Important methodological issues regarding the use of TMS to investigate interoceptive processing: a comment on Pollatos et al (2016)

Comment on: Changes in interoceptive processes following brain stimulation by Pollatos, Herbert, Mai & Kammer, 201

Crossmodal classification of mu rhythm activity during action observation and execution suggests specificity to somatosensory features of actions.

The alpha mu rhythm (8-13 Hz) has been considered to reflect mirror neuron activity due to the fact that it is attenuated by both action observation and action execution. The putative link between mirror neuron system activity and the mu rhythm has been used to study the involvement of the mirror system in a wide range of socio-cognitive processes and clinical disorders. However, previous research has failed to convincingly demonstrate the specificity of the mu rhythm, meaning that it is unclear whether the mu rhythm reflects mirror neuron activity. It also remains unclear if mu rhythm suppression during action observation reflects the processing of motor or tactile information. In an attempt to assess the validity of the mu rhythm as a measure of mirror neuron activity, we used crossmodal pattern classification to assess the specificity of EEG mu rhythm response to action varying in terms of action type (whole-hand or precision grip), concurrent tactile stimulation (stimulation or no stimulation), or object use (transitive or intransitive actions) in twenty human participants. The main results reveal that above-chance crossmodal classification of mu rhythm activity was obtained in the central channels for tactile stimulation and action transitivity but not for action type. Furthermore, traditional univariate analyses applied to the same data were insensitive to differences between conditions. By calling into question the relationship between mirror system activity and the mu rhythm, these results have important implications for the use and interpretation of mu rhythm activity

The importance of stimulus variability when studying face processing using fast periodic visual stimulation:A novel ‘mixed-emotions’ paradigm

Fast Periodic Visual Stimulation (FPVS) with oddball stimuli has been used to investigate discrimination of facial identity and emotion, with studies concluding that oddball responses indicate discrimination of faces at the conceptual level (i.e., discrimination of identity and emotion), rather than low-level perceptual (visual, image-based) discrimination. However, because previous studies have utilised identical images as base stimuli, physical differences between base and oddball stimuli, rather than recognition of identity or emotion, may have been responsible for oddball responses. This study tested two new FPVS paradigms designed to distinguish recognition of expressions of emotion from detection of visual change from the base stream. In both paradigms, the oddball emotional expression was different from that of the base stream images. However, in the ‘fixed-emotion’ paradigm, stimulus image varied at every presentation but the emotion in the base stream remained constant, and in the ‘mixed-emotions’ paradigm, both stimulus image and emotion varied at every presentation, with only the oddball emotion (disgust) remaining constant. In the fixed-emotion paradigm, typical inversion effects were observed at occipital sites. In the mixed-emotions paradigm, however, inversion effects in a central cluster (indicative of higher level emotion processing) were present in typical participants, but not those with alexithymia (who are impaired at emotion recognition), suggesting that only the mixed-emotions paradigm reflects emotion recognition rather than detection of a lower-level visual change from baseline. These results have significant methodological implications for future FPVS studies (of both facial emotion and identity), suggesting that it is crucial to vary base stimuli sufficiently, such that simple physical differences between base and oddball stimuli cannot give rise to neural oddball responses

Differences in Own-Face but not Own-Name Discrimination between Autistic and Neurotypical Adults:A Fast Periodic Visual Stimulation-EEG Study

Self-related processing is thought to be altered in autism, with several studies reporting that autistic individuals show a diminished neural response relative to neurotypicals for their own name and face. However, evidence remains scarce and is mostly based on event-related potential studies. Here, we used EEG to measure the neural activity of autistic adults (20 for faces, 27 for names) and neurotypical adults (24 for faces, 25 for names) while they were watching rapidly alternating faces and names, through a relatively new technique called Fast Periodic Visual Stimulation. We presented strangers’ faces or names at a base frequency of 5.77 Hz, while one’s own, a close other’s, and a specific stranger’s face/name was presented at an oddball frequency of 1.154 Hz. The neurotypical group showed a significantly greater response to their own face than both close other and stranger faces, and a greater response for close other than for stranger faces. In contrast, in the autism group, own and close other faces showed stronger responses than the stranger’s face, but the difference between own and close other faces was not significant in a bilateral parieto-occipital cluster. No group differences in the enhanced response to familiar names were found. These results replicate and extend results obtained using traditional electroencephalographic techniques which suggest atypical responses to self-relevant stimuli in autism

La perception de la douleur d'autrui chez les professionnels de la santé : implication pour l'intervention

La perception de la douleur d’autrui est un phénomène complexe pouvant être influencé par de nombreux facteurs. Dans les milieux cliniques, la perception adéquate de la douleur d’autrui représente une étape importante dans le traitement de celle-ci. Toutefois, certaines études suggèrent que l’exposition répétée à la douleur d’autrui vécue par les professionnels de la santé pourrait mener à une sous-estimation de l’intensité de la douleur des patients et à une diminution des comportements d’aide offerts à ceux-ci. Cette thèse visait donc à utiliser les méthodes des neurosciences cognitives et sociales pour étudier les effets de l’expérience clinique sur la perception et la réponse à la douleur d’autrui. Le premier objectif était d’isoler l’effet d’une exposition répétée à la douleur d’autrui sur la réponse comportementale et cérébrale à celle-ci. La première étude expérimentale de la thèse a permis de mettre en évidence que l’exposition répétée à la douleur d’autrui est associée à des changements dans les réponses comportementales et cérébrales suggérant une diminution de l’intensité perçue et de la saillance des expressions de douleur observées subséquemment. Le second objectif de la thèse était de comparer le comportement d’aide envers la douleur d’autrui entre des professionnels de la santé et des participants sans expérience clinique et les mécanismes cérébraux associés. La seconde étude expérimentale de la thèse montre que lorsque confrontés à la douleur d’autrui, les professionnels de la santé aident davantage les personnes en douleur. Ceci est lié à une plus grande régulation de la réponse émotionnelle indiquée par une activité plus importante de certaines régions préfrontales lors de l’observation de la douleur d’autrui. Ensemble, les résultats de cette thèse suggèrent que l’exposition répétée à la douleur d’autrui mène à une plus grande régulation de la réponse affective lors de l’observation de la douleur d’autrui et que cette plus grande régulation permettrait aux professionnels de la santé de d’aider davantage les patients en douleur rencontrés au quotidien. Les travaux de cette thèse soulignent que la régulation émotionnelle est un phénomène important à tenir compte dans les interactions cliniques et dans la formation des professionnels de la santé.The perception of pain in others is a complex phenomenon that can be influenced by several factors. In clinical settings, the adequate perception of pain in others is an important step in its treatment. However, some studies suggest that the repeated exposure to the pain of others experienced by healthcare providers could lead to an underestimation of the intensity of patients’ pain and to less prosocial behaviours towards persons in pain. This thesis aimed at using methods from the field of cognitive and social neurosciences to study the effects of clinical experience on the perception and response to pain in others. The first objective was to isolate the effect of repeated exposure to the pain of others on the behavioural and cerebral responses to this pain. The first experimental study showed that this repeated exposure to pain in others was associated with a decrease in the perceived saliency and intensity of this pain as indexed by behavioural and cerebral responses. The second objective of this thesis was to compare prosocial behaviour towards persons in pain and the associated cerebral mechanisms between healthcare providers and participants with no healthcare experience. The second experimental study showed that when faced with patients in pain, healthcare providers offer more prosocial behaviour compared to non-clinician participants. This was linked to increased activity in prefrontal regions associated with emotional regulation when facing others in pain. Altogether, the results from this thesis suggest that repeated exposure to persons in pain leads to an increased regulation of the affective response during the observation of pain in others and that this increased regulation allow healthcare professionals to better help patients in pain encountered daily. Results from this thesis underline the importance of emotional regulation in clinical interaction and suggest that it should be taken into account in clinical training programs