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Publications (62)
The safety and efficacy of neuronavigated intermittent theta burst stimulation (iTBS) in patients with bipolar depression has not yet been investigated. We hypothesized the superiority of active iTBS over sham. Twenty-six patients were randomly allocated to receive either active (n=12) or sham (n=14) iTBS. Response and remission rates according to...
Transcranial Magnetic Stimulation (TMS) established itself as a powerful technique for probing and treating the human brain. Major technological evolutions, such as neuronavigation and robotized systems, have continuously increased the spatial reliability and reproducibility of TMS, by minimizing the influence of human and experimental factors. How...
Brain dynamics at rest depend on the large-scale interactions between oscillating cortical microcircuits arranged into macrocolumns. Cytoarchitectonic studies have shown that the structure of those microcircuits differs between cortical regions, but very little is known about interregional differences of their intrinsic dynamics at a macro-scale in...
Auteur correspondant. Grenoble Image Parole Signal et Automatique (GIPSA-lab), CNRS UMR 5216–UGA, 11 rue des Mathématiques, Grenoble Campus, BP46, 38402 Saint-Martin-d’Hères cedex, France.
The study assumed that the antisaccade (AS) task is a relevant psychophysical tool to assess (i) short-term neuromodulation of the dorsolateral prefrontal cortex (DLPFC) induced by intermittent theta burst stimulation (iTBS); and (ii) mood change occurring during the course of the treatment. Saccadic inhibition is known to strongly involve the DLPF...
Drawing on decades of research suggesting an attentional advantage for self-related information, researchers generally assume that self-related stimuli automatically capture attention. However, a literature review reveals that this claim has not been systematically examined. We aimed to fill in this dearth of evidence. Following a feature-based acc...
Les études de trafic montrent généralement une diminution des intervalles entre les véhicules par temps de brouillard (Bulté, 1985 ; White, & Jeffery, 1980). Nous avons cherché à savoir si ce phénomène peut être expliqué par un effet du brouillard sur les mécanismes perceptifs et perceptivo-moteurs impliqués dans la régulation de l'intervalle et da...
Instructing participants to "identify a target" dramatically reduces saccadic reaction times in prosaccade tasks (PS). However, it has been recently shown that this effect disappears in antisaccade tasks (AS). The instruction effect observed in PS may result from top-down processes, mediated by pathways connecting the prefrontal cortex (PFC) to the...
Eight patients with major depression, included in a double-blind study, performed an antisaccade task. Results suggested a link between antisaccade performances and clinical scale scores in patients who respond to therapy. Moreover, error rates may well predict response from day of inclusion, thus serving as a state-marker for mood disorders.
Background:
The understanding of physiopathology and cognitive impairments in mood disorders requires finding objective markers. Mood disorders have often been linked to hypometabolism in the prefrontal dorsolateral cortex, and to GABAergic and glutamatergic neurotransmission dysfunction. The present study aimed to discover whether saccadic tasks...
Bottom-up and top-down processes are involved in visual analysis of scenes. Here we examined the influence of top-down visual demand on natural scene processing.
We measured accuracy and response time in adults performing two stimuli-equivalent tasks. Unfiltered, low or high spatial frequency (SF) natural scenes were presented in central, left, or...
Spatial frequencies in an image influence visual analysis across a distributed, hierarchically organized brain network. Low spatial frequency (LSF) information may rapidly reach high-order areas to allow an initial coarse parsing of the visual scene, which could then be "retroinjected" through feedback into lower level visual areas to guide finer a...
McCollough effects (MEs) are a group of visual contingent aftereffects that involve colour and contour. These effects have been the subject of a large body of literature concerning their properties and theoretical accounts, but the mechanisms underlying the ME have never been fully clarified. We make the assumption that a general adaptive neural pr...
Following unilateral damage of the primary visual cortex one of the most common visual field defects observed is Homonymous Hemianopia (HH), a loss of vision of the contralesional hemifield in each eye. The ipsilesional ("intact") part of the central visual field is often used to compensate for difficulties encountered in the peripheral hemianopic...
The goal of this study was to provide a better understanding of driver behavior in fog.
Impaired perception of changes in headway is hypothesized to be one of the reasons for shorter following distances in foggy conditions as compared with clear weather.
In the experiments described here, we measured response time for discriminating between whether...
V1 receptive fields show different sensitivities to different scales suggesting spatial frequency coding of visual information. The purpose of the present paper is to determine whether such a spectral decomposition at a perceptual level would be efficient for non-linear categorization purposes. Specifically, we compare the advantage of providing an...
A recent brain imaging study (Vuilleumier, Armony, Driver and Dolan 2003, Nature Neuroscience, 6, 624-631) has shown that amygdala responses to fearful expressions are preferentially driven by intact or low spatial frequency (LSF) images of faces, rather than by high spatial frequency (HSF) images. These results suggest that LSF components processe...
In a princeps study, Trottier and Pratt (2005) showed that saccadic latencies were dramatically reduced when subjects were instructed to not simply look at a peripheral target (reflexive saccade) but to identify some of its properties. According to the authors, the shortening of saccadic reactions times may arise from a top-down disinhibition of th...
The physiological structure of the striate cortex is composed of neural columns sensitive to different orientations [9] with an over-representation of cardinal orientations [13]. As an explanation, it seems that statistics of the power spectra of natural images have shown that vertical and horizontal orientations are most present in our visual envi...
Résumé L'oeil a deux fonctions : l'une perceptive (coder l'information lumineuse) et l'autre motrice (amener le regard sur des zones d'intérêts). Le présent article s'intéresse à la fonction motrice de l'oeil, plus précisément aux mouvements oculaires de base que sont les saccades et les antisaccades. En effet, les mesures réalisées sur ces saccade...
Studies on functional hemispheric asymmetries have suggested that the right vs. left hemisphere should be predominantly involved in low vs. high spatial frequency (SF) analysis, respectively. By manipulating exposure duration of filtered natural scene images, we examined whether the temporal characteristics of SF analysis (i.e., the temporal preced...
We examined the neural correlates of spatial frequency (SF) processing through a gender and neuropsychological approach, using a recognition task of filtered (either in low spatial frequencies/LSF or high spatial frequencies/HSF) natural scene images. Experiment 1 provides evidence for hemispheric specialization in SF processing in men (the right h...
Vuilleumier, Armony, Driver & Dolan (2003) have shown that amygdala responses to fearful expressions seem to be more activated by intact or low spatial frequency (LSF) faces than high spatial frequency (HSF) faces. The fMRI results suggest that LSF components processed by the magnocellular layers of the lateral geniculate nucleus (LGN) might be con...
Do image properties drive first ocular explorations of natural scene during free viewing? The response is positive, according to previous works defining image properties with statistical measures or modeled with a saliency map. But, because these works were mainly based on correlation analysis (but see Einhauser, 2002), no causal link could be esta...
The authors studied the influence of canonical orientation on visual search for object orientation. Displays consisted of pictures of animals whose axis of elongation was either vertical or tilted in their canonical orientation. Target orientation could be either congruent or incongruent with the object's canonical orientation. In Experiment 1, ver...
Vuilleumier, Armony, Driver & Dolan (2003) have shown that amygdala cells to fearful expressions of human faces seem to be more activated by intact or low spatial frequency (LSF) faces than high spatial frequency (HSF) faces. These fMRI results may suggest that LSF components might be processed by a subcortical pathway that is assumed to bypass the...
It has been suggested that visual scene recognition is mainly based on spatial frequency (Fourier) analysis of the image. This analysis starts with processing low spatial frequencies (LSF), followed by processing high spatial frequencies (HSF). Within the framework of the spatial frequency analysis, the right/left hemisphere would be predominantly...
Models of the visual cortex are based on image decomposition according to the Fourier spectrum (amplitude and phase). On one hand, it is commonly believed that phase information is necessary to identify a scene. On the other hand, it is known that complex cells of the visual cortex, the most numerous ones, code only the amplitude spectrum. This rai...
Experimental data coming from visual cognitive sciences suggest that visual analysis starts with a parallel extraction of different visual attributes at different scales/frequencies. Neuropsychological and functional imagery data have suggested that each hemisphere (at the level of temporo-parietal junctions-TPJ) could play a key role in spatial fr...
This paper aims at identifying the regions of interest in natural scenes. These regions have been defined by a behavioural measure of eye movement and by a model of saliency map constructed in a biologically plausible manner. The saliency map codes the local region of interest in terms of signal properties such as contrast, orientation, colour, cur...
Three experiments investigated the role of the global spatial structure of two-dimensional (2-D) shapes in terms of symmetry and elongation on visual search for shape orientation. Experiment 1 demonstrated the often reported orientation search asymmetry (i.e., a faster detection of a tilted target among vertical distractors than the reverse) for th...
Three experiments investigated the role of the global spatial structure of two-dimensional (2-D) shapes in terms of symmetry
and elongation on visual search for shape orientation. Experiment 1 demonstrated the often reported orientation search asymmetry
(i.e., a faster detection of a tilted target among vertical distractors than the reverse) for th...
McCollough effects (MEs) are a group of visual contingent aftereffects that involve colour and contour. These effects have been the subject of a large body of literature concerning their properties and theoretical accounts, but the mecha- nisms underlying the ME have never been fully clarified. We make the assump- tion that a general adaptive neura...
The aim of this research is to model and simulate the loss of visual resolution as a function of retinal eccentricity in the perception of natural scenes. The model of visual resolution is based on a space-variant low-pass filter, having a variable convolution kernel according to retinal eccentricity. The parameters of the model are computed from p...
Visual detection of a line target differing in orientation from a background of lines is assumed to occur early in vision and to involve filter mechanisms acting in parallel over the visual field in retinotopic maps (Foster & Ward, 1991; Treisman, 1985; Wolfe, 1994). But retinotopicality does not imply that early vision takes place in a retinal ref...
Two-dimensional (2-D) shape identification is sometimes described in terms of access to structural descriptions based on the extraction of principal axes of elongation and symmetry. In four experiments we examined the effects of implicit axes of elongation and symmetry on visual search for shape orientation, on the basis of previous observations of...
To see if the spatial reference frame used by pre-attentive vision is specified in a retino-centered frame or in a reference frame integrating visual and nonvisual information (vestibular and somatosensory), subjects were centrifuged in a nonpendular cabin and were asked to search for a target distinguishable from distractors by difference in orien...
To see if the spatial reference frame used by pre-attentive vision is specified in a retino-centered frame or in a reference frame integrating visual and nonvisual information (vestibular and somatosensory), subjects were centrifuged in a non-pendular cabin and were asked to search for a target distinguishable from distractors by difference in orie...
To determine whether nonvisual (vestibular and somatosensory) information participates in low-level orientation processing, subjects in different postural conditions (upright, supine, and sitting immobilized) searched for a target distinguishable from distractors by difference in orientation (A. Treisman's, 1985, "pop-out" paradigm). Searches for v...
A qualitative model suggests that orientation is a visual "primitive," the detection of which reveals, in some cases, an opposing ansiotropy to the one obtained in psychophysical or attentive vision. For instance, a target whose location differs by 18° from homogenous distractors in frontoparallel "pops out" if it is tilted and requires attentional...
Interindividual differences in field dependence-independence (FDI) which emerge in situations of vision-posture conflict when subjects are required to orient their bodies vertically were investigated. The first aim was to see whether the same interindividual differences are found in judgements of the orientation of forms in focal vision in which su...
This research was undertaken to demonstrate, with correlational evidence, that presenting the rod-and-frame test (RIT) with
either limited (tachistoscopic) or unlimited (Oltman’s, 1968, portable RFT) exposure time does not significantly affect the
ranking of subjects. The underlying hypothesis is that the intersubject variability of performance on...
