Investigating the spatial characteristics of the crossmodal interaction between nociception and vision using gaze direction

The present study investigated the influence of nociceptive stimuli on visual stimuli processing according to the relative spatial congruence between the two stimuli of different sensory modalities. Participants performed temporal order judgments on pairs of visual stimuli, one presented near the hand on which nociceptive stimuli were occasionally applied, the other one either to its left or to its right. The visual hemifield in which the stimulated hand and the near visual stimulus appeared was manipulated by changing gaze direction. The stimulated hemibody and the stimulated visual hemifield were therefore either congruent or incongruent, in terms of anatomical locations. Despite the changes in anatomical congruence, judgments were always biased in favor of the visual stimuli presented near the stimulated hand. This indicates that nociceptive-visual interaction may rely on a realignment of the respective initial anatomical representations of the somatic and retinotopic spaces toward an integrated, multimodal representation of external space.</p

Investigating the spatial characteristics of the crossmodal interaction between nociception and vision using gaze direction

The present study investigated the influence of nociceptive stimuli on visual stimuli processing according to the relative spatial congruence between the two stimuli of different sensory modalities. Participants performed temporal order judgments on pairs of visual stimuli, one presented near the hand on which nociceptive stimuli were occasionally applied, the other one either to its left or to its right. The visual hemifield in which the stimulated hand and the near visual stimulus appeared was manipulated by changing gaze direction. The stimulated hemibody and the stimulated visual hemifield were therefore either congruent or incongruent, in terms of anatomical locations. Despite the changes in anatomical congruence, judgments were always biased in favor of the visual stimuli presented near the stimulated hand. This indicates that nociceptive-visual interaction may rely on a realignment of the respective initial anatomical representations of the somatic and retinotopic spaces toward an integrated, multimodal representation of external space

Do nociception and pain affect the perception of peripersonal space ? Studies in healthy volunteers and patients with complex regional pain syndrome

This thesis has been articulated around the question whether nociceptive stimuli and pain can impact the perception of the visual space around the body. This was investigated in healthy volunteers by experimentally applying brief nociceptive stimuli, and in patients suffering from chronic pain in one limb. In healthy participants, we showed that nociceptive stimuli can actually facilitate the processing of visual stimuli. Crucially, such crossmodal facilitation is more efficient when visual stimuli occur in close proximity to the hand on which the nociceptive stimuli are applied. We furthermore showed that patients suffering from upper-limb complex regional pain syndrome paid less attention to visual stimuli occurring in the immediate vicinity of their affected limb. This suggests that the way we perceive and represent our near visual surrounding is influenced by somatic, e.g. nociceptive, sensations and that pain is processed according to a representation of the body that is not limited to its physical boundaries.(PSYE - Sciences psychologiques et de l'éducation) -- UCL, 201

Visuo-nociceptive interactions and their effect on the motor system

Pain, besides its contribution to body homeostasis, has also the function of providing information on external stimuli that can potentially harm the body. Such exteroceptive function relies on an optimally integrated multisensory representation of the body and its surrounding space, which is based on interactions between somatic and extra-somatic stimuli occurring near the body. While such interactions between nociceptive and near visual stimuli have recently been demonstrated, showing that visual stimuli can impact the perception of nociceptive stimuli and vice versa, their functional role is not clear yet. It is indeed hypothesized that one of the functions of such multisensory representations would be to optimize defensive reactions against threatening stimuli. However, the idea of this potential defensive purpose has, to date, mainly been based on studies conducted in non-human primates. I will present two studies investigating whether interactions between nociceptive and near visual stimuli can shape motor reactions of the stimulated limb. More precisely, we tested whether visual stimuli approaching the body part on which nociceptive stimuli are applied can modulate spinal, as well as cortico-spinal, excitability (measured with the spinal nociceptive withdrawal reflex and single-pulse transcranial magnetic stimulation, respectively). Spinal nociceptive excitability was shown to be modulated by the presence of the visual stimuli, but neither spinal, nor cortico-spinal excitability, were modulated differently by approaching vs. receding visual stimuli, suggesting that our experimental set-up did not allow to highlight specific visual-nociceptive interaction effects, which might depend on a more complex, time-dependent, interplay between the nociceptive and the visual stimulation

Modulation of Spinal Nociceptive Excitability by Nociceptive-Visual Interaction

Pain, besides its contribution to body homeostasis, has also the function of providing information on external stimuli that can potentially harm the body. Such exteroceptive function relies on an optimally integrated multisensory representation of the body and its surrounding space, which is based on the interaction between somatic and extra-somatic stimuli occurring near the body. While the existence of such interactions between nociceptive and visual stimuli has recently been demonstrated, showing that visual stimuli outside the body can impact the perception of nociceptive stimuli and vice versa, their functional role is not clear yet. It is indeed hypothesized that one of the functions of such multisensory representations would be to optimize defensive reactions against threatening stimuli. However, the idea of this potential defensive purpose has, to date, mainly been based on a set of studies conducted in non-human primates. The aim of the present study was to investigate whether interactions between nociceptive and external visual stimuli can shape motor reactions of the stimulated limb. More specifically, we tested in 24 participants whether spinal nociceptive excitability, as measured by the spinal nociceptive withdrawal reflex (NWR) in response to noxious stimuli, can be modulated by external visual stimuli, specifically those approaching the body part on which the nociceptive stimuli are applied. NWRs were elicited by applying transcutaneous electrical stimuli in the sole of the foot of the participants. Depending on the condition, the electrical stimulus was either preceded by a dynamic visual stimulus rapidly approaching a location near the stimulated foot (NWR-visual near condition), a dynamic visual stimulus approaching a location further away from the stimulated foot (NWR-visual far condition), or was applied without any dynamic visual stimulus (NWR only condition). The electrical stimulation could be applied at one out of two possible time points of the trial, so that the NWR was either induced when the visual stimulus was perceived as still moving (early time point condition) or when it arrived at its endpoint (late time point condition). Furthermore, to avoid that the visual stimulus solely acted as a cue predicting the occurrence of the electrical stimulus, control conditions in which the dynamic visual stimuli (near or far) were presented without an electrical stimulus were also added. Trials of the different conditions were presented randomly and after each trial the participants rated the intensity of the electrical stimulus on a numerical rating scale (NRS) ranging from 0 to 10, anchored as 0: perception threshold, 5: pain threshold, 10: maximum imaginable pain. NWRs were obtained by recording the electromyographic responses in the tibialis anterior muscle of the leg and NWR size was quantified by the root-mean-square (RMS) amplitude in the 60- to 180-ms poststimulus window. For each participant, NWR amplitude and NRS rating change (in %) with regard to NWR amplitude and NRS rating in the NWR only condition (baseline) were calculated. One-sample Wilcoxon signed rank tests (to 0) were performed for all conditions to test for the presence of significant changes in NWR amplitude and NRS rating with regard to baseline and the different conditions were compared with a repeated measures ANOVA with visual condition (2) and time point (2) as within participant factors. Results show that there was a significant increase in NWR size in the NWR-visual near condition for both time points (early: M=33.5%, SD: 42.2%; late: M=30.5%, SD= 56.4%) with regard to the NWR only condition. In the NWR-visual far condition, NWR size was significantly increased for the early time point (M=30.4%, SD= 61.4%), but not for the late time point (M=22.7%, SD= 49.9%). The different conditions were not significantly different from each other. There was no significant change in NRS ratings with regard to the NWR only condition for both NWR-visual near and NWR-visual far conditions, and the different conditions were not significantly different from each other. These results suggest that spinal nociceptive excitability can be modulated by the presence of dynamic visual stimuli. Whether this modulatory effect on the spinal nociceptive reflex system is more important for near vs. far visual stimuli could however not be clearly established, and might depend on a more complex time-dependent interplay between the nociceptive and visual stimulation. This finding corroborates previous research that demonstrated supraspinal descending modulation of the NWR, for example by cognitive and emotional states, but also adds to the current literature by showing that NWR amplitude can already be modulated by external visual stimuli without any explicit emotional or task-related valence, possibly through the existence of a multisensory representation of the body and its surrounding visual space

Revue conceptuelle et empirique du traitement des expressions faciales émotionnelles chez l’enfant anxieux

Anxiety disorders are known to disturb the processing of emotional facial expressions (EFE). Notably, attentional biases toward threatening EFE would play a role in the aetiology and the maintenance of anxious disorders. A large amount of studies has approached these questions in adults but studies on children and youth remain rare and their results are less consistent. This paper reviews the data concerning the features and the behavioural, neuroanatomical and neurophysiological correlates of biases in EFE processing in childhood anxiety. The recognition of EFE will also be discussed within the context of cognitive development. Finally, we will put a critical view on this field in order to outline proposals for future research

Disturbed Spatial Perception and Body Representation in Complex Regional Pain Syndrom

Complex regional pain syndrome (CRPS) is a chronic pain condition associating sensory, motor, trophic and autonomic symptoms in one limb. Cognitive impairments have also been reported, affecting the patients’ ability to mentally represent, perceive and use their painful limb. However, the nature of these deficits is still a matter of debate. Recent studies suggested that cognitive deficits might be limited to body-related information and body perception, while not extending to external space perception. Furthermore, body representation impairments (as for example measured with hand laterality judgment tasks [HLT]) might not be as consistently found as previously thought, with studies obtaining contradictory results. Here I will present several studies that were aimed at (re)examining and clarifying some of these questions and inconsistencies. These studies were performed with upper-limb CRPS patients and relied on sensitive tasks that allow assessing the presence of cognitive biases in body and external space perception, as well as disrupted mental body representations by focusing on the perception of the physical biomechanics of the body. The results suggest the presence of visuo-spatial deficits in CRPS. We furthermore show that CRPS patients might present with non-lateralized impairments of hand representation, partly related to difficulties in perceiving the physical biomechanics of their upper limbs. At the same time, the results also highlight the importance of verifying the mechanisms and strategies that underlie the performance on the HLT, which should lead to more cautious interpretations of future findings. Implications for the potential use of cognitive-based rehabilitation strategies for CRPS will be discussed

Investigating the multisensory influence of vision on nociception-induced corticospinal excitability

Efficiently reacting to painful events requires an optimally integrated multisensory representation of the body and its surrounding space, coordinating the processing and integration of somatic and extra-somatic stimuli occurring near the body. While such representations would allow optimizing manipulation of innocuous objects, they would also optimize defensive actions against threatening stimuli. Multisensory interactions between nociceptive and near visual stimuli have recently been evidenced. Here we investigated the influence of such nociceptive-visual interaction on the motor excitability of the hand on which nociceptive stimuli are applied in healthy volunteers, by testing whether nociception-induced changes of cortico-spinal excitability (n-CSE) can be differently modulated by visual stimuli presented in the space surrounding the hand vs. visual stimuli presented farther away. CO2-laser nociceptive stimuli were applied on the right hand, followed by 80 ms by a visual stimulus rapidly approaching a location either near or far from the stimulated hand. During each trial, single-pulse transcranial magnetic stimulation over the left M1 hand representation was applied at one out of 3 possible time points (at baseline, 150 or 200 ms after the nociceptive stimulus), eliciting motor-evoked potentials (MEPs) in the right first dorsal interosseous muscle. Conditions comprising only nociceptive or visual stimuli (near or far) were also presented. Preliminary results show a general reduction of MEPs 200 ms after the potential occurrence of the nociceptive stimulus. However, this reduction seemed not differently modulated by near vs. far visual stimuli, suggesting that our experimental setting did not allow to highlight specific visual-nociceptive interaction effects on CSE

Seeing or not Seeing Where Your Hands Are. The Influence of Visual Feedback About Hand Position on the Interaction Between Nociceptive and Visual Stimuli

Examining the mechanisms underlying crossmodal interaction between nociceptive and visual stimuli is crucial to understand how humans handle potential bodily threats in their environment. It has recently been shown that nociceptive stimuli can affect the perception of visual stimuli, provided that they occur close together in external space. The present study addresses the question whether these crossmodal interactions between nociceptive and visual stimuli are mediated by the visually perceived proximity between the visual stimuli and the limb on which nociceptive stimuli are applied, by manipulating the presence vs. absence of visual feedback about the position of the stimulated limb. Participants performed temporal order judgments on pairs of visual stimuli, shortly preceded by nociceptive stimuli, either applied on one hand or both hands simultaneously. The hands were placed near the visual stimuli and could either be seen directly, seen through a glass barrier, or hidden from sight with a wooden board. Unilateral nociceptive stimuli induced spatial biases to the advantage of visual stimuli presented near the stimulated hand, which were greater in the conditions in which the hands were seen than in the condition in which vision was prevented. Spatial biases were not modulated by the presence of the glass barrier, minimizing the possibility that the differential effect between the vision and no-vision conditions is solely due to the presence of the barrier between the hands and the visual stimuli. These findings highlight the importance of visual feedback for determining spatial mapping between nociceptive and visual stimuli for crossmodal interaction