDonald, Christopher J.;Eichenbaum, Howard
内侧颞叶（MTL）被认为支持情景记忆，即对特定时间特定地点特定事件的生动回忆。有充分的神经生理学证据表明，MTL计算在allocentric空间的位置和最近的证据表明，MTL也编码的时间。空间和时间代表了一个类似的计算挑战;两者都是变量，不能简单地从立即可用的感官信息中计算出来。我们介绍了一个简单的数学框架，计算函数的空间位置和时间的特殊情况下，一个更一般的计算。在这个框架中，经验展开的时间是通过一组泄漏积分编码。这些泄漏积分器编码其输入的拉普拉斯变换。包含在变换中的信息可以使用逆拉普拉斯变换的近似来恢复。在时间域中，所得到的表示重建时间历史。通过对运动进行积分，这些方程给出了到达当前位置所采取的路径的表示。通过用关于非同心速度的信息调制变换，方程编码地标的位置。模拟细胞显示出与所有三种情况下在各个区域中观察到的神经元的密切对应。在时间域中，海马时间细胞的新的二次分析验证了模型的几个定性预测。时空背景的综合表示可以通过这些元素输入的连接来计算，从而与在背侧CA 1中观察到的连接神经表示相对应。
The medial temporal lobe (MTL) is believed to support episodic memory, vivid recollection of a specific event situated in a particular place at a particular time. There is ample neurophysiological evidence that the MTL computes location in allocentric space and more recent evidence that the MTL also codes for time. Space and time represent a similar computational challenge; both are variables that cannot be simply calculated from the immediately available sensory information. We introduce a simple mathematical framework that computes functions of both spatial location and time as special cases of a more general computation. In this framework, experience unfolding in time is encoded via a set of leaky integrators. These leaky integrators encode the Laplace transform of their input. The information contained in the transform can be recovered using an approximation to the inverse Laplace transform. In the temporal domain, the resulting representation reconstructs the temporal history. By integrating movements, the equations give rise to a representation of the path taken to arrive at the present location. By modulating the transform with information about allocentric velocity, the equations code for position of a landmark. Simulated cells show a close correspondence to neurons observed in various regions for all three cases. In the temporal domain, novel secondary analyses of hippocampal time cells verified several qualitative predictions of the model. An integrated representation of spatiotemporal context can be computed by taking conjunctions of these elemental inputs, leading to a correspondence with conjunctive neural representations observed in dorsal CA1.