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The neuropsychological disorder of anosognosia for hemiplegia (AHP) can offer unique insights into the neurocognitive processes of body consciousness and representation. Previous studies have found associations between selective social cognition deficits and anosognosia. In this study, we examined how such social cognition deficits may directly interact with representations of one's body as disabled in AHP. We used a modified set of previously validated Theory of Mind (ToM) stories to create disability-related content that was related to post-stroke paralysis and to investigate differences between right hemisphere damage patients with (n = 19) and without (n = 19) AHP. We expected AHP patients to perform worse than controls when trying to infer paralysis-related mental states in the paralysis-related ToM stories and explored whether such differences depended on the inference patients were asked to perform (e.g. self or other referent perspective-taking). Using an advanced structural neuroimaging technique, we expected selective social cognitive deficits to be associated with posterior parietal cortex lesions and deficits in self-referent perspective-taking in paralysis-related mentalising to be associated with frontoparietal disconnections. Group- and individual-level results revealed that AHP patients performed worse than HP controls when trying to infer paralysis-related mental states. Exploratory lesion analysis results revealed some of the hypothesised lesions, but also unexpected white matter disconnections in the posterior body and splenium of the corpus collosum associated with a self-referent perspective-taking in paralysis-related ToM stories. The study has implications for the multi-layered nature of body awareness, including abstract, social perspectives and beliefs about the body.
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Background: The COVID-19 pandemic significantly impacted people's mental health significantly. Frontline healthcare workers (HCWs) were arguably most affected, particularly in low-to-middle-income countries like South Africa. Understanding their experiences is important to inform interventions for social and psychological support for future pandemics. Aim: This study explored the experiences of frontline HCWs in South Africa during the COVID-19 pandemic. Setting: The sample included HCWs from various professions and health sectors who worked with COVID-19 patients across South Africa. Methods: An exploratory descriptive qualitative design was used. Semi-structured interviews were conducted with 11 frontline HCWs recruited via purposive sampling. Data were analysed using principles of inductive thematic analysis. Results: Four major themes were identified in the data: (1) Working during COVID-19 was an emotional rollercoaster; (2) Working during COVID-19 was physically and mentally exhausting; (3) Participants held negative attitudes towards the Department of Health; and (4) COVID-19 had a transformative impact on the daily life of HCWs. Conclusion: HCWs' experiences were diverse and marked by contradictions. Limited psychological support and resources aggravated experiences. However, a positive narrative of hope and gratitude also resonated with participants. Qualitative methodologies provided depth and insights into the diverse realities of frontline HCWs. Contribution: This study provides significant insights into the experiences of a diverse group of frontline South African HCWs during COVID-19. It demonstrates a shift in the definition of a 'frontline' HCW and highlights the need for greater psychological support and individualised public health interventions during future pandemics.
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Children from lower socioeconomic status (SES) backgrounds tend to have more negative self-perceptions. More negative self-perceptions are often related to lower academic achievement. Linking these findings, we asked: Do children's self-perceptions help explain socioeconomic disparities in academic achievement around the world? We addressed this question using data from the 2018 Programme for International Student Assessment (PISA) survey, including n = 520,729 records of 15-year-old students from 70 countries. We studied five self-perceptions (self-perceived competency, self-efficacy, growth mindset, sense of belonging, and fear of failure) and assessed academic achievement in terms of reading achievement. As predicted, across countries, children's self-perceptions jointly and separately partially mediated the association between socioeconomic status and reading achievement, explaining additional 11% (ΔR2 = 0.105) of the variance in reading achievement. The positive mediation effect of self-perceived competency was more pronounced in countries with higher social mobility, indicating the importance of environments that "afford" the use of beneficial self-perceptions. While the results tentatively suggest self-perceptions, in general, to be an important lever to address inequality, interventions targeting self-perceived competency might be particularly effective in counteracting educational inequalities in countries with higher social mobility.
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Patients with a disturbed sense of limb ownership (DSO) offer a unique window of insight into the multisensory processes contributing to the sense of body ownership. A limited amount of past research has examined the role of sensory deficits in DSO, and even less is known regarding the role of patient self-reported somatosensory sensations in the pathogenesis of DSO. To address this lack of knowledge we first conducted a systematic scoping review following PRISMA-SR guidelines, examining current research into somatosensory deficits and patient self-reported somatosensory sensations in patients with DSO. Eighty studies, including 277 DSO patients, were identified. The assessment of sensory deficits was generally limited in scope and quality, and deficits in tactile sensitivity and proprioception were most frequently found. The reporting of somatosensory sensations was even less frequent, with instances of paraesthesia (pins-and-needles), stiffness/rigidity, numbness and warmth, coldness and heaviness amongst the deficits recorded. In a second part of the study, we sought to directly address the lack of evidence concerning the impact of patient self-reported somatosensory sensations in DSO by measuring DSO and self-reported somatosensory sensations in a large (n = 121) sample of right-hemisphere stroke patients including N = 65 with DSO and N = 56 hemiplegic controls. Results show that feelings of coldness and stiffness modulate DSO symptoms. Sense of heaviness and numbness are more frequent in patients with DSO but do not have a clear impact on disownership symptomology. Although preliminary, these results suggest a role of subjective sensations about the felt body in the sense of limb ownership.
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Imagen Corporal , Propiedad , Humanos , Autoinforme , Hipoestesia/etiología , PropiocepciónRESUMEN
The COVID-19 pandemic has affected all domains of human life, including the economic and social fabric of societies. One of the central strategies for managing public health throughout the pandemic has been through persuasive messaging and collective behaviour change. To help scholars better understand the social and moral psychology behind public health behaviour, we present a dataset comprising of 51,404 individuals from 69 countries. This dataset was collected for the International Collaboration on Social & Moral Psychology of COVID-19 project (ICSMP COVID-19). This social science survey invited participants around the world to complete a series of moral and psychological measures and public health attitudes about COVID-19 during an early phase of the COVID-19 pandemic (between April and June 2020). The survey included seven broad categories of questions: COVID-19 beliefs and compliance behaviours; identity and social attitudes; ideology; health and well-being; moral beliefs and motivation; personality traits; and demographic variables. We report both raw and cleaned data, along with all survey materials, data visualisations, and psychometric evaluations of key variables.
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COVID-19 , Humanos , Actitud , COVID-19/psicología , Principios Morales , Pandemias , Encuestas y Cuestionarios , Cambio Social , Factores SocioeconómicosRESUMEN
Neuropsychological disturbances in the sense of limb ownership provide unique opportunities to study the neurocognitive basis of body ownership. Previous small sample studies that showed discrete cortical lesions cannot explain why multisensory, affective, and cognitive manipulations alter disownership symptoms. We tested the novel hypothesis that disturbances in the sense of limb ownership would be associated not only with discrete cortical lesions but also with disconnections of white-matter tracts supporting specific functional networks. We drew on an advanced lesion-analysis and Bayesian statistics approach in 49 right-hemisphere patients (23 with and 26 without limb disownership). Our results reveal that disturbances in the sense of ownership are associated with lesions in the supramarginal gyrus and disconnections of a fronto-insular-parietal network, involving the frontal-insular and frontal inferior longitudinal tracts, confirming previous disconnection hypotheses. Together with previous behavioral and neuroanatomical results, these findings lead us to propose that the sense of body ownership involves the convergence of bottom-up, multisensory integration, and top-down monitoring of sensory salience based on contextual demands.
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Imagen Corporal , Propiedad , Humanos , Imagen Corporal/psicología , Teorema de Bayes , Lóbulo Parietal/diagnóstico por imagenRESUMEN
At the beginning of 2020, COVID-19 became a global problem. Despite all the efforts to emphasize the relevance of preventive measures, not everyone adhered to them. Thus, learning more about the characteristics determining attitudinal and behavioral responses to the pandemic is crucial to improving future interventions. In this study, we applied machine learning on the multinational data collected by the International Collaboration on the Social and Moral Psychology of COVID-19 (N = 51,404) to test the predictive efficacy of constructs from social, moral, cognitive, and personality psychology, as well as socio-demographic factors, in the attitudinal and behavioral responses to the pandemic. The results point to several valuable insights. Internalized moral identity provided the most consistent predictive contribution-individuals perceiving moral traits as central to their self-concept reported higher adherence to preventive measures. Similar results were found for morality as cooperation, symbolized moral identity, self-control, open-mindedness, and collective narcissism, while the inverse relationship was evident for the endorsement of conspiracy theories. However, we also found a non-neglible variability in the explained variance and predictive contributions with respect to macro-level factors such as the pandemic stage or cultural region. Overall, the results underscore the importance of morality-related and contextual factors in understanding adherence to public health recommendations during the pandemic.
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In recent decades, the research traditions of (first-person) embodied cognition and of (third-person) social cognition have approached the study of self-awareness with relative independence. However, neurological disorders of self-awareness offer a unifying perspective to empirically investigate the contribution of embodiment and social cognition to self-awareness. This study focused on a neuropsychological disorder of bodily self-awareness following right-hemisphere damage, namely anosognosia for hemiplegia (AHP). A previous neuropsychological study has shown AHP patients, relative to neurological controls, to have a specific deficit in third-person perspective taking and allocentric stance (the other unrelated to the self) in higher order mentalizing tasks. However, no study has tested if verbal awareness of motor deficits is influenced by perspective-taking and centrism and identified the related anatomical correlates. Accordingly, two novel experiments were conducted with right-hemisphere stroke patients with (n = 17) and without AHP (n = 17) that targeted either their own (egocentric, experiment 1) or another stooge patients (allocentric, experiment 2) motor abilities from a first-or-third person perspective. In both experiments, neurological controls showed no significant difference in perspective-taking, suggesting that social cognition is not a necessary consequence of right-hemisphere damage. More specifically, experiment 1 found AHP patients more aware of their own motor paralysis (egocentric stance) when asked from a third compared to a first-person perspective, using both group level and individual level analysis. In experiment 2, AHP patients were less accurate than controls in making allocentric judgements about the stooge patient, but with only a trend towards significance and with no difference between perspectives. As predicted, deficits in egocentric and allocentric third-person perspective taking were associated with lesions in the middle frontal gyrus, superior temporal and supramarginal gyri, and white matter disconnections were more prominent with deficits in allocentricity. Behavioural and neuroimaging results demonstrate the intersecting relationship between bodily self-awareness and self-and-other-directed metacognition or mentalisation.
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Agnosia , Metacognición , Accidente Cerebrovascular , Agnosia/etiología , Agnosia/psicología , Concienciación , Cognición , Hemiplejía/psicología , Humanos , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/diagnóstico por imagen , Accidente Cerebrovascular/psicologíaRESUMEN
BACKGROUND: Although early life factors are associated with increased suicide risk in youth, there is a dearth of research on these associations for individuals growing up in disadvantaged socioeconomic contexts, particularly in low- and middle-income countries (LMICs). We documented the association between individual, familial, and environmental factors in childhood with suicidal ideation among South African youth. METHODS AND FINDINGS: We used data from 2,020 participants in the Birth to Twenty Plus (Bt20+) study, a South African cohort following children born in Soweto, Johannesburg from birth (1990) to age 28 years (2018). Suicidal ideation was self-reported at ages 14, 17, 22, and 28 years, and the primary outcome of interest was suicidal ideation reported at any age. We assessed individual, familial, and socioeconomic characteristics at childbirth and during infancy, adverse childhood experiences (ACEs) between ages 5 and 13 years, and externalizing and internalizing problems between 5 and 10 years. We estimated odds ratios (ORs) of suicidal ideation for individuals exposed to selected childhood factors using logistic regression. Lifetime suicidal ideation was reported by 469 (23.2%) participants, with a 1.7:1 female/male ratio. Suicidal ideation rates peaked at age 17 and decreased thereafter. Socioeconomic adversity, low birth weight, higher birth order (i.e., increase in the order of birth in the family: first, second, third, fourth, or later born child), ACEs, and childhood externalizing problems were associated with suicidal ideation, differently patterned among males and females. Socioeconomic adversity (OR 1.13, CI 1.01 to 1.27, P = 0.031) was significantly associated with suicidal ideation among males only, while birth weight (OR 1.20, CI 1.02 to 1.41, P = 0.03), ACEs (OR 1.11, CI 1.01 to 1.21, P = 0.030), and higher birth order (OR 1.15, CI 1.07 to 1.243, P < 0.001) were significantly associated with suicidal ideation among females only. Externalizing problems in childhood were significantly associated with suicidal ideation among both males (OR 1.23, 1.08 to 1.40, P = 0.002) and females (OR 1.16, CI 1.03 to 1.30, P = 0.011). Main limitations of the study are the high attrition rate (62% of the original sample was included in this analysis) and the heterogeneity in the measurements of suicidal ideation. CONCLUSIONS: In this study from South Africa, we observed that early life social and environmental adversities as well as childhood externalizing problems are associated with increased risk of suicidal ideation during adolescence and early adulthood.
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Ideación Suicida , Suicidio , Adolescente , Adulto , Niño , Preescolar , Estudios de Cohortes , Femenino , Humanos , Estudios Longitudinales , Masculino , Factores de Riesgo , Sudáfrica/epidemiologíaRESUMEN
Human capital-that is the cumulative abilities, education, social skills, and mental and physical health one possesses-is increasingly recognized as key to the reduction of inequality in societies. Adverse childhood experiences have been linked to a range of human capital indicators, with the majority of research in high-income, western settings. This study aims to examine the link between adverse childhood experiences and adult human capital in a South African birth cohort and to test whether associations differ by measurement of adversity. Secondary analysis of data from the Birth to Thirty study was undertaken. Exposure data on adversity was collected prospectively throughout childhood and retrospectively at age 22. Human capital outcomes were collected at age 28. Adversity was measured as single adverse experiences, cumulative adversity, and clustered adversity. All three measurements of adversity were linked to poor human capital outcomes, with risk for poor human capital increasing with the accumulation of adversity. Adversity was clustered by quantity (low versus high) and type (household dysfunction versus abuse). Adversity in childhood was linked to a broad range of negative outcomes in young adulthood regardless of how it was measured. Nevertheless, issues of measurement are important to understand the risk mechanisms that underlie the association between adversity and poor human capital.
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Experiencias Adversas de la Infancia , Maltrato a los Niños , Adulto , Niño , Recolección de Datos , Composición Familiar , Humanos , Estudios Retrospectivos , Adulto JovenRESUMEN
Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = -0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics.
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Pandemias/legislación & jurisprudencia , Salud Pública/legislación & jurisprudencia , Conformidad Social , COVID-19/epidemiología , COVID-19/prevención & control , COVID-19/psicología , Comparación Transcultural , Conductas Relacionadas con la Salud , Humanos , Liderazgo , Pandemias/prevención & control , Pandemias/estadística & datos numéricos , SARS-CoV-2 , Autoinforme , Identificación SocialRESUMEN
Importance: Few studies from low-and-middle income countries have investigated long-term associations between maternal postnatal depression and offspring internalizing (ie, depressive and anxiety) symptoms, and none have investigated interactions in this association. Objective: To investigate the association between maternal postnatal depression and offspring internalizing symptoms from adolescence to adulthood and the interaction with exposure to socioeconomic adversity and with the child's sex. Design, Setting, and Participants: This secondary analysis used data from Birth to Twenty Plus (BT20+), a prospective birth cohort study of children born in Soweto, South Africa, and followed up until age 28 years. Data were collected from 1990 to 2018, and data were analyzed for this study from February 16 through December 15, 2020. Exposures: Maternal postnatal depression self-reported by mothers 6 months after childbirth. Main Outcomes and Measures: The main outcome was offspring internalizing symptoms, assessed at offspring ages 14 years, 22 years, and 28 years and modeled longitudinally. Participants with the highest probability of experiencing high internalizing symptoms (ie, those in the top 20% of the distribution) from age 14 to 28 years were categorized as belonging to the high internalizing symptoms trajectory (vs the low trajectory). Socioeconomic adversity was measured with an index (continuous variable) including low maternal education, household crowding, low assets, and low maternal age. This variable was further stratified into more than 1 SD above the mean index, more than 1 SD below the mean index, and from 1 SD below to 1 SD above the mean index to conduct subgroup analyses. Associations were investigated using multivariable regression models. Results: Among 1087 participants born in Soweto, South Africa (543 [50.0%] male participants; 544 [50.0%] female participants), 118 individuals (10.8%) showed a high trajectory of internalizing symptoms from age 14 to 28 years vs 969 individuals (89.1%) with a low trajectory. Children exposed to maternal postnatal depression had statistically significantly increased odds of following the high trajectory (adjusted odds ratio [aOR] per 1-SD increase in maternal postnatal depression, 1.20; 95% CI, 1.02-1.41). This increase in odds differed by exposure to socioeconomic adversity and by child sex: for male participants, the increase in odds was greater in a context of higher vs lower socioeconomic adversity (eg, for >1 SD above the mean: aOR, 3.28; 95% CI, 1.06-10.14 vs for >1 SD below the mean: aOR, 0.98; 95% CI, 0.64-1.50; P for interaction = .12), while for female participants, the increase in odds was greater in a context of lower vs higher socioeconomic adversity (eg, for >1 SD below the mean: aOR, 1.82; 95 % CI, 1.12-2.98 vs for >1 SD above the mean: aOR, 0.59; 95 % CI, 0.30-1.17; P for interaction = .002) (P for 3-way interaction = .003). Conclusions and Relevance: This study found that postnatal depression was associated with higher odds of persistently increased internalizing symptoms among offspring from adolescence to adulthood in a middle-income country, with variation by socioeconomic adversity and sex. These findings suggest that better understanding of these associations is needed to implement targeted interventions and maximize the impact of public health initiatives aimed at breaking the intergenerational transmission of mental health problems.
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Trastornos de Ansiedad/terapia , Orden de Nacimiento/psicología , Hijo de Padres Discapacitados/psicología , Depresión Posparto/psicología , Depresión Posparto/terapia , Madres/psicología , Adolescente , Adulto , Trastornos de Ansiedad/epidemiología , Niño , Hijo de Padres Discapacitados/estadística & datos numéricos , Preescolar , Estudios de Cohortes , Depresión Posparto/epidemiología , Composición Familiar , Femenino , Humanos , Lactante , Recién Nacido , Efectos Adversos a Largo Plazo , Masculino , Estudios Prospectivos , Factores de Riesgo , Factores Sexuales , Factores Socioeconómicos , Sudáfrica/epidemiología , Adulto JovenRESUMEN
PURPOSE: We investigated associations between adolescent internalizing and externalizing problems and adult human capital in a non-Western setting. Little is known about adolescent mental health problems and adult outcomes in low- and middle-income countries, many of which are characterized by high levels of adversities. METHODS: Data came from the Birth to Twenty Plus cohort, started in Soweto, Johannesburg, South Africa, in 1990. We estimated associations of internalizing and externalizing problems at the age of 14 years with self-reported educational, employment, welfare receipt, psychosocial (psychological distress, criminality, substance use), interpersonal (social isolation, intimate partner violence, partnership status), and HIV outcomes at the age of 28 years. RESULTS: Adolescents with high internalizing problems were less likely to have completed secondary school or be formally employed and more likely to report psychological distress. Those with high levels of externalizing problems were more likely to report adulthood criminal activity and substance use. We found significant associations between internalizing and externalizing problems and intimate partner violence. There was no association between adolescent mental health problems and welfare receipt, HIV, social isolation, or partnership status. Men were more likely to report incomplete secondary education, no formal employment, criminality and substance use, social isolation, and no serious relationship, whereas women were more likely to experience psychological distress and be in receipt of welfare. CONCLUSIONS: Adolescent mental health problems are associated with long-term negative adult functioning under varying socioeconomic conditions. Interventions to recognize and address youth mental health problems in low- and middle-income countries are needed to avert serious adverse adult and societal consequences.
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Salud Mental , Trastornos Relacionados con Sustancias , Adolescente , Adulto , Estudios de Cohortes , Escolaridad , Femenino , Humanos , Masculino , Sudáfrica/epidemiología , Trastornos Relacionados con Sustancias/epidemiologíaRESUMEN
Introduction: Anosognosia for hemiplegia (AHP) is a condition in which patients with paralysis are unaware of their motor deficits. Research into AHP is important for improving its treatment and providing insight into the neurocognitive mechanism of motor awareness. Unfortunately, most studies use assessments with widely recognized limitations.The study aims at developing a psychometrically validated assessment of AHP.Method: We developed a 40-item Motor Unawareness Assessment (MUNA) and administered it to 131 right-hemisphere stroke patients. Principal Component Analysis (PCA) was used to identify the underlying factor structure. Receiver Operating Characteristics (ROC) analysis was used to determine diagnostic cutoffs, and Area Under the Curve (AUC) analysis used to assess these cutoffs. Relationships with demographic, clinical and neuropsychological variables were explored.Results: Five factors were identified: explicit motor awareness, implicit motor awareness, impaired sense of ownership, agency and illusory movement, and emotional reactions. Established cutoffs had excellent sensitivity and specificity. Clinical, neuropsychological and demographic variables did not predict overall MUNA score but were related to specific subcomponents.Conclusion: The MUNA can differentiate various facets of AHP and provides a detailed profile of (un)awareness. The MUNA can therefore provide robust assessment for research purposes and assist clinicians when developing targeted rehabilitation.
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Agnosia/diagnóstico , Agnosia/fisiopatología , Concienciación/fisiología , Hemiplejía/complicaciones , Pruebas Neuropsicológicas , Accidente Cerebrovascular/complicaciones , Anciano , Agnosia/etiología , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Right-hemisphere stroke can impair the ability to recognize one's contralesional body parts as belonging to one's self. The study of this so-called 'disturbed sense of limb ownership' can provide unique insights into the neurocognitive mechanisms of body ownership. In this study, we address a hypothesis built upon experimental studies on body ownership in healthy volunteers. These studies have shown that affective (pleasant) touch, an interoceptive modality associated with unmyelinated, slow-conducting C-tactile afferents, has a unique role in the sense of body ownership. In this study, we systematically investigated whether affective touch stimulation could increase body ownership in patients with a disturbed sense of limb ownership following right-hemisphere stroke. An initial feasibility study in 16 adult patients with acute stroke enabled us to optimize and calibrate an affective touch protocol to be administered by the bedside. The main experiment, conducted with a different sample of 26 right hemisphere patients, assessed changes in limb ownership elicited following self- (patient) versus other- (experimenter) generated tactile stimulation, using a velocity known to optimally activate C-tactile fibres (i.e. 3 cm/s), and a second velocity that is suboptimal for C-tactile activation (i.e. 18 cm/s). We further examined the specificity and mechanism of observed changes in limb ownership in secondary analyses looking at (i) the influence of perceived intensity and pleasantness of touch, (ii) touch laterality and (iii) level of disturbed sense of limb ownership on ownership change and (iv) changes in unilateral neglect arising from touch. Findings indicated a significant increase in limb ownership following experimenter-administered, C-tactile-optimal touch. Voxel-based lesion-symptom mapping identified damage to the right insula and, more substantially, the right corpus callosum, associated with a failure to increase body ownership following experimenter-administered, affective touch. Our findings suggest that affective touch can increase the sense of body-part ownership following right-hemisphere stroke, potentially due to its unique role in the multisensory integration processes that underlie the sense of body ownership.
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Specific, peripheral C-tactile afferents contribute to the perception of tactile pleasure, but the brain areas involved in their processing remain debated. We report the first human lesion study on the perception of C-tactile touch in right hemisphere stroke patients (N = 59), revealing that right posterior and anterior insula lesions reduce tactile, contralateral and ipsilateral pleasantness sensitivity, respectively. These findings corroborate previous imaging studies regarding the role of the posterior insula in the perception of affective touch. However, our findings about the crucial role of the anterior insula for ipsilateral affective touch perception open new avenues of enquiry regarding the cortical organization of this tactile system.
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Vías Aferentes , Corteza Cerebral , Placer/fisiología , Accidente Cerebrovascular/fisiopatología , Percepción del Tacto/fisiología , Adulto , Vías Aferentes/fisiología , Vías Aferentes/fisiopatología , Anciano , Anciano de 80 o más Años , Corteza Cerebral/fisiología , Corteza Cerebral/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estimulación Física , Tacto/fisiologíaRESUMEN
The various neurocognitive processes contributing to the sense of body ownership have been investigated extensively in healthy participants, but studies in neurological patients can shed unique light into such phenomena. Here, we aimed to investigate whether visual capture by a fake hand (without any synchronous or asynchronous tactile stimulation) affects body ownership in a group of hemiplegic patients with or without disturbed sensation of limb ownership (DSO) following damage to the right hemisphere. We recruited 31 consecutive patients, including seven patients with DSO. The majority of our patients (64.5% overall and up to 86% of the patients with DSO) experienced strong feelings of ownership over a rubber hand within 15 sec following mere visual exposure, which correlated with the degree of proprioceptive deficits across groups and in the DSO group. Using voxel-based lesion-symptom mapping analysis, we were able to identify lesions associated with this pathological visual capture effect in a selective fronto-parietal network, including significant voxels (p < .05) in the frontal operculum and the inferior frontal gyrus. By contrast, lesions associated with DSO involved more posterior lesions, including the right temporoparietal junction and a large area of the supramarginal gyrus, and to a lesser degree the middle frontal gyrus. Thus, this study suggests that our sense of ownership includes dissociable mechanisms of multisensory integration.
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Imagen Corporal/psicología , Deluciones/psicología , Ilusiones/psicología , Interocepción/fisiología , Trastornos de la Percepción/psicología , Propiocepción/fisiología , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Trastornos de la Percepción/etiología , Accidente Cerebrovascular/complicaciones , Percepción Visual/fisiologíaRESUMEN
Following right-hemisphere damage, a specific disorder of motor awareness can occur called anosognosia for hemiplegia, i.e. the denial of motor deficits contralateral to a brain lesion. The study of anosognosia can offer unique insights into the neurocognitive basis of awareness. Typically, however, awareness is assessed as a first person judgement and the ability of patients to think about their bodies in more 'objective' (third person) terms is not directly assessed. This may be important as right-hemisphere spatial abilities may underlie our ability to take third person perspectives. This possibility was assessed for the first time in the present study. We investigated third person perspective taking using both visuospatial and verbal tasks in right-hemisphere stroke patients with anosognosia (n = 15) and without anosognosia (n = 15), as well as neurologically healthy control subjects (n = 15). The anosognosic group performed worse than both control groups when having to perform the tasks from a third versus a first person perspective. Individual analysis further revealed a classical dissociation between most anosognosic patients and control subjects in mental (but not visuospatial) third person perspective taking abilities. Finally, the severity of unawareness in anosognosia patients was correlated to greater impairments in such third person, mental perspective taking abilities (but not visuospatial perspective taking). In voxel-based lesion mapping we also identified the lesion sites linked with such deficits, including some brain areas previously associated with inhibition, perspective taking and mentalizing, such as the inferior and middle frontal gyri, as well as the supramarginal and superior temporal gyri. These results suggest that neurocognitive deficits in mental perspective taking may contribute to anosognosia and provide novel insights regarding the relation between self-awareness and social cognition.