Considering perinatal human maturation of the cerebral cortex, movement occurs before consciousness. Considering human motor control, consciousness endorses voluntary action. On the arduous road to understanding consciousness and its mechanisms, new and refined experimental paradigms may determine the next avenue. From this perspective, involuntary and voluntary movements can be considered the starting point of consciousness, the consequence of consciousness, or just a tool for approaching it. From the recent consciousness models including neural group selection and the integrated information theories, we highlight some of the experimental considerations that could indicate that movement frames consciousness. On the one hand, it may be a trigger for searching the key features in the environment (e.g., eye-scan path), but on the other hand it may conclude the final reporting of consciousness (e.g., goal vocal or manual-oriented action). The aim of this opinion paper is to encourage a discussion in the framework of the research topic, “Understanding Neural Oscillation in the Human Brain: Consciousness of Movement Execution,” and to promote new scientific interest about the hypothesis that movement is inescapable in understanding consciousness. In the following subsections we underline that oscillatory brain mechanisms integrate movement into the dynamics of the default mode network, the bottom up and top down modulations, the intentional actions in social contexts, the individual selfness and body identity, suggesting that movement may be essential to consciousness and that the oscillations-movement-consciousness triad should be inextricable. Before the emergence of long-range cortical connections that allow consciousness (Varela et al., 2001), the early emergence of spontaneous electrical activity in the brain is based on well-shaped intermittent spontaneous oscillations that produce fetal movements (Khazipov et al., 2004; Khazipov and Milh, 2018). In rat pups, these stochastic motor actions, which are described as “popcorn” movements, generate reafferentation activities via the thalamocortical system, allowing self-organized dynamics in the brain (Buzsaki, 2011). These immature movements allow exploration of the physic world, and finally conduct humans toward self-consciousness, for which body perception and action play an important role in elaborating a sense of self and differentiating between self and others (Keromnes et al., 2018). Recent theories about consciousness (Edelman, 2003; Seth et al., 2006; Edelman et al., 2011; Park and Blanke, 2019) have paved the way for new experimental paradigms. Thirteen features have been proposed (Seth et al., 2006) in order to better characterize the theoretical frame of reference for consciousness. Among these items, the first three established that: (1) fast, irregular, and low-amplitude oscillations (~12–70 Hz) convey consciousness; (2) these oscillatory neuronal activities are organized by the thalamocortical system acting as a “dynamic core” modulated by subcortical influences; and (3) consciousness is dispatched in different cortical areas depending on the conscious content. The other 10 items highlight that the conscious events are unitary, and that only one conscious experience emerges at a time. Accordingly, the theory of neuronal group selection (TNGS) (Edelman, 1987) is advanced as a biological foundation of consciousness. Following the TNGS, Darwinistic selection has ontogenetically shaped neuronal circuits based on positive or negative outcomes on the environment and related feedback. In this context, the reentry process linking numerous brainstem nuclei with the thalamocortical system (Edelman and Gally, 2013) and the recurrent circuit in the cortex that assumes the function of working memory (McCormick, 2001) are crucial for consciousness (Edelman et al., 2011). This implies that consciousness is a dynamic embodied process (Seth et al., 2006) that is closely related not only to voluntary movement production, but also to internal body signals from visceral organs (Park et al., 2018; Park and Blanke, 2019). Electroencephalography (EEG) (Haegens et al., 2010; Braboszcz and Delorme, 2011; Baird et al., 2014; Horschig et al., 2014; Shafto and Pitts, 2015; Koivisto et al., 2016; Ye et al., 2019) and functional magnetic resonance imaging (fMRI) (Kucyi, 2018; Kucyi et al., 2018; Demertzi et al., 2019; Golkowski et al., 2019; Liegeois et al., 2019; Yin et al., 2019) are commonly used to study general attention and consciousness in humans. Although the high temporal resolution of the EEG (timing in milliseconds range) and high spatial resolution of the fMRI (location in millimeters range) are viewed as complementary for understanding neural processes (Brechet et al., 2019; Shen et al., 2019), recent evidence (Itthipuripat et al., 2019) demonstrated that hemodynamic attentional modulations measured in the early sensory cortex are differentially related to evoked EEG potentials, as they are linked more to later than early evoked potentials.
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Sep 23, 2021
Marcella Faria 
Open Access