Department of Psychology, Department of Clinical Neuroscience, Karolinska Institute, Solna, Sweden.
The Picower Institute for Learning and Memory and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Sci Rep. 2022 Sep 5;12(1):15050. doi: 10.1038/s41598-022-18577-y.
Working memories have long been thought to be maintained by persistent spiking. However, mounting evidence from multiple-electrode recording (and single-trial analyses) shows that the underlying spiking is better characterized by intermittent bursts of activity. A counterargument suggested this intermittent activity is at odds with observations that spike-time variability reduces during task performance. However, this counterargument rests on assumptions, such as randomness in the timing of the bursts, which may not be correct. Thus, we analyzed spiking and LFPs from monkeys' prefrontal cortex (PFC) to determine if task-related reductions in variability can co-exist with intermittent spiking. We found that it does because both spiking and associated gamma bursts were task-modulated, not random. In fact, the task-related reduction in spike variability could largely be explained by a related reduction in gamma burst variability. Our results provide further support for the intermittent activity models of working memory as well as novel mechanistic insights into how spike variability is reduced during cognitive tasks.
工作记忆长期以来一直被认为是通过持续的尖峰活动来维持的。然而，来自多电极记录（和单次试验分析）的越来越多的证据表明，潜在的尖峰活动更好地表征为间歇性的活动爆发。一个反论点认为，这种间歇性活动与观察到的在任务执行过程中尖峰时间变异性降低的现象不一致。然而，这个反论点基于一些假设，例如爆发时间的随机性，这些假设可能不正确。因此，我们分析了猴子前额叶皮层（PFC）的尖峰和 LFPs，以确定与任务相关的变异性降低是否可以与间歇性尖峰共存。我们发现，这是可以的，因为尖峰和相关的伽马爆发都是任务调节的，而不是随机的。事实上，尖峰变异性的与任务相关的降低在很大程度上可以用伽马爆发变异性的相关降低来解释。我们的结果为工作记忆的间歇性活动模型提供了进一步的支持，并为在认知任务期间如何降低尖峰变异性提供了新的机制见解。
