The cerebellar role in Executive Functions:new insights from behavioral and structural neuroimaging data

“Executive functions” (EFs) are a set of cognitive processes that allow to select and monitor behaviours to achieve specific goals. Although it has been proposed that the cerebellum is involved in EFs by means of specific anatomical connections with the lateral prefrontal cortex, its specific role in these processes needs to be clarified. Aim of the present study was to investigate the EFs in subject with cerebellar pathology to characterize their profile of executive impairment. Twenty-three patients with cerebellar atrophy (CA), 18 patients with focal cerebellar damage (FCD), and 43 matched healthy controls (CT) were enrolled in the study and underwent an extensive evaluation of the EFs. A one-way Anova and Tukey’s post hoc test were performed. Moreover a principal components analysis with 3 factors (Planning, Set shifting and Cognitive Inhibition) was executed to identify possible shared process among impaired EFs tasks. Finally, in order to investigate the link between executive impairment and the pattern of cerebellar structural alterations, T1 weighted scans were also collected for voxel-based morphometry analysis and cerebellar lesion characterization. The neuropsychological assessment evidenced that CA was significantly impaired in planning tasks while FCD was significantly impaired in set shifting tasks. By using the neuroimaging analysis, the damaged cerebellar regions have been identified in CA and FCD. The structural alteration patterns have been related to the executive impairment patterns. The hypothesis that, in presence of a cerebellar pathology, different profiles of EFs alteration depend on cerebellar damage localization will be discussed

The role of the cerebellum in unconsciuos and conscious processing of emotions: a review

Studies from the past three decades have demonstrated that there is cerebellar involvement in the emotional domain. Emotional processing in humans requires both unconscious and conscious mechanisms. A significant amount of evidence indicates that the cerebellum is one of the cerebral structures that subserve emotional processing, although conflicting data have been reported on its function in unconscious and conscious mechanisms. This review discusses the available clinical, neuroimaging and neurophysiological data on this issue. We also propose a model in which the cerebellum acts as a mediator between the internal state and external environment for the unconscious and conscious levels of emotional processing

The cerebellar topography of attention sub-components in Spinocerebellar Ataxia Type 2

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease characterized by a progressive cerebellar syndrome and multiple-domain cognitive impairments. The cerebellum is known to contribute to distinct functional networks related to higher-level functions. The aims of the present study were to investigate the different sub-components of attention and to analyse possible correlations between attention deficits and specific cerebellar regions in SCA2 patients. To this purpose, 11 SCA2 patients underwent an exhaustive attention battery that evaluated several attention sub-components. The SCA2 group performed below the normal range in tasks assessing selective attention, divided attention, and sustained attention, obtaining negative Z-scores. These results were confirmed by non-parametric Mann-Whitney U tests that showed significant differences between SCA2 and control subjects in the same sub-components of the attention battery, allowing us to speculate on cerebellar involvement when a high cognitive demand is required (i.e., multisensory integration, sequencing, prediction of events, and inhibition of inappropriate response behaviours). The voxel-based morphometry analysis showed a pattern of significantly reduced grey matter volume in specific cerebellar lobules. In particular, the SCA2 patients showed significant grey matter loss in bilateral regions of the anterior cerebellar hemisphere (I-V) and in the posterior lobe (VI-IX) and posterior vermis (VI-IX). Statistical analysis found significant correlations between grey matter reductions in the VIIb/VIIIa cerebellar lobules and impairments in Sustained and Divided Attention tasks and between grey matter reduction in the vermal VI lobule and impairment in the Go/NoGo task. For the first time, the study demonstrated the involvement of specific cerebellar lobules in different sub-components of the attention domain, giving further support to the inclusion of the cerebellum within the attention network

Neural substrates of motor and cognitive dysfunctions in SCA2 patients. A network based statistics analysis

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease characterized by a progressive cerebellar syndrome, which can be isolated or associated with extracerebellar signs. It has been shown that patients affected by SCA2 present also cognitive impairments and psychiatric symptoms. The cerebellum is known to modulate cortical activity and to contribute to distinct functional networks related to higher-level functions beyond motor control. It is therefore conceivable that one or more networks, rather than isolated regions, may be dysfunctional in cerebellar degenerative diseases and that an abnormal connectivity within specific cerebello-cortical regions might explain the widespread deficits typically observed in patients. In the present study, the network-based statistics (NBS) approach was used to assess differences in functional connectivity between specific cerebellar and cerebral “nodes” in SCA2 patients. Altered inter-nodal connectivity was found between more posterior regions in the cerebellum and regions in the cerebral cortex clearly related to cognition and emotion. Furthermore, more anterior cerebellar lobules showed altered inter-nodal connectivity with motor and somatosensory cerebral regions. The present data suggest that in SCA2 a cerebellar dysfunction affects long-distance cerebral regions and that the clinical symptoms may be specifically related with connectivity changes between motor and non-motor cerebello-cortical nodes