Parkinson’s disease is prototypically a movement disorder. Although perceptual and motor functions are highly interdependent, much less is known about perceptual deficits in Parkinson’s disease, which are less observable by nature, and might go unnoticed if not tested directly. It is therefore imperative to seek and identify these, to fully understand the challenges facing patients with Parkinson’s disease. Also, perceptual deficits may be related to motor symptoms. Posture, gait and balance, affected in Parkinson’s disease, rely on veridical perception of one’s own motion (self-motion) in space. Yet it is not known whether self-motion perception is impaired in Parkinson’s disease. Using a well-established multisensory paradigm of heading discrimination (that has not been previously applied to Parkinson’s disease), we tested unisensory visual and vestibular self-motion perception, as well as multisensory integration of visual and vestibular cues, in 19 Parkinson’s disease, 23 healthy age-matched and 20 healthy young-adult participants. After experiencing vestibular (on a motion platform), visual (optic flow) or multisensory (combined visual–vestibular) self-motion stimuli at various headings, participants reported whether their perceived heading was to the right or left of straight ahead. Parkinson’s disease participants and age-matched controls were tested twice (Parkinson’s disease participants on and off medication). Parkinson’s disease participants demonstrated significantly impaired visual self-motion perception compared with age-matched controls on both visits, irrespective of medication status. Young controls performed slightly (but not significantly) better than age-matched controls and significantly better than the Parkinson’s disease group. The visual self-motion perception impairment in Parkinson’s disease correlated significantly with clinical disease severity. By contrast, vestibular performance was unimpaired in Parkinson’s disease. Remarkably, despite impaired visual self-motion perception, Parkinson’s disease participants significantly overweighted the visual cues during multisensory (visual–vestibular ) integration (compared with Bayesian predictions of optimal integration) and significantly more than controls. These findings indicate that self-motion perception in Parkinson’s disease is affected by impaired visual cues and by suboptimal visual–vestibular integration (overweighting of visual cues). Notably, vestibular self-motion perception was unimpaired. Thus, visual self-motion perception is specifically impaired in early-stage Parkinson’s disease. This can impact Parkinson’s disease diagnosis and subtyping. Overweighting of visual cues could reflect a general multisensory integration deficit in Parkinson’s disease, or specific overestimation of visual cue reliability. Finally, impaired self-motion perception in Parkinson’s disease may contribute to impaired balance and gait control. Future investigation into this connection might open up new avenues of alternative therapies to better treat these difficult symptoms.

Parkinson's disease (PD), best characterized by its classic motor symptoms, also manifests non-motor symptoms including perceptual impairments. Normal motor and perceptual brain functions interact continuously in an action-perception loop; hence, perceptual and motor dysfunction in PD are likely also intertwined. A vital skill in order to maintain balance, and to move around in the environment is the ability to perceive one's own motion in space (self-motion perception). Self-motion perception is a complex brain process, that requires the integration of information from visual (optic flow), vestibular (gravito-inertial), and somatosensory senses. Yet, not much is known about self-motion perception or multisensory integration in PD.In this review, we highlight the need to better study these important functions in PD.We review perceptual deficits in underlying functions required for adept self-motion perception (visual, vestibular and somatosensory, as well as multisensory integration) and address how these might affect self-motion perception and motor function in PD. We propose that dysfunction of central brain mechanisms, implicated in impaired visual, vestibular and somatosensory function, likely impact self-motion perception in PD. Recent evidence suggests that visual and multisensory integration mechanisms of self-motion perception are indeed impaired in PD. This can affect motor control, gait and balance. Future research is needed to better investigate this important topic. A better understanding of self-motion perception and multisensory integration in PD may aid diagnosis and subtyping and may open new avenues for novel therapies to treat debilitating motor symptoms, including gait and balance impairment, using sensory augmentation devices or sensory retraining.

Background Researchers are increasingly acknowledging the importance of understanding patterns of engagement in multiple, as opposed to isolated, health behaviours. Accordingly, several studies, targeting various geographical regions, have begun to identify and characterize unique classes of individuals in terms of their engagement in health behaviours, towards gaining insights that might guide tailored health interventions. Our study extends this stream of research to the Israeli context, as well as examines whether certain sociodemographic characteristics tend to be associated with affiliation to a specific group of individuals, i.e., class membership. Methods Two large representative samples were obtained from the 2010 and 2017 National Social Surveys of the Israel Central Bureau of Statistics. Latent Class Analysis was used to identify different classes, based on levels of engagement in five health behaviours: fruit-and-vegetable consumption, physical activity, smoking avoidance, sleep, and influenza vaccination. Multinomial logistic regression was applied to test the associations between sociodemographic characteristics (age, gender, religion, education level) and class membership. Results We identified three distinct classes (denoted “healthy”, “unhealthy”, and “mixed”). Overall, the “healthy” class was characterized by healthy levels of fruit-and-vegetable consumption and physical activity, a low rate of currently-smoking individuals, and a high proportion of influenza vaccination. The “mixed” class was characterized by healthy levels of fruit-and-vegetable consumption and sleep duration, moderate levels of physical exercise, a high proportion of currently light smokers, and a low rate of vaccination. The “unhealthy” class was marked by relatively low levels of engagement in health behaviours. Generally, older, Jewish, and more-educated individuals were more likely to belong to the “healthy” class, while young, non-Jewish, and less-educated individuals were more likely to belong to the “unhealthy” class. We further identified differences between the 2010 and 2017 samples (e.g., differences in men’s likelihood of being in the “unhealthy” class), suggesting that some behavioural patterns might have changed over time. Conclusion This research identified three classes of engagement in health behaviours across two large and representative samples. Moreover, the classes were associated with unique sociodemographic characteristics. Consequently, our findings can highlight health-behavioural patterns relevant to different sub-populations that should be considered in public health interventions.

Background: Parkinson's disease (PD) is prototypically a movement disorder.Although perceptual and motor functions are interdependent, much less is known about perceptual dysfunction in PD. Perceptual deficits can impact activities of daily living, and contribute to motor symptoms, but might go unnoticed if not tested directly. Posture, gait and balance, affected in PD, rely on veridical perception of one's own motion in space. Yet it is unknown whether self-motion perception is impaired in PD. Objectives:To test self-motion perception in PD, separately for visual and vestibular cues (unisensory), and multisensory integration thereof.Methods: Participants (19 early stage PD, 23 age-matched and 20 young adult controls) experienced vestibular (motion platform), visual (optic flow), and combined visual-vestibular self-motion stimuli, and discriminated whether the stimulus headings were rightward or leftward of straight ahead. PD participants and age-matched controls were tested on two visits (PD on and off medication).Results: PD participants had significantly impaired visual self-motion perception, both on and off medication. This deficit correlated significantly with clinical disease severity. By contrast, their vestibular performance was unimpaired. Remarkably, despite impaired visual self-motion perception, PD participants significantly overweighted visual cues during multisensory (visual-vestibular) integration. Conclusions:Self-motion perception is affected already in early stage PD, specifically by impaired visual (vs. vestibular) function, and by suboptimal visualvestibular integration. This may contribute to impaired balance and gait control. Future investigation into this connection might open up new avenues for alternativetherapies to better treat these symptoms. Furthermore, these results may also impact early PD diagnosis and subtyping.

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