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BACKGROUND: The rapid advancement of technology-focused strategies in neurorehabilitation has brought optimism to individuals with neurological disorders, caregivers, and physicians while reshaping medical practice and training. OBJECTIVES: We critically examine the implications of technology in neurorehabilitation, drawing on discussions from the 2021 and 2024 World Congress for NeuroRehabilitation. While acknowledging the value of technology, it highlights inherent limitations and ethical concerns, particularly regarding the potential overshadowing of humanistic approaches. The integration of technologies such as robotics, artificial intelligence, neuromodulation, and brain-computer interfaces enriches neurorehabilitation by offering interdisciplinary solutions. However, ethical considerations arise regarding the balance between compensation for deficits, accessibility of technologies, and their alignment with fundamental principles of care. Additionally, the pitfalls of relying solely on neuroimaging data are discussed, stressing the necessity for a more comprehensive understanding of individual variability and clinical skills in rehabilitation. RESULTS: From a clinical perspective, the article advocates for realistic solutions that prioritize individual needs, quality of life, and social inclusion over technological allure. It underscores the importance of modesty and honesty in responding to expectations while emphasizing the uniqueness of each individual's experience. Moreover, it argues for the preservation of human-centric approaches alongside technological advancements, recognizing the invaluable role of clinical observation and human interaction in rehabilitation. CONCLUSION: Ultimately, the article calls for a balanced attitude that integrates both scientific and humanistic perspectives in neurorehabilitation. It highlights the symbiotic relationship between the sciences and humanities, advocating for philosophical questioning to guide the ethical implementation of new technologies and foster interdisciplinary dialogue.
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BACKGROUND: "Cancer Related Cognitive Impairment" (CRCI) defines cognitive disorders related to cancer and its treatments. Many people with breast cancer experience signs of CRCI (incidence between 20 and 30 %) and, although several intervention options exist, there is no established standard of care. Our main objective was to provide a detailed description of the methods and results of randomized controlled trials of interventions for CRCI in breast cancer survivors, paying particular attention to the timing of the interventions within the care pathway. METHODS: We conducted a systematic literature review following the PRISMA guidelines from 01 to 01-2019 to 16-07-2023 and included randomized controlled trials of interventions for CRCI after breast cancer with at least one objective cognitive assessment as a primary or secondary outcome. RESULTS: Among 228 identified studies, 35 (including 2821 participants) were retained for inclusion. The interventions were classified into 4 categories: cognitive rehabilitation, physical activity, complementary therapy and pharmacological treatment. Our analysis revealed that pharmacological interventions have no effect, whereas physical activity interventions proposed in the months following the initial cancer treatment improve Quality of Life and Speed of Information Processing while interventions proposed later improve Memory and Attention (Cognitive Rehabilitation) and Perceived Cognitive Function and Depression/Anxiety/Mood (Complementary Therapies). CONCLUSION: CRCI is multifactorial and affected individuals frequently experience high levels of fatigue, pain, anxiety and depression and are most likely to benefit from holistic approaches that include cognition, physical activity, relaxation, psychoeducation, group support and/or psychological counselling. Thus, rehabilitation programs should be designed on multi-modal approaches, using innovative, cost-effective delivery methods that increase access to treatment, and intervention outcomes should be evaluated using measures of participation. DATABASE REGISTRATION: The review was recorded on Prospero (01-03-2020), with the registration number 135,627.
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Neoplasias da Mama , Disfunção Cognitiva , Feminino , Humanos , Neoplasias da Mama/reabilitação , Neoplasias da Mama/psicologia , Neoplasias da Mama/complicações , Sobreviventes de Câncer/psicologia , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/reabilitação , Terapias Complementares/métodos , Exercício Físico , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
PURPOSE: Cognitive rehabilitation research has progressed slowly, in part due to incomplete reporting of intervention content and delivery and the difficulties this produces for discerning program effectiveness. This knowledge gap can be reduced by providing detailed intervention descriptions. We document the content/ingredients and therapeutic targets of a cognitive rehabilitation program for adults with mild-to-moderate cognitive impairment. METHODS: The documentation process used a method of participatory/collaborative research. Discussions with the clinical team identified session content/ingredients and therapeutic targets, which were then described using Body Functions, and Activities & Participation domains from the International Classification of Function, Disability and Health (ICF). Domains most frequently targeted by each clinician were identified as Primary Targets. RESULTS: Each clinician produced a detailed description of session content, implementation, and ICF-coded therapeutic targets. This revealed that the whole program targets 29 ICF domains, seven of which were identified as Primary Targets: Higher-level Cognitive; Attention; Memory; Emotional; Global Psychosocial, Temperament and Personality, and Conversation. CONCLUSIONS: Documentation of treatment targets enabled identification of appropriate outcome measures which are now being used to investigate program efficacy. This step-by-step explanation of the documentation process could serve as a guide for other teams wanting to document their rehabilitation interventions and/or establish similar programs.IMPLICATIONS FOR REHABILITATIONIncomplete reporting of intervention content and delivery contributes to difficulties in discerning the effectiveness of complex rehabilitation programs.Current recommendations for rehabilitation intervention reporting suggest that these difficulties can be partially overcome by providing detailed descriptions of intervention content/ingredients and treatment targets.Human and physical resources differ widely from one clinical setting to another and the existence of clear program descriptions can guide clinicians who wish to create similar programs.Detailed descriptions of rehabilitation interventions are necessary to accurately measure patient outcomes and generate testable hypotheses about proposed mechanisms of action.Program descriptions are needed for the development of treatment theories and the advancement of evidence-based practice in rehabilitation.
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Lesões Encefálicas , Disfunção Cognitiva , Pessoas com Deficiência , Humanos , Treino Cognitivo , Disfunção Cognitiva/etiologia , Pessoas com Deficiência/reabilitação , Pesquisa de ReabilitaçãoRESUMO
Background: Interactions between the somatosensory and motor cortices are of fundamental importance for motor control. Although physically distant, face and hand representations are side by side in the sensorimotor cortex and interact functionally. Traumatic brachial plexus injury (TBPI) interferes with upper limb sensorimotor function, causes bilateral cortical reorganization, and is associated with chronic pain. Thus, TBPI may affect sensorimotor interactions between face and hand representations. Objective: The aim of this study was to investigate changes in hand-hand and face-hand sensorimotor integration in TBPI patients using an afferent inhibition (AI) paradigm. Method: The experimental design consisted of electrical stimulation (ES) applied to the hand or face followed by transcranial magnetic stimulation (TMS) to the primary motor cortex to activate a hand muscle representation. In the AI paradigm, the motor evoked potential (MEP) in a target muscle is significantly reduced when preceded by an ES at short-latency (SAI) or long-latency (LAI) interstimulus intervals. We tested 18 healthy adults (control group, CG), evaluated on the dominant upper limb, and nine TBPI patients, evaluated on the injured or the uninjured limb. A detailed clinical evaluation complemented the physiological investigation. Results: Although hand-hand SAI was present in both the CG and the TBPI groups, hand-hand LAI was present in the CG only. Moreover, less AI was observed in TBPI patients than the CG both for face-hand SAI and LAI. Conclusion: Our results indicate that sensorimotor integration involving both hand and face sensorimotor representations is affected by TBPI.
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Introduction: We report a very unique clinical presentation of a patient who complained, after a left parietal brain damage, about feeling tactile stimulations on his right upper limb without being able to localize them. Methods: Using a single case study approach, we report three experiments relying on several custom-made tasks to explore the different levels of somatosensory information processing, ranging from somato-sensation to somato-representation. Results: Our results showed a preserved ability to localize tactile stimuli applied on the right upper limb when using pointing responses while the ability to localize was less efficient when having to name the stimulated part (akin Numbsense). When the stimuli were applied on more distal locations (i.e., on the hand and on fingers), the number of correct responses decreased significantly independently of the modality of response. Finally, when visually presented with a stimulus delivered on the hand of an examiner in synchrony with the stimulation on the hidden hand of the patient, responses were largely influenced by the visual information available. Altogether, the convergence of these different customized tasks revealed an absence of autotopagnosia for motor responses for the right upper limb, associated with altered abilities to discriminate stimulus applied on distal and restricted/closer zones in the hand. Discussion: The somato-representation of our patient seemed to significantly rely on visual information, leading to striking deficits to localize tactile stimuli when vision and somesthesic afferences are discordant. This case report offers a clinical illustration of pathological imbalance between vision and somesthesia. Implications of these troubles in somato-representation on higher cognitive level processes are discussed.
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PURPOSE: To develop and validate a new questionnaire, the Kid-SSQ, for the rapid screening of hearing abilities in children with hearing impairment, aged 7-17 years. METHODS: The questionnaire was constructed from two existing, validated versions of the 'Speech, Spatial and Qualities of Hearing' - (SSQ) questionnaire (pediatric form and adult short-form). The 12 selected items included auditory aspects from three subscales: speech perception, spatial hearing, and qualities of hearing. This new short form was then validated in 154 children with cochlear implants (100 bilaterally, and 54 unilaterally implanted children). Construct validity was assessed by testing relationships between Kid-SSQ scores and objective clinical parameters (e.g., age at test, pure-tone audiometry-PTA threshold, speech reception threshold-SRT, duration of binaural experience). RESULTS: Completion time was acceptable for use with children (less than 10 min) and the non-response rate was less than 1%. Good internal consistency was obtained (Cronbach's α = 0.78), with a stable internal structure corresponding to the 3 intended subscales. External validity showed the specificity of each subscale: speech subscale scores were significantly predicted (r = 0.32, p < 0.001) by both 2 kHz PTA threshold (ß = 0.33, p < 0.001) and SRT (ß = - 0.23, p < 0.001). Children with more binaural experience showed significantly higher scores on the spatial subscale than children with less binaural experience (F(1,98) = 5.1, p < 0.03) and the qualities of hearing subscale scores significantly depended on both age and SRT (r = 0.32, p < 0.001). CONCLUSIONS: The Kid-SSQ questionnaire is a robust and clinically useful questionnaire for self-assessment of difficulties in various auditory domains.
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Implantes Cocleares , Perda Auditiva , Percepção da Fala , Adulto , Humanos , Criança , Fala , Perda Auditiva/diagnóstico , Audição/fisiologia , Inquéritos e Questionários , Percepção da Fala/fisiologia , Audiometria de Tons PurosRESUMO
OBJECTIVE: The aim of this study was to evaluate the feasibility of a virtual reality-based spatial hearing training protocol in bilateral cochlear implant (CI) users and to provide pilot data on the impact of this training on different qualities of hearing. DESIGN: Twelve bilateral CI adults aged between 19 and 69 followed an intensive 10-week rehabilitation program comprised eight virtual reality training sessions (two per week) interspersed with several evaluation sessions (2 weeks before training started, after four and eight training sessions, and 1 month after the end of training). During each 45-minute training session, participants localized a sound source whose position varied in azimuth and/or in elevation. At the start of each trial, CI users received no information about sound location, but after each response, feedback was given to enable error correction. Participants were divided into two groups: a multisensory feedback group (audiovisual spatial cue) and an unisensory group (visual spatial cue) who only received feedback in a wholly intact sensory modality. Training benefits were measured at each evaluation point using three tests: 3D sound localization in virtual reality, the French Matrix test, and the Speech, Spatial and other Qualities of Hearing questionnaire. RESULTS: The training was well accepted and all participants attended the whole rehabilitation program. Four training sessions spread across 2 weeks were insufficient to induce significant performance changes, whereas performance on all three tests improved after eight training sessions. Front-back confusions decreased from 32% to 14.1% ( p = 0.017); speech recognition threshold score from 1.5 dB to -0.7 dB signal-to-noise ratio ( p = 0.029) and eight CI users successfully achieved a negative signal-to-noise ratio. One month after the end of structured training, these performance improvements were still present, and quality of life was significantly improved for both self-reports of sound localization (from 5.3 to 6.7, p = 0.015) and speech understanding (from 5.2 to 5.9, p = 0.048). CONCLUSIONS: This pilot study shows the feasibility and potential clinical relevance of this type of intervention involving a sensorial immersive environment and could pave the way for more systematic rehabilitation programs after cochlear implantation.
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Implante Coclear , Implantes Cocleares , Localização de Som , Percepção da Fala , Adulto , Humanos , Recém-Nascido , Implante Coclear/métodos , Projetos Piloto , Qualidade de Vida , Percepção da Fala/fisiologia , Audição/fisiologiaRESUMO
Reorganization of the sensorimotor cortex following permanent (e.g., amputation) or temporary (e.g., local anaesthesia) deafferentation of the hand has revealed large-scale plastic changes between the hand and face representations that are accompanied by perceptual correlates. The physiological mechanisms underlying this reorganization remain poorly understood. The aim of this study was to investigate sensorimotor interactions between the face and hand using an afferent inhibition transcranial magnetic stimulation protocol in which the motor evoked potential elicited by the magnetic pulse is inhibited when it is preceded by an afferent stimulus. We hypothesized that if face and hand representations in the sensorimotor cortex are functionally coupled, then electrocutaneous stimulation of the face would inhibit hand muscle motor responses. In two separate experiments, we delivered an electrocutaneous stimulus to either the skin over the right upper lip (Experiment 1) or right cheek (Experiment 2) and recorded muscular activity from the right first dorsal interosseous. Both lip and cheek stimulation inhibited right first dorsal interosseous motor evoked potentials. To investigate the specificity of this effect, we conducted two additional experiments in which electrocutaneous stimulation was applied to either the right forearm (Experiment 3) or right upper arm (Experiment 4). Forearm and upper arm stimulation also significantly inhibited the right first dorsal interosseous motor evoked potentials, but this inhibition was less robust than the inhibition associated with face stimulation. These findings provide the first evidence for face-to-hand afferent inhibition.
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Córtex Motor , Estimulação Elétrica , Potencial Evocado Motor/fisiologia , Mãos/fisiologia , Córtex Motor/fisiologia , Músculo Esquelético/fisiologia , Inibição Neural/fisiologia , Estimulação Magnética TranscranianaRESUMO
Caloric vestibular stimulation (CVS) can temporarily reduce visuospatial neglect and related symptoms. The present study examined the effect of CVS on representational neglect during free exploration of the map of France. We asked patients to name cities they could mentally "see" on the map of France, without giving them any directional instructions related to the left or right sides of the map. In right brain damaged patients with left visuospatial neglect, the mental representation of the map was asymmetrical (favoring the right side). After stimulation, neglect patients named more towns on the left side of the map, leading to a significant reduction in map representation asymmetry. Our findings are consistent with previous studies on visuospatial neglect and are in favor of a central effect of vestibular stimulation on mechanisms involved in space representation.
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Objectives: Recent clinical studies and meta-analyses have reported the clinical effects of mindfulness-based interventions as a complementary treatment for patients with schizophrenia, but their possible efficacy in patients with first episode of psychosis (FEP) and in individuals with ultra-high risk (UHR) of transition to psychosis is less clear. Here, we investigated the current evidence on the usefulness of mindfulness-based interventions in these two populations. Methods: We conducted a systematic search of the literature according to the PRISMA guidelines. Results: Among the 102 references retrieved, 9 responded to the inclusion criteria (8 in FEP patients and 1 in UHR individuals). In FEP patients, mindfulness interventions are well-tolerated and have a satisfactory level of adherence. The clinical benefits consist primarily of reduced anxiety and sadness and improved quality of life. None of the studies reported any increase in positive symptoms. Conclusion: Future sham-controlled studies with large sample sizes are needed to definitively conclude on the clinical interest of mindfulness-based interventions in FEP patients and UHR individuals as well as to understand their underlying mechanisms of action.
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BACKGROUND: Motor imagery (MI) training is often used to improve physical practice (PP), and the functional equivalence between imagined and practiced movements is widely considered essential for positive training outcomes. OBJECTIVE: We previously showed that a 5-week MI training program improved tenodesis grasp in individuals with C6-C7 quadriplegia. Here we investigated whether functional equivalence changed during the course of this training program. METHODS: In this descriptive pilot study, we retrospectively analyzed data for 6 individuals with C6-C7 quadriplegia (spinal cord injured [SCI]) and 6 healthy age-matched controls who trained for 5 weeks in visual and kinesthetic motor imagery or visualization of geometric shapes (controls). Before training, we assessed MI ability by using the Kinesthetic and Visual Imagery Questionnaire (KVIQ). We analyzed functional equivalence by vividness measured on a visual analog scale (0-100) and MI/PP time ratios computed from imagined and physically practiced movement durations measured during MI training. These analyses were re-run considering that half of the participants with quadriplegia were good imagers and the other half were poor imagers based on KVIQ scores. To investigate generalization of training effects, we analyzed MI/PP ratios for an untrained pointing task before (3 baseline measures), immediately after, and 2 months after training. RESULTS: During MI training, imagery vividness increased significantly. Only the good imagers evolved toward temporal equivalence during training. Good imagers were also the only participants who showed changes in temporal equivalence on the untrained pointing task. CONCLUSION: This is the first study reporting improvement in functional equivalence during an MI training program that improved tenodesis grasp in individuals with C6-C7 quadriplegia. We recommend that clinical MI programs focus primarily on vividness and suggest that feedback about movement duration could potentially improve temporal equivalence, which could in turn lead to further improvement in PP.
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Imaginação , Modalidades de Fisioterapia , Desempenho Psicomotor , Quadriplegia/reabilitação , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Cinestesia , Masculino , Projetos Piloto , Adulto JovemRESUMO
Adaptation to rightward shifting prisms (rightward prism adaptation, RPA) ameliorates neglect symptoms in patients while adaptation to leftward shifting prisms (leftward prism adaptation, LPA) induces neglect-like behaviors in healthy subjects. It has been hypothesized that prism adaptation (PA) modulates interhemispheric balance between the parietal cortices by inhibiting the posterior parietal cortex (PPC) contralateral to the prismatic deviation, but PA's effects on interhemispheric inhibition (IHI) have not been directly investigated. Since there are hyper-excitable connections between the PPC and primary motor cortex (M1) in the left hemisphere of neglect patients, we reasoned that LPA might mimic right hemisphere lesions by reducing parietal IHI, hyper-exciting the left PPC and PPC-M1 connections, and in turn altering IHI at the motor level. Namely, we hypothesized that LPA would increase IHI from the left to the right M1. We examined changes in left-to-right and right-to-left IHI between the 2 M1s using the ipsilateral silent period (iSP) (Meyer et al. 1995) before and after either LPA or RPA. The iSP was significantly longer after LPA but only from left-to-right and it did not change at all after RPA. This is the first physiological demonstration that LPA alters IHI in the healthy brain.
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Adaptação Fisiológica/fisiologia , Córtex Motor/fisiologia , Lobo Parietal/fisiologia , Estimulação Luminosa/métodos , Desempenho Psicomotor/fisiologia , Percepção Visual/fisiologia , Feminino , Lateralidade Funcional/fisiologia , Humanos , Masculino , Inibição Neural/fisiologia , Adulto JovemRESUMO
Rightward prismatic adaptation (RPA) can reduce neglect symptoms in patients whereas adaptation to leftward deviating prisms (LPA) can induce neglect-like behavior in healthy subjects. One influential anatomo-functional model of prismatic adaptation (PA) postulates that it inhibits activity of the posterior parietal cortex (PPC) contralateral to the prismatic deviation. By hypo-activating the PPC and thus eventually acting on interhemispheric balance, both LPA and RPA could possibly affect visuospatial perception in healthy subjects, however, such behavioral modulation has seldom been reported after RPA. In the light of recent evidence showing that LPA-induced visuospatial shift need time to develop we hypothesized that RPA might induce significant changes in visuospatial cognition on a longer time scale. We thus assessed the Landmark task, as well as sensorimotor aftereffects, several times over 8 h after a single session of either LPA or RPA. In agreement with previous reports, sensorimotor effects were symmetrical and long-lasting, with both LPA and RPA inducing shifts of comparable amplitudes in the direction opposite to the deviation that lasted up to 8 h. Visuospatial cognition assessed by Landmark performance, was also significantly modulated for up to 8 h, but only after LPA. Interestingly, the timing and direction of this modulation differed according to participants' baseline bias. An initial leftward bias led to a rapid, but short-lasting rightward shift, whereas an initial rightward bias led to a slower-developing and longer-lasting leftward shift. These findings shed new light on a so-far relatively overlooked feature of spatial cognition that may interact with the effect of PA: the state of the visuospatial system prior to PA should be taken into account when attempting to understand and modulate visuospatial cognition in healthy and brain-damaged populations. This highlights the need for refining current models of PA's mechanisms of action.
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Adaptação Fisiológica/fisiologia , Cognição/fisiologia , Lateralidade Funcional/fisiologia , Lobo Parietal/fisiologia , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa , Campos Visuais/fisiologia , Adulto JovemRESUMO
Pain influences plasticity within the sensorimotor system and the aim of this study was to assess the effect of pain on changes in motor performance and corticospinal excitability during training for a novel motor task. A total of 30 subjects were allocated to one of two groups (Pain, NoPain) and performed ten training blocks of a visually-guided isometric pinch task. Each block consisted of 15 force sequences, and subjects modulated the force applied to a transducer in order to reach one of five target forces. Pain was induced by applying capsaicin cream to the thumb. Motor performance was assessed by a skill index that measured shifts in the speed-accuracy trade-off function. Neurophysiological measures were taken from the first dorsal interosseous using transcranial magnetic stimulation. Overall, the Pain group performed better throughout the training (p = 0.03), but both groups showed similar improvements across training blocks (p < 0.001), and there was no significant interaction. Corticospinal excitability in the NoPain group increased halfway through the training, but this was not observed in the Pain group (Time × Group interaction; p = 0.01). These results suggest that, even when pain does not negatively impact on the acquisition of a novel motor task, it can affect training-related changes in corticospinal excitability.
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Dor Crônica/diagnóstico , Síndromes da Dor Regional Complexa/diagnóstico , Lateralidade Funcional/fisiologia , Transtornos da Percepção/diagnóstico , Percepção Espacial/fisiologia , Dor Crônica/fisiopatologia , Síndromes da Dor Regional Complexa/fisiopatologia , Feminino , Humanos , Pessoa de Meia-Idade , Transtornos da Percepção/fisiopatologiaRESUMO
Sensorimotor integration is altered in people with chronic pain. While there is substantial evidence that pain interferes with neural activity in primary sensory and motor cortices, much less is known about its impact on integrative sensorimotor processes. Here, the short latency afferent inhibition (SAI) paradigm was used to assess sensorimotor integration in the presence and absence of experimental cutaneous heat pain applied to the hand. Ulnar nerve stimulation was combined with transcranial magnetic stimulation to condition motor evoked potentials (MEPs) in the first dorsal interosseous muscle. Four interstimulus intervals (ISI) were tested, based on the latency of the N20 component of the afferent sensory volley (N20-5 ms, N20+2 ms, N20+4 ms, N20+10 ms). In the PAIN condition, MEPs were smaller compared to the NEUTRAL condition (p = 0.005), and were modulated as a function of the ISI (p = 0.012). Post-hoc planned comparisons revealed that MEPs at N20+2 and N20+4 were inhibited compared to unconditioned MEPs. However, the level of inhibition (SAI) was similar in the PAIN and NEUTRAL conditions. This suggests that the interplay between pain and sensorimotor integration is not mediated through direct and rapid pathways as assessed by SAI, but rather might involve higher-order integrative areas.
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Interaction with visual objects in the environment requires an accurate correspondence between visual space and its internal representation within the brain. Many clinical conditions involve some impairment in visuo-motor control and the errors created by the lesion of a specific brain region are neither random nor uninformative. Modern approaches to studying the neuropsychology of action require powerful data-driven analyses and error modeling in order to understand the function of the lesioned areas. In the present paper we carried out mixed-effect analyses of the pointing errors of seven optic ataxia patients and seven control subjects. We found that a small parameter set is sufficient to explain the pointing errors produced by unilateral optic ataxia patients. In particular, the extremely stereotypical errors made when pointing toward the contralesional visual field can be fitted by mathematical models similar to those used to model central magnification in cortical or sub-cortical structure(s). Our interpretation is that visual areas that contain this footprint of central magnification guide pointing movements when the posterior parietal cortex (PPC) is damaged and that the functional role of the PPC is to actively compensate for the under-representation of peripheral vision that accompanies central magnification. Optic ataxia misreaching reveals what would be hand movement accuracy and precision if the human motor system did not include elaborated corrective processes for reaching and grasping to non-foveated targets.
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Rightward prism adaptation ameliorates neglect symptoms while leftward prism adaptation (LPA) induces neglect-like biases in healthy individuals. Similarly, inhibitory repetitive transcranial magnetic stimulation (rTMS) on the right posterior parietal cortex (PPC) induces neglect-like behavior, whereas on the left PPC it ameliorates neglect symptoms and normalizes hyperexcitability of left hemisphere parietal-motor (PPC-M1) connectivity. Based on this analogy we hypothesized that LPA increases PPC-M1 excitability in the left hemisphere and decreases it in the right one. In an attempt to shed some light on the mechanisms underlying LPA's effects on cognition, we investigated this hypothesis in healthy individuals measuring PPC-M1 excitability with dual-site paired-pulse TMS (ppTMS). We found a left hemisphere increase and a right hemisphere decrease in the amplitude of motor evoked potentials elicited by paired as well as single pulses on M1. While this could indicate that LPA biases interhemispheric connectivity, it contradicts previous evidence that M1-only MEPs are unchanged after LPA. A control experiment showed that input-output curves were not affected by LPA per se. We conclude that LPA combined with ppTMS on PPC-M1 differentially alters the excitability of the left and right M1.
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Adaptação Fisiológica/fisiologia , Córtex Motor/fisiologia , Lobo Parietal/fisiologia , Estimulação Luminosa/métodos , Tratos Piramidais/fisiologia , Estimulação Magnética Transcraniana/métodos , Adulto , Estimulação Elétrica/métodos , Eletromiografia/métodos , Potencial Evocado Motor/fisiologia , Feminino , Humanos , Masculino , Distribuição AleatóriaRESUMO
Predicting intentions from observing another agent's behaviours is often thought to depend on motor resonance - i.e., the motor system's response to a perceived movement by the activation of its stored motor counterpart, but observers might also rely on prior expectations, especially when actions take place in perceptually uncertain situations. Here we assessed motor resonance during an action prediction task using transcranial magnetic stimulation to probe corticospinal excitability (CSE) and report that experimentally-induced updates in observers' prior expectations modulate CSE when predictions are made under situations of perceptual uncertainty. We show that prior expectations are updated on the basis of both biomechanical and probabilistic prior information and that the magnitude of the CSE modulation observed across participants is explained by the magnitude of change in their prior expectations. These findings provide the first evidence that when observers predict others' intentions, motor resonance mechanisms adapt to changes in their prior expectations. We propose that this adaptive adjustment might reflect a regulatory control mechanism that shares some similarities with that observed during action selection. Such a mechanism could help arbitrate the competition between biomechanical and probabilistic prior information when appropriate for prediction.