Cognitive and sensorimotor processes are based on the activation of highly distributed networks in the brain involving numerous interacting modules and brain regions. It is widely assumed that neuronal network interaction, at multiple spatiotemporal scales, is one of the crucial determinants of cognition and behavior, and that it is the ability for flexible configuration of functional coupling that underlies the information processing capabilities of the brain and the complexity of its dynamics.
Indeed, functional coupling is a hallmark of brain networks, and there is a wealth of studies that have observed a relation between functional connectivity patterns and cognition or sensorimotor processing. However, despite the advances they have provided, the vast majority of studies available on this topic are still correlative in nature, revealing only associations between dynamic neural coupling and network functions.
The vast majority of functional connectivity patterns observed in the brain are intrinsically generated, i.e. they are not imposed by entrainment to external stimuli but emerge from network connectivity and brain-internal factors. We term these patterns intrinsic coupling modes (ICMs). ICMs can be studied with a broad variety of methods, ranging from single-cell and local field potential (LFP) recordings to electroencephalography (EEG) and magnetoencephalography (MEG).
ICMs occur on a broad range of spatial and temporal scales, involving two distinct types of dynamics. One type of ICMs involves oscillatory signals with band-limited dynamics, can be quantified by measures of phase coupling and typically occurs at frequencies between about 1 Hz and 150 Hz. The second type of ICMs corresponds to coupled fluctuations on slower time scales and can be uncovered by correlation of signal envelopes. We designate these as phase ICMs and envelope ICMs, respectively.
The cICMs project aims to obtain causal evidence on the functional roles of ICMs. We use multi-site interventions to manipulate phase and envelope coupling and test the impact on stimulus processing and behavior. We investigate ICMs during tasks in order to test differences between both types of ICMs regarding their relation to cognitive processing. Furthermore, we aim to unravel potential interactions between phase and envelope ICMs. Importantly, we aim to develop a coherent framework for multiscale coupling dynamics. Modeling and information-theoretic analyses of the experimental data serve to integrate the results across scales and species and, thus, to derive a unified framework for multiscale coupling dynamics.
The central hypothesis of this project is that both types of ICMs have causal relevance for cognitive processing and behavior. Phase ICMs have been proposed to enable communication between neuronal populations in a spatiotemporally precise manner and to serve for flexible routing of signals. Envelope ICMs, in contrast, may couple excitability fluctuations between neuronal populations and, thus, regulate their recruitment into the same cognitive process or task. What is currently lacking is a research program that puts these different coupling modes in a unifying perspective. The overarching goal of this project is to provide such an integrated view.
