School of Computer and Communication Sciences and School of Life Sciences, Brain Mind Institute, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Institute for Zoology, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany.
PLoS Comput Biol. 2019 Apr 19;15(4):e1006928. doi: 10.1371/journal.pcbi.1006928. eCollection 2019 Apr.
Continuous attractor models of working-memory store continuous-valued information in continuous state-spaces, but are sensitive to noise processes that degrade memory retention. Short-term synaptic plasticity of recurrent synapses has previously been shown to affect continuous attractor systems: short-term facilitation can stabilize memory retention, while short-term depression possibly increases continuous attractor volatility. Here, we present a comprehensive description of the combined effect of both short-term facilitation and depression on noise-induced memory degradation in one-dimensional continuous attractor models. Our theoretical description, applicable to rate models as well as spiking networks close to a stationary state, accurately describes the slow dynamics of stored memory positions as a combination of two processes: (i) diffusion due to variability caused by spikes; and (ii) drift due to random connectivity and neuronal heterogeneity. We find that facilitation decreases both diffusion and directed drifts, while short-term depression tends to increase both. Using mutual information, we evaluate the combined impact of short-term facilitation and depression on the ability of networks to retain stable working memory. Finally, our theory predicts the sensitivity of continuous working memory to distractor inputs and provides conditions for stability of memory.
连续吸引子模型以连续状态空间存储连续值信息，但对记忆保留产生负面影响的噪声过程较为敏感。先前已经表明，神经元的重复突触的短期可塑性会影响连续吸引子系统：短期易化可以稳定记忆保留，而短期抑制可能会增加连续吸引子的不稳定性。在这里，我们全面描述了短期易化和短期抑制对一维连续吸引子模型中噪声诱导的记忆退化的综合影响。我们的理论描述适用于率模型以及接近稳定状态的尖峰网络，可以准确地描述存储记忆位置的缓慢动力学，这是由两个过程组合而成的：（i）由于尖峰引起的可变性导致的扩散；（ii）由于随机连接和神经元异质性引起的漂移。我们发现，易化作用会降低扩散和定向漂移，而短期抑制则往往会增加两者。我们使用互信息来评估短期易化和短期抑制对网络保持稳定工作记忆能力的综合影响。最后，我们的理论预测了连续工作记忆对干扰输入的敏感性，并为记忆的稳定性提供了条件。
