Tactile motor attention induces sensory attenuation for sounds

Virtual reality in functional neurological disorder: a theoretical framework and research agenda for use in the real world

Functional neurological disorder (FND) is a common and disabling condition at the intersection of neurology and psychiatry. Despite remarkable progress over recent decades, the mechanisms of FND are still poorly understood and there are limited diagnostic tools and effective treatments. One potentially promising treatment modality for FND is virtual reality (VR), which has been increasingly applied to a broad range of conditions, including neuropsychiatric disorders. FND has unique features, many of which suggest the particular relevance for, and potential efficacy of, VR in both better understanding and managing the disorder. In this review, we describe how VR might be leveraged in the treatment and diagnosis of FND (with a primary focus on motor FND and persistent perceptual-postural dizziness given their prominence in the literature), as well as the elucidation of neurocognitive mechanisms and symptom phenomenology. First, we review what has been published to date on the applications of VR in FND and related neuropsychiatric disorders. We then discuss the hypothesised mechanism(s) underlying FND, focusing on the features that are most relevant to VR applications. Finally, we discuss the potential of VR in (1) advancing mechanistic understanding, focusing specifically on sense of agency, attention and suggestibility, (2) overcoming diagnostic challenges and (3) developing novel treatment modalities. This review aims to develop a theoretical foundation and research agenda for the use of VR in FND that might be applicable or adaptable to other related disorders.

Self-initiation enhances perceptual processing of auditory stimuli in an online study

Understanding how the brain incorporates sensory and motor information will enable better theory building on human perception and behavior. In this study, we aimed to estimate the influence of predictive mechanisms on the magnitude and variability of sensory attenuation in two online samples. After the presentation of a visual cue stimulus, participants (Experiment 1: N = 224, Experiment 2: N = 84) compared the loudness of two consecutive tones in a two-alternative forced-choice task. In Experiment 1, the first tone was either self-initiated or not; in Experiment 2, the second tone was either self-initiated or not (active and passive condition, respectively). We further manipulated identity prediction (i.e., the congruence of pre-learned cue-sound combinations; congruent vs. incongruent), and the duration of the onset delay (to account for effects of attentional differences between the passive and active condition, 50 ms vs. 0 ms). We critically discuss our results within the framework of both classical (i.e., motor-based forward models) and contemporary approaches (i.e., predictive processing framework). Contrary to our preregistered hypothesis, we observed enhanced perceptual processing, instead of attenuation, for self-initiated auditory sensory input. Further, our results reveal an effect of fixed sound delays on the processing of motor and non-motor-based predictive information, and may point to according shifts in attention, leading to a perceptual bias. These results might best be captured by a hybrid explanatory model, combining predictions based on self-initiated motor action with a global predictive mechanism.

Temporal adaptation of sensory attenuation for self-touch

The sensory consequences of our actions appear attenuated to us. This effect has been reported for external sensations that are evoked by auditory or visual events and for body-related sensations which are produced by self-touch. In the present study, we investigated the effects of prolonged exposure to a delay between an action and the generated sensation on sensory attenuation for self-touch. Previously, it has been shown that after being presented to a systematic exposure delay, artificially delayed touch can feel more intense and non-delayed touches can appear less intense. Here, we investigated the temporal spread of the temporal recalibration effect. Specifically, we wondered whether this temporal recalibration effect would affect only the delay that was used during exposure trials or if it would also modulate longer test delays. In the first two experiments, we tested three test delays (0, 100 and 400 ms) either in randomized or in blocked order. We found sensory attenuation in all three test intervals but no effect of the exposure delay. In Experiment 3, we replicated the experiment by Kilteni et al. (ELife 8:e42888, 2019. https://doi.org/10.7554/eLife.42888 ) and found evidence for temporal recalibration by exposure delay. Our data show that the temporal selectivity of sensory attenuation of self-touch depends on presenting a singular test delay only. Presenting multiple test delays leads to a temporally broad spread of sensory attenuation.