Short-term memory trace in rapidly adapting synapses of inferior temporal cortex.
Short-term memory trace in rapidly adapting synapses of inferior temporal cortex.
复制标题
下颞叶皮层快速适应突触的短期记忆痕迹。
DOI：
10.1371/journal.pcbi.1000073
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发表时间：
2008-05-16
影响因子：
4.3
通讯作者：
Richmond BJ
中科院分区：
文献类型：
--
作者：
Sugase-Miyamoto Y;Liu Z;Wiener MC;Optican LM;Richmond BJ
视觉短期记忆任务依赖于下颞叶皮质(ITC)和前额叶皮质(PFC)。在显示第一个(样本)刺激后，一些神经元的活动持续存在。这种延迟期活动被认为是工作记忆的一种重要机制。在ITC神经元中，干预(非匹配)刺激消除了延迟期活动；因此，ITC在记忆中的作用必须依赖于不同的机制。在这里，我们通过对比ITC两个不同结构部分的记忆效应来寻找一种可能的机制：TE区和虹膜周围皮质。我们发现猕猴ITCs的TE区有很大比例(80%)的刺激选择神经元在刺激间隔期间表现出记忆效应。在顺序延迟匹配到样本任务(DMS)中，神经元对测试图像的反应中的噪声与神经元对样本图像的反应中的噪声相关。而周边皮质的神经元则没有表现出这种相关性。这些结果让我们假设，TE区通过充当匹配过滤器来促进短期记忆。当样本图像出现时，每个TE神经元通过快速调整其突触权重以匹配其单独输入的强度来捕获其输入的静态副本。来自后续图像的输入信号被乘以这些突触权重，从而计算出过去和现在输入之间的相关性的度量。TE区的总活跃度足以量化两幅图像之间的相似性。这种匹配过滤器理论解释了记忆什么、轨迹存储在哪里以及如何跨时间进行比较，所有这些都不需要延迟期活动。对匹配过滤器模型的模拟与实验结果相吻合，表明TE区神经元在短期视觉记忆过程中存储了突触记忆痕迹。要知道一个人是否在看几秒钟前看到的物体，取决于视觉短期记忆。为了研究短期记忆，我们记录了猴子大脑的两个区域--TE和颞叶周围皮质--的单个神经元活动，这两个区域在视觉模式识别和记忆中起着重要作用。这些猴子完成了一项短期的视觉记忆任务，也就是顺序的样本匹配。当样本刺激在短序列刺激中重新出现时，猴子必须发出信号。仅在TE区，当匹配刺激重新出现时，样本诱导反应发生的小波动与反应相关，就好像样本诱导反应的快照被存储和回忆一样。在我们的模型中，我们假设每个TE神经元通过将对样本的反应存储在局部和快速适应突触来存储和比较短期记忆期间的信号。随后由刺激引起的响应被自动乘以本地存储的信号。在这里，我们证明了当TE神经元群体的输出之和超过阈值时，可以检测到匹配。相关的波动将是这种局部记忆存储的标志，无论它发生在大脑中的任何地方。
Visual short-term memory tasks depend upon both the inferior temporal cortex (ITC) and the prefrontal cortex (PFC). Activity in some neurons persists after the first (sample) stimulus is shown. This delay-period activity has been proposed as an important mechanism for working memory. In ITC neurons, intervening (nonmatching) stimuli wipe out the delay-period activity; hence, the role of ITC in memory must depend upon a different mechanism. Here, we look for a possible mechanism by contrasting memory effects in two architectonically different parts of ITC: area TE and the perirhinal cortex. We found that a large proportion (80%) of stimulus-selective neurons in area TE of macaque ITCs exhibit a memory effect during the stimulus interval. During a sequential delayed matching-to-sample task (DMS), the noise in the neuronal response to the test image was correlated with the noise in the neuronal response to the sample image. Neurons in perirhinal cortex did not show this correlation. These results led us to hypothesize that area TE contributes to short-term memory by acting as a matched filter. When the sample image appears, each TE neuron captures a static copy of its inputs by rapidly adjusting its synaptic weights to match the strength of their individual inputs. Input signals from subsequent images are multiplied by those synaptic weights, thereby computing a measure of the correlation between the past and present inputs. The total activity in area TE is sufficient to quantify the similarity between the two images. This matched filter theory provides an explanation of what is remembered, where the trace is stored, and how comparison is done across time, all without requiring delay period activity. Simulations of a matched filter model match the experimental results, suggesting that area TE neurons store a synaptic memory trace during short-term visual memory. To know whether one is looking at an object seen a few seconds ago or not depends on visual short-term memory. To study short-term memory, we recorded single neuronal activity from two brain areas of monkeys, the TE and the perirhinal cortex of the temporal lobe, known to be important in visual pattern recognition and memory. The monkeys performed a short-term visual memory task, a sequential match-to-sample. The monkeys had to signal when a sample stimulus reappeared in a short sequence of stimuli. In area TE only, small fluctuations occurring for a sample-elicited response were correlated with the responses when a match stimulus reappeared, as if a snapshot of the sample-induced response was stored and recalled. In our modeling, we propose that each TE neuron stores and compares the signals during short-term memory by storing the response to the sample in local and rapidly adapting synapses. Subsequent stimulus-elicited responses are then automatically multiplied by the locally stored signal. Here, we show that the match can be detected when the sum of the outputs of the population of TE neurons crosses a threshold. Correlated fluctuations will be a signature this type of local memory storage wherever it occurs in the brain.
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影响因子：
56.9
作者：
FUSTER, JM;ALEXANDER, GE
通讯作者：
ALEXANDER, GE
影响因子：
1.2
作者：
Brunel, N;Wang, XJ
通讯作者：
Wang, XJ
影响因子：
2.9
作者：
FUSTER, JM;BAUER, RH;JERVEY, JP
通讯作者：
JERVEY, JP
影响因子：
2.9
作者：
FUSTER, JM;ALEXANDER, GE
通讯作者：
ALEXANDER, GE
DOI：
10.1073/pnas.93.2.739
发表时间：
1996-01-23
影响因子：
11.1
作者：
Higuchi, S;Miyashita, Y
通讯作者：
Miyashita, Y