The brain and its time: intrinsic neural timescales are key for input processing

Abstract

We process and integrate multiple timescales into one meaningful whole. Recent evidence suggests that the brain displays a complex multiscale temporal organization. Different regions exhibit different timescales as described by the concept of intrinsic neural timescales (INT); however, their function and neural mechanisms remains unclear. We review recent literature on INT and propose that they are key for input processing. Specifically, they are shared across different species, i.e., input sharing. This suggests a role of INT in encoding inputs through matching the inputs’ stochastics with the ongoing temporal statistics of the brain’s neural activity, i.e., input encoding. Following simulation and empirical data, we point out input integration versus segregation and input sampling as key temporal mechanisms of input processing. This deeply grounds the brain within its environmental and evolutionary context. It carries major implications in understanding mental features and psychiatric disorders, as well as going beyond the brain in integrating timescales into artificial intelligence.

From Shorter to Longer Timescales: Converging Integrated Information Theory (IIT) with the Temporo-Spatial Theory of Consciousness (TTC)

“…Recent studies provide a possible answer to the role of intrinsic neural timescales in inferring future inputs; with an empirical prior and prediction error, based on the temporo-spatial carry-over and continuation of ongoing activity within the post-stimulus interval, the task states during which the respective content is consciously experienced [ 39 , 40 ]. In this regard, the prediction error is the difference between the ongoing (from pre-stimulus to stimulus period) relevant timescale in the primary sensory area (e.g., a short timescale) to the related timescale of the input at a discrete point in time (e.g., a musical note).…”

“…Finally, and third, there is the integration of phenomenal contents with the ongoing consciousness itself in a time range greater than 3 s, i.e., the stream of consciousness. Following James’ account of consciousness, who distinguishes the very contents of the experience (the ‘substantive parts’) from the transitional periods that provide the temporal link between the contents (the ‘transitive parts’) [ 15 , 33 , 35 ], the stream of consciousness is conceived here neither as additional content of consciousness nor simply as the frame-by-frame sequence of short-duration contents [ 26 , 27 , 36 ] but rather as activity that gives duration, continuity, coherence, and unity of the experience [ 13 , 14 , 15 , 37 , 38 , 39 , 40 , 41 ]. In this regard, it can be assumed that various timescales of integration in turn integrate and select extended chunks of experience into even longer units of experiences, in which functions such as working memory, attention, and autobiographical self support a balance between continuity of experience and change.…”

“…The entire temporal range from a few milliseconds to 100 s is methodologically explorable by estimating the duration and characteristics of the intrinsic neural timescales (with fMRI, e.g., 0.01–0.1 Hz and EEG, e.g., 0.5–100 Hz). Recently, dynamical measurements such as the Power-law Exponent and Autocorrelation Window, which can span shorter and longer timescale intervals (even up to 100 s), have shown a repertoire of scale-free dynamics associated with various features of consciousness, e.g., wakefulness, self-consciousness, perception, input integration, and segregation [ 38 , 39 , 40 , 41 ]. The stream of consciousness could therefore not be linked to a specific duration but could extend over different and overlapping timescales, depending on the experiential context and the different features of consciousness involved, rather than bound only to the onset of a paradigmatic stimulus or content of consciousness.…”

The Self and Its Right Insula—Differential Topography and Dynamic of Right vs. Left Insula

“…INT are key in the temporal integration and segregation of inputs at different points in time [22][23][24]. The longer the time windows of the neural activity of a region, the more inputs at different even distant points in time can be lumped and pooled together under the umbrella of one temporal window and subsequently elicit one (rather than multiple) neural activity change, i.e., task-related activity [57].…”

“…That was investigated in an EEG data set applying resting state and a morphed self-face task. We focused specifically on the Intrinsic Neural Timescales (INT; also called temporal receptive window; TRW [19]) defined as the duration of the brain to integrate information [20] and is known to mediate input processing and, more specifically temporal integration or segregation of different inputs [21][22][23]. The longer the time windows of the neural activity of a region, the more inputs at multiple distant points in time can be summed and pooled together under the umbrella of one temporal window and subsequently elicit one (rather than multiple) neural activity change, i.e., task-related activity [24].…”