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1.
J Neural Eng ; 20(1)2023 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-36669203

RESUMO

Background. Low-intensity transcranial ultrasound stimulation (TUS) could induce both immediate and long-lasting neuromodulatory effects in human brains. Interhemispheric imbalance at prefrontal or motor cortices generally associates with various cognitive decline in aging and mental disorders. However, whether TUS could modulate the interhemispheric balance of excitability in human brain remains unknown.Objective. This study aims to explore whether repetitive TUS (rTUS) intervention can modulate the interhemispheric balance of excitability between bilateral motor cortex (M1) in healthy subjects.Approach. Motor evoked potentials (MEPs) at bilateral M1 were measured at 15 min and 0 min before a 15 min active or sham rTUS intervention on left M1 and at 0 min, 15 min and 30 min after the intervention, and the Chinese version of brief neurocognitive test battery (C-BCT) was conducted before and after the intervention respectively. Cortical excitability was quantified by MEPs, and the long-lasting changes of MEP amplitude was used as an index of plasticity.Results. In the active rTUS group (n= 20), the ipsilateral MEP amplitude increased significantly compared with baselines and lasted for up to 30 min after intervention, while the contralateral MEP amplitude decreased lasting for 15 min, yielding increased laterality between bilateral MEPs. Furthermore, rTUS intervention induced changes in some C-BCT scores, and the changes of scores correlated with the changes of MEP amplitudes induced by rTUS intervention. The sham rTUS group (n= 20) showed no significant changes in MEPs and C-BCT scores. In addition, no participants reported any adverse effects during and after the rTUS intervention, and no obvious temperature increase appeared in skull or brain tissues in simulation.Significance. rTUS intervention modulated the plasticity of ipsilateral M1 and the interhemispheric balance of M1 excitability in human brain, and improved cognitive performance, suggesting a considerable potential of rTUS in clinical interventions.


Assuntos
Transtornos Mentais , Córtex Motor , Humanos , Córtex Motor/fisiologia , Estimulação Magnética Transcraniana/métodos , Potencial Evocado Motor/fisiologia , Lateralidade Funcional/fisiologia
2.
Proc Natl Acad Sci U S A ; 120(6): e2212726120, 2023 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-36716370

RESUMO

Human motor adaptability is of utmost utility after neurologic injury such as unilateral stroke. For successful adaptive control of movements, the nervous system must learn to correctly identify the source of a movement error and predictively compensate for this error. The current understanding is that in bimanual tasks, this process is flexible such that errors are assigned to, and compensated for, by the limb that is more likely to produce those errors. Here, we tested the flexibility of the error assignment process in right-handed chronic stroke survivors using a bimanual reaching task in which the hands jointly controlled a single cursor. We predicted that the nondominant left hand in neurotypical adults and the paretic hand in chronic stroke survivors will be more responsible for cursor errors and will compensate more within a trial and learn more from trial to trial. We found that in neurotypical adults, the nondominant left hand does compensate more than the right hand within a trial but learns less trial-to-trial. After a left hemisphere stroke, the paretic right hand compensates more than the nonparetic left hand within-trial but learns less trial-to-trial. After a right hemisphere stroke, the paretic left hand neither corrects more within-trial nor learns more trial-to-trial. Thus, adaptive control of visually guided bimanual reaching movements is reversed between hands after the left hemisphere stroke and lost following the right hemisphere stroke. These results indicate that responsibility assignment is not fully flexible but depends on a central mechanism that is lateralized to the right hemisphere.


Assuntos
Desempenho Psicomotor , Acidente Vascular Cerebral , Adulto , Humanos , Desempenho Psicomotor/fisiologia , Lateralidade Funcional/fisiologia , Mãos/fisiologia , Movimento
3.
J Neurophysiol ; 129(1): 102-114, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36475891

RESUMO

Bilateral training systems look to promote the paretic hand's use in individuals with hemiplegia. Although this is normally achieved using mechanical coupling (i.e., a physical connection between the hands), a virtual reality system relying on virtual coupling (i.e., through a shared virtual object) would be simpler to use and prevent slacking. However, it is not clear whether different coupling modes differently impact task performance and effort distribution between the hands. We explored how 18 healthy right-handed participants changed their motor behaviors in response to the uninstructed addition of mechanical coupling, and virtual coupling using a shared cursor mapped to the average hands' position. In a second experiment, we then studied the impact of connection stiffness on performance, perception, and effort imbalance. The results indicated that both coupling types can induce the hands to actively contribute to the task. However, the task asymmetry introduced by using a cursor mapped to either the left or right hand only modulated the hands' contribution when not mechanically coupled. The tracking performance was similar for all coupling types, independent of the connection stiffness, although the mechanical coupling was preferred and induced the hands to move with greater correlation. These findings suggest that virtual coupling can induce the hands to actively contribute to a task in healthy participants without hindering their performance. Further investigation on the coupling types' impact on the performance and hands' effort distribution in patients with hemiplegia could allow for the design of simpler training systems that promote the affected hand's use.NEW & NOTEWORTHY We showed that the uninstructed addition of a virtual and/or a mechanical coupling can induce both hands to actively contribute in a continuous redundant bimanual tracking task without impacting performance. In addition, we showed that the task asymmetry can only alter the effort distribution when the hands are not connected, independent of the connection stiffness. Our findings suggest that virtual coupling could be used in the development of simpler VR-based training devices.


Assuntos
Hemiplegia , Desempenho Psicomotor , Humanos , Desempenho Psicomotor/fisiologia , Mãos/fisiologia , Análise e Desempenho de Tarefas , Força da Mão/fisiologia , Lateralidade Funcional/fisiologia
4.
Stroke ; 54(1): 10-19, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36542072

RESUMO

Unilateral spatial neglect (USN) is a common and disabling cognitive consequence of stroke wherein individuals demonstrate decreased response to contralesional information. Here, we provide an updated narrative review of studies that shed light on the neural mechanisms and predictors of recovery of USN. Additionally, we report a rapid review of randomized controlled trials focusing on USN intervention, both nonpharmacological and pharmacological, published in the last 5 years. Randomized controlled trials are reviewed within the context of systematic reviews and meta-analyses of USN interventions published within the same time frame. The quality of randomized controlled trials of treatment is higher compared to quality reported in previous reviews and meta-analyses. However, remaining weaknesses in participant demographic reporting, as well as small, heterogenous samples, render generalizability and cross-study interpretation a challenge. Nevertheless, evidence regarding neural mechanisms underlying USN recovery and regarding the effectiveness of targeted USN interventions is accumulating and strengthening, setting the foundation for future investigations into patient-specific factors that may influence treatment response. We identify gaps and provide suggestions for future USN intervention research.


Assuntos
Transtornos da Percepção , Reabilitação do Acidente Vascular Cerebral , Acidente Vascular Cerebral , Humanos , Revisões Sistemáticas como Assunto , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/terapia , Transtornos da Percepção/etiologia , Transtornos da Percepção/terapia , Lateralidade Funcional/fisiologia
5.
Neuroscience ; 510: 21-31, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36521590

RESUMO

Dominance of the left hemisphere for language processing is a prominent feature of brain organisation. Whereas structural models clarify the functional asymmetry due to direct access to local language circuits, dynamic models propose functional states of intrahemispheric activation and interhemispheric inhibition that are coupled with attentional processes. Real word settings often require modulations of lateralised neural processing and further express individual heterogeneity. In this research, we tested left- and right-handers, and used a behavioural paradigm with presentation of lateralised cue-target pairs to the same or opposite visual field. We observed that handedness distinctly affected word processing in the left hemisphere following contralateral cueing. Moreover, left-hemispheric dominance strengthened for right-handers vs abolished for left-handers, influencing behavioural efficiency. In combination with eye dominance recordings, these data suggest that attentional biases guided the processing strategies of both groups and in turn their achievements. Therefore, hand and eye dominance are both essential factors with a functional role in directing the communication of visual information between both hemispheres. Overall, the findings underline the importance of interacting hand-eye control systems in contributing to interhemispheric patterns in the context of language processing.


Assuntos
Encéfalo , Lateralidade Funcional , Lateralidade Funcional/fisiologia , Encéfalo/fisiologia , Idioma , Dominância Ocular , Atenção/fisiologia , Dominância Cerebral/fisiologia
6.
Hum Mov Sci ; 87: 103050, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36549085

RESUMO

Action imagery practice (AIP) is effective to improve motor performance in a variety of tasks, though it is often less effective than action execution practice (AEP). In sequence learning, AIP and AEP result in the acquisition of effector-independent representations. However, it is unresolved whether effector-dependent representations can be acquired in AIP. In the present study, we investigated the acquisition of effector-independent representations and effector-dependent representations in AEP and AIP in an implicit sequence learning task (a visual serial-reaction-time task, involving a twelve-element sequence). Participants performed six sessions, each starting with tests. A practice sequence, a mirror sequence, and a different sequence were tested with the practice and transfer hand. In the first four sessions, after the tests, two groups performed either AIP (N = 50) or AEP (N = 54). Improvement in the different sequence indicated sequence-unspecific learning in both AEP and AIP. Importantly, reaction times of the practice hand became shorter in the practice sequence than in the other sequences, indicating implicit sequence learning in both, AEP and AIP. This effect was stronger in the practice hand than in the transfer hand, indicating effector-dependent sequence representations in both AEP and AIP. However, effector-dependent sequence representations were stronger in AEP than in AIP. No significant differences between groups were observed in the transfer hand, although effector-independent sequence representations were observed in AEP only. In conclusion, AIP promotes not only sequence-unspecific stimulus-response coupling and anticipations of the subsequent stimuli, but also anticipations of the subsequent responses.


Assuntos
Lateralidade Funcional , Desempenho Psicomotor , Humanos , Desempenho Psicomotor/fisiologia , Lateralidade Funcional/fisiologia , Aprendizagem/fisiologia , Tempo de Reação , Mãos/fisiologia
7.
Adv Exp Med Biol ; 1395: 205-209, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36527638

RESUMO

The Internet of Medical Things (IoMT) system plays a role in various areas of social activity, including healthcare. Telemetry of cardiovascular function, such as blood pressure and pulse, in daily life is useful in the treatment of cardiovascular disease and stress management. However, until now, brain function monitoring technology has not been installed in the IoMT system.In this study, we used near-infrared spectroscopy (NIRS) installed in the IoMT system to evaluate whether consumers who are not medical experts can measure their own brain function correctly. In addition, the IoMT system was used to assess the long-term effects of physical exercise on physical and mental health.We studied a total of 119 healthy adults recruited from a fitness gym in Koriyama, Japan. After receiving instruction in the usage of the IoMT monitoring system including NIRS, the subjects monitored their physical and mental conditions by themselves when they visited the gym. We evaluated the relations between blood pressure (BP), pulse rate (PR), body weight (BW) and age. In addition, we evaluated the left/right asymmetry of the prefrontal cortex (PFC) at rest and BP. We calculated the laterality index at rest (LIR) for assessment of left/right asymmetry of PFC activity; a positive LIR (>0) indicates right-dominant PFC activity associated with higher stress responses, while a negative LIR (<0) indicates left-dominant PFC activity associated with lower stress responses. We studied 47 out of 119 cases who monitored their physiological conditions before and after physical exercise for 6 months for this study.The results showed that the systolic blood pressure and mean blood pressure (p < 0.05) were significantly reduced after the physical exercise for 6 months; body weight did not change significantly (p > 0.05). In addition, NIRS demonstrated that LIR changed to plus values from minus values after exercise (p < 0.01).These results show that (1) consumers who are not-medical experts can measure their own brain function correctly using NIRS; (2) after long-term physical exercise, systemic blood pressure decreased, associated with modulation of PFC activity (i.e., from right-dominant PFC activity to left-dominant activity), indicating that long-term physical exercises caused relaxation in the brain and the autonomic nervous system.


Assuntos
Córtex Pré-Frontal , Espectroscopia de Luz Próxima ao Infravermelho , Adulto , Humanos , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Córtex Pré-Frontal/fisiologia , Lateralidade Funcional/fisiologia , Terapia por Exercício , Arritmias Cardíacas , Peso Corporal
8.
Neuropsychologia ; 177: 108417, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36356702

RESUMO

The prevailing theory concerning the pathophysiology of unilateral spatial neglect is that it is caused by an interhemispheric imbalance in attention networks. Previous studies have demonstrated that repetitive transcranial magnetic stimulation or transcranial direct current stimulation (tDCS) delivered over the right posterior parietal cortex can induce transitory neglect-like deficits in healthy individuals. We examined whether right cathodal and left anodal tDCS delivered over the posterior parietal cortex could produce neglect-like deficits and change the resting-state functional connectivity (rsFC) of attention networks. We found that the reaction time for targets in the left hemifield was significantly prolonged during two different types of visual search tasks, and rsFC of the attention networks was altered by tDCS. Furthermore, the change in the reaction times for the left visual target in the two different tasks significantly correlated with the change in the rsFC of either the right dorsal attention network (DAN) or right ventral attention network (VAN) based on the tasks. These results suggest that tDCS delivered to the posterior parietal cortex bilaterally induced neglect-like deficits by altering the connectivity of the attentional networks through excitability changes in the cortical area under the electrode. The results of this study are consistent with the hypothesis that the cause of neglect is the interhemispheric imbalance of attention networks. This is the first study to demonstrate that local cortical stimulation can induce changes not only in the local brain function but also in the cortical networks in healthy individuals.


Assuntos
Transtornos da Percepção , Estimulação Transcraniana por Corrente Contínua , Humanos , Estimulação Transcraniana por Corrente Contínua/efeitos adversos , Lateralidade Funcional/fisiologia , Lobo Parietal/fisiologia , Transtornos da Percepção/etiologia , Estimulação Magnética Transcraniana
9.
Sci Rep ; 12(1): 19566, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36379961

RESUMO

Visually-induced self-motion perception (vection) relies on interaction of the visual and vestibular systems. Neuroimaging studies have identified a lateralization of the thalamo-cortical multisensory vestibular network, with left-handers exhibiting a dominance of the left hemisphere and right-handers exhibiting a dominance of the right hemisphere. Using electroencephalography (EEG), we compare the early processing of a vection-consistent visual motion stimulus against a vection-inconsistent stimulus, to investigate the temporal activation of the vection network by visual motion stimulation and the lateralization of these processes in left- versus right-handers. In both groups, vection-consistent stimulation evoked attenuated central event-related potentials (ERPs) in an early (160-220 ms) and a late (260-300 ms) time window. Differences in estimated source activity were found across visual, sensorimotor, and multisensory vestibular cortex in the early window, and were observed primarily in the posterior cingulate, retrosplenial cortex, and precuneus in the late window. Group comparisons revealed a larger ERP condition difference (i.e. vection-consistent stimulation minus vection-inconsistent stimulation) in left-handers, which was accompanied by group differences in the cingulate sulcus visual (CSv) area. Together, these results suggest that handedness may influence ERP responses and activity in area CSv during vection-consistent and vection-inconsistent visual motion stimulation.


Assuntos
Percepção de Movimento , Vestíbulo do Labirinto , Eletroencefalografia , Percepção de Movimento/fisiologia , Vestíbulo do Labirinto/fisiologia , Lateralidade Funcional/fisiologia , Córtex Cerebral/fisiologia
10.
Proc Natl Acad Sci U S A ; 119(42): e2207293119, 2022 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-36215488

RESUMO

The mature human brain is lateralized for language, with the left hemisphere (LH) primarily responsible for sentence processing and the right hemisphere (RH) primarily responsible for processing suprasegmental aspects of language such as vocal emotion. However, it has long been hypothesized that in early life there is plasticity for language, allowing young children to acquire language in other cortical regions when LH areas are damaged. If true, what are the constraints on functional reorganization? Which areas of the brain can acquire language, and what happens to the functions these regions ordinarily perform? We address these questions by examining long-term outcomes in adolescents and young adults who, as infants, had a perinatal arterial ischemic stroke to the LH areas ordinarily subserving sentence processing. We compared them with their healthy age-matched siblings. All participants were tested on a battery of behavioral and functional imaging tasks. While stroke participants were impaired in some nonlinguistic cognitive abilities, their processing of sentences and of vocal emotion was normal and equal to that of their healthy siblings. In almost all, these abilities have both developed in the healthy RH. Our results provide insights into the remarkable ability of the young brain to reorganize language. Reorganization is highly constrained, with sentence processing almost always in the RH frontotemporal regions homotopic to their location in the healthy brain. This activation is somewhat segregated from RH emotion processing, suggesting that the two functions perform best when each has its own neural territory.


Assuntos
Idioma , Acidente Vascular Cerebral , Adolescente , Encéfalo/fisiologia , Mapeamento Encefálico/métodos , Criança , Pré-Escolar , Lateralidade Funcional/fisiologia , Humanos , Imageamento por Ressonância Magnética/métodos , Plasticidade Neuronal/fisiologia , Adulto Jovem
11.
Clin Neurophysiol ; 144: 123-134, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36307364

RESUMO

OBJECTIVE: To understand the impact of interictal spikes on brain connectivity in patients with Self-Limited Epilepsy with Centrotemporal Spikes (SeLECTS). METHODS: Electroencephalograms from 56 consecutive SeLECTS patients were segmented into periods with and without spikes. Connectivity between electrodes was calculated using the weighted phase lag index. To determine if there are chronic alterations in connectivity in SeLECTS, we compared spike-free connectivity to connectivity in 65 matched controls. To understand the acute impact of spikes, we compared connectivity immediately before, during, and after spikes versus baseline, spike-free connectivity. We explored whether behavioral state, spike laterality, or antiseizure medications affected connectivity. RESULTS: Children with SeLECTS had markedly higher connectivity than controls during sleep but not wakefulness, with greatest difference in the right hemisphere. During spikes, connectivity increased globally; before and after spikes, left frontal and bicentral connectivity increased. Right hemisphere connectivity increased more during right-sided than left-sided spikes; left hemisphere connectivity was equally affected by right and left spikes. CONCLUSIONS: SeLECTS patient have persistent increased connectivity during sleep; connectivity is further elevated during the spike and perispike periods. SIGNIFICANCE: Testing whether increased connectivity impacts cognition or seizure susceptibility in SeLECTS and more severe epilepsies could help determine if spikes should be treated.


Assuntos
Epilepsia Rolândica , Criança , Humanos , Eletroencefalografia , Convulsões , Encéfalo , Lateralidade Funcional/fisiologia
12.
Acta Psychol (Amst) ; 230: 103765, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36242923

RESUMO

The Spatial-Numerical Association of Response Codes (SNARC) effect (i.e., faster left/right sided responses to small/large magnitude numbers, respectively) is considered to be strong evidence for the link between numbers and space. Studies have shown considerable variation in this effect. Among the factors determining individual differences in the SNARC effect is the hand an individual uses to start the finger counting sequence. Left-starters show a stronger and less variable SNARC effect than right-starters. This observation has been used as an argument for the embodied nature of the SNARC effect. For this to be the case, one must assume that the finger counting sequence (especially the starting hand) is stable over time. Subsequent studies challenged the view that the SNARC differs depending on the finger counting starting hand. At the same time, it has been pointed out that the temporal stability of the finger counting starting hand should not be taken for granted. Thus, in this preregistered study, we aimed to replicate the difference in the SNARC between left- and right-starters and explore the relationship between the self-reported temporal stability of the finger counting starting hand and the SNARC effect. In line with the embodied cognition account, left-starters who declare more temporarily stable finger counting habits should reveal a stronger SNARC effect. Results of the preregistered analysis did not show the difference between left- and right-starters. However, further exploratory analysis provided weak evidence that this might be the case. Lastly, we found no evidence for the relationship between finger counting starting hand stability and the SNARC effect. Overall, these results challenge the view on the embodied nature of the SNARC effect.


Assuntos
Lateralidade Funcional , Percepção Espacial , Humanos , Percepção Espacial/fisiologia , Lateralidade Funcional/fisiologia , Dedos , Cognição/fisiologia , Hábitos , Tempo de Reação/fisiologia
13.
Brain Struct Funct ; 227(8): 2797-2808, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36194276

RESUMO

fMRI language mapping studies report right-hemispheric contribution to language in healthy individuals. However, it remains unclear whether these right-hemispheric patterns of activity are critical for language, which is highly relevant for clinical preoperative language mapping. The available findings are controversial. In this study, we first measured individual patterns of language lateralization with an fMRI language localizer in healthy participants with different handedness (N = 31). Then, the same participants received rTMS over the individual coordinates of peak fMRI-based activation in the left and right inferior frontal gyri. During rTMS, participants performed a picture naming task. It included both objects and actions to test whether naming of nouns and verbs would be equally modulated by rTMS. Stimulation of the left inferior frontal gyrus resulted in accuracy facilitation of verb production regardless of individual language lateralization. No modulation of object naming was found at any stimulation site in terms of accuracy nor reaction time. This study causally confirmed the critical contribution of the left, but not the right hemisphere to verb production regardless of the language lateralization patterns observed with fMRI. Also, the results stress that action rather than object naming is the task of choice for mapping language in the frontal lobe.


Assuntos
Idioma , Estimulação Magnética Transcraniana , Humanos , Estimulação Magnética Transcraniana/métodos , Córtex Pré-Frontal , Lateralidade Funcional/fisiologia , Lobo Frontal , Imageamento por Ressonância Magnética/métodos , Mapeamento Encefálico/métodos
14.
J Vis ; 22(10): 3, 2022 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-36069943

RESUMO

Patients with lesions of the parieto-occipital cortex typically misreach visual targets that they correctly perceive (optic ataxia). Although optic ataxia was described more than 30 years ago, distinguishing this condition from physiological behavior using kinematic data is still far from being an achievement. Here, combining kinematic analysis with machine learning methods, we compared the reaching performance of a patient with bilateral occipitoparietal damage with that of 10 healthy controls. They performed visually guided reaches toward targets located at different depths and directions. Using the horizontal, sagittal, and vertical deviation of the trajectories, we extracted classification accuracy in discriminating the reaching performance of patient from that of controls. Specifically, accurate predictions of the patient's deviations were detected after the 20% of the movement execution in all the spatial positions tested. This classification based on initial trajectory decoding was possible for both directional and depth components of the movement, suggesting the possibility of applying this method to characterize pathological motor behavior in wider frameworks.


Assuntos
Lateralidade Funcional , Desempenho Psicomotor , Braço , Ataxia , Fenômenos Biomecânicos , Lateralidade Funcional/fisiologia , Humanos , Aprendizado de Máquina , Desempenho Psicomotor/fisiologia
15.
J Neurol Sci ; 442: 120434, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36170765

RESUMO

This review aims to update the current knowledge on the cerebral control of swallowing. We review data from both animal and human studies spanning across the fields of neuroanatomy, neurophysiology and neuroimaging to evaluate advancements in our understanding in the brain's role in swallowing. Studies have collectively shown that swallowing is mediated by multiple distinct cortical and subcortical regions and that lesions to these regions can result in dysphagia. These regions are functionally connected in separate groups within and between the two hemispheres. While hemispheric dominance for swallowing has been reported in most human studies, the laterality is inconsistent across individuals. Moreover, there is a shift in activation location and laterality between swallowing preparation and execution, although such activation changes are less well-defined than that for limb motor control. Finally, we discussed recent neurostimulation treatments that may be beneficial for dysphagia after brain injury through promoting the reorganization of the swallowing neural network.


Assuntos
Transtornos de Deglutição , Deglutição , Animais , Humanos , Deglutição/fisiologia , Transtornos de Deglutição/etiologia , Transtornos de Deglutição/terapia , Imageamento por Ressonância Magnética , Lateralidade Funcional/fisiologia
16.
Neurosci Biobehav Rev ; 141: 104830, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36031009

RESUMO

A systematic review of investigations evaluating hemispheric asymmetries for emotions in primates was undertaken to individuate the most consistent lines of research allowing to check the hypothesis of a continuum in emotional lateralization across vertebrates. We reviewed studies on the lateralization of emotional expression (N = 31) and perception (N = 32) and of markers of emotional activation (N = 9), trying to distinguish those which had given respectively more consistent or more conflicting outcomes. Furthermore, we tried to identify the most strongly supported model of emotional lateralization. The most consistent results were obtained in studies investigating asymmetries in emotional expression at the facial level and in the perception of emotional facial expressions, whereas the most disappointing data were obtained in investigations evaluating possible neurophysiological markers of lateralized emotional activation. These results supported more the hypothesis of a continuity between humans and non-human primates than the more general hypothesis of a continuum between humans and all vertebrates. Furthermore, results supported more the 'right hemisphere' than the 'valence' model of emotional lateralization.


Assuntos
Emoções , Expressão Facial , Animais , Emoções/fisiologia , Face , Lateralidade Funcional/fisiologia , Humanos , Primatas
17.
BMC Neurol ; 22(1): 303, 2022 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-35982397

RESUMO

BACKGROUND: Polymicrogyria refers to the disruption of normal cerebral cortical development late in neuronal migration or in early cortical organization. Although patients with polymicrogyria feature relatively favorable motor outcomes, polymicrogyric lesions accompanied by extensive unilateral hemispheric atrophy and ipsilateral brainstem atrophy may induce poorer motor outcomes. This study is the first to employ transcranial magnetic stimulation (TMS) and diffusion tensor imaging (DTI) to characterize changes to motor organization and white matter tracts induced by polymicrogyria. CASE PRESENTATION: We document a case of a 16-year-old female with left hemiplegic unilateral polymicrogyria associated with ipsilateral brainstem atrophy. Magnetic resonance imaging (MRI) of the brain revealed unilateral polymicrogyria to have affected anterior cortical areas, including the perisylvian region on the right side. The right halves of the brain and brainstem were significantly smaller than the left halves. Although our patient was found to exhibit cortical dysplasia of the right frontoparietal and sylvian fissure areas and a decreased number of fibers in the corticospinal tract (CST) of the affected side on DTI, the connectivity of the CST was preserved up to the motor cortex. We also measured the cross-sectional area of the CST at the level of the pons. In TMS, contralateral motor evoked potentials (MEPs) were evoked from both hands, but the ipsilateral MEPs were evoked only from the left hand. The left hand featured a long duration, polyphasic pattern of contralateral MEPs. DISCUSSION AND CONCLUSION: TMS revealed that the concurrent bilateral projections to the paretic hand from the affected and unaffected hemispheres and contralateral MEPs in the paretic hand were polyphasic, indicating delayed electrophysiological maturation or a pathologic condition of the corticospinal motor pathways. In DTI, the cross-sectional area of the CST at the level of the pons on the affected side was smaller than that on the unaffected side. These DTI findings reveal an inadequate CST volume. Despite extensive brain malformation and ipsilateral brainstem atrophy, our patient had less severe motor dysfunction and presented with involuntary mirror movements. Mirror movements in the paretic hand are considered to indicate ipsilateral corticospinal projections from the unaffected hemisphere and may suggest favorable motor outcomes in early brain injury.


Assuntos
Córtex Motor , Transtornos dos Movimentos , Malformações do Sistema Nervoso , Polimicrogiria , Adolescente , Atrofia/patologia , Tronco Encefálico/diagnóstico por imagem , Tronco Encefálico/patologia , Imagem de Tensor de Difusão , Potencial Evocado Motor , Feminino , Lateralidade Funcional/fisiologia , Humanos , Córtex Motor/patologia , Transtornos dos Movimentos/patologia , Polimicrogiria/patologia , Tratos Piramidais/patologia , Estimulação Magnética Transcraniana/métodos
18.
Cortex ; 155: 107-131, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35985123

RESUMO

BACKGROUND: Neurocognitive models of language processing highlight the role of the left inferior frontal gyrus (IFG) in the functional network underlying language. Furthermore, neuroscience research has shown that IFG is not a uniform region anatomically, cytoarchitectonically or functionally. However, no previous study explored the language-related functional connectivity patterns of IFG subdivisions using a meta-analytic connectivity modeling (MACM) approach. PURPOSE: The present MACM study aimed to identify language-related coactivation patterns of the left and right IFG subdivisions. METHOD: Six regions of interest (ROIs) were defined using a probabilistic brain atlas corresponding to pars opercularis, pars triangularis and pars orbitalis of IFG in both hemispheres. The ROIs were used to search the BrainMap functional database to identify neuroimaging experiments with healthy, right-handed participants reporting language-related activations in each ROI. Activation likelihood estimation analyses were then performed on the foci extracted from the identified studies to compute functional convergence for each ROI, which was also contrasted with the other ROIs within the same hemisphere. RESULTS: A primarily left-lateralized functional network was revealed for the left and right IFG subdivisions. The left-hemispheric ROIs exhibited more robust coactivation than the right-hemispheric ROIs. Particularly, the left pars opercularis was associated with the most extensive coactivation pattern involving bilateral frontal, bilateral parietal, left temporal, left subcortical, and right cerebellar regions, while the left pars triangularis and orbitalis revealed a predominantly left-lateralized involvement of frontotemporal regions. CONCLUSION: The findings align with the neurocognitive models of language processing that propose a division of labor among the left IFG subdivisions and their respective functional networks. Also, the opercular part of left IFG stands out as a major hub in the language network with connections to diverse cortical, subcortical and cerebellar structures.


Assuntos
Mapeamento Encefálico , Lateralidade Funcional , Encéfalo/fisiologia , Mapeamento Encefálico/métodos , Lateralidade Funcional/fisiologia , Humanos , Imageamento por Ressonância Magnética/métodos , Córtex Pré-Frontal
19.
Restor Neurol Neurosci ; 40(3): 125-135, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35964212

RESUMO

BACKGROUND: Traditional repetitive Transcranial Magnetic Stimulation (rTMS) remains applicable in speech studies on healthy participants. Although the procedure of inducing speech arrest by rTMS has been used for over 25 years, there are still significant discrepancies in its methodology. OBJECTIVE: The study aimed to simplify and improve the old methodology of triggering speech arrest by (rTMS). Our goal was to establish the best step-by-step algorithm and verify the procedure on a representative group of participants. METHODS: 47 healthy, right-handed volunteers (23 men and 24 women) at a median age of 23 (range 19-34) were included in the study. Handedness was determined using the Edinburgh Handedness Inventory Test. After setting the individual's motor threshold (MT) and heuristic choice of the place of stimulation, which targeted Inferior Frontal Gyrus (IFG), participants were asked to count downwards from 20 to 10. While counting, a series of 2-second pulses was generated at a frequency of 2 Hz at 120% or 150% of MT. The procedure was video-recorded and subsequently assessed by 3 independent reviewers and self-assessed by participants on visual analogue scales for the effect and comfort of stimulation. RESULTS: Speech arrest was induced in 45 people (95.7%). Language dominance was determined to be either left-sided (for 42.2%) or bilateral (55.3%). Total speech arrest was observed more often in participants for whom Broca's area was active exclusively in the left hemisphere. CONCLUSION: In our study, we present the step-by-step procedure for a simplified, as far as possible, methodology of inducing speech arrest using rTMS with its verification on a representative group of right-handed healthy individuals. Our results prove that the chosen stimulation parameters present a good efficacy ratio and seems to be justified. The traditional applications of rTMS in speech studies may be highly broadened if the methods used are further improved and simplified.


Assuntos
Fala , Estimulação Magnética Transcraniana , Feminino , Lateralidade Funcional/fisiologia , Humanos , Idioma , Masculino , Fala/fisiologia , Estimulação Magnética Transcraniana/métodos
20.
Epilepsia ; 63(10): 2597-2622, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35848050

RESUMO

OBJECTIVE: Temporal lobe epilepsy (TLE) affects brain networks and is associated with impairment of episodic memory. Temporal and extratemporal reorganization of memory functions is described in functional magnetic resonance imaging (fMRI) studies. Functional reorganizations have been shown at the local activation level, but network-level alterations have been underinvestigated. We aim to investigate the functional anatomy of memory networks using memory fMRI and determine how this relates to memory function in TLE. METHODS: Ninety patients with unilateral TLE (43 left) and 29 controls performed a memory-encoding fMRI paradigm of faces and words with subsequent out-of-scanner recognition test. Subsequent memory event-related contrasts of words and faces remembered were generated. Psychophysiological interaction analysis investigated task-associated changes in functional connectivity seeding from the mesial temporal lobes (MTLs). Correlations between changes in functional connectivity and clinical memory scores, epilepsy duration, age at epilepsy onset, and seizure frequency were investigated, and between connectivity supportive of better memory and disease burden. Connectivity differences between controls and TLE, and between TLE with and without hippocampal sclerosis, were explored using these confounds as regressors of no interest. RESULTS: Compared to controls, TLE patients showed widespread decreased connectivity between bilateral MTLs and frontal lobes, and increased local connectivity between the anterior MTLs bilaterally. Increased intrinsic connectivity within the bilateral MTLs correlated with better out-of-scanner memory performance in both left and right TLE. Longer epilepsy duration and higher seizure frequency were associated with decreased connectivity between bilateral MTLs and left/right orbitofrontal cortex (OFC) and insula, connections supportive of memory functions. TLE due to hippocampal sclerosis was associated with greater connectivity disruption within the MTL and extratemporally. SIGNIFICANCE: Connectivity analyses showed that TLE is associated with temporal and extratemporal memory network reorganization. Increased bilateral functional connectivity within the MTL and connectivity to OFC and insula are efficient, and are disrupted by greater disease burden.


Assuntos
Epilepsia do Lobo Temporal , Memória Episódica , Epilepsia do Lobo Temporal/patologia , Lateralidade Funcional/fisiologia , Hipocampo/patologia , Humanos , Imageamento por Ressonância Magnética/métodos , Esclerose/complicações , Convulsões
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