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1.
J Neurophysiol ; 130(3): 547-556, 2023 09 01.
Article in English | MEDLINE | ID: mdl-37492898

ABSTRACT

Somatosensory evoked potential (SEP) studies typically characterize short-latency components following median nerve stimulations of the wrist. However, these studies rarely considered 1) skin type (glabrous/hairy) at the stimulation site, 2) nerve being stimulated, and 3) middle-latency (>30 ms) components. Our aim was to investigate middle-latency SEPs following simple mechanical stimulation of two skin types innervated by two different nerves. Eighteen adults received 400 mechanical stimulations over four territories of the right hand (two nerves: radial/median; two skin types: hairy/glabrous skin) while their EEG was recorded. Four middle-latency components were identified: P50, N80, N130, and P200. As expected, significantly shorter latencies and larger amplitudes were found over the contralateral hemisphere for all components. A skin type effect was found for the N80; glabrous skin stimulations induced larger amplitude than hairy skin stimulations. Regarding nerve effects, median stimulations induced larger P50 and N80. Latency of the N80 was longer after median nerve stimulation compared with radial nerve stimulation. This study showed that skin type and stimulated nerve influence middle-latency SEPs, highlighting the importance of considering these parameters in future studies. These modulations could reflect differences in cutaneous receptors and somatotopy. Middle-latency SEPs can be used to evaluate the different steps of tactile information cortical processing. Modulation of SEP components before 100 ms possibly reflects somatotopy and differential processing in primary somatosensory cortex.NEW & NOTEWORTHY The current paper highlights the influences of stimulated skin type (glabrous/hairy) and nerve (median/radial) on cortical somatosensory evoked potentials. Mechanical stimulations were applied over four territories of the right hand in 18 adults. Four middle-latency components were identified: P50, N80, N130, and P200. A larger N80 was found after glabrous skin stimulations than after hairy skin ones, regardless of the nerve being stimulated. P50 and N80 were larger after median than radial nerve stimulations.


Subject(s)
Evoked Potentials, Somatosensory , Wrist , Evoked Potentials, Somatosensory/physiology , Median Nerve/physiology , Touch , Skin , Electric Stimulation , Somatosensory Cortex/physiology
2.
J Clin Med ; 11(23)2022 Dec 01.
Article in English | MEDLINE | ID: mdl-36498717

ABSTRACT

This study aimed at evaluating the autonomic response to pleasant affective touch in children with Autism Spectrum Disorders (ASD) and age-matched typically developing (TD) peers, thanks to multiple autonomic nervous system (ANS) parameters and by contrasting CT (C-tactile fibers) high- vs. low-density territory stimulations. We measured pupil diameter, skin conductance, and heart rate during gentle stroking of two skin territories (CT high- and low-density, respectively, forearm and palm of the hand) in thirty 6-12-year-old TD children and twenty ASD children. TD children showed an increase in pupil diameter and skin conductance associated with a heart rate deceleration in response to tactile stimulations at the two locations. Only the pupil was influenced by the stimulated location, with a later dilation peak following CT low-density territory stimulation. Globally, ASD children exhibited reduced autonomic responses, as well as different ANS baseline values compared to TD children. These atypical ANS responses to pleasant touch in ASD children were not specific to CT-fiber stimulation. Overall, these results point towards both basal autonomic dysregulation and lower tactile autonomic evoked responses in ASD, possibly reflecting lower arousal and related to social disengagement.

3.
Front Neurosci ; 16: 1033243, 2022.
Article in English | MEDLINE | ID: mdl-36478875

ABSTRACT

Introduction: The COVID-19 pandemic has imposed to wear a face mask that may have negative consequences for social interactions despite its health benefits. A lot of recent studies focused on emotion recognition of masked faces, as the mouth is, with the eyes, essential to convey emotional content. However, none have studied neurobehavioral and neurophysiological markers of masked faces perception, such as ocular exploration and pupil reactivity. The purpose of this eye tracking study was to quantify how wearing a facial accessory, and in particular a face mask, affected the ocular and pupillary response to a face, emotional or not. Methods: We used videos of actors wearing a facial accessory to characterize the visual exploration and pupillary response in several occlusion (no accessory, sunglasses, scarf, and mask) and emotional conditions (neutral, happy, and sad) in a population of 44 adults. Results: We showed that ocular exploration differed for face covered with an accessory, and in particular a mask, compared to the classical visual scanning pattern of a non-covered face. The covered areas of the face were less explored. Pupil reactivity seemed only slightly affected by the mask, while its sensitivity to emotions was observed even in the presence of a facial accessory. Discussion: These results suggest a mixed impact of the mask on attentional capture and physiological adjustment, which does not seem to be reconcilable with its strong effect on behavioral emotional recognition previously described.

4.
Front Neurosci ; 16: 982899, 2022.
Article in English | MEDLINE | ID: mdl-36213730

ABSTRACT

With the COVID-19 pandemic, we have become used to wearing masks and have experienced how masks seem to impair emotion and speech recognition. While several studies have focused on facial emotion recognition by adding images of masks on photographs of emotional faces, we have created a video database with actors really wearing masks to test its effect in more ecological conditions. After validating the emotions displayed by the actors, we found that surgical mask impaired happiness and sadness recognition but not neutrality. Moreover, for happiness, this effect was specific to the mask and not to covering the lower part of the face, possibly due to a cognitive bias associated with the surgical mask. We also created videos with speech and tested the effect of mask on emotion and speech recognition when displayed in auditory, visual, or audiovisual modalities. In visual and audiovisual modalities, mask impaired happiness and sadness but improved neutrality recognition. Mask impaired the recognition of bilabial syllables regardless of modality. In addition, it altered speech recognition only in the audiovisual modality for participants above 70 years old. Overall, COVID-19 masks mainly impair emotion recognition, except for older participants for whom it also impacts speech recognition, probably because they rely more on visual information to compensate age-related hearing loss.

5.
Int J Psychophysiol ; 180: 68-78, 2022 10.
Article in English | MEDLINE | ID: mdl-35914548

ABSTRACT

Considering the suspected involvement of the autonomic nervous system (ANS) in several neurodevelopmental disorders, a description of its tonus in typical populations and of its maturation between childhood and adulthood is necessary. We aimed to arrive at a better understanding of the maturation of the sympathetic (SNS) and parasympathetic (PNS) tonus by comparing children and adults at rest, via recordings of multiple ANS indices. We recorded simultaneously pupil diameter, electrodermal activity (EDA) and cardiac activity (RR interval and HRV: heart rate variability) in 29 children (6-12 years old) and 30 adults (20-42 years old) during a 5-min rest period. Children exhibited lower RR intervals, higher LF peak frequencies, and lower LF/HF (low frequency/high frequency) ratios compared to adults. Children also produced more spontaneous EDA peaks, reflected in a larger EDA AUC (area under the curve), in comparison with adults. Finally, children displayed a larger median pupil diameter and a higher pupillary hippus frequency than adults. Our results converged towards higher SNS and PNS tones in children compared to adults. Childhood would thus be characterized by a high autonomic tone, possibly reflecting a physiological state compatible with developmental acquisitions.


Subject(s)
Autonomic Nervous System , Pupil , Adult , Autonomic Nervous System/physiology , Caffeine , Child , Heart Rate/physiology , Humans , Pupil/physiology , Young Adult
6.
Neuroimage ; 209: 116517, 2020 04 01.
Article in English | MEDLINE | ID: mdl-31923605

ABSTRACT

Frontal Eye Field (FEF) neurons discriminate between relevant and irrelevant visual stimuli and their response magnitude predicts conscious perception. How this is reflected in the spatial representation of a visual stimulus at the neuronal population level is unknown. We recorded neuronal population activity in the FEF while monkeys were performing a forced choice cued detection task with identical target and distractor stimuli. We quantified, using machine learning techniques, estimates of target and distractor location from FEF population multiunit activities. We found that the FEF population activity provides a precise single trial estimate of reported stimuli locations. Importantly, the closer this prefrontal population single trial estimate is to the veridical stimulus location, the higher the probability that the target or the distractor is reported as perceived. We show that stimulus perception is rescued by the estimate of attention allocation specifically when the latter is close enough to the actual stimulus location, thus indicating a partial independence between attention and perception. Overall, we thus show that how and what we perceive of our environment depends on the spatial precision with which this environment is coded by prefrontal neuronal populations.


Subject(s)
Attention/physiology , Machine Learning , Prefrontal Cortex/physiology , Space Perception/physiology , Visual Perception/physiology , Animals , Electroencephalography , Macaca mulatta , Male , Neurons/physiology
7.
J Child Psychol Psychiatry ; 61(7): 768-778, 2020 07.
Article in English | MEDLINE | ID: mdl-31823380

ABSTRACT

BACKGROUND: Faces are crucial social stimuli, eliciting automatic processing associated with increased physiological arousal in observers. The level of arousal can be indexed by pupil diameter (the 'Event-Related Pupil Dilation', ERPD). However, many parameters could influence the arousal evoked by a face and its social saliency (e.g. virtual vs. real, neutral vs. emotional, static vs. dynamic). A few studies have shown an atypical ERPD in autism spectrum disorder (ASD) patients using several kinds of faces but no study has focused on identifying which parameter of the stimulus is the most interfering with face processing in ASD. METHODS: In order to disentangle the influence of these parameters, we propose an original paradigm including stimuli along an ecological social saliency gradient: from static objects to virtual faces to dynamic emotional faces. This strategy was applied to 186 children (78 ASD and 108 typically developing (TD) children) in two pupillometric studies (22 ASD and 47 TD children in the study 1 and 56 ASD and 61 TD children in the study 2). RESULTS: Strikingly, the ERPD in ASD children is insensitive to any of the parameters tested: the ERPD was similar for objects, static faces or dynamic faces. On the opposite, the ERPD in TD children is sensitive to all the parameters tested: the humanoid, biological, dynamic and emotional quality of the stimuli. Moreover, ERPD had a good discriminative power between ASD and TD children: ASD had a larger ERPD than TD in response to virtual faces, while TD had a larger ERPD than ASD for dynamic faces. CONCLUSIONS: This novel approach evidences an abnormal physiological adjustment to socially relevant stimuli in ASD.


Subject(s)
Arousal , Autism Spectrum Disorder/psychology , Emotions , Facial Expression , Facial Recognition , Pupil , Child , Child, Preschool , Female , Humans , Male
8.
Cereb Cortex ; 29(6): 2588-2606, 2019 06 01.
Article in English | MEDLINE | ID: mdl-29901747

ABSTRACT

The brain has a remarkable capacity to recover after lesions. However, little is known about compensatory neural adaptations at the systems level. We addressed this question by investigating behavioral and (correlated) functional changes throughout the cortex that are induced by focal, reversible inactivations. Specifically, monkeys performed a demanding covert spatial attention task while the lateral intraparietal area (LIP) was inactivated with muscimol and whole-brain fMRI activity was recorded. The inactivation caused LIP-specific decreases in task-related fMRI activity. In addition, these local effects triggered large-scale network changes. Unlike most studies in which animals were mainly passive relative to the stimuli, we observed heterogeneous effects with more profound muscimol-induced increases of task-related fMRI activity in areas connected to LIP, especially FEF. Furthermore, in areas such as FEF and V4, muscimol-induced changes in fMRI activity correlated with changes in behavioral performance. Notably, the activity changes in remote areas did not correlate with the decreased activity at the site of the inactivation, suggesting that such changes arise via neuronal mechanisms lying in the intact portion of the functional task network, with FEF a likely key player. The excitation-inhibition dynamics unmasking existing excitatory connections across the functional network might initiate these rapid adaptive changes.


Subject(s)
Adaptation, Physiological/physiology , Neural Pathways/physiology , Parietal Lobe/physiology , Recovery of Function/physiology , Animals , GABA-A Receptor Agonists/toxicity , Macaca mulatta , Magnetic Resonance Imaging , Male , Muscimol/toxicity , Neural Pathways/drug effects , Parietal Lobe/drug effects
9.
Neuroimage ; 176: 164-178, 2018 08 01.
Article in English | MEDLINE | ID: mdl-29679734

ABSTRACT

While extra-personal space is often erroneously considered as a unique entity, early neuropsychological studies report a dissociation between near and far space processing both in humans and in monkeys. Here, we use functional MRI in a naturalistic 3D environment to describe the non-human primate near and far space cortical networks. We describe the co-occurrence of two extended functional networks respectively dedicated to near and far space processing. Specifically, far space processing involves occipital, temporal, parietal, posterior cingulate as well as orbitofrontal regions not activated by near space, possibly subserving the processing of the shape and identity of objects. In contrast, near space processing involves temporal, parietal, prefrontal and premotor regions not activated by far space, possibly subserving the preparation of an arm/hand mediated action in this proximal space. Interestingly, this network also involves somatosensory regions, suggesting a cross-modal anticipation of touch by a nearby object. Last, we also describe cortical regions that process both far and near space with a preference for one or the other. This suggests a continuous encoding of relative distance to the body, in the form of a far-to-near gradient. We propose that these cortical gradients in space representation subserve the physically delineable peripersonal spaces described in numerous psychology and psychophysics studies.


Subject(s)
Body Image , Cerebral Cortex/physiology , Personal Space , Space Perception/physiology , Visual Perception/physiology , Animals , Brain Mapping , Female , Macaca mulatta , Magnetic Resonance Imaging , Male , Neural Pathways/physiology
10.
J Chem Neuroanat ; 89: 69-72, 2018 04.
Article in English | MEDLINE | ID: mdl-29128349

ABSTRACT

Autism and Autism Spectrum Disorder (ASD) cover a large variety of clinical profiles which share two main dimensions: social and communication impairment and repetitive behaviors or restricted interests, which are present during childhood. There is now no doubt that genetic factors are a major component in the etiology of autism but precise physiopathological pathways are still being investigated. Furthermore, developmental trajectories combined with compensatory mechanisms will lead to various clinical and neurophysiological profiles which together constitute this Autism Spectrum Disorder. To better understand the pathophysiology of autism, comprehension of key neurophysiological mechanisms and brain circuits underlying the different bioclinical profiles is thus crucial. To achieve this goal we propose a strategy which investigates different levels of information processing from sensory perception to complex cognitive processing, taking into account the complexity of the stimulus and whether it is social or non-social in nature. In order to identify different developmental trajectories and to take into account compensatory mechanisms, we further propose that such protocols should be carried out in individuals from childhood to adulthood representing a wide variety of clinical forms.


Subject(s)
Autism Spectrum Disorder/physiopathology , Brain/physiopathology , Neural Pathways/physiopathology , Humans , Research Design
11.
J Neurophysiol ; 119(3): 1037-1044, 2018 03 01.
Article in English | MEDLINE | ID: mdl-29212922

ABSTRACT

Several premotor areas have been identified within primate cingulate cortex; however their function is yet to be uncovered. Recent brain imaging work in humans revealed a topographic anatomofunctional overlap between feedback processing during exploratory behaviors and the corresponding body fields in the rostral cingulate motor area (RCZa), suggesting an embodied representation of feedback. In particular, a face field in RCZa processes juice feedback. Here we tested an extension of the embodied principle in which unexpected or relevant information obtained through the eye or the face would be processed by face fields in cingulate motor areas, and whether this applied to monkey cingulate cortex. We show that activations for juice reward, eye movement, eye blink, and tactile stimulation on the face overlap over two subfields within the cingulate sulcus likely corresponding to the rostral and caudal cingulate motor areas. This suggests that in monkeys as is the case in humans, behaviorally relevant information is processed through multiple cingulate body/effector maps. NEW & NOTEWORTHY What is the role of cingulate motor areas? In this study we observed in monkeys that, as in humans, neural responses to face-related events, juice reward, eye movement, eye blink, and tactile stimulations, clustered redundantly in two separate cingulate subfields. This suggests that behaviorally relevant information is processed by multiple cingulate effector maps. Importantly, this overlap supports the principle that the cingulate cortex processes feedback based on where it is experienced on the body.


Subject(s)
Facial Recognition , Gyrus Cinguli/physiology , Reward , Animals , Eye Movements , Face , Female , Macaca mulatta , Male , Physical Stimulation , Touch Perception
12.
J Neurosci ; 37(44): 10656-10670, 2017 11 01.
Article in English | MEDLINE | ID: mdl-28993482

ABSTRACT

In the jungle, survival is highly correlated with the ability to detect and distinguish between an approaching predator and a putative prey. From an ecological perspective, a predator rapidly approaching its prey is a stronger cue for flight than a slowly moving predator. In the present study, we use functional magnetic resonance imaging in the nonhuman primate, to investigate the neural bases of the prediction of an impact to the body by a looming stimulus, i.e., the neural bases of the interaction between a dynamic visual stimulus approaching the body and its expected consequences onto an independent sensory modality, namely, touch. We identify a core cortical network of occipital, parietal, premotor, and prefrontal areas maximally activated by tactile stimulations presented at the predicted time and location of impact of the looming stimulus on the faces compared with the activations observed for spatially or temporally incongruent tactile and dynamic visual cues. These activations reflect both an active integration of visual and tactile information and of spatial and temporal prediction information. The identified cortical network coincides with a well described multisensory visuotactile convergence and integration network suggested to play a key role in the definition of peripersonal space. These observations are discussed in the context of multisensory integration and spatial, temporal prediction and Bayesian causal inference.SIGNIFICANCE STATEMENT Looming stimuli have a particular ecological relevance as they are expected to come into contact with the body, evoking touch or pain sensations and possibly triggering an approach or escape behavior depending on their identity. Here, we identify the nonhuman primate functional network that is maximally activated by tactile stimulations presented at the predicted time and location of impact of the looming stimulus. Our findings suggest that the integration of spatial and temporal predictive cues possibly rely on the same neural mechanisms that are involved in multisensory integration.


Subject(s)
Anticipation, Psychological/physiology , Photic Stimulation/methods , Touch/physiology , Visual Perception/physiology , Animals , Eye Movements/physiology , Female , Forecasting , Macaca mulatta , Magnetic Resonance Imaging/methods , Male , Physical Stimulation/methods , Reaction Time/physiology
13.
Curr Biol ; 26(13): 1699-1704, 2016 07 11.
Article in English | MEDLINE | ID: mdl-27238280

ABSTRACT

Direct access to motor cortical information now enables tetraplegic patients to precisely control neuroprostheses and recover some autonomy. In contrast, explicit access to higher cortical cognitive functions, such as covert attention, has been missing. Indeed, this cognitive information, known only to the subject, can solely be inferred by an observer from the subject's overt behavior. Here, we present direct two-dimensional real-time access to where monkeys are covertly paying attention, using machine-learning decoding methods applied to their ongoing prefrontal cortical activity. Decoded attention was highly predictive of overt behavior in a cued target-detection task. Indeed, monkeys had a higher probability of detecting a visual stimulus as the distance between decoded attention and stimulus location decreased. This was true whether the visual stimulus was presented at the cued target location or at another distractor location. In error trials, in which the animals failed to detect the cued target stimulus, both the locations of attention and visual cue were misencoded. This misencoding coincided with a specific state of the prefrontal cortical population in which the shared variability between its different neurons (or noise correlations) was high, even before trial onset. This observation strongly suggests a functional link between high noise-correlation states and attentional failure. Overall, this real-time access to the attentional spotlight, as well as the identification of a neural signature of attentional lapses, open new perspectives both to the study of the neural bases of attention and to the remediation or enhancement of the attentional function using neurofeedback.


Subject(s)
Attention , Macaca mulatta/physiology , Prefrontal Cortex/physiology , Space Perception , Animals , Cues , Male
14.
J Neurophysiol ; 115(1): 80-91, 2016 Jan 01.
Article in English | MEDLINE | ID: mdl-26467517

ABSTRACT

In nonhuman primates, tactile representation at the cortical level has mostly been studied using single-cell recordings targeted to specific cortical areas. In this study, we explored the representation of tactile information delivered to the face or the shoulders at the whole brain level, using functional magnetic resonance imaging (fMRI) in the nonhuman primate. We used air puffs delivered to the center of the face, the periphery of the face, or the shoulders. These stimulations elicited activations in numerous cortical areas, encompassing the primary and secondary somatosensory areas, prefrontal and premotor areas, and parietal, temporal, and cingulate areas as well as low-level visual cortex. Importantly, a specific parieto-temporo-prefrontal network responded to the three stimulations but presented a marked preference for air puffs directed to the center of the face. This network corresponds to areas that are also involved in near-space representation, as well as in the multisensory integration of information at the interface between this near space and the skin of the face, and is probably involved in the construction of a peripersonal space representation around the head.


Subject(s)
Brain Mapping , Cerebral Cortex/physiology , Head/physiology , Shoulder/physiology , Touch Perception , Animals , Female , Macaca mulatta , Magnetic Resonance Imaging , Male , Personal Space
15.
Neuroimage ; 117: 93-102, 2015 Aug 15.
Article in English | MEDLINE | ID: mdl-25988226

ABSTRACT

The proposal that sensory processing is achieved in segregated anatomical pathways has been profoundly revisited following the description of cross-modal anatomical connections both at higher and at lower processing levels. However, an understanding of the cortical extent of these long range cross-modal functional influences has been missing. Here, we use functional magnetic resonance imaging (fMRI) to map, in the non-human primate brain, the cortical regions which are activated by both visual and tactile stimulations. We describe an unprecedented pattern of functional visuo-tactile convergence, encompassing both low-level visual and somatosensory areas and multiple higher-order associative areas. We also show that the profile of this convergence depends on the physical properties of the mapping stimuli, indicating that visuo-tactile convergence is most probably even more prevailing than what we actually describe. Overall, these observations substantiate the view that the brain is massively multisensory.


Subject(s)
Brain/physiology , Touch Perception/physiology , Visual Perception/physiology , Animals , Brain Mapping , Female , Macaca mulatta , Magnetic Resonance Imaging , Male , Photic Stimulation , Physical Stimulation
16.
J Neurosci ; 35(10): 4179-89, 2015 Mar 11.
Article in English | MEDLINE | ID: mdl-25762665

ABSTRACT

From an ecological point of view, approaching objects are potentially more harmful than receding objects. A predator, a dominant conspecific, or a mere branch coming up at high speed can all be dangerous if one does not detect them and produce the appropriate escape behavior fast enough. And indeed, looming stimuli trigger stereotyped defensive responses in both monkeys and human infants. However, while the heteromodal somatosensory consequences of visual looming stimuli can be fully predicted by their spatiotemporal dynamics, few studies if any have explored whether visual stimuli looming toward the face predictively enhance heteromodal tactile sensitivity around the expected time of impact and at its expected location on the body. In the present study, we report that, in addition to triggering a defensive motor repertoire, looming stimuli toward the face provide the nervous system with predictive cues that enhance tactile sensitivity on the face. Specifically, we describe an enhancement of tactile processes at the expected time and location of impact of the stimulus on the face. We additionally show that a looming stimulus that brushes past the face also enhances tactile sensitivity on the nearby cheek, suggesting that the space close to the face is incorporated into the subjects' body schema. We propose that this cross-modal predictive facilitation involves multisensory convergence areas subserving the representation of a peripersonal space and a safety boundary of self.


Subject(s)
Attention/physiology , Signal Detection, Psychological/physiology , Space Perception/physiology , Touch/physiology , Visual Perception/physiology , Adult , Analysis of Variance , Electromyography , Evoked Potentials, Motor , Female , Humans , Male , Muscle Contraction , Photic Stimulation , Predictive Value of Tests , Psychophysics , Young Adult
17.
Neuropsychologia ; 70: 313-26, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25447371

ABSTRACT

While space is perceived as unitary, experimental evidence indicates that the brain actually contains a modular representation of space, specific cortical regions being involved in the processing of extra-personal space, that is the space that is far away from the subject and that cannot be directly acted upon by the body, while other cortical regions process peripersonal space, that is the space that directly surrounds us and which we can act upon. In the present review, we focus on non-human primate research and we review the single cells, areal and cortical functional network mechanisms that are proposed to underlie extrapersonal and peripersonal space representations. Importantly, the current dominant framework for the study of peripersonal space is centered on the key notion that actions and specifically arm and hand-related actions, shape cortical peripersonal space representations. In the present review, we propose to enlarge this framework to include other variables that have the potential to shape peripersonal space representations, namely emotional and social information. In the initial section of the manuscript, we thus first provide an extensive up-to-date review of the low level sensory and oculomotor signals that contribute to the construction of a core cortical far and near space representation, in key parietal, premotor and prefrontal periarcuate cortical regions. We then highlight the key functional properties that are needed to encode peripersonal space and we narrow down our discussion to the specific parietal and periarcuate areas that share these properties: the parieto-premotor peripersonal space network and the parieto-premotor network for grasping. Last, we review evidence for a changing peripersonal space representation. While plastic changes in peripersonal space representation have been described during tool use and their underlying neural bases have been well characterized, the description of dynamical changes in peripersonal space representation as a function of the emotional or social context is quite novel and relies on behavioral human studies. The neural bases of such a dynamic adjustments of peripersonal space coding are yet unknown. We thus review these novel observations and we discuss their putative underlying neural bases.


Subject(s)
Brain Mapping , Cerebral Cortex/physiology , Personal Space , Space Perception/physiology , Animals , Cerebral Cortex/blood supply , Emotions , Hand Strength , Humans , Neuroimaging , Photic Stimulation , Sensation/physiology
18.
Cereb Cortex ; 25(9): 2333-45, 2015 Sep.
Article in English | MEDLINE | ID: mdl-24654257

ABSTRACT

Eyeblinks are defined as a rapid closing and opening of the eyelid. Three types of blinks are defined: spontaneous, reflexive, and voluntary. Here, we focus on the cortical correlates of spontaneous blinks, using functional magnetic resonance imaging (fMRI) in the nonhuman primate. Our observations reveal an ensemble of cortical regions processing the somatosensory, proprioceptive, peripheral visual, and possibly nociceptive consequences of blinks. These observations indicate that spontaneous blinks have consequences on the brain beyond the visual cortex, possibly contaminating fMRI protocols that generate in the participants heterogeneous blink behaviors. This is especially the case when these protocols induce (nonunusual) eye fatigue and corneal dryness due to demanding fixation requirements, as is the case here. Importantly, no blink related activations were observed in the prefrontal and parietal blinks motor command areas nor in the prefrontal, parietal, and medial temporal blink suppression areas. This indicates that the absence of activation in these areas is not a signature of the absence of blink contamination in the data. While these observations increase our understanding of the neural bases of spontaneous blinks, they also strongly call for new criteria to identify whether fMRI recordings are contaminated by a heterogeneous blink behavior or not.


Subject(s)
Blinking/physiology , Cerebral Cortex/blood supply , Cerebral Cortex/physiology , Magnetic Resonance Imaging , Acoustic Stimulation , Animals , Face/innervation , Female , Image Processing, Computer-Assisted , Macaca mulatta , Male , Oxygen , Regression Analysis , Statistics, Nonparametric , Time Factors , Touch/physiology
19.
Front Syst Neurosci ; 8: 144, 2014.
Article in English | MEDLINE | ID: mdl-25161613

ABSTRACT

Brain-machine interfaces (BMIs) using motor cortical activity to drive an external effector like a screen cursor or a robotic arm have seen enormous success and proven their great rehabilitation potential. An emerging parallel effort is now directed to BMIs controlled by endogenous cognitive activity, also called cognitive BMIs. While more challenging, this approach opens new dimensions to the rehabilitation of cognitive disorders. In the present work, we focus on BMIs driven by visuospatial attention signals and we provide a critical review of these studies in the light of the accumulated knowledge about the psychophysics, anatomy, and neurophysiology of visual spatial attention. Importantly, we provide a unique comparative overview of the several studies, ranging from non-invasive to invasive human and non-human primates studies, that decode attention-related information from ongoing neuronal activity. We discuss these studies in the light of the challenges attention-driven cognitive BMIs have to face. In a second part of the review, we discuss past and current attention-based neurofeedback studies, describing both the covert effects of neurofeedback onto neuronal activity and its overt behavioral effects. Importantly, we compare neurofeedback studies based on the amplitude of cortical activity to studies based on the enhancement of cortical information content. Last, we discuss several lines of future research and applications for attention-driven cognitive brain-computer interfaces (BCIs), including the rehabilitation of cognitive deficits, restored communication in locked-in patients, and open-field applications for enhanced cognition in normal subjects. The core motivation of this work is the key idea that the improvement of current cognitive BMIs for therapeutic and open field applications needs to be grounded in a proper interdisciplinary understanding of the physiology of the cognitive function of interest, be it spatial attention, working memory or any other cognitive signal.

20.
J Neurosci ; 33(9): 4128-39, 2013 Feb 27.
Article in English | MEDLINE | ID: mdl-23447621

ABSTRACT

The parietal cortex is highly multimodal and plays a key role in the processing of objects and actions in space, both in human and nonhuman primates. Despite the accumulated knowledge in both species, we lack the following: (1) a general description of the multisensory convergence in this cortical region to situate sparser lesion and electrophysiological recording studies; and (2) a way to compare and extrapolate monkey data to human results. Here, we use functional magnetic resonance imaging (fMRI) in the monkey to provide a bridge between human and monkey studies. We focus on the intraparietal sulcus (IPS) and specifically probe its involvement in the processing of visual, tactile, and auditory moving stimuli around and toward the face. We describe three major findings: (1) the visual and tactile modalities are strongly represented and activate mostly nonoverlapping sectors within the IPS. The visual domain occupies its posterior two-thirds and the tactile modality its anterior one-third. The auditory modality is much less represented, mostly on the medial IPS bank. (2) Processing of the movement component of sensory stimuli is specific to the fundus of the IPS and coincides with the anatomical definition of monkey ventral intraparietal area (VIP). (3) A cortical sector within VIP processes movement around and toward the face independently of the sensory modality. This amodal representation of movement may be a key component in the construction of peripersonal space. Overall, our observations highlight strong homologies between macaque and human VIP organization.


Subject(s)
Afferent Pathways/physiology , Brain Mapping , Nerve Net/physiology , Parietal Lobe/physiology , Acoustic Stimulation , Afferent Pathways/blood supply , Analysis of Variance , Animals , Female , Functional Laterality , Image Processing, Computer-Assisted , Macaca mulatta , Magnetic Resonance Imaging , Male , Movement , Nerve Net/blood supply , Oxygen/blood , Parietal Lobe/blood supply , Photic Stimulation , Reaction Time , Touch/physiology
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