Gait characterization in rare bone diseases in a real-world environment - A comparative controlled study.

BACKGROUND: Rare bone diseases (RBD) cause physical and sensory disability that affects quality of life. Mobility challenges are common for people with RBDs, and travelling to gait analysis labs can be very complex. Smartphone sensors could provide remote monitoring. RESEARCH QUESTION: This study aimed to search for and identify variables that can be used to discriminate between people with RBD and healthy people by using built-in smartphone sensors in a real-world setting. METHODS: In total, 18 participants (healthy: n=9; RBD: n=9), controlled by age and sex, were included in this cross-sectional study. A freely available App (Phyphox) was used to gather data from built-in smartphone sensors (accelerometer & gyroscope) at 60 Hz during a 15-min walk on a level surface without turns or stops. Temporal gait parameters like cadence, mean stride time and, coefficient variance (CoVSt) and nonlinear analyses, as the largest Lyapunov exponent (LLE) & sample entropy (SE) in the three accelerometer axes were used to distinguish between the groups and describe gait patterns. RESULTS: The LLE (p=0.04) and the SE of the z-axis (p=0.01), which are correlated with balance control during walking and regularity of the gait, are sufficiently sensitive to distinguish between RBD and controls. SIGNIFICANCE: The use of smartphone sensors to monitor gait in people with RBD allows for the identification of subtle changes in gait patterns, which can be used to inform assessment and management strategies in larger cohorts.

When seeing is not believing: A mechanistic basis for predictive divergence.

Visual illusions provide a compelling case for the idea that perception and belief may remain incongruent. This can be explained by modular theories of mind, but it is not straightforwardly accommodated by the Predictive Processing framework, which takes perceptual and cognitive predictions to derive from the same underlying inferential hierarchy. Recent insights concerning the neural implementation of Predictive Processing may help elucidate this. Specifically, prior information is proposed to be approximated by mechanisms in both the top-down and bottom-up streams of information processing. While the former is context-dependent and flexible in updating, the latter is context-independent and difficult to revise. We propose that a stable divergence between perception and belief may emerge when flexible prior information at higher hierarchical levels contradicts inflexible prior information at lower ones. This allows Predictive Processing to account for conflicting percepts and beliefs while still maintaining a hierarchical and unitary conception of cognition.

A Deeper Look at the "Neural Correlate of Consciousness".

A main goal of the neuroscience of consciousness is: find the neural correlate to conscious experiences (NCC). When have we achieved this goal? The answer depends on our operationalization of "NCC." Chalmers (2000) shaped the widely accepted operationalization according to which an NCC is a neural system with a state which is minimally sufficient (but not necessary) for an experience. A deeper look at this operationalization reveals why it might be unsatisfactory: (i) it is not an operationalization of a correlate for occurring experiences, but of the capacity to experience; (ii) it is unhelpful for certain cases which are used to motivate a search for neural correlates of consciousness; (iii) it does not mirror the usage of "NCC" by scientists who seek for unique correlates; (iv) it hardly allows for a form of comparative testing of hypotheses, namely experimenta crucis. Because of these problems (i-iv), we ought to amend or improve on Chalmers's operationalization. Here, I present an alternative which avoids these problems. This "NCC2.0" also retains some benefits of Chalmers's operationalization, namely being compatible with contributions from extended, embedded, enacted, or embodied accounts (4E-accounts) and allowing for the possibility of non-biological or artificial experiencers.