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

Abstract

Time is a key element of consciousness as it includes multiple timescales from shorter to longer ones. This is reflected in our experience of various short-term phenomenal contents at discrete points in time as part of an ongoing, more continuous, and long-term ‘stream of consciousness.’ Can Integrated Information Theory (IIT) account for this multitude of timescales of consciousness? According to the theory, the relevant spatiotemporal scale for consciousness is the one in which the system reaches the maximum cause-effect power; IIT currently predicts that experience occurs on the order of short timescales, namely, between 100 and 300 ms (theta and alpha frequency range). This can well account for the integration of single inputs into a particular phenomenal content. However, such short timescales leave open the temporal relation of specific phenomenal contents to others during the course of the ongoing time, that is, the stream of consciousness. For that purpose, we converge the IIT with the Temporo-spatial Theory of Consciousness (TTC), which, assuming a multitude of different timescales, can take into view the temporal integration of specific phenomenal contents with other phenomenal contents over time. On the neuronal side, this is detailed by considering those neuronal mechanisms driving the non-additive interaction of pre-stimulus activity with the input resulting in stimulus-related activity. Due to their non-additive interaction, the single input is not only integrated with others in the short-term timescales of 100–300 ms (alpha and theta frequencies) (as predicted by IIT) but, at the same time, also virtually expanded in its temporal (and spatial) features; this is related to the longer timescales (delta and slower frequencies) that are carried over from pre-stimulus to stimulus-related activity. Such a non-additive pre-stimulus-input interaction amounts to temporo-spatial expansion as a key mechanism of TTC for the constitution of phenomenal contents including their embedding or nesting within the ongoing temporal dynamic, i.e., the stream of consciousness. In conclusion, we propose converging the short-term integration of inputs postulated in IIT (100–300 ms as in the alpha and theta frequency range) with the longer timescales (in delta and slower frequencies) of temporo-spatial expansion in TTC.

Non-Separability of Physical Systems as a Foundation of Consciousness

“…These considerations are consistent with the IIT’s view on the causal emergence of a conscious complex relying on macroscopic components of the system rather than its microscopic constituents [ 69 , 70 ]. They are also congruent with the idea that brains organize spatio-temporal nestedness that supports consciousness, which is a central concept in the Temporo-spatial theory of consciousness [ 17 , 35 , 71 ].…”

Beyond noise to function: reframing the global brain activity and its dynamic topography

“…sleep or anesthesia 41,49,60,61 , or a temporary alteration of the vigilance/alertness level 59 . Quantitatively, the level of arousal can be measured by clinical scales 60,62 , behavioral index (e.g., pupillometry) 49 , EEG spectrum (e.g., alpha power, alpha/theta ratio or sequential spectral transitions, SST) 41,49,59,63 or fMRI arousal spatiotemporal markers 41,59,[64][65][66] .…”

Highly connected and highly variable: A Core brain network during resting state supports Propofol‐induced unconsciousness

“…Notably, our proposed analytic framework, leveraging graph‐theoretical tools to locate the NCC architecture, highlights the importance of characterizing the spatio‐temporal features of the brain in understanding consciousness, which seems to fit well with the TTC theory. The TTC proposes that the key to consciousness lies in the topography and temporal dynamics of brain activity (Northoff & Huang, 2017 ; Northoff & Lamme, 2020 ; Northoff & Zilio, 2022a , 2022b ). Especially, the TTC postulates four different neuronal mechanisms accounting for the different dimensions of consciousness, of which the “temporo‐spatial nestedness” of the spontaneous activity accounting for the level/state of consciousness may be particularly relevant to our results obtained using resting‐state data.…”