RESUMO
Social interactions involve processes ranging from face recognition to understanding others' intentions. To guide appropriate behavior in a given context, social interactions rely on accurately predicting the outcomes of one's actions and the thoughts of others. Because social interactions are inherently dynamic, these predictions must be continuously adapted. The neural correlates of social processing have largely focused on emotion, mentalizing, and reward networks, without integration of systems involved in prediction. The cerebellum forms predictive models to calibrate movements and adapt them to changing situations, and cerebellar predictive modeling is thought to extend to nonmotor behaviors. Primary cerebellar dysfunction can produce social deficits, and atypical cerebellar structure and function are reported in autism, which is characterized by social communication challenges and atypical predictive processing. We examine the evidence that cerebellar-mediated predictions and adaptation play important roles in social processes and argue that disruptions in these processes contribute to autism.
Assuntos
Doenças Cerebelares , Cerebelo , Emoções , Humanos , Comportamento Social , Meio SocialRESUMO
Cerebellar neuroscience has undergone a paradigm shift. The theories of the universal cerebellar transform and dysmetria of thought and the principles of organization of cerebral cortical connections, together with neuroanatomical, brain imaging, and clinical observations, have recontextualized the cerebellum as a critical node in the distributed neural circuits subserving behavior. The framework for cerebellar cognition stems from the identification of three cognitive representations in the posterior lobe, which are interconnected with cerebral association areas and distinct from the primary and secondary cerebellar sensorimotor representations linked with the spinal cord and cerebral motor areas. Lesions of the anterior lobe primary sensorimotor representations produce dysmetria of movement, the cerebellar motor syndrome. Lesions of the posterior lobe cognitive-emotional cerebellum produce dysmetria of thought and emotion, the cerebellar cognitive affective/Schmahmann syndrome. The notion that the cerebellum modulates thought and emotion in the same way that it modulates motor control advances the understanding of the mechanisms of cognition and opens new therapeutic opportunities in behavioral neurology and neuropsychiatry.
Assuntos
Encéfalo/fisiologia , Cognição/fisiologia , Emoções/fisiologia , Neurociências , Animais , Encéfalo/patologia , Ataxia Cerebelar/fisiopatologia , Doenças Cerebelares/fisiopatologia , Humanos , Neurociências/métodosRESUMO
Cerebellar differences have long been documented in autism spectrum disorder (ASD), yet the extent to which such differences might impact language processing in ASD remains unknown. To investigate this, we recorded brain activity with magnetoencephalography (MEG) while ASD and age-matched typically developing (TD) children passively processed spoken meaningful English and meaningless Jabberwocky sentences. Using a novel source localization approach that allows higher resolution MEG source localization of cerebellar activity, we found that, unlike TD children, ASD children showed no difference between evoked responses to meaningful versus meaningless sentences in right cerebellar lobule VI. ASD children also had atypically weak functional connectivity in the meaningful versus meaningless speech condition between right cerebellar lobule VI and several left-hemisphere sensorimotor and language regions in later time windows. In contrast, ASD children had atypically strong functional connectivity for in the meaningful versus meaningless speech condition between right cerebellar lobule VI and primary auditory cortical areas in an earlier time window. The atypical functional connectivity patterns in ASD correlated with ASD severity and the ability to inhibit involuntary attention. These findings align with a model where cerebro-cerebellar speech processing mechanisms in ASD are impacted by aberrant stimulus-driven attention, which could result from atypical temporal information and predictions of auditory sensory events by right cerebellar lobule VI.
Assuntos
Transtorno do Espectro Autista , Criança , Humanos , Transtorno do Espectro Autista/diagnóstico por imagem , Magnetoencefalografia , Cerebelo/diagnóstico por imagem , Imageamento por Ressonância Magnética , Mapeamento EncefálicoRESUMO
BACKGROUND: Aphasia is a common, debilitating consequence of stroke, and speech therapy is often inadequate to achieve a satisfactory outcome. Neuromodulation techniques have emerged as a potential augmentative treatment for improving aphasia outcomes. Most studies have targeted the cerebrum, but there are theoretical and practical reasons that stimulation over the cerebral hemispheres might not be ideal. On the other hand, the right cerebellum is functionally and anatomically linked to major language areas in the left hemisphere, making it a promising alternative target site for stimulation. OBJECTIVE: To provide preliminary effect sizes for the ability of a short course of anodal transcranial direct current stimulation (tDCS) targeted over the right cerebellum to enhance language processing in individuals with chronic poststroke aphasia. METHOD: Ten individuals received five sessions of open-label anodal tDCS targeting the right cerebellum. The effects of the tDCS were compared with the effects of sham tDCS on 14 controls from a previous clinical trial. In total, 24 individuals with chronic poststroke aphasia participated in the study. Behavioral testing was conducted before treatment, immediately following treatment, and at the 3-month follow-up. RESULTS: Cerebellar tDCS did not significantly enhance language processing measured either immediately following treatment or at the 3-month follow-up. The effect sizes of tDCS over sham treatment were generally nil or small, except for the mean length of utterance on the picture description task, for which medium to large effects were observed. CONCLUSION: These results may provide guidance for investigators who are planning larger trials of tDCS for individuals with chronic poststroke aphasia.
Assuntos
Afasia , Acidente Vascular Cerebral , Estimulação Transcraniana por Corrente Contínua , Adulto , Idoso , Afasia/etiologia , Afasia/terapia , Cerebelo , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/terapiaRESUMO
BACKGROUND: Premature birth is associated with high prevalence of neurodevelopmental impairments in surviving infants. The putative role of cerebellar and brainstem dysfunction remains poorly understood, particularly in the absence of overt structural injury. METHOD: We compared in-utero versus ex-utero global, regional and local cerebellar and brainstem development in healthy fetuses (n â= â38) and prematurely born infants without evidence of structural brain injury on conventional MRI studies (n â= â74) that were performed at two time points: the first corresponding to the third trimester, either in utero or ex utero in the early postnatal period following preterm birth (30-40 weeks of gestation; 38 control fetuses; 52 premature infants) and the second at term equivalent age (37-46 weeks; 38 control infants; 58 premature infants). We compared 1) volumetric growth of 7 regions in the cerebellum (left and right hemispheres, left and right dentate nuclei, and the anterior, neo, and posterior vermis); 2) volumetric growth of 3 brainstem regions (midbrain, pons, and medulla); and 3) shape development in the cerebellum and brainstem using spherical harmonic description between the two groups. RESULTS: Both premature and control groups showed regional cerebellar differences in growth rates, with the left and right cerebellar hemispheres showing faster growth compared to the vermis. In the brainstem, the pons grew faster than the midbrain and medulla in both prematurely born infants and controls. Using shape analyses, premature infants had smaller left and right cerebellar hemispheres but larger regional vermis and paravermis compared to in-utero control fetuses. For the brainstem, premature infants showed impaired growth of the superior surface of the midbrain, anterior surface of the pons, and inferior aspects of the medulla compared to the control fetuses. At term-equivalent age, premature infants had smaller cerebellar hemispheres bilaterally, extending to the superior aspect of the left cerebellar hemisphere, and larger anterior vermis and posteroinferior cerebellar lobes than healthy newborns. For the brainstem, large differences between premature infants and healthy newborns were found in the anterior surface of the pons. CONCLUSION: This study analyzed both volumetric growth and shape development of the cerebellum and brainstem in premature infants compared to healthy fetuses using longitudinal MRI measurements. The findings in the present study suggested that preterm birth may alter global, regional and local development of the cerebellum and brainstem even in the absence of structural brain injury evident on conventional MRI.
Assuntos
Tronco Encefálico/crescimento & desenvolvimento , Cerebelo/crescimento & desenvolvimento , Recém-Nascido Prematuro/crescimento & desenvolvimento , Feminino , Feto , Idade Gestacional , Humanos , Recém-Nascido , Imageamento por Ressonância Magnética/métodos , Masculino , GravidezRESUMO
Sporadically advocated over the last two centuries, a cerebellar role in cognition and affect has been rigorously established in the past few decades. In the clinical domain, such progress is epitomized by the "cerebellar cognitive affective syndrome" ("CCAS") or "Schmahmann syndrome." Introduced in the late 1990s, CCAS reflects a constellation of cerebellar-induced sequelae, comprising deficits in executive function, visuospatial cognition, emotion-affect, and language, over and above speech. The CCAS thus offers excellent grounds to investigate the functional topography of the cerebellum, and, ultimately, illustrate the precise mechanisms by which the cerebellum modulates cognition and affect. The primary objective of this task force paper is thus to stimulate further research in this area. After providing an up-to-date overview of the fundamental findings on cerebellar neurocognition, the paper substantiates the concept of CCAS with recent evidence from different scientific angles, promotes awareness of the CCAS as a clinical entity, and examines our current insight into the therapeutic options available. The paper finally identifies topics of divergence and outstanding questions for further research.
Assuntos
Comitês Consultivos , Doenças Cerebelares/diagnóstico por imagem , Disfunção Cognitiva/diagnóstico por imagem , Transtornos do Humor/diagnóstico por imagem , Doenças Cerebelares/epidemiologia , Doenças Cerebelares/psicologia , Disfunção Cognitiva/epidemiologia , Disfunção Cognitiva/psicologia , Humanos , Transtornos do Humor/epidemiologia , Transtornos do Humor/psicologia , SíndromeRESUMO
The traditional view on the cerebellum is that it controls motor behavior. Although recent work has revealed that the cerebellum supports also nonmotor functions such as cognition and affect, only during the last 5 years it has become evident that the cerebellum also plays an important social role. This role is evident in social cognition based on interpreting goal-directed actions through the movements of individuals (social "mirroring") which is very close to its original role in motor learning, as well as in social understanding of other individuals' mental state, such as their intentions, beliefs, past behaviors, future aspirations, and personality traits (social "mentalizing"). Most of this mentalizing role is supported by the posterior cerebellum (e.g., Crus I and II). The most dominant hypothesis is that the cerebellum assists in learning and understanding social action sequences, and so facilitates social cognition by supporting optimal predictions about imminent or future social interaction and cooperation. This consensus paper brings together experts from different fields to discuss recent efforts in understanding the role of the cerebellum in social cognition, and the understanding of social behaviors and mental states by others, its effect on clinical impairments such as cerebellar ataxia and autism spectrum disorder, and how the cerebellum can become a potential target for noninvasive brain stimulation as a therapeutic intervention. We report on the most recent empirical findings and techniques for understanding and manipulating cerebellar circuits in humans. Cerebellar circuitry appears now as a key structure to elucidate social interactions.
Assuntos
Cerebelo/diagnóstico por imagem , Cerebelo/fisiologia , Consenso , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Cognição Social , Mapeamento Encefálico/métodos , Humanos , Mentalização/fisiologia , Desempenho Psicomotor/fisiologia , Comportamento SocialRESUMO
It has been proposed that the cerebellum acquires internal models of mental processes that enable prediction, allowing for the optimization of behavior. In language, semantic prediction speeds speech production and comprehension. Right cerebellar lobules VI and VII (including Crus I/II) are engaged during a variety of language processes and are functionally connected with cerebral cortical language networks. Further, right posterolateral cerebellar neuromodulation modifies behavior during predictive language processing. These data are consistent with a role for the cerebellum in semantic processing and semantic prediction. We combined transcranial direct current stimulation (tDCS) and fMRI to assess the behavioral and neural consequences of cerebellar tDCS during a sentence completion task. Task-based and resting-state fMRI data were acquired in healthy human adults (n = 32; µ = 23.1 years) both before and after 20 min of 1.5 mA anodal (n = 18) or sham (n = 14) tDCS applied to the right posterolateral cerebellum. In the sentence completion task, the first four words of the sentence modulated the predictability of the final target word. In some sentences, the preceding context strongly predicted the target word, whereas other sentences were nonpredictive. Completion of predictive sentences increased activation in right Crus I/II of the cerebellum. Relative to sham tDCS, anodal tDCS increased activation in right Crus I/II during semantic prediction and enhanced resting-state functional connectivity between hubs of the reading/language networks. These results are consistent with a role for the right posterolateral cerebellum beyond motor aspects of language, and suggest that cerebellar internal models of linguistic stimuli support semantic prediction.SIGNIFICANCE STATEMENT Cerebellar involvement in language tasks and language networks is now well established, yet the specific cerebellar contribution to language processing remains unclear. It is thought that the cerebellum acquires internal models of mental processes that enable prediction, allowing for the optimization of behavior. Here we combined neuroimaging and neuromodulation to provide evidence that the cerebellum is specifically involved in semantic prediction during sentence processing. We found that activation within right Crus I/II was enhanced when semantic predictions were made, and we show that modulation of this region with transcranial direct current stimulation alters both activation patterns and functional connectivity within whole-brain language networks. For the first time, these data show that cerebellar neuromodulation impacts activation patterns specifically during predictive language processing.
Assuntos
Cerebelo/fisiologia , Imageamento por Ressonância Magnética/métodos , Rede Nervosa/fisiologia , Tempo de Reação/fisiologia , Semântica , Estimulação Transcraniana por Corrente Contínua/métodos , Adolescente , Adulto , Cerebelo/diagnóstico por imagem , Feminino , Previsões , Humanos , Masculino , Rede Nervosa/diagnóstico por imagem , Estimulação Luminosa/métodos , Distribuição Aleatória , Método Simples-Cego , Adulto JovemRESUMO
This study examines the influence of trait anxiety on working memory (WM) in safety and threat. Interactions between experimentally induced anxiety and WM performance (on different cognitive loads) have been reported in healthy, nonanxious subjects. Differences in trait anxiety may moderate these interactions. Accordingly, these interactions may be potentiated by high trait anxiety (HTA), or show a resilient pattern that protects cognitive performance. HTA and low trait anxiety (LTA) were defined by a median split of scores on the trait component of the state-trait anxiety inventory. Sustained anxiety was evoked by a probabilistic exposure to an aversive scream, and was measured by eyeblink startle and self-report. WM was tested using an n-back task (1-, 2-, and 3-back). Results revealed that, as expected, the HTA group reported greater anxiety during the task. However, trait anxiety did not impact the modulation of WM performance by induced anxiety. Notably, HTA influenced anxiety-potentiated startle (startle during threat minus startle during safe; APS) differently as a function of memory load. Accordingly, APS decreased with increasing WM load, but HTA antagonized this reduction. The HTA group showed no impairment on the 3-back WM task despite a higher APS. The amplified APS could be associated with the increase in effort-related cognitive arousal. Furthermore, this third replication of the interaction of induced anxiety by load on WM performance testifies to the robustness of the unique interplay between anxiety and WM.
Assuntos
Ansiedade/fisiopatologia , Memória de Curto Prazo/fisiologia , Aprendizagem Verbal/fisiologia , Adulto , Análise de Variância , Aprendizagem da Esquiva/fisiologia , Piscadela/fisiologia , Cognição/fisiologia , Feminino , Humanos , Masculino , Escalas de Graduação Psiquiátrica , Tempo de Reação/fisiologia , Inquéritos e Questionários , Fatores de Tempo , Adulto JovemRESUMO
Cerebellar dysfunction is evident in several developmental disorders, including autism, attention deficit-hyperactivity disorder (ADHD), and developmental dyslexia, and damage to the cerebellum early in development can have long-term effects on movement, cognition, and affective regulation. Early cerebellar damage is often associated with poorer outcomes than cerebellar damage in adulthood, suggesting that the cerebellum is particularly important during development. Differences in cerebellar development and/or early cerebellar damage could impact a wide range of behaviors via the closed-loop circuits connecting the cerebellum with multiple cerebral cortical regions. Based on these anatomical circuits, behavioral outcomes should depend on which cerebro-cerebellar circuits are affected. Here, we briefly review cerebellar structural and functional differences in autism, ADHD, and developmental dyslexia, and discuss clinical outcomes following pediatric cerebellar damage. These data confirm the prediction that abnormalities in different cerebellar subregions produce behavioral symptoms related to the functional disruption of specific cerebro-cerebellar circuits. These circuits might also be crucial to structural brain development, as peri-natal cerebellar lesions have been associated with impaired growth of the contralateral cerebral cortex. The specific contribution of the cerebellum to typical development may therefore involve the optimization of both the structure and function of cerebro-cerebellar circuits underlying skill acquisition in multiple domains; when this process is disrupted, particularly in early development, there could be long-term alterations of these neural circuits, with significant impacts on behavior.
Assuntos
Cerebelo/patologia , Cerebelo/fisiopatologia , Transtornos do Neurodesenvolvimento/patologia , Animais , HumanosRESUMO
In less than three decades, the concept "cerebellar neurocognition" has evolved from a mere afterthought to an entirely new and multifaceted area of neuroscientific research. A close interplay between three main strands of contemporary neuroscience induced a substantial modification of the traditional view of the cerebellum as a mere coordinator of autonomic and somatic motor functions. Indeed, the wealth of current evidence derived from detailed neuroanatomical investigations, functional neuroimaging studies with healthy subjects and patients and in-depth neuropsychological assessment of patients with cerebellar disorders shows that the cerebellum has a cardinal role to play in affective regulation, cognitive processing, and linguistic function. Although considerable progress has been made in models of cerebellar function, controversy remains regarding the exact role of the "linguistic cerebellum" in a broad variety of nonmotor language processes. This consensus paper brings together a range of different viewpoints and opinions regarding the contribution of the cerebellum to language function. Recent developments and insights in the nonmotor modulatory role of the cerebellum in language and some related disorders will be discussed. The role of the cerebellum in speech and language perception, in motor speech planning including apraxia of speech, in verbal working memory, in phonological and semantic verbal fluency, in syntax processing, in the dynamics of language production, in reading and in writing will be addressed. In addition, the functional topography of the linguistic cerebellum and the contribution of the deep nuclei to linguistic function will be briefly discussed. As such, a framework for debate and discussion will be offered in this consensus paper.
Assuntos
Cerebelo/fisiologia , Cognição/fisiologia , Idioma , Memória/fisiologia , Fala , Animais , HumanosRESUMO
Reading fluency, the ability to read quickly and accurately, is a critical marker of successful reading and is notoriously difficult to improve in reading disabled populations. Despite its importance to functional literacy, fluency is a relatively under-studied aspect of reading, and the neural correlates of reading fluency are not well understood. Here, we review the literature of the neural correlates of reading fluency as well as rapid automatized naming (RAN), a task that is robustly related to reading fluency. In a qualitative review of the neuroimaging literature, we evaluated structural and functional MRI studies of reading fluency in readers from a range of skill levels. This was followed by a quantitative activation likelihood estimate (ALE) meta-analysis of fMRI studies of reading speed and RAN measures. We anticipated that reading speed, relative to untimed reading and reading-related tasks, would harness ventral reading pathways that are thought to enable the fast, visual recognition of words. The qualitative review showed that speeded reading taps the entire canonical reading network. The meta-analysis indicated a stronger role of the ventral reading pathway in rapid reading and rapid naming. Both reviews identified regions outside the canonical reading network that contribute to reading fluency, such as the bilateral insula and superior parietal lobule. We suggest that fluent reading engages both domain-specific reading pathways as well as domain-general regions that support overall task performance and discuss future avenues of research to expand our understanding of the neural bases of fluent reading.
RESUMO
Autism spectrum disorder (ASD) is a neurodevelopmental condition frequently associated with structural cerebellar abnormalities. Whether cerebellar grey matter volumes (GMV) are linked to verbal impairments remains controversial. Here, the association between cerebellar GMV and verbal abilities in ASD was examined across the lifespan. Lobular segmentation of the cerebellum was performed on structural MRI scans from the ABIDE I dataset in male individuals with ASD (N=144, age: 8.5-64.0 years) and neurotypical controls (N=188; age: 8.0-56.2 years). Stepwise linear mixed effects modeling including group (ASD vs. neurotypical controls), lobule-wise GMV, and age was performed to identify cerebellar lobules which best predicted verbal abilities as measured by verbal IQ (VIQ). An age-specific association between VIQ and GMV of bilateral Crus II was found in ASD relative to neurotypical controls. In children with ASD, higher VIQ was associated with larger GMV of left Crus II but smaller GMV of right Crus II. By contrast, in adults with ASD, higher VIQ was associated with smaller GMV of left Crus II and larger GMV of right Crus II. These findings indicate that relative to the contralateral hemisphere, an initial reliance on the language-nonspecific left cerebellar hemisphere is offset by more typical right-lateralization in adulthood.
Assuntos
Transtorno do Espectro Autista , Cerebelo , Substância Cinzenta , Imageamento por Ressonância Magnética , Humanos , Masculino , Transtorno do Espectro Autista/diagnóstico por imagem , Cerebelo/diagnóstico por imagem , Substância Cinzenta/patologia , Substância Cinzenta/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Criança , Adulto , Adolescente , Adulto Jovem , Pessoa de Meia-Idade , Comportamento Verbal/fisiologiaRESUMO
Developmental dyslexia is a genetically based neurobiological syndrome, which is characterized by reading difficulty despite normal or high general intelligence. Even remediated dyslexic readers rarely achieve fast, fluent reading. Some dyslexics also have impairments in attention, short-term memory, sequencing (letters, word sounds, and motor acts), eye movements, poor balance, and general clumsiness. The presence of "cerebellar" motor and fluency symptoms led to the proposal that cerebellar dysfunction contributes to the etiology of dyslexia. Supporting this, functional imaging studies suggest that the cerebellum is part of the neural network supporting reading in typically developing readers, and reading difficulties have been reported in patients with cerebellar damage. Differences in both cerebellar asymmetry and gray matter volume are some of the most consistent structural brain findings in dyslexics compared with good readers. Furthermore, cerebellar functional activation patterns during reading and motor learning can differ in dyslexic readers. Behaviorally, some children and adults with dyslexia show poorer performance on cerebellar motor tasks, including eye movement control, postural stability, and implicit motor learning. However, many dyslexics do not have cerebellar signs, many cerebellar patients do not have reading problems, and differences in dyslexic brains are found throughout the whole reading network, and not isolated to the cerebellum. Therefore, impaired cerebellar function is probably not the primary cause of dyslexia, but rather a more fundamental neurodevelopmental abnormality leads to differences throughout the reading network.
Assuntos
Cerebelo/fisiopatologia , Dislexia/patologia , Mapeamento Encefálico , Humanos , Aprendizagem , Imageamento por Ressonância Magnética , LeituraRESUMO
Disorders of reading (developmental dyslexia) and attention (ADHD) have a high rate of comorbidity (25-40%), yet little is known about the neural underpinnings of this phenomenon. The current study investigated the shared and unique neural correlates of reading and attention in 330 typically developing children ages 8-18 from the Philadelphia Neurodevelopmental Cohort. Multiple regression analyses were used to identify regions of the brain where grey matter (GM) volume was associated with reading or attention scores (p < 0.001, cluster FDR p < 0.05). Better attention scores correlated with increased GM in the precuneus and higher reading scores were associated with greater thalamic GM. An exploratory conjunction analysis (p < 0.05, k > 239) found that GM in the caudate and precuneus correlated with both reading and attention scores. These results are consistent with a recent meta-analysis which identified GM reductions in the caudate in both dyslexia and ADHD and reveal potential shared neural correlates of reading and attention.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade , Dislexia , Criança , Humanos , Adolescente , Substância Cinzenta/diagnóstico por imagem , Leitura , Imageamento por Ressonância Magnética/métodos , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico por imagem , Dislexia/diagnóstico por imagemRESUMO
Anatomical, clinical and imaging findings suggest that the cerebellum is engaged in cognitive and affective functions as well as motor control. Evidence from converging modalities also indicates that there is a functional topography in the human cerebellum for overt control of movement vs. higher functions, such that the cerebellum can be divided into zones depending on connectivity with sensorimotor vs. multimodal association cortices. Using functional MRI, we show that regions active during overt movement differ from those involved in higher-level language, spatial processing and working memory tasks. Nine healthy participants each completed five tasks in order to determine the relative activation patterns for the different paradigms. Right-handed finger-tapping activated right cerebellar lobules IV-V and VIII, consistent with descriptions of the cerebellar homunculi. Verb generation engaged right cerebellar lobules VI-Crus I and a second cluster in lobules VIIB-VIIIA. Mental rotation activation peaks were localized to medial left cerebellar lobule VII (Crus II). A 2-back working memory task activated bilateral regions of lobules VI-VII. Viewing arousing vs. neutral images did not reliably activate the cerebellum or cerebral limbic areas in this study. The cerebellar functional topography identified in this study reflects the involvement of different cerebro-cerebellar circuits depending on the demands of the task being performed: overt movement activated sensorimotor cortices along with contralateral cerebellar lobules IV-V and VIII, whereas more cognitively demanding tasks engaged prefrontal and parietal cortices along with cerebellar lobules VI and VII. These findings provide further support for a cerebellar role in both motor and cognitive tasks, and better establish the existence of functional subregions in the cerebellum. Future studies are needed to determine the exact contribution of the cerebellum - and different cerebro-cerebellar circuits - to task performance.
Assuntos
Cerebelo/fisiologia , Cognição/fisiologia , Imageamento por Ressonância Magnética/métodos , Movimento/fisiologia , Rede Nervosa/fisiologia , Adulto , Humanos , MasculinoRESUMO
Evidence for a role of the human cerebellum in cognitive functions comes from anatomical, clinical and neuroimaging data. Functional neuroimaging reveals cerebellar activation during a variety of cognitive tasks, including language, visual-spatial, executive, and working memory processes. It is important to note that overt movement is not a prerequisite for cerebellar activation: the cerebellum is engaged during conditions which either control for motor output or do not involve motor responses. Resting-state functional connectivity data reveal that, in addition to networks underlying motor control, the cerebellum is part of "cognitive" networks with prefrontal and parietal association cortices. Consistent with these findings, regional differences in activation patterns within the cerebellum are evident depending on the task demands, suggesting that the cerebellum can be broadly divided into functional regions based on the patterns of anatomical connectivity between different regions of the cerebellum and sensorimotor and association areas of the cerebral cortex. However, the distinct contribution of the cerebellum to cognitive tasks is not clear. Here, the functional neuroimaging evidence for cerebellar involvement in cognitive functions is reviewed and related to hypotheses as to why the cerebellum is active during such tasks. Identifying the precise role of the cerebellum in cognition-as well as the mechanism by which the cerebellum modulates performance during a wide range of tasks-remains a challenge for future investigations.
Assuntos
Cerebelo/fisiologia , Cognição/fisiologia , Neuroimagem Funcional , Animais , Doenças Cerebelares/fisiopatologia , Emoções/fisiologia , Função Executiva , Humanos , Imageamento por Ressonância Magnética , Memória de Curto Prazo/fisiologia , Percepção Espacial/fisiologiaRESUMO
Logographic symbols are visually complex, and thus children's abilities for visual short-term memory (VSTM) predict their reading competence in logographic systems. In the present study, we investigated the importance of VSTM in logographic reading in adults, both behaviorally and by means of fMRI. Outside the scanner, VSTM predicted logographic Kanji reading in native Japanese adults (n=45), a finding consistent with previous observations in Japanese children. In the scanner, participants (n=15) were asked to perform a visual one-back task. For this fMRI experiment, we took advantage of the unique linguistic characteristic of the Japanese writing system, whereby syllabic Kana and logographic Kanji can share the same sound and meaning, but differ only in the complexity of their visual features. Kanji elicited greater activation than Kana in the cerebellum and two regions associated with VSTM, the lateral occipital complex and the superior intraparietal sulcus, bilaterally. The same regions elicited the highest activation during the control condition (an unfamiliar, unpronounceable script to the participants), presumably due to the increased VSTM demands for processing the control script. In addition, individual differences in VSTM performance (outside the scanner) significantly predicted blood oxygen level-dependent signal changes in the identified VSTM regions, during the Kanji and control conditions, but not during the Kana condition. VSTM appears to play an important role in reading logographic words, even in skilled adults, as evidenced at the behavioral and neural level, most likely due to the increased VSTM/visual attention demands necessary for processing complex visual features inherent in logographic symbols.
Assuntos
Mapeamento Encefálico , Encéfalo/fisiologia , Memória de Curto Prazo/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Leitura , Adulto , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Idioma , Imageamento por Ressonância Magnética , MasculinoRESUMO
The human cerebellum contributes to both motor and non-motor processes. Within the cerebellum, different subregions support sensorimotor and broader cognitive functions, due to regional patterns in anatomical connectivity with the cerebral cortex and spinal and vestibular systems. We evaluated the effects of transcranial direct current stimulation (tDCS) targeting different cerebellar regions on language task performance and whole-brain functional activation patterns. Functional MRI data were acquired while 43 healthy young adults (15 males, 28 females; 23.3⯱â¯3.0â¯years) performed a sentence completion task before and after 20â¯min of 1.5â¯mA anodal tDCS. Participants received tDCS targeting either the anterior sensorimotor cerebellum (nâ¯=â¯11; 3â¯cm right of inion, over lobule V); the right posterolateral cerebellum (nâ¯=â¯18; 1â¯cm down and 4â¯cm right of inion, over lobule VII); or sham tDCS (nâ¯=â¯14). TDCS targeting the right posterolateral cerebellum improved task accuracy relative to the sham condition (pâ¯=â¯0.04) and increased activation in left frontal and temporal cortices relevant to task performance (post-tDCSâ¯>â¯pre-tDCS; T 3.17, FDR pâ¯<â¯0.05 cluster correction). The regions of increased BOLD signal after right posterolateral cerebellar tDCS fell within the network showing functional connectivity with right cerebellar lobule VII, suggesting specific modulation of this network. In contrast, tDCS targeting the sensorimotor cerebellum did not impact task performance and increased BOLD signal only in one cluster extending into the precentral gyrus. These findings indicate that sensorimotor and cognitive functional cerebellar subregions differentially impact behavioral task performance and task-relevant activation patterns, further contributing to our understanding of the cerebellar modulation of motor and non-motor functions.
Assuntos
Estimulação Transcraniana por Corrente Contínua , Encéfalo , Cerebelo , Cognição , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Adulto JovemRESUMO
Quantitative magnetic resonance imaging (MRI) investigations of brain anatomy in children and young adults with Down syndrome (DS) are limited, with no diffusion tensor imaging (DTI) studies covering that age range. We used DTI-driven tensor based morphometry (DTBM), a novel technique that extracts morphometric information from diffusion data, to investigate brain anatomy in 15 participants with DS and 15 age- and sex-matched typically developing (TD) controls, ages 6-24 years (mean age ~17 years). DTBM revealed marked hypoplasia of cerebellar afferent systems in DS, including fronto-pontine (middle cerebellar peduncle) and olivo-cerebellar (inferior cerebellar peduncle) connections. Prominent gray matter hypoplasia was observed in medial frontal regions, the inferior olives, and the cerebellum. Very few abnormalities were detected by classical diffusion MRI metrics, such as fractional anisotropy and mean diffusivity. Our results highlight the potential importance of cerebro-cerebellar networks in the clinical manifestations of DS and suggest a role for DTBM in the investigation of other brain disorders involving white matter hypoplasia or atrophy.