Biology subjects

Bouyer, L.

Publications and source records attributed to Bouyer, L..

3 recordsLinked to original sources

bioRxiv2025

Vividness of mental imagery is a broad trait measure of internally generated visual experiences

Research on mental visual imagery typically relies on vividness ratings. However, vividness is ill-defined as it lacks an objective reference. Here, we present survey results that suggest vividness is nevertheless a robust measure. It explains individual differences of a broad range of subjective experiences, from the detail of mental imagery, the propensity to report having other internally generated visual experiences, and the vividness of visual dreams. Critically, simple vividness ratings can replace the protracted questionnaires commonly used for this purpose and reduce methodological issues with these instruments. We further find that vividness is closely linked with the experience of "seeing" mental images or projecting them into the external world. People who report seeing mental images with their eyes shut are also more likely to experience externally projected imagery. Nevertheless, many people report having mental depictions but without seeing. Overall, our results indicate we should redefine visual aphantasia to distinguish individuals with faint or unseen visual images from those completely lacking a pictorial representation.

neuroscience↗

bioRxiv2024

Imagery priming of binocular rivalry is not a reliable metric of individual differences in the subjective vividness of visualisations.

Most people can imagine images that they experience within their minds eye. However, there are marked individual differences, with some people reporting that they are unable to construct mental images at all (aphantasics), and others who report having imagined experiences that are as realistic as seeing (hyper-phantasics). The vividness of imagined images is most often measured via subjective self-report. Chang and Pearson (2018), however, have suggested that a binocular rivalry (BR) protocol can be used as an objective measure. They found that pre-imagining a moving input could enhance performance on an objective probe detection task when probes were embedded in imagery consistent inputs, as opposed to imagery inconsistent inputs. To date, nobody has assessed if this type of objective imagery priming can be used to predict the vividness of different peoples visualisations. Here, we report that imagery priming of objective sensitivity to probes within static BR inputs does not correlate with the typical ratings people use to describe the vividness of their visualisations (a between participants effect). However, objective priming of sensitivity to probes embedded in BR inputs was greater on trials when participants reported that their pre-imagined experience had been relatively vivid (a within participants effect). Overall, our data suggest that while imagery can prime objective sensitivity to probes during BR, there is currently no strong evidence that this effect can be used as an objective method of predicting the subjective vividness of different peoples visualisations. Highlights[tpltrtarr] There are marked individual differences in the subjective intensity of visual imagery [tpltrtarr]Most measures of the subjective intensity of visual imagery are subjective [tpltrtarr]A binocular rivalry probe-detection protocol has been suggested as an objective measure [tpltrtarr]The authors find that there is only a very small predictive relationship between outcomes in a binocular rivalry task and participants reported imagery strength [tpltrtarr]We still lack an objective measure that reliably predicts the subjective intensity of visual imagery

animal behavior and cognition↗

bioRxiv2019

Ancestral persistence of vestibulo-spinal reflexes in axial muscles in humans

Accurate control of the trunk is essential for maintaining balance in an upright subject. Most studies addressing vestibulo-spinal reflexes have investigated the role of the lower limbs, while limited attention has been paid to the back muscles. To address this issue, we challenged the persistence of vestibular evoked myogenic potentials (VEMPs) in back muscles in situations in which the leg muscle responses were modulated. Nineteen subjects were submitted to galvanic vestibular stimulations (GVS). Body sway and VEMPs were recorded in the paraspinal and limb muscles. During treadmill locomotion, the VEMPS in the lower limbs were observed only during the stance phase, whereas the axial VEMPs were observed during all phases. In upright standing subjects, slight head contact was sufficient to abolish the VEMPs in the lower limbs, while the VEMPs remained present in the paraspinal muscles. Similarly, during parabolic flight-induced microgravity, the VEMPs in the lower limb muscles were suppressed, while those in the axial muscles persisted despite the absence of gravitational information from the otolithic system. Our results depict a differentiated control mechanism of axial and appendicular muscles when a perturbation is detected by vestibular inputs. The persistent feature of axial myogenic adjustments suggests that a hard-wired reflex is functionally efficient to maintain posture. By contrast, the ankle responses to perturbations occur only when the accompanying sensory feedback is congruent, challenging the balance task and gravity. Overall, this study using GVS in microgravity is the first to present an approach delineating feed-forward vestibular control in the absence of all feedback.

neuroscience↗