Adaptation to motor-visual and motor-auditory temporal lags transfer across modalities

Previous research has shown that the timing of a sensor-motor event is recalibrated after a brief exposure to a delayed feedback of a voluntary action (Stetson et al. 2006). Here, we examined whether it is the sensory or motor event that is shifted in time. We compared lag adaption for action-feedback in visuo-motor pairs and audio-motor pairs using an adaptation-test paradigm. Participants were exposed to a constant lag (50 or 150 ms) between their voluntary action (finger tap) and its sensory feedback (flash or tone pip) during an adaptation period (~3 min). Immediately after that, they performed a temporal order judgment (TOJ) task about the tap-feedback test stimulus pairings. The modality of the feedback stimulus was either the same as the adapted one (within-modal) or different (cross-modal). The results showed that the point of subjective simultaneity (PSS) was uniformly shifted in the direction of the exposed lag within and across modalities (motor-visual, motor-auditory). This suggests that the TRE of sensor-motor events is mainly caused by a shift in the motor component

Atypical visual-auditory predictive coding in Autism Spectrum Disorder:Electrophysiological evidence from stimulus omissions

Autism spectrum disorder is a pervasive neurodevelopmental disorder that has been linked to a range of perceptual processing alterations, including hypo- and hyperresponsiveness to sensory stimulation. A recently proposed theory that attempts to account for these symptoms, states that autistic individuals have a decreased ability to anticipate upcoming sensory stimulation due to overly precise internal prediction models. Here, we tested this hypothesis by comparing the electrophysiological markers of prediction errors in auditory prediction by vision between a group of autistic individuals and a group of age-matched individuals with typical development. Between-group differences in prediction error signaling were assessed by comparing event-related potentials evoked by unexpected auditory omissions in a sequence of audiovisual recordings of a handclap in which the visual motion reliably predicted the onset and content of the sound. Unexpected auditory omissions induced an increased early negative omission response in the autism spectrum disorder group, indicating that violations of the prediction model produced larger prediction errors in the autism spectrum disorder group compared to the typical development group. The current results show that autistic individuals have alterations in visual-auditory predictive coding, and support the notion of impaired predictive coding as a core deficit underlying atypical sensory perception in autism spectrum disorder.  Lay abstract:  Many autistic individuals experience difficulties in processing sensory information (e.g. increased sensitivity to sound). Here we show that these difficulties may be related to an inability to process unexpected sensory stimulation. In this study, 29 older adolescents and young adults with autism and 29 age-matched individuals with typical development participated in an electroencephalography study. The electroencephalography study measured the participants’ brain activity during unexpected silences in a sequence of videos of a handclap. The results showed that the brain activity of autistic individuals during these silences was increased compared to individuals with typical development. This increased activity indicates that autistic individuals may have difficulties in processing unexpected incoming sensory information, and might explain why autistic individuals are often overwhelmed by sensory stimulation. Our findings contribute to a better understanding of the neural mechanisms underlying the different sensory perception experienced by autistic individuals

Electrophysiological alterations in motor‐auditory predictive coding in autism spectrum disorder

The amplitude of the auditory N1 component of the event‐related potential (ERP) is typically attenuated for self‐initiated sounds, compared to sounds with identical acoustic and temporal features that are triggered externally. This effect has been ascribed to internal forward models predicting the sensory consequences of one's own motor actions. The predictive coding account of autistic symptomatology states that individuals with autism spectrum disorder (ASD) have difficulties anticipating upcoming sensory stimulation due to a decreased ability to infer the probabilistic structure of their environment. Without precise internal forward prediction models to rely on, perception in ASD could be less affected by prior expectations and more driven by sensory input. Following this reasoning, one would expect diminished attenuation of the auditory N1 due to self‐initiation in individuals with ASD. Here, we tested this hypothesis by comparing the neural response to self‐ versus externally‐initiated tones between a group of individuals with ASD and a group of age matched neurotypical controls. ERPs evoked by tones initiated via button‐presses were compared with ERPs evoked by the same tones replayed at identical pace. Significant N1 attenuation effects were only found in the TD group. Self‐initiation of the tones did not attenuate the auditory N1 in the ASD group, indicating that they may be unable to anticipate the auditory sensory consequences of their own motor actions. These results show that individuals with ASD have alterations in sensory attenuation of self‐initiated sounds, and support the notion of impaired predictive coding as a core deficit underlying autistic symptomatology

Auditory grouping occurs prior to intersensory pairing: evidence from temporal ventriloquism

The authors examined how principles of auditory grouping relate to intersensory pairing. Two sounds that normally enhance sensitivity on a visual temporal order judgement task (i.e. temporal ventriloquism) were embedded in a sequence of flanker sounds which either had the same or different frequency (Exp. 1), rhythm (Exp. 2), or location (Exp. 3). In all experiments, we found that temporal ventriloquism only occurred when the two capture sounds differed from the flankers, demonstrating that grouping of the sounds in the auditory stream took priority over intersensory pairing. By combining principles of auditory grouping with intersensory pairing, we demonstrate that capture sounds were, counter-intuitively, more effective when their locations differed from that of the lights rather than when they came from the same position as the lights

No effect of synesthetic congruency on temporal ventriloquism

A sound presented in temporal proximity to a light can alter the perceived temporal occurrence of that light (temporal ventriloquism). Recent studies have suggested that pitch–size synesthetic congruency (i.e., a natural association between the relative pitch of a sound and the relative size of a visual stimulus) might affect this phenomenon. To reexamine this, participants made temporal order judgements about small- and large-sized visual stimuli while high- or low-pitched tones were presented before the first and after the second light. We replicated a previous study showing that, at large sound–light intervals, sensitivity for visual temporal order was better for synesthetically congruent than for incongruent pairs. However, this congruency effect could not be attributed to temporal ventriloquism, since it disappeared at short sound–light intervals, if compared with a synchronous audiovisual baseline condition that excluded response biases. In addition, synesthetic congruency did not affect temporal ventriloquism even if participants were made explicitly aware of congruency before testing. Our results thus challenge the view that synesthetic congruency affects temporal ventriloquism

Factors of resilience in informal caregivers of people with dementia from integrative international data analysis

Background/Aims: Although caring for a person with dementia can be stressful, some caregivers appear to experience few negative consequences to their well-being. This study aimed to examine what proportion of caregivers demonstrates resilience under different challenging circumstances and to identify factors related to their resilience. Methods: Baseline data from 4 studies from the Netherlands and UK among informal caregivers of people with dementia were harmonized and integrated. Caregiver resilience was defined as high levels of psychological well-being despite different types of high caregiving demands. Multivariate regression analyses identified factors significantly related to caregiver resilience. Results: The integrated data set included 15 harmonized variables with data from 1,048 caregivers facing a high care demand. The prevalence of resilience varied between 35 and 43%, depending on the demand for high care. Being a male caregiver, caring for a female, living apart from your relative, and low caregiver burden were positively related to caregiver resilience. Conclusion: Caregivers have the capacity to demonstrate resilience despite significant challenges. This study demonstrates how harmonization of data from multiple existing studies can be used to increase power and explore the consistency of findings. This contributes to a better understanding of which factors are likely to facilitate caregiver resilience and offers insights for developing services