Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico;
Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico.
Proc Natl Acad Sci U S A. 2021 Jan 19;118(3). doi: 10.1073/pnas.2021843118.
The ability of cortical networks to integrate information from different sources is essential for cognitive processes. On one hand, sensory areas exhibit fast dynamics often phase-locked to stimulation; on the other hand, frontal lobe areas with slow response latencies to stimuli must integrate and maintain information for longer periods. Thus, cortical areas may require different timescales depending on their functional role. Studying the cortical somatosensory network while monkeys discriminated between two vibrotactile stimulus patterns, we found that a hierarchical order could be established across cortical areas based on their intrinsic timescales. Further, even though subareas (areas 3b, 1, and 2) of the primary somatosensory (S1) cortex exhibit analogous firing rate responses, a clear differentiation was observed in their timescales. Importantly, we observed that this inherent timescale hierarchy was invariant between task contexts (demanding vs. nondemanding). Even if task context severely affected neural coding in cortical areas downstream to S1, their timescales remained unaffected. Moreover, we found that these time constants were invariant across neurons with different latencies or coding. Although neurons had completely different dynamics, they all exhibited comparable timescales within each cortical area. Our results suggest that this measure is demonstrative of an inherent characteristic of each cortical area, is not a dynamical feature of individual neurons, and does not depend on task demands.
皮质网络整合来自不同来源信息的能力对于认知过程至关重要。一方面，感觉区域表现出快速的动力学，通常与刺激锁相；另一方面，对刺激有较慢反应潜伏期的额叶区域必须整合和维持更长时间的信息。因此，皮质区域可能需要根据其功能作用而具有不同的时间尺度。在猴子区分两种振动触觉刺激模式时，我们研究了皮质躯体感觉网络，发现可以根据其内在时间尺度在皮质区域之间建立一个层次顺序。此外，尽管初级躯体感觉（S1）皮质的子区域（区域 3b、1 和 2）表现出类似的放电率反应，但在其时间尺度上观察到明显的分化。重要的是，我们观察到这种固有时间尺度层次结构在任务环境（要求和非要求）之间是不变的。即使任务环境严重影响 S1 下游皮质区域的神经编码，其时间尺度仍然不受影响。此外，我们发现这些时间常数在具有不同潜伏期或编码的神经元之间是不变的。尽管神经元具有完全不同的动力学，但它们在每个皮质区域内都表现出可比的时间尺度。我们的结果表明，该度量值是每个皮质区域固有特征的表现，不是单个神经元的动力学特征，也不依赖于任务需求。
