Sense of agency in schizophrenia: A reconciliation of conflicting findings through a theory-driven literature review.

The sense of agency is the experience of being the author of self-generated actions and their outcomes. Both clinical manifestations and experimental evidence suggest that the agency experience and the mechanisms underlying agency attribution may be dysfunctional in schizophrenia. Yet, studies investigating the sense of agency in these patients show seemingly conflicting results: some indicated under-attribution of self-agency (coherently with certain positive symptoms), while others suggested over-attribution of self-agency. In this review, we assess whether recent theoretical frameworks can reconcile these divergent results. We examine whether the identification of agency abnormalities in schizophrenia might depend on the measure of self-agency considered (depending on the specific task requirements) and the available agency-related cues. We conclude that all these aspects are relevant to predict and characterize the type of agency misattribution that schizophrenia patients might show. We argue that one particular model, based on the predictive coding theory, can reconcile the interpretation of the multifarious phenomenology of agency manifestations in schizophrenia, paving the way for testing agency disorders in novel ways.

Mapping the emotional homunculus with fMRI.

Emotions are commonly associated with bodily sensations, e.g., boiling with anger when overwhelmed with rage. Studies have shown that emotions are related to specific body parts, suggesting that somatotopically organized cortical regions that commonly respond to somatosensory and motor experiences might be involved in the generation of emotions. We used functional magnetic resonance imaging to investigate whether the subjective feelings of emotion are accompanied by the activation of somatotopically defined sensorimotor brain regions, thus aiming to reconstruct an "emotional homunculus." By defining the convergence of the brain activation patterns evoked by self-generated emotions during scanning onto a sensorimotor map created on participants' tactile and motor brain activity, we showed that all the evoked emotions activated parts of this sensorimotor map, yet with considerable overlap among different emotions. Although we could not find a highly specific segmentation of discrete emotions over sensorimotor regions, our results support an embodied experience of emotions.

Trait food craving predicts functional connectivity between dopaminergic midbrain and the fusiform food area during eating imagery.

Neurofunctional coupling between the dopaminergic midbrain (i.e., ventral tegmental area, VTA) and higher-order visual regions may contribute to food craving, leading to the onset or maintenance of obesity. We recently showed that the VTA resting-state functional connectivity with the occipitotemporal cortex, at the level of the fusiform gyrus (FFG), was specifically associated with trait food craving and the implicit bias for food images, suggesting that VTA-FFG connectivity may reflect the association between the visual representations of food and its motivational properties. To further test this hypothesis, this time we studied task-based functional connectivity in twenty-eight healthy-weight participants while imagining eating their most liked high-calorie (HC) or least liked low-calorie food (LC) or drinking water (control condition). Trait food craving scores were used to predict changes in task-based functional connectivity of the VTA during imagery of HC compared to LC foods (relative to the control condition). Trait food craving was positively associated with the functional connectivity of the VTA with the left FFG: people with higher trait food craving scores show stronger VTA-FFG connectivity, specifically for the imagery of the liked HC foods. This association was not linked to the quality of imagery nor to state measures of craving, appetite, or thirst. These findings emphasize the contribution of the functional coupling between dopaminergic midbrain and higher-order visual regions to food craving, suggesting a neurofunctional mechanism by which the mental representations of the HC food we like can become much more salient if not irresistible.

The sense of agency in near and far space.

The sense of agency is the ability to recognize that we are the actors of our actions and their consequences. We explored whether and how spatial cues may modulate the agency experience by manipulating the ecological validity of the experimental setup (real-space or computer-based setup) and the distance of the action-outcome (near or far). We tested 58 healthy adults collecting explicit agency judgments and the perceived time interval between movements and outcomes (to quantify the intentional binding phenomenon, an implicit index of agency). Participants show greater implicit agency for voluntary actions when there is a temporal and spatial action-outcome contingency. Conversely, participants reported similar explicit agency for outcomes appearing in the near and far space. Notably, these effects were independent of the ecological validity of the setting. These results suggest that spatial proximity, realistic or illusory, is essential for feeling implicitly responsible for the consequences of our actions.

Sensory Attenuation Deficit and Auditory Hallucinations in Schizophrenia: A Causal Mechanism or a Risk Factor? Evidence From Meta-Analyses on the N1 Event-Related Potential Component.

BACKGROUND: Sensory attenuation (SA), the dampened perception of self-generated sensory information, is typically associated with reduced event-related potential signals, such as for the N1 component of auditory event-related potentials. SA, together with efficient monitoring of intentions and actions, should facilitate the distinction between self-generated and externally generated sensory events, thereby optimizing interaction with the world. According to many, SA is deficient in schizophrenia. The question arises whether altered SA reflects a sufficient mechanism to explain positive symptoms such as auditory hallucinations. A systematic association of reduced auditory SA in hallucinating patients would support this hypothesis. METHODS: We conducted a series of meta-analyses on 15 studies on auditory SA in which the N1 component of event-related potential-electroencephalogram signals was measured during talking (self-generated sensory signals condition) or when listening to prerecorded vocalizations (externally generated sensory signals condition). RESULTS: We found that individuals with schizophrenia did show some auditory SA because their N1 signal was significantly attenuated in talking conditions compared with listening conditions. However, the magnitude of such attenuation was reduced in individuals with schizophrenia compared to healthy control participants. This phenomenon generalizes independently from the stage of the disease, the severity of positive symptoms, and whether patients have auditory hallucinations or not. CONCLUSIONS: These findings suggest that reduced SA cannot be a sufficient mechanism for explaining positive symptoms such as auditory hallucinations in schizophrenia. Because reduced SA was also present in participants at risk of schizophrenia, reduced SA may represent a risk factor for the disorder. We discuss the implications of these results for clinical-cognitive models of schizophrenia.

How aging shapes our sense of agency.

The sense of agency refers to the feeling of controlling one's actions and their effects on the external environment. Here, we tested how the physiological process of aging affects the agency experience by taking advantage of a validated ecological experimental paradigm and exploring the different dimensions of agency. We tested 60 young and older adults during active and passive movements, causing, after a variable time delay, an external sensorial event. We collected overt agency judgments (i.e., explicit agency dimension), and we measured the perceived compression of the time interval between the active/passive movements and outcomes (to quantify the intentional binding phenomenon, an implicit index of agency). Our results indicate that the sense of agency significantly changes across the adult life span, with older participants exhibiting a reduced sense of agency, both at the explicit and implicit level. Crucially, the temporal dimension of the action outcome did not affect their agency experience. We suggest that elderly adults are more reliant on internal predictions, making them less sensitive to cognitive biases and external manipulations. We discuss these results in the domain of neurocognitive models of motor control, with reference to how aging affects the weighting process of predictive and sensory signals for efficient sensorimotor integration.

Mapping Gilles de la Tourette syndrome through the distress and relief associated with tic-related behaviors: an fMRI study.

Personal distress associated with tic urges or inhibition and relief associated with tic production are defining features of the personal experience in Gilles de la Tourette syndrome (GTS). These affective phenomena have not been studied using fMRI, hindering our understanding of GTS pathophysiology and possible treatments. Here, we present a novel cross-sectional fMRI study designed to map tic-related phenomenology using distress and relief as predicting variables. We adopted a mental imagery approach and dissected the brain activity associated with different phases of tic behaviors, premonitory urges, and the ensuing tic execution or inhibition: these were compared with the mental simulation of "relaxed situations" and pre-determined stereotyped motor behaviors. We then explored whether the ensuing brain patterns correlated with the distress or relief perceived for the different phases of the tasks. Patients experienced a higher level of distress during the imagery of tic-triggering scenarios and no relief during tic inhibition. On the other hand, patients experienced significant relief during tic imagery. Distress during tic-triggering scenarios and relief during tic imagery were significantly correlated. The distress perceived during urges correlated with increased activation in cortical sensorimotor areas, suggesting a motor alarm. Conversely, relief during tic execution was positively associated with the activity of a subcortical network. The activity of the putamen was associated with both distress during urges and relief during tic execution. These findings highlight the importance of assessing the affective component of tic-related phenomenology. Subcortical structures may be causally involved in the affective component of tic pathophysiology, with the putamen playing a central role in both tic urge and generation. We believe that our results can be readily translated into clinical practice for the development of personalized treatment plans tailored to each patient's unique needs.

The squat exercise recruits core muscles as much as localized exercises / O exercício de agachamento recruta músculos do tronco tanto quanto exercícios localizados

Abstract Introduction In the context of resistance training, which encompasses both strengthening and rehabilitation, the incorporation of global range exercises demands intense activation of the trunk muscle groups, which play a primary role in body stabilization. The squat, notorious for its complexity and effectiveness in activating stabilizers during execution, raises a central question: whether this exercise recruits the muscles more significantly compared to localized exercises, such as push-ups and trunk exten-sions. Objective To identify the degree of activation of the trunk muscles during squats and compare it with localized exercises for the trunk muscles: lumbar and abdominal. Methods Using surface electromyography, the activation of the iliocostalis, multifidus, internal oblique, external oblique and rectus abdominis muscles was evaluated. The sample included 16 physically active volunteers of both sexes. A repeated measures t-test (α < 0.05) was used as an analysis method. Results The iliocostalis, multifidus and internal oblique muscles showed similar levels of activation both in the squat and in their respective isolated exercises, while the rectus abdominis and external oblique muscles showed greater activity during trunk flexion. Conclusion It is possible to infer that squats are an effective exercise for training the iliocostalis, multifidus and internal oblique muscles, while localized exercises are more suitable for strengthening the external oblique and rectus abdominis muscles. Such conclusion can contribute to optimizing the planning of exercise sessions by replacing isolated trunk exercises with squats.

Resumo Introdução No contexto do treinamento resistido, que engloba tanto o fortalecimento quanto a reabilitação, a incorporação de exercícios de alcance global demanda uma intensa ativação dos grupos musculares do tronco, os quais desempenham um papel primordial na estabilização corporal. O agachamento, notório por sua complexidade e eficácia na ativação dos estabilizadores durante a execução, suscita uma questão central: se o agachamento recruta de forma mais acentuada a musculatura do tronco comparativamente a exercícios localizados, tais como flexões e extensões do tronco. Objetivo Identificar o grau de ativação dos músculos do tronco durante o agachamento e confrontá-lo com exercícios localizados para a musculatura do tronco: lombar e abdominal. Métodos Através da aplicação da eletromiografia de superfície, avaliou-se a ativação dos músculos iliocostal, multífido, oblíquo interno, oblíquo externo e reto abdominal. A amostra englobou 16 voluntários de ambos os gêneros, fisicamente ativos. Empregou-se um teste t de medidas repetidas (α < 0,05) como método de análise. Resultados Os músculos iliocostal, multífido e oblíquo interno manifestaram níveis semelhantes de ativação tanto no agachamento quanto em seus respectivos exercícios isolados, enquanto os músculos reto abdominal e oblíquo externo apresentaram maior atividade durante a flexão do tronco. Conclusão É possível inferir que o agachamento se configura como um exercício eficaz para o treinamento do iliocostal, multífido e oblíquo interno, enquanto os exercícios localizados se revelam mais indicados para o fortalecimento do oblíquo externo e dos músculos reto abdominais. Tais conclusões podem contribuir para a otimização do planejamento de sessões de exercícios, mediante a substituição de exercícios isolados de tronco pelo agachamento.

Alterações na cinemática angular da marcha de pacientes hemiparéticos após Acidente Vascular Encefálico / Changes in gait angular kinematics of hemiparetic patients After Cerebrovascular Accident

O objetivo deste estudo foi analisar as alterações na cinemática angular da marcha de adultos com hemiparesia após acidente vascular encefálico (AVE). A amostra foi composta por 17 pacientes pós-AVE; e, para a avaliação da marcha, foi utilizado um sistema de captura da trajetória tridimensional da marcha. Quanto aos membros sadio e afetado, as variáveis estudadas foram: velocidade, ângulos máximos de flexão e extensão do quadril e joelho. Para as comparações entre os membros, foi utilizado o teste t pareado; e, para as comparações com valores normais, o teste t para uma amostra, considerando, como critério de decisão, o nível de significância p ≤ 0,05. Os resultados demonstraram, na comparação entre os membros, diferenças significantes na flexão (0,001) e extensão de joelho (0,05). Já na comparação entre o membro afetado e o sadio, destaca-se a diferença significante das angulações de flexão de joelho (<0,000) e extensão de quadril (0,004). Os pacientes com hemiparesia pós-AVE apresentam alterações na cinemática angular da marcha quando comparado o membro afetado com o sadio e com os valores da normalidade. Observou se um padrão de marcha predominantemente flexor, com grande variabilidade entre os pacientes avaliados.

This study aimed to analyze changes in gait angular kinematics of adults with hemiparesis after cerebrovascular accident (CVA). The sample consisted of 17 post- cerebrovascular accident (CVA) patients; and, for gait evaluation, it used a three-dimensional gait trajectory capture system. As for healthy and affected limbs, the variables studied were: speed, maximum angles of flexion, and extension of the hip and knee. For the comparisons between the members, the study used the t-paired test; and, for comparisons with normal values, it used the t test for a sample, whereas, as a decision criterion, the significance level p ≤ 0.05. The results showed, in the comparison between the limbs, significant differences in flexion (0.001) and knee extension (0.05). In the comparison between the affected limb and the healthy one, there is a significant difference in knee flexion angles (<0.000) and hip extension (0.004). Patients with post-CVA hemiparesis present changes in gait angular kinematics when the affected limb is compared with the healthy limb and with normal values. The study observed a predominantly flexor gait pattern, with a considerable variability among the evaluated patients.

How images of food become cravingly salient in obesity.

OBJECTIVE: This case-control study was aimed at testing two main hypotheses: (i) obesity is characterized by neurofunctional alterations within the mesocorticolimbic reward system, a brain network originating from the midbrain ventral tegmental area (VTA); and (ii) these alterations are associated with a bias for food-related stimuli and craving. METHODS: Normal-weight individuals and individuals with obesity underwent a resting-state functional magnetic resonance imaging scan and the assessment of impulsivity, food craving, appetite, and implicit bias for food and non-food stimuli. The VTA was used as a seed to map, for each participant, the strength of its functional connections with the rest of the brain. The between-group difference in functional connectivity was then computed, and brain-behavior correlations were performed. RESULTS: Individuals with obesity showed hyper-connectivity of the VTA with part of the ventral occipitotemporal cortex, recently found to be specialized for food images, and hypo-connectivity with the left inferior frontal gyrus, devoted to cognitive control. VTA-ventral occipitotemporal cortex connectivity was positively associated with food craving and food-related bias; the reverse correlation was observed for VTA-inferior frontal gyrus connectivity. CONCLUSIONS: These findings reveal that, in obesity, food-related visual stimuli become cravingly salient through an imbalanced connectivity of the reward system with sensory-specific regions and the frontal cortex involved in cognitive control.

When action prediction grows old: An fMRI study.

Predicting the unfolding of others' actions (action prediction) is crucial for successfully navigating the social world and interacting efficiently. Age-related changes in this domain have remained largely unexplored, especially for predictions regarding simple gestures and independent of contextual information or motor expertise. Here, we evaluated whether healthy aging impacts the neurophysiological processes recruited to anticipate, from the observation of implied-motion postures, the correct conclusion of simple grasping and pointing actions. A color-discrimination task served as a control condition to assess the specificity of the age-related effects. Older adults showed reduced efficiency in performance that was yet not specific to the action prediction task. Nevertheless, fMRI results revealed task-specific age-related differences: while both groups showed stronger recruitment of the lateral occipito-temporal cortex bilaterally during the action prediction than the control task, the younger participants additionally showed a higher bilateral engagement of parietal regions. Importantly, in both groups, the recruitment of visuo-motor processes in the right posterior parietal cortex was a predictor of good performance. These results support the hypothesis of decreased involvement of sensorimotor processes in cognitive tasks when processing action- and body-related stimuli in healthy aging. These results have implications for social interaction, which requires the fast reading of others' gestures.

A influência dos níveis de atividade física nos parâmetros da marcha durante atividades de dupla tarefa em idosos / The influence of physical activity on gait parameters during dual-task activities in the older people

Resumo Objetivo Analisar as possíveis diferenças nas variáveis ​​cinemáticas da marcha entre idosos fisicamente ativos e fisicamente inativos durante a realização de atividades de dupla tarefa. Metodo: Participaram idosos, com idade entre 60 e 75 anos, divididos em dois grupos: fisicamente inativo (FI) (n=20) e fisicamente ativo (FA) (n=20). Os participantes foram agrupados igualmente em dez indivíduos do sexo feminino e masculino, classificados por meio do Questionário Internacional de Atividade Física (International Physical Activity Questionnaire - IPAQ). Os participantes realizaram inicialmente tarefas simples (aritmética, fluência verbal e marcha) e depois realizaram atividades de dupla tarefa, associando a marcha com as duas atividades cognitivas (aritmética e fluência verbal). Foram analisadas as variáveis ​​velocidade, cadência, comprimento da passada, largura do passo, tempo da passada e duplo apoio. Para comparar as variáveis ​​por tarefa e grupo, foi utilizado o modelo de Equações de Estimativas Generalizadas (GEE) complementado pelo teste de Bonferroni. Resultados Na análise intragrupo, ambos os grupos apresentaram reduções significativas na velocidade, cadência, largura da passada, tempo da passada e duplo apoio, tanto na dupla tarefa aritmética quanto na dupla tarefa de fluência verbal. No entanto, nas comparações entre os grupos, não houve diferenças estatisticamente significativas em nenhum parâmetro cinemático analisado, tanto na análise da marcha simples quanto nas tarefas duplas. Conclusão As duplas tarefas influenciaram negativamente os parâmetros cinemáticos da marcha em ambos os grupos. No entanto, o nível de atividade física não pode ser considerado um fator que minimiza os efeitos da dupla tarefa na marcha de idosos.

Abstract Objective To analyze the possible differences in the kinematic variables of gait between physically active and physically inactive older people while performing dual-task activities. Method Older individuals, aged between 60 and 75 years, participated, divided into two groups: physically inactive (PI) (n=20) and physically active (PA) (n=20). Participants were equally grouped into ten female and male individuals, classified using the International Physical Activity Questionnaire (IPAQ). Participants initially performed simple tasks (arithmetic, verbal fluency, and gait) and then performed dual task activities, associating gait with the two cognitive activities (arithmetic and verbal fluency). The variables velocity, cadence, stride length, step width, stride time and double support were analyzed. To compare variables according to task and group, the Generalized Estimating Equations (GEE) model complemented by the Bonferroni test was used. Results In the intragroup analysis both groups showed significant decreases in velocity, cadence, step width, stride time and double support, both in the arithmetic dual task and in the verbal fluency dual task. However, in the comparisons between the groups, there were no statistically significant differences in any kinematic parameter analyzed, both in the single gait analysis and in the dual tasks. Conclusion The dual tasks had a negative influence on the kinematic gait parameters in both groups. However, the level of physical activity can not be considered a factor that minimizes the effects of the dual task on gait in the older people.

Neural structural abnormalities behind altered brain activation in obesity: Evidence from meta-analyses of brain activation and morphometric data.

Obesity represents a risk factor for disability with a major bearing on life expectancy. Neuroimaging techniques are contributing to clarify its neurobiological underpinnings. Here, we explored whether structural brain abnormalities might accompany altered brain activations in obesity. We combined and compared data from brain activation studies for food stimuli and the data reported in structural voxel-based morphometry studies. We found that obese individuals have reduced grey matter density and functional activations in the thalamus and midbrain. A functional connectivity analysis based on these two clusters and its quantitative decoding showed that these regions are part of the reward system functional brain network. Moreover, we found specific grey matter hypo-densities in prefrontal cortex for the obese subjects, regions involved in controlled behaviour. These results support theories of obesity that point to reduced bottom-up reward processes (i.e., the Reward Deficit Theory), but also top-down theories postulating a deficit in cognitive control (i.e., the Inhibitory Control Deficit Theory). The same results also warrant a more systematic exploration of obesity whereby the reward of food and the intentional control over consummatory behaviour is manipulated.

Imaging the neural underpinnings of freezing of gait in Parkinson's disease.

Freezing of gait (FoG) is a paroxysmal and sporadic gait impairment that severely affects PD patients' quality of life. This review summarizes current neuroimaging investigations that characterize the neural underpinnings of FoG in PD. The review presents and discusses the latest advances across multiple methodological domains that shed light on structural correlates, connectivity changes, and activation patterns associated with the different pathophysiological models of FoG in PD. Resting-state fMRI studies mainly report cortico-striatal decoupling and disruptions in connectivity along the dorsal stream of visuomotor processing, thus supporting the 'interference' and the 'perceptual dysfunction' models of FoG. Task-based MRI studies employing virtual reality and motor imagery paradigms reveal a disruption in functional connectivity between cortical and subcortical regions and an increased recruitment of parieto-occipital regions, thus corroborating the 'interference' and 'perceptual dysfunction' models of FoG. The main findings of fNIRS studies of actual gait primarily reveal increased recruitment of frontal areas during gait, supporting the 'executive dysfunction' model of FoG. Finally, we discuss how identifying the neural substrates of FoG may open new avenues to develop efficient treatment strategies.

White matter abnormalities in the amputation variant of body integrity dysphoria.

"Body integrity dysphoria" (BID) is a severe condition affecting nonpsychotic individuals. In the amputation variant of BID, a limb may be experienced as not being part of the body, despite normal anatomical development and intact sensorimotor functions. We previously demonstrated altered brain structural (gray matter) and functional connectivity in 16 men with BID with a long-lasting and exclusive desire for left leg amputation. Here, we aimed to identify, in the same sample, altered patterns of white matter structural connectivity. Fractional anisotropy (FA), derived from diffusion tensor imaging data, was considered as a measure of structural connectivity. Results showed reduced structural connectivity of: (i) the right superior parietal lobule (rSPL) with the right cuneus, with the superior occipital and with the posterior cingulate gyri, (ii) the pars orbitalis of the right middle frontal gyrus (rMFGOrb) with the putamen, and (iii) the left middle temporal gyrus (lMTG) with the pars triangularis of the left inferior frontal gyrus. Increased connectivity was found between the right paracentral lobule (rPLC) and the right caudate nucleus. By using a complementary method of investigation, we confirmed and extended previous results from the same sample of individuals with BID, showing structural alterations between areas tuned to the processing of the sensorimotor representations of the affected leg (rPCL), and to higher-order components of bodily representation such as the body image (rSPL) and visual processing. Alongside this network for bodily awareness, other networks such as the limbic (rMFGOrb) and the mirror (lMTG) systems showed alterations in structural connectivity. These findings consolidate current understanding of the neural correlates of the amputation variant of BID, which might in turn guide diagnostics and rehabilitative treatments.

The sense of agency in joint actions: A theory-driven meta-analysis.

The sense of agency is the feeling of voluntarily controlling our actions and their effects. It represents a crucial component of self-awareness, and it is foundational to our perception of responsibility toward what we do as individuals acting in a social context. While the sense of agency has been widely investigated in individual contexts, much less is known about the agency experienced when subjects are involved in motor interactions, despite its relevance in the social domain. To fill this gap, here we review the literature on the sense of agency experienced during motor interactions. We aimed to test the reliability of this sense of joint agency across studies and define what features can modulate its explicit and implicit components. To this end, we performed a formal meta-analysis of studies investigating the implicit feeling of agency in joint actions and a systematic review of studies addressing explicit judgments of agency during motor interactions. Our review indicates that, during interactions, a sense of agency can also be experienced for the partner's actions, both at an implicit and explicit level, and that this possibility strongly depends on predictive sensorimotor mechanisms. Contextual cues play a crucial role too, but mainly on explicit agency judgments, while they do not affect the implicit feeling of agency. These results are discussed in light of current cognitive theories on motor awareness and motor interactions. We also propose a hierarchical model based on recursive predictive and comparative processes whereby the sense of joint agency is grounded on a weighted combination of sensorimotor and contextual cues. Finally, we discuss how this model may provide a framework for future research in the social and clinical domains.

How the motor system copes with aging: a quantitative meta-analysis of the effect of aging on motor function control.

Motor cognitive functions and their neurophysiology evolve and degrade along the lifespan in a dramatic fashion. Current models of how the brain adapts to aging remain inspired primarily by studies on memory or language processes. Yet, aging is strongly associated with reduced motor independence and the associated degraded interaction with the environment: accordingly, any neurocognitive model of aging not considering the motor system is, ipso facto, incomplete. Here we present a meta-analysis of forty functional brain-imaging studies to address aging effects on motor control. Our results indicate that motor control is associated with aging-related changes in brain activity, involving not only motoric brain regions but also posterior areas such as the occipito-temporal cortex. Notably, some of these differences depend on the specific nature of the motor task and the level of performance achieved by the participants. These findings support neurocognitive models of aging that make fewer anatomical assumptions while also considering tasks-dependent and performance-dependent manifestations. Besides the theoretical implications, the present data also provide additional information for the motor rehabilitation domain, indicating that motor control is a more complex phenomenon than previously understood, to which separate cognitive operations can contribute and decrease in different ways with aging.

Attention to body parts prompts thermoregulatory reactions in Body Integrity Dysphoria.

In healthy subjects, the transient perturbation of body part ownership is accompanied by regional skin temperature decrease. This observation leaves an open question about a possible body part-specific thermoregulatory response in pathological conditions, in which the sense of ownership over that body part is altered. For instance, Body Integrity Dysphoria (BID), a poorly understood neuropsychiatric disorder, is characterised by the non-acceptance of one or more of one's extremities. This unsettling feeling pervasively captures the individuals' attention towards the unwanted limb. Previous studies characterised BID in terms of absent ownership feeling with preserved ownership judgment. We explored for the first time whether this altered feeling is also associated with a specific thermoregulatory response. We recorded thermal image sequences of circumscribed regions of the limbs' skin in seven individuals with BID desiring to remove one leg while they were invited to focus their attention toward one particular limb (arm or leg). Their event-related thermoregulatory pattern was compared to a group of healthy matched controls. In individuals with BID but not in control persons, we found a bilateral decrease in leg temperature when focusing their attention on either the unwanted or accepted leg. The event-related thermoregulatory response for both upper limbs was similar between individuals with BID and healthy controls. Our results suggest that the alteration of the sense of body ownership in neuropsychiatric conditions such as BID may critically rest on specific event-related thermoregulatory patterns in response to modulation of attention to body parts.

Brain Abnormalities in Individuals with a Desire for a Healthy Limb Amputation: Somatosensory, Motoric or Both? A Task-Based fMRI Verdict.

Body integrity dysphoria (BID), a long-lasting desire for the amputation of physically healthy limbs, is associated with reduced fMRI resting-state functional connectivity of somatosensory cortices. Here, we used fMRI to evaluate whether these findings could be replicated and expanded using a task-based paradigm. We measured brain activations during somatosensory stimulation and motor tasks for each of the four limbs in ten individuals with a life-long desire for the amputation of the left leg and fourteen controls. For the left leg, BID individuals had reduced brain activation in the right superior parietal lobule for somatosensory stimulation and in the right paracentral lobule for the motor task, areas where we previously found reduced resting-state functional connectivity. In addition, for somatosensory stimulation only, we found a robust reduction in activation of somatosensory areas SII bilaterally, mostly regardless of the stimulated body part. Areas SII were regions of convergent activations for signals from all four limbs in controls to a significantly greater extent than in subjects with BID. We conclude that BID is associated with altered integration of somatosensory and, to a lesser extent, motor signals, involving limb-specific cortical maps and brain regions where the first integration of body-related signals is achieved through convergence.