A signature of attractor dynamics in the CA3 region of the hippocampus.
A signature of attractor dynamics in the CA3 region of the hippocampus.
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DOI：
10.1371/journal.pcbi.1003641
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发表时间：
2014-05
影响因子：
4.3
通讯作者：
Verschure PF
中科院分区：
文献类型：
--
作者：
Rennó-Costa C;Lisman JE;Verschure PF
吸引子网络的概念是关于联想记忆是如何储存和回忆的主要假设。这种神经网络的一个明确的解剖学特征是兴奋性循环连接。即使外部输入不完整（模式完成），这些“吸引”网络的放电模式到存储模式。海马体的CA3区域被认为是这样一个吸引网络；然而，实验证据一直模棱两可，导致CA3不是一个吸引子网络的建议。为了解决这一争议并更好地理解CA3的功能，我们模拟了CA3及其输入结构。在我们的模拟中，我们可以重现关键的实验结果，并建立识别吸引子性质的标准。值得注意的是，在有连续输入的条件下，输出应该被“吸引”到存储模式。然而，与先前的预期相反，当模式逐渐从一种存储模式“变形”到另一种存储模式时，预计输出模式之间不会出现急剧过渡。观察到的CA3的放电模式符合这些标准，并且可以用我们的模型定量地解释。值得注意的是，随着变形的进行，齿状回的活动模式发生了变化；相反，下游CA3网络的活动模式被存储模式所吸引，因此变化很小。我们进一步表明，观察到的放电模式的其他方面可以通过行为测试期间发生的学习来解释。因此，CA3同时显示了一个吸引子网络的学习和回忆特征。这些观察结果，结合现有的解剖学和行为学证据，有力地证明了CA3是基于吸引子动力学构建联想记忆的。一种被称为“吸引子网络”的神经网络被认为是记忆关联的基础。重要的是，当这样一个网络呈现一部分记忆时，网络活动被完整的记忆所吸引。然而，这种吸引子网络很难获得明确的实验证据。事实上，最近专门设计用于观察海马体中这些吸引子动态的“变形”实验并没有获得预期的结果，这导致了对记忆吸引子假说有效性的争议。在此，我们建立了相关海马区域的计算模型，包括其核心解剖和生理特征，并通过大规模计算机模拟详细揭示了海马吸引子网络在变形实验中的生理特性。我们表明，当考虑到实验协议的具体情况时，所获得的实验结果实际上是对吸引子网络的期望。最重要的是，结果直接证明了CA3活性对存储模式的吸引力。我们的结果，连同先前的行为和体外研究，提供了强有力的证据，证明CA3是联想记忆的吸引子网络。
The notion of attractor networks is the leading hypothesis for how associative memories are stored and recalled. A defining anatomical feature of such networks is excitatory recurrent connections. These “attract” the firing pattern of the network to a stored pattern, even when the external input is incomplete (pattern completion). The CA3 region of the hippocampus has been postulated to be such an attractor network; however, the experimental evidence has been ambiguous, leading to the suggestion that CA3 is not an attractor network. In order to resolve this controversy and to better understand how CA3 functions, we simulated CA3 and its input structures. In our simulation, we could reproduce critical experimental results and establish the criteria for identifying attractor properties. Notably, under conditions in which there is continuous input, the output should be “attracted” to a stored pattern. However, contrary to previous expectations, as a pattern is gradually “morphed” from one stored pattern to another, a sharp transition between output patterns is not expected. The observed firing patterns of CA3 meet these criteria and can be quantitatively accounted for by our model. Notably, as morphing proceeds, the activity pattern in the dentate gyrus changes; in contrast, the activity pattern in the downstream CA3 network is attracted to a stored pattern and thus undergoes little change. We furthermore show that other aspects of the observed firing patterns can be explained by learning that occurs during behavioral testing. The CA3 thus displays both the learning and recall signatures of an attractor network. These observations, taken together with existing anatomical and behavioral evidence, make the strong case that CA3 constructs associative memories based on attractor dynamics. A type of neural network called an “attractor network” is thought to underlie memory associations. Importantly, when such a network is presented with part of a memory, the network activity is attracted to the complete memory. However, it has been difficult to obtain clear experimental evidence for such attractor networks. Indeed, recent “morphing” experiments that were specifically designed to observe these attractor dynamics in the hippocampus did not obtain the expected results, leading to a controversy on the validity of the attractor hypothesis of memory. Here, we have built a computational model of the relevant hippocampal areas, including its core anatomical and physiological features, and through the use of large-scale computer simulations reveal in detail the physiological properties expected of the hippocampal attractor network during morphing experiments. We show that the experimental results obtained are actually those to be expected of an attractor network when the specifics of the experimental protocol are taken into account. Most importantly, the results directly demonstrate the attraction of CA3 activity to a stored pattern. Our results, together with previous behavioral and in vitro studies, provide strong evidence that CA3 is an attractor network for associative memory.
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DOI：
10.1523/jneurosci.6044-08.2009
发表时间：
2009-06-10
期刊：
The Journal of neuroscience : the official journal of the Society for Neuroscience
影响因子：
--
作者：
de Almeida L;Idiart M;Lisman JE
通讯作者：
Lisman JE
DOI：
10.1002/jemt.1060120203
发表时间：
1989-06-01
期刊：
JOURNAL OF ELECTRON MICROSCOPY TECHNIQUE
影响因子：
--
作者：
HAMA, K;ARII, T;KOSAKA, T
通讯作者：
KOSAKA, T
影响因子：
25
作者：
Bains, JS;Longacher, JM;Staley, KJ
通讯作者：
Staley, KJ
影响因子：
25
作者：
Henze, DA;Wittner, L;Buzsáki, G
通讯作者：
Buzsáki, G
影响因子：
16.2
作者：
Leutgeb, JK;Leutgeb, S;Moser, EI
通讯作者：
Moser, EI