Olivier Collignon - Academia.edu (original) (raw)

Papers by Olivier Collignon

Current Biology, 2015

Animal and human studies have demonstrated that transient visual deprivation early in life, even ... more Animal and human studies have demonstrated that transient visual deprivation early in life, even for a very short period, permanently alters the response properties of neurons in the visual cortex and leads to corresponding behavioral visual deficits [1-7]. While it is acknowledged that early-onset and longstanding blindness leads the occipital cortex to respond to non-visual stimulation [8, 9], it remains unknown whether a short and transient period of postnatal visual deprivation is sufficient to trigger crossmodal reorganization that persists after years of visual experience. In the present study, we characterized brain responses to auditory stimuli in 11 adults who had been deprived of all patterned vision at birth by congenital cataracts in both eyes until they were treated at 9 to 238 days of age. When compared to controls with typical visual experience, the cataract-reversal group showed enhanced auditory-driven activity in focal visual regions. A combination of dynamic causal modeling with Bayesian model selection [10] indicated that this auditory-driven activity in the occipital cortex was better explained by direct cortico-cortical connections with the primary auditory cortex than by subcortical connections. Thus, a short and transient period of visual deprivation early in life leads to enduring large-scale crossmodal reorganization of the brain circuitry typically dedicated to vision.

Journal of Cognitive Neuroscience

It has been suggested that both the posterior parietal cortex (PPC) and the extrastriate occipita... more It has been suggested that both the posterior parietal cortex (PPC) and the extrastriate occipital cortex (OC) participate in the spatial processing of sounds. However, the precise time-course of their contribution remains unknown, which is of particular interest, considering that it could give new insights into the mechanisms underlying auditory space perception. To address this issue, we have used event-related transcranial magnetic stimulation (TMS) to induce virtual lesions of either the right PPC or right OC at different delays in subjects performing a sound lateralization task. Our results confirmed that these two areas participate in the spatial processing of sounds. More precisely, we found that TMS applied over the right OC 50 msec after the stimulus onset significantly impaired the localization of sounds presented either to the right or to the left side. Moreover, right PPC virtual lesions induced 100 and 150 msec after sound presentation led to a rightward bias for stimul...

Brain Topography

It is well known that, following an early visual deprivation, the neural network involved in proc... more It is well known that, following an early visual deprivation, the neural network involved in processing auditory spatial information undergoes a profound reorganization. In particular, several studies have demonstrated an extensive activation of occipital brain areas, usually regarded as essentially "visual", when early blind subjects (EB) performed a task that requires spatial processing of sounds. However, little is known about the possible consequences of the activation of occipitals area on the function of the large cortical network known, in sighted subjects, to be involved in the processing of auditory spatial information. To address this issue, we used event-related transcranial magnetic stimulation (TMS) to induce virtual lesions of either the right intra-parietal sulcus (rIPS) or the right dorsal extrastriate occipital cortex (rOC) at different delays in EB subjects performing a sound lateralization task. Surprisingly, TMS applied over rIPS, a region critically in...

Multisensory Research, 2013

Cognition, 2015

Across many cultures people conceptualize time as extending along a horizontal Mental Time Line (... more Across many cultures people conceptualize time as extending along a horizontal Mental Time Line (MTL). This spatial mapping of time has been shown to depend on experience with written text, and may also depend on other graphic conventions such as graphs and calendars. All of this information is typically acquired visually, suggesting that visual experience may play an important role in the development of the MTL. Do blind people develop a MTL? If so, how does it compare with the MTL in sighted? In this study we tested early blind, late blind and sighted participants in a space-time congruity task. Participants had to classify temporal words by pressing a right and a left key, either with crossed or uncrossed hands. We found that the MTL develops in the absence of vision, and that it is based on the same external frame of reference in sighted and blind people. Reading braille may provide the same experiential link between space and time in the manual modality as reading printed text provides in the visual modality. These results showing a similar MTL in sighted and blind participants contrast with previous results showing that the Mental Number Line (MNL) depends on different spatial coordinates in the sighted and the blind, and suggest that spatial representations of time and number may have different experiential bases.

Background: Searching for a visual target from among a spatially complex environment is facilitat... more Background: Searching for a visual target from among a spatially complex environment is facilitated when an auditory tone or pip is presented in synchrony with a visual change in the target's attribute (i.e., color change). This pip and pop effect (van de Burg et al., 2008) is argued to result from the integration between temporally synchronized changes in auditory (non-spatial auditory pip) and visual (target color change) events, resulting in a salient multi-modal feature that typically draws attention to the target. This paradigm is well-suited to test the hypothesis that persons with autism integrate input from multiple sensory modalities less efficiently (Iarocci & McDonald, 2006). Such hypotheses are congruent with findings of atypical pattern of neural connectivity between specific brain areas that are sensitive to information from different sensory modalities in autism. Objectives: To assess audio-visual integration abilities for non-social information in person with aut...

Background: The ability of nonautistics to recognize emotional expression through voice and facia... more Background: The ability of nonautistics to recognize emotional expression through voice and facial affect usually leads to the correct interpretation of others' feelings, representing a fundamental cognitive ability for the effective regulation of social interactions. Although limitations in the expected, overt behaviors typically associated with the processing of emotion represents a core symptom of the autistic spectrum, empirical evidence using ecologically-validated stimuli and methods is rather limited. Objectives: To assess atypical processing of facial and vocal affect in the autistic spectrum, using a recently validated set of ecological stimuli comprised of dynamic visual and auditory (non-verbal) vocal clips of emotional expression (Belin et al., 2008; Simon et al., 2007). Methods: Twelve autistic, 10 nonautistic, and 11 Asperger syndrome participants matched for chronological age, full-scale IQ, gender, and handedness were asked to distinguish between facial and vocal...

B-ENT, 2011

While the effects of early visual deprivation on auditory and tactile functions have been widely ... more While the effects of early visual deprivation on auditory and tactile functions have been widely studied, little is known about olfactory function in early blind subjects. The present study investigated the potential effect of early blindness on the electrophysiological correlates of passive odour perception. Event-related potentials (ERPs) were recorded in eight early blind humans and eight sighted controls matched for age, sex and handedness during olfactory stimulation with 2-phenyl ethyl alcohol and trigeminal stimulation with CO2 Latencies, amplitudes and topographical distributions were analysed. As expected, the olfactory and trigeminal ERP components showed normal latencies, amplitudes and topography in both groups. Olfactory stimuli generated responses of smaller amplitude than those observed in response to trigeminal stimulation. In addition, ERP analyses did not reveal any major difference in electrocortical responses in occipital areas in early blind and sighted subjects...

Multisensory research, 2014

Sensory substitution devices (SSDs) have been developed with the ultimate purpose of supporting s... more Sensory substitution devices (SSDs) have been developed with the ultimate purpose of supporting sensory deprived individuals in their daily activities. However, more than forty years after their first appearance in the scientific literature, SSDs still remain more common in research laboratories than in the daily life of people with sensory deprivation. Here, we seek to identify the reasons behind the limited diffusion of SSDs among the blind community by discussing the ergonomic, neurocognitive and psychosocial issues potentially associated with the use of these systems. We stress that these issues should be considered together when developing future devices or improving existing ones. We provide some examples of how to achieve this by adopting a multidisciplinary and participatory approach. These efforts would contribute not solely to address fundamental theoretical research questions, but also to better understand the everyday needs of blind people and eventually promote the use ...

Neuroscience, Jan 26, 2014

One of the most striking demonstrations of experience-dependent plasticity comes from studies of ... more One of the most striking demonstrations of experience-dependent plasticity comes from studies of sensory-deprived individuals (e.g., blind or deaf), showing that brain regions deprived of their natural inputs change their sensory tuning to support the processing of inputs coming from the spared senses. These mechanisms of crossmodal plasticity have been traditionally conceptualized as having a double-edged sword effect on behavior. On one side, crossmodal plasticity is conceived as adaptive for the development of enhanced behavioral skills in the remaining senses of early-deaf or blind individuals. On the other side, crossmodal plasticity raises crucial challenges for sensory restoration and is typically conceived as maladaptive since its presence may prevent optimal recovery in sensory-re-afferented individuals. In the present review we stress that this dichotomic vision is oversimplified and we emphasize that the notions of the unavoidable adaptive/maladaptive effects of crossmoda...

Neural plasticity, 2012

Studies on visually deprived individuals provide one of the most striking demonstrations that the... more Studies on visually deprived individuals provide one of the most striking demonstrations that the brain is highly plastic and is able to rewire as a function of the sensory input it receives from the environment. In the current paper, we focus on spatial abilities that are typically related to the dorsal visual pathway (i.e., spatial/motion processing). Bringing together evidence from cataract-reversal individuals, early- and late-blind individuals and sight-recovery cases of long-standing blindness, we suggest that the dorsal "spatial" pathway is mostly plastic early in life and is then more resistant to subsequent experience once it is set, highlighting some limits of neuroplasticity.

Progress in brain research, 2011

The purpose of this review is to consider new sensory rehabilitation avenues in the context of th... more The purpose of this review is to consider new sensory rehabilitation avenues in the context of the brain's remarkable ability to reorganize itself following sensory deprivation. Here, deafness and blindness are taken as two illustrative models. Mainly, two promising rehabilitative strategies based on opposing theoretical principles will be considered: sensory substitution and neuroprostheses. Sensory substitution makes use of the remaining intact senses to provide blind or deaf individuals with coded information of the lost sensory system. This technique thus benefits from added neural resources in the processing of the remaining senses resulting from crossmodal plasticity, which is thought to be coupled with behavioral enhancements in the intact senses. On the other hand, neuroprostheses represent an invasive approach aimed at stimulating the deprived sensory system directly in order to restore, at least partially, its functioning. This technique therefore relies on the neurona...

Psychological science, 2011

It has been shown that congenital blindness can lead to anomalies in the integration of auditory ... more It has been shown that congenital blindness can lead to anomalies in the integration of auditory and tactile information, at least under certain conditions. In the present study, we used the parchment-skin illusion, a robust illustration of sound-biased perception of touch based on changes in frequency, to investigate the specificities of audiotactile interactions in early- and late-onset blind individuals. Blind individuals in both groups did not experience any illusory change in tactile perception when the frequency of the auditory signal was modified, whereas sighted individuals consistently experienced the illusion. This demonstration that blind individuals had reduced susceptibility to an auditory-tactile illusion suggests either that vision is necessary for the establishment of audiotactile interactions or that auditory and tactile information can be processed more independently in blind individuals than in sighted individuals. In addition, the results obtained in late-onset b...

Neuroscience and biobehavioral reviews, 2014

The phenotype of autism involves heterogeneous adaptive traits (strengths vs. disabilities), diff... more The phenotype of autism involves heterogeneous adaptive traits (strengths vs. disabilities), different domains of alterations (social vs. non-social), and various associated genetic conditions (syndromic vs. nonsyndromic autism). Three observations suggest that alterations in experience-dependent plasticity are an etiological factor in autism: (1) the main cognitive domains enhanced in autism are controlled by the most plastic cortical brain regions, the multimodal association cortices; (2) autism and sensory deprivation share several features of cortical and functional reorganization; and (3) genetic mutations and/or environmental insults involved in autism all appear to affect developmental synaptic plasticity, and mostly lead to its upregulation. We present the Trigger-Threshold-Target (TTT) model of autism to organize these findings. In this model, genetic mutations trigger brain reorganization in individuals with a low plasticity threshold, mostly within regions sensitive to co...

Cognitive Brain Research, 2005

Previous neuroimaging studies devoted to auditory motion processing have shown the involvement of... more Previous neuroimaging studies devoted to auditory motion processing have shown the involvement of a cerebral network encompassing the temporoparietal and premotor areas. Most of these studies were based on a comparison between moving stimuli and static stimuli placed at a single location. However, moving stimuli vary in spatial location, and therefore motion detection can include both spatial localisation and motion processing. In this study, we used fMRI to compare neural processing of moving sounds and static sounds in various spatial locations in blindfolded sighted subjects. The task consisted of simultaneously determining both the nature of a sound stimulus (pure tone or complex sound) and the presence or absence of its movement. When movement was present, subjects had to identify its direction. This comparison of how moving and static stimuli are processed showed the involvement of the parietal lobules, the dorsal and ventral premotor cortex and the planum temporale during auditory motion processing. It also showed the specific recruitment of V5, the visual motion area. These results suggest that the previously proposed network of auditory motion processing is distinct from the network of auditory localisation. In addition, they suggest that the occipital cortex can process non-visual stimuli and that V5 is not restricted to visual processing.

Neuroinformatics, Jan 4, 2015

Blindness represents a unique model to study how visual experience may shape the development of b... more Blindness represents a unique model to study how visual experience may shape the development of brain organization. Exploring how the structure of the corpus callosum (CC) reorganizes ensuing visual deprivation is of particular interest due to its important functional implication in vision (e.g., via the splenium of the CC). Moreover, comparing early versus late visually deprived individuals has the potential to unravel the existence of a sensitive period for reshaping the CC structure. Here, we develop a novel framework to capture a complete set of shape differences in the CC between congenitally blind (CB), late blind (LB) and sighted control (SC) groups. The CCs were manually segmented from T1-weighted brain MRI and modeled by 3D tetrahedral meshes. We statistically compared the combination of local area and thickness at each point between subject groups. Differences in area are found using surface tensor-based morphometry; thickness is estimated by tracing the streamlines in the...

Proceedings of the National Academy of Sciences, 2007

Virtually all cancer biological attributes are heterogeneous. Because of this, it is currently di... more Virtually all cancer biological attributes are heterogeneous. Because of this, it is currently difficult to reconcile results of cancer transcriptome and proteome experiments. It is also established that cancer somatic mutations arise at rates higher than suspected, but yet are insufficient to explain all cancer cell heterogeneity. We have analyzed sequence variations of 17 abundantly expressed genes in a large set of human ESTs originating from either normal or cancer samples. We show that cancer ESTs have greater variations than normal ESTs for >70% of the tested genes. These variations cannot be explained by known and putative SNPs. Furthermore, cancer EST variations were not random, but were determined by the composition of the substituted base (b0) as well as that of the bases located upstream (up to b ؊ 4) and downstream (up to b ؉ 3) of the substitution event. The replacement base was also not randomly selected but corresponded in most cases (73%) to a repetition of b ؊ 1 or of b ؉ 1. Base substitutions follow a specific pattern of affected bases: A and T substitutions were preferentially observed in cancer ESTs. In contrast, cancer somatic mutations Science 314:268 -274] and SNPs identified in the genes of the current study occurred preferentially with C and G. On the basis of these observations, we developed a working hypothesis that cancer EST heterogeneity results primarily from increased transcription infidelity.