Biology subjects

Goericke, S. L.

Publications and source records attributed to Goericke, S. L..

3 recordsLinked to original sources

bioRxiv2024

Altered cortico-cerebellar connectivity in cerebellar degeneration patients improves with motor training

People with cerebellar degeneration show characteristic ataxic motor impairments. Despite cerebellar dysfunction, they can still improve motor performance through sensorimotor training. Yet, how such training affects functional brain networks affected by cerebellar degeneration is unknown. We here investigated neuroplastic changes in the cortico-cerebellar network after a five-day forearm movement training in 40 patients with mild to severe cerebellar degeneration and 40 age- and sex-matched healthy controls. Participants were assigned to one of four motor training conditions, varying online visual feedback and explicit verbal feedback. Anatomical and resting-state fMRI was collected on the days before and after training. To overcome the limitations of standard brain templates that fail in the presence of severe anatomical abnormalities, we developed a specific template for comparing cerebellar patients with age-matched controls. Our new template reduced the spatial spread of cerebellar anatomical landmarks by 30% relative to existing templates and tripled fMRI noise classification accuracy. Using this pipeline, we found that patients showed impaired connectivity between cerebellar motor regions and neocortical visuomotor and premotor regions at baseline compared to controls, whereas their cortico-cortical connectivity remained intact. Training with vision strengthened connectivity in the cortico-cerebellar visuomotor network contralateral to the trained arm in all participants. Cerebellar patients exhibited additional increased connectivity ipsilateral to the training arm in this network. Further, training with explicit verbal feedback facilitated connectivity between a cerebellar cognitive region and dorsolateral prefrontal cortex. These results indicate that motor training in cerebellar degeneration leads to enhanced functional connectivity of the cortico-cerebellar network.

neuroscience↗

bioRxiv2020

Cerebellar degeneration reduces memory resilience after extended training

Cerebellar patients are impaired in motor adaptation. Further, motor adaptation can be divided into a fast component and a slow component, and the cerebellum is known to be especially crucial for the slow component. We tested whether the cerebellar deficit in motor adaptation can be ameliorated by training paradigms targeting slow learning using four visuomotor tasks: standard, gradual, overlearning and long intertrial intervals. We measured slow learning in patients and age-matched controls using a standard paradigm developed for reaching movements by Smith in 2006. The paradigm quantifies slow learning as the magnitude of spontaneous recovery of a previously learned and washed-out adaptation. Cerebellar patients had slower learning and reached a lower level of final adaptation, as seen in previous studies. Nevertheless, both groups had robust spontaneous recovery. Moreover, spontaneous recovery was increased in both groups in the overlearning paradigm with no significant difference between them. Computational modeling suggested that increased spontaneous recovery in the Control group reflects a changed slow adaptation system. That is, in the overlearning in controls, the slow system forgot more slowly and had a slower response to errors. In contrast, the same modeling suggests that no such change in the slow system occurred in the Cerebellar group. Rather, increased spontaneous recovery in this group seems to be the result of greater accumulated slow adaptation in the overlearning. We used our modeling results to predict that overlearning should have slower adaptation in the counterperturbation. Modeling further suggested we would not see these difference in the cerebellar patients. Follow-up analysis confirmed these model predictions. Taken together, our results imply that residual slow learning in cerebellar patients is expressed during increased training trials, but the primary cerebellar deficit is not improved.

neuroscience↗

bioRxiv2019

Cerebellar involvement in learning to balance a cart-pole system

The role of the cerebellum in error-based motor adaptation is well examined. In contrast, the involvement of the cerebellum in reward-based motor learning is less clear. In this study, we examined cerebellar involvement in a reward-based motor learning task, namely learning to control a virtual cart-pole system, over five consecutive days. Subjects with focal cerebellar lesions were compared to age-matched controls in terms of learning performance and underlying control mechanisms.\n\nBased on the overall balancing performance we have identified two subgroups of patients: (1) patients with learning performance comparable to healthy controls and (2) patients with decelerated learning, unsaturated learning progress after five days and decreased inter-manual transfer. Furthermore, we found that online learning is impaired while offline learning is partly preserved in cerebellar subjects. Regarding control mechanisms, decreased control performance was associated with impairments in predictive action timing.\n\nVoxel-wise lesion symptom mapping based on the two subgroups revealed strong associations between impairments in controlling the virtual cart-pole system and lesions in intermediate and lateral parts of lobules V and VI. These results together with previous reports suggest that the ability to predict the dynamics of the cart-pole system is an important factor for the reward-based skill acquisition process.

neuroscience↗