Invariant timescale hierarchy across the cortical somatosensory network

Abstract

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.

Intrinsic timescales as an organizational principle of neural processing across the whole rhesus macaque brain

“…Additional studies have replicated and extended the INT hierarchy, reinforcing the idea that brain regions exhibit unique timescales in their intrinsic activity, which reflect functional specialization in terms of temporal integration (Cavanagh, Wallis, Kennerley, & Hunt, 2016;Cirillo, Fascianelli, Ferrucci, & Genovesio, 2018;Fascianelli, Tsujimoto, Marcos, & Genovesio, 2019;Murray et al, 2014;Ogawa & Komatsu, 2010;Rossi-Pool et al, 2021, Maisson et al, 2021. The concept of INT hierarchy has even been extended to subcortical regions-specifically the basal ganglia (Nougaret, Fascianelli, Ravel, & Genovesio, 2021).…”

Interacting cortical gradients of neural timescales and functional connectivity and their relationship to perceptual behavior

“…This architecture may help the brain achieve abstract and conceptual representations seen in more anterior VTC neural populations (32,34,35). While the present study examined these effects in visual processing, it is likely that similar principles apply to other hierarchically organized sensory and cognitive systems (2,12,14,50). Indeed, gradients in physiological, and thus functional, organization are likely in part conferred by corresponding gradients in growth factors and, in turn, gene expression during and persisting after cortical development (2,7,40,41).…”

“…This architecture may help the brain achieve abstract and conceptual representations seen in more anterior VTC neural populations (32, 34, 35). While the present study examined these effects in visual processing, it is likely that similar principles apply to other hierarchically organized sensory and cognitive systems (2, 12, 14, 50).…”

“…There is no single principle or process that governs a neural population’s timescales, e.g. timescales are not a static and inherent property of a neural population (10, 50). Rather, these results suggest that different kinds of timescales are governed by different combinations of factors that can depend on cognitive and neural context.…”

Intrinsic timescales as an organizational principle of neural processing across the whole rhesus macaque brain

“…Additional studies have replicated and extended the INT hierarchy, reinforcing the idea that brain regions exhibit unique timescales in their intrinsic activity, which reflect functional specialization in terms of temporal integration (Cavanagh, Wallis, Kennerley, & Hunt, 2016; Cirillo, Fascianelli, Ferrucci, & Genovesio, 2018; Fascianelli, Tsujimoto, Marcos, & Genovesio, 2019; Murray et al, 2014; Ogawa & Komatsu, 2010; Rossi-Pool et al, 2021, Maisson et al, 2021). The concept of INT hierarchy has even been extended to subcortical regions—specifically the basal ganglia (Nougaret, Fascianelli, Ravel, & Genovesio, 2021).…”