Temporal integration by stochastic recurrent network dynamics with bimodal neurons.
Temporal integration by stochastic recurrent network dynamics with bimodal neurons.
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DOI：
10.1152/jn.01100.2006
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发表时间：
2007-06
影响因子：
2.5
通讯作者：
H. Okamoto;Y. Isomura;M. Takada;T. Fukai
中科院分区：
文献类型：
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作者：
H. Okamoto;Y. Isomura;M. Takada;T. Fukai
各种认知过程都需要外部或内部驱动信息的时间整合。这种计算通常与皮层神经元的分级速率变化有关，这种变化通常出现在前额叶和其他皮层区域的认知任务的延迟期。在这里，我们提出了一个神经网络模型，以产生分级（攀登或下降）的神经元活动。模型神经元通过AMPA受体介导的快速兴奋性突触随机互连，并受到噪声背景兴奋性和抑制性突触输入的影响。在每个神经元中，延长后去极化电位遵循每个尖峰产生。然后，在外部输入的驱动下，单个神经元显示出基线状态和升高的放电状态之间的双峰速率变化，后者由再生后去极化电位维持。当背景输入的方差和经常性突触的均匀权重得到充分调整时，我们发现随机噪声和混响突触输入将这些双峰变化组织成一个序列，该序列表现出分级的种群活动，具有几乎恒定的斜率。为了验证所提出的机制的有效性，我们分析了猴子执行延迟条件Go/No-go辨别任务时前扣带皮层神经元的分级活动。扣带回神经元的延迟期活动表现出双峰活动模式和试验到试验的变异性，这与所提出的模型预测的相似。
Temporal integration of externally or internally driven information is required for a variety of cognitive processes. This computation is generally linked with graded rate changes in cortical neurons, which typically appear during a delay period of cognitive task in the prefrontal and other cortical areas. Here, we present a neural network model to produce graded (climbing or descending) neuronal activity. Model neurons are interconnected randomly by AMPA-receptor-mediated fast excitatory synapses and are subject to noisy background excitatory and inhibitory synaptic inputs. In each neuron, a prolonged afterdepolarizing potential follows every spike generation. Then, driven by an external input, the individual neurons display bimodal rate changes between a baseline state and an elevated firing state, with the latter being sustained by regenerated afterdepolarizing potentials. When the variance of background input and the uniform weight of recurrent synapses are adequately tuned, we show that stochastic noise and reverberating synaptic input organize these bimodal changes into a sequence that exhibits graded population activity with a nearly constant slope. To test the validity of the proposed mechanism, we analyzed the graded activity of anterior cingulate cortex neurons in monkeys performing delayed conditional Go/No-go discrimination tasks. The delay-period activities of cingulate neurons exhibited bimodal activity patterns and trial-to-trial variability that are similar to those predicted by the proposed model.