Papers by Christophe Lopez
Journal of Neurology, 2020
Neuroscience, Jan 5, 2011
Constructing and updating an internal model of verticality is fundamental for maintaining an erec... more Constructing and updating an internal model of verticality is fundamental for maintaining an erect posture and facilitating visuo-spatial processing. The judgment of the visual vertical (VV) has been intensively studied in psychophysical investigations and relies mainly on the integration of visual and vestibular signals, although a contribution of postural and somatosensory signals has been reported. Here we used high-density 192-channel evoked potential (EP) mapping and distributed source localization techniques to reveal the neural mechanisms of VV judgments. VV judgments (judging the orientation of visual lines with respect to the subjective vertical) were performed with and without a tilted visual frame. EP mapping revealed a sequence of neural processing steps (EP maps) of which two were specific for VV judgments. An early EP map, observed at ∼75-105 ms post-stimulus, was localized in right lateral temporo-occipital cortex. A later EP map (∼260-290 ms) was localized in bilater...
To answer Alsmith's questions about the existence of a vestibular sense, we outline in the first ... more To answer Alsmith's questions about the existence of a vestibular sense, we outline in the first part of our reply why we believe the vestibular sense is a true "sixth sense". We argue that vestibular information constitutes distinct sensory events and that absolute coding of body orientation and motion in the gravity-centered space is the important unique feature of the vestibular system. In the last part of our reply, we extend Alsmith's experimental suggestions to investigate the vestibular contribution to various perspectival experiences.
Background: The observation of conspecifics influences our bodily perceptions and actions: Contag... more Background: The observation of conspecifics influences our bodily perceptions and actions: Contagious yawning, contagious itching, or empathy for pain, are all examples of mechanisms based on resonance between our own body and others. While there is evidence for the involvement of the mirror neuron system in the processing of motor, auditory and tactile information, it has not yet been associated with the perception of self-motion.
ABSTRACT Notre capacité à s’abstraire de notre propre point de vue pour adopter celui d’autrui, o... more ABSTRACT Notre capacité à s’abstraire de notre propre point de vue pour adopter celui d’autrui, ou « prise de perspective visuo-spatiale », joue un rôle important dans la cognition sociale (1). Cette étude a pour objectif de mesurer l’influence des informations vestibulaires sur la prise de perspective en combinant des stimulations rotatoires naturelles du système vestibulaire à des tâches d’imagerie mentale.
There is increasing evidence that vestibular signals and the vestibular cortex are not only invol... more There is increasing evidence that vestibular signals and the vestibular cortex are not only involved in oculomotor and postural control, but also contribute to higher-level cognition. Yet, despite the effort that has recently been made in the field, the exact location of the human vestibular cortex and its implications in various perceptional, emotional, and cognitive processes remain debated. Here, we argue for a vestibular contribution to what is thought to fundamentally underlie human consciousness, i.e., the bodily self. We will present empirical evidence from various research fields to support our hypothesis of a vestibular contribution to aspects of the bodily self, such as basic multisensory integration, body schema, body ownership, agency, and self-location. We will argue that the vestibular system is especially important for global aspects of the self, most crucially for implicit and explicit spatiotemporal self-location. Furthermore, we propose a novel model on how vestibular signals could not only underlie the perception of the self but also the perception of others, thereby playing an important role in embodied social cognition.
Background: The observation of conspecifics influences our bodily perceptions and actions: Contag... more Background: The observation of conspecifics influences our bodily perceptions and actions: Contagious yawning, contagious itching, or empathy for pain, are all examples of mechanisms based on resonance between our own body and others. While there is evidence for the involvement of the mirror neuron system in the processing of motor, auditory and tactile information, it has not yet been associated with the perception of self-motion.
Neurophysiologie Clinique/Clinical Neurophysiology, 2014
ABSTRACT La posture de notre corps influence de façon préconsciente la perception émotionnelle qu... more ABSTRACT La posture de notre corps influence de façon préconsciente la perception émotionnelle que nous avons de nos congénères. Peu de données sont en revanche disponibles sur l’utilisation des informations proprioceptives liées au corps entier pour la perception visuo-spatiale. Cette étude décrit (Tâche1) comment ces informations proprioceptives sont utilisées pour adopter la perspective d’un avatar et (Tâche2) comment l’observation d’un avatar influence nos perceptions visuo-spatiales.
Annals of Physical and Rehabilitation Medicine, 2014
Annals of Physical and Rehabilitation Medicine, 2014
Psychological science, 2014
Revue de neuropsychologie, 2010
Annals of Neurology, 2014
PLoS ONE, 2013
Background: The observation of conspecifics influences our bodily perceptions and actions: Contag... more Background: The observation of conspecifics influences our bodily perceptions and actions: Contagious yawning, contagious itching, or empathy for pain, are all examples of mechanisms based on resonance between our own body and others. While there is evidence for the involvement of the mirror neuron system in the processing of motor, auditory and tactile information, it has not yet been associated with the perception of self-motion.
PLoS ONE, 2013
In three experiments we investigated the effects of visuo-tactile and visuo-vestibular conflict a... more In three experiments we investigated the effects of visuo-tactile and visuo-vestibular conflict about the direction of gravity on three aspects of bodily self-consciousness: self-identification, self-location, and the experienced direction of the firstperson perspective. Robotic visuo-tactile stimulation was administered to 78 participants in three experiments. Additionally, we presented participants with a virtual body as seen from an elevated and downward-directed perspective while they were lying supine and were therefore receiving vestibular and postural cues about an upward-directed perspective. Under these conditions, we studied the effects of different degrees of visuo-vestibular conflict, repeated measurements during illusion induction, and the relationship to a classical measure of visuo-vestibular integration. Extending earlier findings on experimentally induced changes in bodily self-consciousness, we show that self-identification does not depend on the experienced direction of the first-person perspective, whereas self-location does. Changes in bodily self-consciousness depend on visual gravitational signals. Individual differences in the experienced direction of first-person perspective correlated with individual differences in visuo-vestibular integration. Our data reveal important contributions of visuovestibular gravitational cues to bodily self-consciousness. In particular we show that the experienced direction of the firstperson perspective depends on the integration of visual, vestibular, and tactile signals, as well as on individual differences in idiosyncratic visuo-vestibular strategies.
Neuroscience Letters, 2012
Ownership for body parts depends on multisensory integration of visual, tactile and proprioceptiv... more Ownership for body parts depends on multisensory integration of visual, tactile and proprioceptive signals. In a previous study, we demonstrated that vestibular signals also contribute to ownership for body parts, since vestibular stimulation increased illusory ownership for a rubber hand. However, it remained an open question whether the vestibular information acts on the visual or on the tactile input. Here, we used a non-visual variant of the rubber hand illusion, manipulating the synchrony between tactile signals from the participant's left and right hand. The results revealed a strong illusory ownership through self-reports (questionnaires) and proprioceptive drift measures. Interestingly, however, there was no influence of vestibular stimulation on illusory ownership and the proprioceptive drift. The present data suggest that vestibular signals do not interfere with the tactile-proprioceptive mechanisms underlying ownership for body parts when visual feedback from the body surface is absent.
Neuroscience, 2012
The vestibular system contributes to the control of posture and eye movements and is also involve... more The vestibular system contributes to the control of posture and eye movements and is also involved in various cognitive functions including spatial navigation and memory. These functions are subtended by projections to a vestibular cortex, whose exact location in the human brain is still a matter of debate (Lopez and Blanke, 2011). The vestibular cortex can be defined as the network of all cortical areas receiving inputs from the vestibular system, including areas where vestibular signals influence the processing of other sensory (e.g. somatosensory and visual) and motor signals. Previous neuroimaging studies used caloric vestibular stimulation (CVS), galvanic vestibular stimulation (GVS), and auditory stimulation (clicks and short-tone bursts) to activate the vestibular receptors and localize the vestibular cortex. However, these three methods differ regarding the receptors stimulated (otoliths, semicircular canals) and the concurrent activation of the tactile, thermal, nociceptive and auditory systems. To evaluate the convergence between these methods and provide a statistical analysis of the localization of the human vestibular cortex, we performed an activation likelihood estimation (ALE) meta-analysis of neuroimaging studies using CVS, GVS, and auditory stimuli. We analyzed a total of 352 activation foci reported in 16 studies carried out in a total of 192 healthy participants. The results reveal that the main regions activated by CVS, GVS, or auditory stimuli were located in the Sylvian fissure, insula, retroinsular cortex, fronto-parietal operculum, superior temporal gyrus, and cingulate cortex. Conjunction analysis indicated that regions showing convergence between two stimulation methods were located in the median (short gyrus III) and posterior (long gyrus IV) insula, parietal operculum and retroinsular cortex (Ri). The only area of convergence between all three methods of stimulation was located in Ri. The data indicate that Ri, parietal operculum and posterior insula are vestibular regions where afferents converge from otoliths and semicircular canals, and may thus be involved in the processing of signals informing about body rotations, translations and tilts. Results from the meta-analysis are in agreement with electrophysiological recordings in monkeys showing main vestibular projections in the transitional zone between Ri, the insular granular field (Ig), and SII.
Neuropsychologia, 2007
This study investigates how unilateral and bilateral vestibular deafferentation modifies visual v... more This study investigates how unilateral and bilateral vestibular deafferentation modifies visual vertical perception in the presence of dynamic and static visual cues. We tested 40 Menière's patients before and after (from 1 week to 1 year) a curative unilateral vestibular neurotomy (UVN), and 4 patients with bilateral vestibular loss. Patients' performances were compared with those of 24 healthy subjects. The perception of the dynamic visual vertical (DVV) was investigated during optokinetic stimulations around the line of sight at various angular velocities. The static visual vertical (SVV) was recorded with a stationary visual pattern. In the acute stage after UVN, Menière's patients exhibited drastic impairment of DVV, which was tilted towards the lesioned side, whatever the direction of the optokinetic stimulation. In addition, the SVV was systematically tilted towards the lesioned side. The optokinetic-induced tilt of the vertical was asymmetrically organized around the new SVV with a significant decrease for contralesional stimulations and no change for ipsilesional stimulations, whatever the postoperative time. The SVV regained normal values 1 year postoperatively. For the patients with bilateral vestibular loss, the optokinetic-induced tilt of the visual vertical was drastically increased and symmetrically organized around an unmodified SVV aligned with the gravitational vertical. This study constitutes the first description of the recovery time-course of DVV perception after unilateral vestibular loss. Data reveal a long-term impairment of the DVV perception after unilateral vestibular loss, suggesting an asymmetrical processing of visual information and a permanent increased weight of dynamic visual cues after bilateral vestibular loss.
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Papers by Christophe Lopez