Cerebellar contributions to visuomotor adaptation and motor sequence learning: an ALE meta-analysis

Cerebellar contributions to motor learning are well-documented. For example, under some conditions, patients with cerebellar damage are impaired at visuomotor adaptation and at acquiring new action sequences. Moreover, cerebellar activation has been observed in functional MRI (fMRI) investigations of various motor learning tasks. The early phases of motor learning are cognitively demanding, relying on processes such as working memory, which have been linked to the cerebellum as well. Here, we investigated cerebellar contributions to motor learning using activation likelihood estimation (ALE) meta-analysis. This allowed us to determine, across studies and tasks, whether or not the location of cerebellar activation is constant across differing motor learning tasks, and whether or not cerebellar activation in early learning overlaps with that observed for working memory. We found that different regions of the anterior cerebellum are engaged for implicit and explicit sequence learning and visuomotor adaptation, providing additional evidence for the modularity of cerebellar function. Furthermore, we found that lobule VI of the cerebellum, which has been implicated in working memory, is activated during the early stages of explicit motor sequence learning. This provides evidence for a potential role for the cerebellum in the cognitive processing associated with motor learning. However, though lobule VI was activated across both early explicit sequence learning and working memory studies, there was no spatial overlap between these two regions. Together, our results support the idea of modularity in the formation of internal representations of new motor tasks in the cerebellum, and highlight the cognitive processing relied upon during the early phases of motor skill learning

Cerebellar contributions to visual attention and working memory

Attention and working memory (WM) are processes that enable the efficient prioritization or storage of a subset of available information. Consequently, a substantial body of work has sought to determine the specific brain structures that support attention and WM. To date, this literature has predominantly focused on the contributions of a limited set of cortical areas referred to as the dorsal attention network (DAN). The cerebellum, a subcortical structure traditionally implicated in motor control, has received scant consideration as a locus of attentional control, despite findings of robust anatomical and functional connectivity between cerebellum and DAN areas. This project comprises several functional magnetic resonance imaging experiments aimed at elucidating the role of the cerebellum in attention and WM (n = 38; 20-38 years). The functional implications of cortico-cerebellar DAN connectivity have received only modest scientific attention. Experiment 1 examined the hypothesis that cortico-cerebellar DAN functional connectivity predicts recruitment by canonical visual WM and attention tasks. Task-driven responses of DAN-coupled cerebellar areas were found to mirror those of their cortical counterparts. These results argue for the reconceptualization of the DAN as a cortico-cerebellar network. Previous work indicates that the functional topography of the cerebellum is relatively coarse compared with cerebral cortex. Experiment 2 examined the organization of closely related aspects of visual attention and WM within the cerebellum, and found that spatial attention and visual WM recruit overlapping yet dissociable portions of cerebellar lobule VIIb/VIIIa. This functional organization was further shown to be predicted by fine-scale patterns of functional connectivity with occipito-parietal cortex. These findings indicate that the functional specificity of cerebellar cortex mirrors that of cerebral cortex and provides direct empirical support for the hypothesis that functional specialization within the cerebellum arises due to variation in afferent input. Experiment 3 tested the hypothesis that the cerebellum can be specifically implicated in the persistent representation of information in WM. Lobule VIIb/VIIIa delay-period activity patterns were shown to exhibit stimulus-selectivity, a critical marker of WM storage processes. These results indicate that lobule VIIb/VIIIa contains a robust representation of a stimulus stored in WM, thereby refuting long-standing cortico-centric models of WM maintenance.2021-02-10T00:00:00

Functional Correlates Of Verbal Working Memory In Healthy Aging And Early Alzheimer\u27s Disease

Deficits in the working memory system are common in patients diagnosed with Alzheimer\u27s disease (AD). However, little is known regarding the neurobiological basis of this impairment. The current study examined the neurobiological functional correlates of the working memory system in early AD patients and cognitively intact control participants using a word list repetition task performed during positron emission tomography (PET). Compared to a reading control task, both the AD and control groups utilized a network of parietal, frontal, and cerebellar regions while completing the word rehearsal task. However, control participants displayed greater activation in all regions, especially in the parietal lobes. In the frontal lobes, AD patients displayed right-lateralized recruitment compared to bilateral frontal recruitment in the control group. Comparison of 10-word list rehearsal to 5-word indicated a shift from parietal activity to more prominent frontal and cerebellar activity in the control group with increased load demands. This type of shift in activity was not observed in the patient group. Additionally, parietal activity was inversely correlated with working memory performance in the control group only. Left cerebellar activity was correlated with behavioral performance in both groups. Overall, it appears that the working memory deficits observed in AD patients may be related to dysfunction in parietal contributions to the working memory network, and compensatory activity may occur in the frontal lobes

Remembering Forward: Neural Correlates of Memory and Prediction in Human Motor Adaptation

We used functional MR imaging (FMRI), a robotic manipulandum and systems identification techniques to examine neural correlates of predictive compensation for spring-like loads during goal-directed wrist movements in neurologically-intact humans. Although load changed unpredictably from one trial to the next, subjects nevertheless used sensorimotor memories from recent movements to predict and compensate upcoming loads. Prediction enabled subjects to adapt performance so that the task was accomplished with minimum effort. Population analyses of functional images revealed a distributed, bilateral network of cortical and subcortical activity supporting predictive load compensation during visual target capture. Cortical regions – including prefrontal, parietal and hippocampal cortices – exhibited trial-by-trial fluctuations in BOLD signal consistent with the storage and recall of sensorimotor memories or “states” important for spatial working memory. Bilateral activations in associative regions of the striatum demonstrated temporal correlation with the magnitude of kinematic performance error (a signal that could drive reward-optimizing reinforcement learning and the prospective scaling of previously learned motor programs). BOLD signal correlations with load prediction were observed in the cerebellar cortex and red nuclei (consistent with the idea that these structures generate adaptive fusimotor signals facilitating cancelation of expected proprioceptive feedback, as required for conditional feedback adjustments to ongoing motor commands and feedback error learning). Analysis of single subject images revealed that predictive activity was at least as likely to be observed in more than one of these neural systems as in just one. We conclude therefore that motor adaptation is mediated by predictive compensations supported by multiple, distributed, cortical and subcortical structures

Anomalies in the cognitive-executive functions in patients with chiari malformation type I

Resumen tomado de la publicaciónAnomalías en las funciones cognitivo-ejecutivas en pacientes con la Malformación de Chiari Tipo I. Antecedentes: en la última década, existen evidencias crecientes de que déficits neuropsicológicos, esencialmente en funciones ejecutivas, pueden estar involucrados en la patogenia de la enfermedad de Chiari Tipo I. El objetivo del estudio es evaluar la influencia de anormalidades estructurales sobre las funciones neuropsicológicas, fundamentalmente ejecutivas, en pacientes con Chiari Tipo I. Método: para ello se comparó el perfil neuropsicológico de estos pacientes con controles sanos. Tanto a los pacientes Chiari Tipo I como a los controles sanos se les aplicó pruebas neuropsicológicas que valoraron funciones ejecutivas frontales de vigilancia o atención sostenida, flexibilidad mental, y planificación y formación de conceptos (Stroop, CPT, WCST). Resultados: los resultados obtenidos sugieren una afectación de los pacientes Chiari Tipo I en los procesos de inhibición y autocontrol (Stroop) y en la capacidad atencional y en el mantenimiento del curso del pensamiento y la acción (WCST). Conclusiones: estos resultados proporcionan evidencias de posibles déficits o anomalías en las funciones ejecutivas cognitivas, que permitirían diferenciar los pacientes con Chiari Tipo I.Universidad de Oviedo. Biblioteca de Psicología; Plaza Feijoo, s/n.; 33003 Oviedo; Tel. +34985104146; Fax +34985104126; [email protected]

Cerebellar Morphometry and Cognition in the Context of Chronic Alcohol Consumption and Cigarette Smoking.

BackgroundCerebellar atrophy (especially involving the superior-anterior cerebellar vermis) is among the most salient and clinically significant effects of chronic hazardous alcohol consumption on brain structure. Smaller cerebellar volumes are also associated with chronic cigarette smoking. The present study investigated effects of both chronic alcohol consumption and cigarette smoking on cerebellar structure and its relation to performance on select cognitive/behavioral tasks.MethodsUsing T1-weighted Magnetic Resonance Images (MRIs), the Cerebellar Analysis Tool Kit segmented the cerebellum into bilateral hemispheres and 3 vermis parcels from 4 participant groups: smoking (s) and nonsmoking (ns) abstinent alcohol-dependent treatment seekers (ALC) and controls (CON) (i.e., sALC, nsALC, sCON, and nsCON). Cognitive and behavioral data were also obtained.ResultsWe found detrimental effects of chronic drinking on all cerebellar structural measures in ALC participants, with largest reductions seen in vermis areas. Furthermore, both smoking groups had smaller volumes of cerebellar hemispheres but not vermis areas compared to their nonsmoking counterparts. In exploratory analyses, smaller cerebellar volumes were related to lower measures of intelligence. In sCON, but not sALC, greater smoking severity was related to smaller cerebellar volume and smaller superior-anterior vermis area. In sALC, greater abstinence duration was associated with larger cerebellar and superior-anterior vermis areas, suggesting some recovery with abstinence.ConclusionsOur results show that both smoking and alcohol status are associated with smaller cerebellar structural measurements, with vermal areas more vulnerable to chronic alcohol consumption and less affected by chronic smoking. These morphometric cerebellar deficits were also associated with lower intelligence and related to duration of abstinence in sALC only

From Parallel Sequence Representations to Calligraphic Control: A Conspiracy of Neural Circuits

Calligraphic writing presents a rich set of challenges to the human movement control system. These challenges include: initial learning, and recall from memory, of prescribed stroke sequences; critical timing of stroke onsets and durations; fine control of grip and contact forces; and letter-form invariance under voluntary size scaling, which entails fine control of stroke direction and amplitude during recruitment and derecruitment of musculoskeletal degrees of freedom. Experimental and computational studies in behavioral neuroscience have made rapid progress toward explaining the learning, planning and contTOl exercised in tasks that share features with calligraphic writing and drawing. This article summarizes computational neuroscience models and related neurobiological data that reveal critical operations spanning from parallel sequence representations to fine force control. Part one addresses stroke sequencing. It treats competitive queuing (CQ) models of sequence representation, performance, learning, and recall. Part two addresses letter size scaling and motor equivalence. It treats cursive handwriting models together with models in which sensory-motor tmnsformations are performed by circuits that learn inverse differential kinematic mappings. Part three addresses fine-grained control of timing and transient forces, by treating circuit models that learn to solve inverse dynamics problems.National Institutes of Health (R01 DC02852

The substantia Nigra pars compacta and temporal processing

The basal ganglia and cerebellum are considered to play a role in timing, although their differential roles in timing remain unclear. It has been proposed that the timing of short milliseconds-range intervals involves the cerebellum, whereas longer seconds-range intervals engage the basal ganglia (Ivry, 1996). We tested this hypothesis using positron emission tomography to measure regional cerebral blood flow in eight right-handed males during estimation and reproduction of long and short intervals. Subjects performed three tasks: (1) reproduction of a short 500 ms interval, (2) reproduction of a long 2 s interval, and (3) a control simple reaction time (RT) task. We compared the two time reproduction tasks with the control RT task to investigate activity associated with temporal processing once additional cognitive, motor, or sensory processing was controlled. We found foci in the left substantia nigra and the left lateral premotor cortex to be significantly more activated in the time reproduction tasks than the control RT task. The left caudate nucleus and right cerebellum were more active in the short relative to the long interval, whereas greater activation of the right putamen and right cerebellum occurred in the long rather than the short interval. These results suggest that the basal ganglia and the cerebellum are engaged by reproduction of both long and short intervals but play different roles. The fundamental role of the substantia nigra in temporal processing is discussed in relation to previous animal lesion studies and evidence for the modulating influence of dopamine on temporal processing

The cerebellum and motor dysfunction in neuropsychiatric disorders

The cerebellum is densely interconnected with sensory-motor areas of the cerebral cortex, and in man, the great expansion of the association areas of cerebral cortex is also paralleled by an expansion of the lateral cerebellar hemispheres. It is therefore likely that these circuits contribute to non-motor cognitive functions, but this is still a controversial issue. One approach is to examine evidence from neuropsychiatric disorders of cerebellar involvement. In this review, we narrow this search to test whether there is evidence of motor dysfunction associated with neuropsychiatric disorders consistent with disruption of cerebellar motor function. While we do find such evidence, especially in autism, schizophrenia and dyslexia, we caution that the restricted set of motor symptoms does not suggest global cerebellar dysfunction. Moreover, these symptoms may also reflect involvement of other, extra-cerebellar circuits and detailed examination of specific sub groups of individuals within each disorder may help to relate such motor symptoms to cerebellar morphology