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Cerebellar degeneration affects cortico-cortical connectivity in motor learning networks.

ABSTRACT: The cerebellum plays an important role in motor learning as part of a cortico-striato-cerebellar network. Patients with cerebellar degeneration typically show impairments in different aspects of motor learning, including implicit motor sequence learning. How cerebellar dysfunction affects interactions in this cortico-striato-cerebellar network is poorly understood. The present study investigated the effect of cerebellar degeneration on activity in causal interactions between cortical and subcortical regions involved in motor learning. We found that cerebellar patients showed learning-related increase in activity in two regions known to be involved in learning and memory, namely parahippocampal cortex and cerebellar Crus I. The cerebellar activity increase was observed in non-learners of the patient group whereas learners showed an activity decrease. Dynamic causal modeling analysis revealed that modulation of M1 to cerebellum and putamen to cerebellum connections were significantly more negative for sequence compared to random blocks in controls, replicating our previous results, and did not differ in patients. In addition, a separate analysis revealed a similar effect in connections from SMA and PMC to M1 bilaterally. Again, neural network changes were associated with learning performance in patients. Specifically, learners showed a negative modulation from right SMA to right M1 that was similar to controls, whereas this effect was close to zero in non-learners. These results highlight the role of cerebellum in motor learning and demonstrate the functional role cerebellum plays as part of the cortico-striato-cerebellar network.

SUBMITTER: Tzvi E

PROVIDER: S-EPMC5521032 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Cerebellar degeneration affects cortico-cortical connectivity in motor learning networks.

Tzvi Elinor E Zimmermann Christoph C Bey Richard R Münte Thomas F TF Nitschke Matthias M Krämer Ulrike M UM

NeuroImage. Clinical 20170715

The cerebellum plays an important role in motor learning as part of a cortico-striato-cerebellar network. Patients with cerebellar degeneration typically show impairments in different aspects of motor learning, including implicit motor sequence learning. How cerebellar dysfunction affects interactions in this cortico-striato-cerebellar network is poorly understood. The present study investigated the effect of cerebellar degeneration on activity in causal interactions between cortical and subcort ...[more]

PMID: 28761810

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Project description:The robust, reciprocal anatomical connections between the cerebellum and contralateral sensorimotor cerebral hemisphere underscores the strong physiological interdependence between these two regions in relation to human behavior. Previous studies have shown that damage to sensorimotor cortex can result in a lasting reduction of cerebellar metabolism, the magnitude of which has been linked to poor rehabilitative outcomes. A better understanding of movement-related cerebellar physiology as well as cortico-cerebellar coherence (CCC) in the chronic, post-stroke state may be key to developing novel neuromodulatory techniques that promote upper limb motor rehabilitation. As a part of the first in-human phase-I trial investigating the effects of deep brain stimulation of the cerebellar dentate nucleus (DN) on chronic, post-stroke motor rehabilitation, we collected invasive recordings from DN and scalp EEG in subjects (both sexes) with middle cerebral artery stroke during a visuo-motor tracking task. We investigated the excitability of ipsilesional cortex, DN and the their interaction as a function of motor impairment and performance. Our results indicate that 1) event-related oscillations in the ipsilesional cortex and DN were significantly correlated at movement onset in the low-β band, with moderately and severely impaired subjects showing desynchronization and synchronization, respectively. 2) Significant CCC was observed during isometric 'hold' period in the low-β band, which was critical for maintaining task accuracy. Our findings support a strong coupling between ipsilesional cortex and DN in the low-β band during motor control across all impairment levels which encourages the exploitation of the cerebello-thalamo-cortical pathway as a neuromodulation target to promote rehabilitation.Significance Statement:Cerebral infarct due to stroke can lead to lasting reduction in cerebellar metabolism resulting in poor rehabilitative outcomes. Thorough investigation of the cerebellar electrophysiology as well as cortico-cerebellar connectivity in humans that could provide key insights to facilitate development of novel neuromodulatory technologies, has been lacking. As a part of the first in-human phase-I trial investigating deep brain stimulation of the cerebellar dentate nucleus (DN) for chronic, post-stroke motor rehabilitation, we collected invasive recordings from DN and scalp EEG while stroke patients performed a motor task. Our data indicate strong coupling between ipsilesional sensorimotor cortex and DN in the low-β band across all impairment levels encouraging the exploration of electrical stimulation of the DN.

Project description:Schizophrenia is a devastating illness characterized by disturbances in multiple domains. The cerebellum is involved in both motor and non-motor functions, and the "cognitive dysmetria" and "dysmetria of thought" models propose that abnormalities of the cerebellum may contribute to schizophrenia signs and symptoms. The cerebellum and cerebral cortex are reciprocally connected via a modular, closed-loop network architecture, but few schizophrenia neuroimaging studies have taken into account the topographical and functional heterogeneity of the cerebellum. In this study, using a previously defined 17-network cerebral cortical parcellation system as the basis for our functional connectivity seeds, we systematically investigated connectivity abnormalities within the cerebellum of 44 schizophrenia patients and 28 healthy control participants. We found selective alterations in cerebro-cerebellar functional connectivity. Specifically, schizophrenia patients showed decreased cerebro-cerebellar functional connectivity in higher level association networks (ventral attention, salience, control, and default mode networks) relative to healthy control participants. Schizophrenia patients also showed increased cerebro-cerebellar connectivity in somatomotor and default mode networks, with the latter showing no overlap with the regions found to be hypoconnected within the same default mode network. Finally, we found evidence to suggest that somatomotor and default mode networks may be inappropriately linked in schizophrenia. The relationship of these dysconnectivities to schizophrenia symptoms, such as neurological soft signs and altered sense of agency, is discussed. We conclude that the cerebellum ought to be considered for analysis in all future studies of network abnormalities in SZ, and further suggest the cerebellum as a potential target for further elucidation, and possibly treatment, of the underlying mechanisms and network abnormalities producing symptoms of schizophrenia.

Dataset Information

Cerebellar degeneration affects cortico-cortical connectivity in motor learning networks.

Publications

Cerebellar degeneration affects cortico-cortical connectivity in motor learning networks.

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