The influence of visual perspective on the somatosensory steady-state response during pain observation

The observation and evaluation of other's pain activate part of the neuronal network involved in the actual experience of pain, including those regions subserving the sensori-discriminative dimension of pain. This was largely interpreted as evidence showing that part of the painful experience can be shared vicariously. Here, we investigated the effect of the visual perspective from which other people’s pain is seen on the cortical response to continuous 25 Hz non-painful somatosensory stimulation (somatosensory steady-state response: SSSR). Based on the shared representation framework, we expected first-person visual perspective (1PP) to yield more changes in cortical activity than third-person visual perspective (3PP) during pain observation. Twenty healthy adults were instructed to rate a series of pseudo-dynamic pictures depicting hands in either painful or non-painful scenarios, presented either in 1PP (0°-45° angle) or 3PP (180° angle), while changes in brain activity was measured with a 128-electode EEG system. The ratings demonstrated that the same scenarios were rated on average as more painful when observed from the 1PP than from the 3PP. As expected from previous works, the SSSR response was decreased after stimulus onset over the left caudal part of the parieto-central cortex, contralateral to the stimulation side. Moreover, the difference between the SSSR was of greater amplitude when the painful situations were presented from the 1PP compared to the 3PP. Together, these results suggest that a visuospatial congruence between the viewer and the observed scenarios is associated with both a higher subjective evaluation of pain and an increased modulation in the somatosensory representation of observed pain. These findings are discussed with regards to the potential role of visual perspective in pain communication and empathy

La prise de perspective lors de l'évaluation de la douleur d'autrui : études auprès d'adultes ayant un trouble psychotique d'évolution récente et d'adultes en bonne santé générale

L’empathie désigne la capacité de partager et de se mettre à la place d’autrui afin d’appréhender son expérience affective. Cette faculté complexe favorise la communication et l’ajustement des comportements sociaux. Les recherches en neurosciences observent une activation partielle des circuits neuronaux reliés aux dimensions sensorielles et affectives de la douleur somatique lorsque les individus partagent et apprécient l’expérience douloureuse d’autrui. Les processus contrôlés de l’empathie, principalement les habiletés de prise de perspective, permettent d’adopter le point de vue d’une autre personne afin de mieux évaluer sa douleur. Les paradigmes d’observation de la douleur représentent une nouvelle avenue pour étudier le fonctionnement de l’empathie dans la schizophrénie. L’étude des troubles psychotiques à début récent favorise l’identification des facteurs qui prédisposent à l'apparition de la psychose. L'objectif de cette thèse consiste à examiner le fonctionnement de la prise de perspective durant l’évaluation de la douleur d’autrui. Dans une première étude, nous démontrons que les adultes en bonne santé évaluent plus intensément des images représentant des scènes douloureuses lorsqu’elles sont présentées selon leur perspective visuelle en comparaison à celle d’une autre personne. En utilisant un EEG, une modulation somatosensorielle plus importante est aussi observée lorsque de la douleur d’autrui est évaluée selon une perspective visuelle à la première personne. Dans une deuxième étude, aucune différence n’est observée entre un groupe de personnes atteintes d’un trouble psychotique d’évolution récente et un groupe témoin quant à l’évaluation de la douleur. Cependant, chez ces derniers, une relation existe entre une faible disposition à la prise de perspective et une évaluation plus intense de la douleur observée selon une perspective visuelle à la première personne. De façon générale, cette thèse souligne le rôle modulateur de la prise de perspective lorsque les gens évaluent l’expérience douloureuse d’un tiers. De plus, nos travaux permettent de considérer de manière nouvelle le fonctionnement de l’empathie dans la schizophrénie en faisant ressortir certaines difficultés d’empathie dans les premières années suivant le déclenchement de la psychose. La discussion met en lien les modèles théoriques sur l’empathie et sur la communication de la douleur.Empathy refers to the capacity to share and understand other people’s emotional states. This faculty can promote communication and social behaviours adjustment. By investigating how people experienced someone else’s suffering, neuroscience research has shown that vicarious pain partially activates the neuronal networks underlying the sensory and affective dimensions of somatic pain. Controlled empathic processes, such as perspective taking abilities, can also be used to deliberately put oneself into another person’s perspective in order to evaluate the painful experience from that person’s perspective. Pain observation paradigms could offer a new insight on the examination of empathy in schizophrenia. Emphasis on the characterization of these abilities during recent onset evolution of psychosis could provide indicators of individuals’ vulnerability to develop schizophrenia. The main objective of this thesis was to examine perspective taking processes when evaluating pain in others. In a first study, we demonstrate that healthy adults evaluate pictures of hands in pain more intensely when they are presented in their own visual perspective in comparison with another person’s viewpoint. Using EEG, we showed that evaluating these painful pictures in one’s own perspective is also associated with a stronger somatosensory modulation. In a second study, we found no difference in the evaluation of painful pictures between adults with recent onset of psychosis and healthy controls. However, a reduction of dispositional perspective taking traits and illness duration in adults with recent onset of psychosis had been found to be related their evaluation of pain observed. Thus, these findings expose possible links between the development of controlled empathy processes and recent of psychosis. In sum, this thesis highlights the modulating influence of perspective taking when people appreciate someone else’s painful experience. Also, this work further characterizes the limited empathy impairment observed in recent onset of psychosis. The discussion proposes an integration of theoretical knowledge from models of empathy and communication of pain

The influence of visual perspective on the somatosensory steady-state response during pain observation

The observation and evaluation of other's pain activate part of the neuronal network involved in the actual experience of pain, including those regions subserving the sensori-discriminative dimension of pain. This was largely interpreted as evidence showing that part of the painful experience can be shared vicariously. Here, we investigated the effect of the visual perspective from which other people’s pain is seen on the cortical response to continuous 25 Hz non-painful somatosensory stimulation (somatosensory steady-state response: SSSR). Based on the shared representation framework, we expected first-person visual perspective (1PP) to yield more changes in cortical activity than third-person visual perspective (3PP) during pain observation. Twenty healthy adults were instructed to rate a series of pseudo-dynamic pictures depicting hands in either painful or non-painful scenarios, presented either in 1PP (0°-45° angle) or 3PP (180° angle), while changes in brain activity was measured with a 128-electode EEG system. The ratings demonstrated that the same scenarios were rated on average as more painful when observed from the 1PP than from the 3PP. As expected from previous works, the SSSR response was decreased after stimulus onset over the left caudal part of the parieto-central cortex, contralateral to the stimulation side. Moreover, the difference between the SSSR was of greater amplitude when the painful situations were presented from the 1PP compared to the 3PP. Together, these results suggest that a visuospatial congruence between the viewer and the observed scenarios is associated with both a higher subjective evaluation of pain and an increased modulation in the somatosensory representation of observed pain. These findings are discussed with regards to the potential role of visual perspective in pain communication and empathy

I am touched by your pain : limb-specific modulation of the cortical response to a tactile stimulation during pain observation

The observation of pain in other individuals is known to impact the cerebral activity in regions dedicated to one’s nociception, as well as the behavior toward the person in pain. However, it remains unclear whether this shared representation for pain modulates somatosensory processing to nonpainful stimuli and whether this modulation is limb specific. Twenty right-handed healthy participants viewed a series of pictures depicting right hands or right feet in painful or nonpainful situations while light repetitive (25 Hz) mechanical stimuli were applied to the hand. The cortical excitability to these nonpainful stimuli was measured through the energy in the 25-Hz frequency band of electroencephalographic data. Following picture onset, a combination of nonspecific and specific modulation of cortical excitability was found. The former was widespread over the parieto-central region and likely related to factors such as attention. The latter was mostly restricted to 3 electrodes over the parietal cortex contralateral to the stimulation of the hand, and was specifically associated with the observation of others’ hand in painful scenarios. This result confirms that the observation of pain can modulate somatosensory cortical excitability in an effector-specific way. The findings add to the accumulating evidence that other people’s somatic pain is mapped onto the observer’s sensori-motor system and offers a new paradigm to investigate potential neurophysiological changes in care providers who are often overexposed to others' pain. Perspective This electroencephalography study demonstrates with a quick, easily implementable, and noninvasive paradigm that the change in cortical somatosensory excitability during pain observation is limb-specific, and confirms from a neuroscience perspective that being exposed to others’ pain implies more than the sharing of an affective experience