Biology subjects

Cataldo, A.

Publications and source records attributed to Cataldo, A..

5 recordsLinked to original sources

bioRxiv2024

Investigating the effect of mechanical adaptation on mid-air ultrasound vibrotactile stimuli

Gesture control systems based on mid-air haptics are increasingly used in infotainment systems in cars, where they can provide rich haptic feedback to improve human-computer interactions. Laboratory studies show that mid-air haptic feedback reduces drivers distractions and improve safety. However, it is unclear how the perception of mid-air ultrasound stimuli is affected by prolonged exposure to vibrational noise, e.g., from the steering wheel of a moving vehicle. Studies on vibrotactile adaptation show that perception of mechanical vibration is impaired by prior exposure to stimuli of the same frequency. Here, we investigated the effect of mechanical adaptation on the perception of mid-air ultrasound stimuli. We measured participants detection threshold for ultrasound stimuli of different frequencies both before and after exposure to 30 s mechanical vibrations. Across two experiments, we systematically manipulated the frequency and amplitude of the adapting stimulus. We found that exposure to low-frequency mechanical vibrations significantly impaired the detection of low-frequency ultrasound stimuli. In contrast, exposure to high-frequency mechanical vibrations equally impaired perception of both low- and high-frequency ultrasound stimuli. This effect was mediated by the amplitude of the adapting stimulus, with stronger mechanical vibrations producing a larger increase in participants detection threshold. Overall, these findings show that perception of mid-air ultrasound stimuli is affected by specific sources of mechanical noise. Crucially, frequency-specificity in the low-frequency band also points toward possible mitigating solutions that could help minimising unwanted desensitization of mechanoreceptor channels during mid-air haptic interactions.

neuroscience↗

bioRxiv2023

Active self-touch restores bodily self-awareness following disruption by the rubber hand illusion

Bodily self-awareness relies on a constant integration of visual, tactile, proprioceptive, and motor signals. In the "Rubber Hand Illusion" (RHI), conflicting visuo-tactile stimuli lead to changes in self- awareness. It remains unclear whether other, somatic signals could compensate for the alterations in self-awareness caused by visual information about the body. Here, we used the RHI in combination with robot-mediated self-touch to systematically investigate the role of tactile, proprioceptive, and motor signals in protecting and restoring bodily self-awareness. Participants moved the handle of a leader robot with their right hand and simultaneously received corresponding tactile feedback on their left hand from a follower robot. This self-touch stimulation was performed either before or after the induction of a classical RHI. Across three experiments, active self-touch delivered after - but not before - the RHI, significantly reduced the proprioceptive drift caused by RHI, supporting a restorative role of active self-touch on bodily self-awareness. The effect was not present during involuntary self-touch, where the participants hand was passively moved, suggesting that the restorative effect depends on the presence of a voluntary motor command, and that synchrony of bilateral sensory events is insufficient. Unimodal control conditions confirmed that the coordination of both tactile and motor components of self-touch was necessary to restore bodily self-awareness. These results suggest that voluntary self-touch can restore an intrinsic representation of the body following visual capture during RHI.

neuroscience↗

bioRxiv2023

The Limits of Touch: Spatial acuity for frequency-resolved air-borne ultrasound vibrotactile stimuli

Spatial acuity is a fundamental property of any sensory system. In the case of the somatosensory system, the two-point discrimination (2PD) test has long been used to investigate the spatial resolution of tactile perception. The somatosensory system comprises multiple mechanoreceptive channels, each tuned to specific vibrotactile frequencies. In particular, the rapidly adapting channel (RA) responds to low-frequency vibration and is thought to have high spatial acuity. The Pacinian channel (PC) responds to high-frequency vibration and is thought to convey little or no spatial information. However, the mechanical stimulations used in most 2PD tests make it difficult to disentangle the contribution of each mechanoreceptive channel to spatial tactile perception. Here we developed a novel 2PD test based on ultrasound stimulation to deliver frequency-resolved vibrotactile stimuli designed to preferentially activate specific tactile channels. Across four experiments, we systematically investigated the spatial resolution of the two main vibrotactile channels. Contrary to the textbook view of poor spatial resolution for PC-like stimuli, we found that high-frequency vibration produced surprisingly good spatial acuity. This effect remained after controlling for differences between the channels in stimulus detectability and perceived intensity. Laser doppler vibrometry experiments confirmed that the acuity of the PC channel was not simply an artifact of the skins resonance to high-frequency mechanical stimulation. Thus, PC receptors may transmit substantial spatial information, despite their sparse distribution, deep location, and large receptive fields.

neuroscience↗

bioRxiv2020

Touch inhibits touch: sanshool-induced paradoxical tingling reveals perceptual interference between somatosensory submodalities

Human perception of touch is mediated by inputs from multiple channels. Classical theories postulate independent contributions of each channel to each tactile feature, with little or no interaction between channels. In contrast to this view, we show that inputs from two sub-modalities of mechanical input channels interact to determine tactile perception. The flutter-range vibration channel was activated anomalously using hydroxy--sanshool, a bioactive compound of Szechuan pepper, which chemically induces tingling sensations. We tested whether this tingling sensation on the lips was modulated by sustained mechanical pressure. Across four experiments, we show that sustained touch inhibits sanshool tingling sensations in a location-specific, pressure-level and time-dependent manner. Additional experiments ruled out mediation of nociceptive or affective (C-tactile) channels underlying this interaction. These results reveal novel inhibitory influence from steady-pressure onto flutter-range tactile perceptual channels, consistent with early-stage interactions between mechanoreceptor inputs within the somatosensory pathway.

neuroscience↗

bioRxiv2020

Constructing spatial perception through self-touch

Classical accounts of spatial perception are based either on the topological layout of sensory receptors, or on implicit spatial information provided by motor commands. In everyday self-touch, as when stroking the left arm with the right hand, these elements are inextricably linked, meaning that tactile and motor contributions to spatial perception cannot readily be disentangled. Here, we developed a robot-mediated form of self-touch in order to decouple the spatial extent of active or passive movements from their tactile consequences. Participants judged the spatial extent of either the movement of the right hand, or of the resulting tactile stimulation to their left forearm. Across five experiments, we found bidirectional interference between motor and tactile information. Crucially, both directions of interference were stronger during active than passive movements. Thus, voluntary motor commands produced stronger integration of multiple signals relevant to spatial perception.

neuroscience↗