Díaz Héctor, Bayones Lucas, Alvarez Manuel, Andrade-Ortega Bernardo, Valero Sebastián, Zainos Antonio, Romo Ranulfo, Rossi-Pool Román
Instituto de Fisiología Celular, Departamento de Neurociencia Cognitiva, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico.
El Colegio Nacional, Mexico City 06020, Mexico.
Proc Natl Acad Sci U S A. 2025 Feb 11;122(6):e2420356122. doi: 10.1073/pnas.2420356122. Epub 2025 Feb 6.
Understanding how time perception adapts to cognitive demands remains a significant challenge. In some contexts, the brain encodes time categorically (as "long" or "short"), while in others, it encodes precise time intervals on a continuous scale. Although the ventral premotor cortex (VPC) is known for its role in complex temporal processes, such as speech, its specific involvement in time estimation remains underexplored. In this study, we investigated how the VPC processes temporal information during a time interval comparison task (TICT) and a time interval categorization task (TCT) in primates. We found a notable heterogeneity in neuronal responses associated with time perception across both tasks. While most neurons responded during time interval presentation, a smaller subset retained this information during the working memory periods. Population-level analysis revealed distinct dynamics between tasks: In the TICT, population activity exhibited a linear and parametric relationship with interval duration, whereas in the TCT, neuronal activity diverged into two distinct dynamics corresponding to the interval categories. During delay periods, these categorical or parametric representations remained consistent within each task context. This contextual shift underscores the VPC's adaptive role in interval estimation and highlights how temporal representations are modulated by cognitive demands.
理解时间感知如何适应认知需求仍然是一项重大挑战。在某些情况下，大脑对时间进行分类编码（如“长”或“短”），而在其他情况下，它在连续尺度上对精确的时间间隔进行编码。尽管腹侧运动前皮层（VPC）因其在复杂时间过程（如言语）中的作用而闻名，但其在时间估计中的具体参与仍未得到充分探索。在本研究中，我们调查了灵长类动物在时间间隔比较任务（TICT）和时间间隔分类任务（TCT）期间VPC如何处理时间信息。我们发现在这两项任务中，与时间感知相关的神经元反应存在显著异质性。虽然大多数神经元在时间间隔呈现期间做出反应，但一小部分神经元在工作记忆期间保留了这些信息。群体水平分析揭示了任务之间的不同动态：在TICT中，群体活动与间隔持续时间呈现线性和参数关系，而在TCT中，神经元活动分为对应于间隔类别的两种不同动态。在延迟期间，这些分类或参数表示在每个任务背景下保持一致。这种背景转变强调了VPC在间隔估计中的适应性作用，并突出了时间表示如何受到认知需求的调节。
