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arXiv 1310.3754q-bio.NC
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重复皮层兴奋异质性对工作记忆的优化作用

Optimizing working memory with heterogeneity of recurrent cortical excitation

Zachary P. Kilpatrick, Bard Ermentrout, Brent Doiron

摘要:

参数工作记忆的神经相关性是神经元放电率的刺激特异性升高,其在刺激去除后持续很长时间。具有局部兴奋和广泛抑制的网络模型支持持久的神经活动,将网络结构和参数化工作记忆联系起来。皮层神经元接收噪声输入波动,这导致持续的活动在网络中扩散,随着时间的推移降低记忆。我们探讨了支持参数化工作记忆的皮层结构如何影响持久性神经活动的扩散。通过研究尖峰网络和简化的势阱模型,我们发现空间异质性兴奋性耦合稳定了离散数量的持续状态,减少了持续活动在网络上的扩散。然而,异质耦合也粗粒刺激表征空间,限制了参数工作记忆的容量。由于粗粒化和扩散的折衷,使初始和回忆的刺激之间的信息传递是优化在一个固定的网络异质性的存储错误。对于足够长的延迟时间,吸引子的最佳数量小于可能的刺激的数量,这表明记忆网络可以低估刺激空间以优化性能。我们的研究结果清楚地表明了网络结构和随机波动对参数记忆存储的影响。

英文摘要:

A neural correlate of parametric working memory is a stimulus specific rise in neuron firing rate that persists long after the stimulus is removed. Network models with local excitation and broad inhibition support persistent neural activity, linking network architecture and parametric working memory. Cortical neurons receive noisy input fluctuations which causes persistent activity to diffusively wander about the network, degrading memory over time. We explore how cortical architecture that supports parametric working memory affects the diffusion of persistent neural activity. Studying both a spiking network and a simplified potential well model, we show that spatially heterogeneous excitatory coupling stabilizes a discrete number of persistent states, reducing the diffusion of persistent activity over the network. However, heterogeneous coupling also coarse-grains the stimulus representation space, limiting the capacity of parametric working memory. The storage errors due to coarse-graining and diffusion tradeoff so that information transfer between the initial and recalled stimulus is optimized at a fixed network heterogeneity. For sufficiently long delay times, the optimal number of attractors is less than the number of possible stimuli, suggesting that memory networks can under-represent stimulus space to optimize performance. Our results clearly demonstrate the effects of network architecture and stochastic fluctuations on parametric memory storage.

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