Shaky Scaffolding: Age Differences In Cerebellar Activation Revealed Through Activation Likelihood Estimation Meta-Analysis

Abstract

Cognitive neuroscience research has provided foundational insights into aging, but has focused primarily on the cerebral cortex. However, the cerebellum is subject to the effects of aging. Given the importance of this structure in the performance of motor and cognitive tasks, cerebellar differences stand to provide critical insights into age differences in behavior. But, our understanding of cerebellar functional activation in aging is limited. Thus, we completed a meta-analysis of neuroimaging studies across task domains. Unlike in the cortex where an increase in bilateral activation is seen during cognitive task performance with advanced age, cerebellar activation is decreased. Conversely, we see an increase in activation in older adults during motor tasks. We propose that this is due to inputs for comparator processing in the context of control theory (cortical and spinal) that may be differentially impacted in aging. These findings advance our understanding of the aging mind and brain.

Differential vulnerability of the cerebellum in healthy ageing and Alzheimer’s disease

“…Prior work has also suggested that connectivity between the cerebellum and the cerebral cortex is reduced in ageing (Bernard & Seidler, 2014). This may explain recent data showing age differences in cerebellar engagement across cognitive domains including lobule VI and Crus I/II, the regions observed in our findings (Bernard et al, 2020). The authors hypothesise that fewer cerebellar resources reduce the support of automatic processes based on internal behavioural models (Bernard et al, 2020).…”

“…This may explain recent data showing age differences in cerebellar engagement across cognitive domains including lobule VI and Crus I/II, the regions observed in our findings (Bernard et al, 2020). The authors hypothesise that fewer cerebellar resources reduce the support of automatic processes based on internal behavioural models (Bernard et al, 2020). If that is indeed the case and additional resources are required to compensate for the lack of automatic processing, this may be particularly demanding on executive functions, which may have to engage in compensatory processes.…”

“…If that is indeed the case and additional resources are required to compensate for the lack of automatic processing, this may be particularly demanding on executive functions, which may have to engage in compensatory processes. Moreover, underactivation of posterior regions situated in FPN (Bernard et al, 2020) and the grey matter loss observed here in the same areas may contribute to a reduction in efficiency of cerebellar recruitment during cognitive tasks. Without longitudinal data, it remains unclear whether these changes in cerebellar engagement and neocortical-cerebellar connectivity are a result of grey matter loss or whether the opposite is the case.…”

“…Positive associations between grey matter volume and long-term memory performance have been found for total cerebellar volume and lobules VI and Crus II [3,11,31,32], while greater scores on tasks involving executive function and processing speed are correlated with greater volumes in lobule VI and Crus I [33,34]. A recent meta-analysis has shown underactivation in the ageing cerebellum to be a common finding compared to younger brains [35]. Future studies might examine whether decreases in grey matter in these regions identified here are driving such changes in BOLD activation.…”

“…The importance of the cerebellum for multiple cognitive, affective and motor domains is increasingly being recognised (Schmahmann et al, 2019), as is its role in age- and AD-related functional changes (Bernard et al, 2020; Bernard & Seidler, 2014; Gellersen et al, 2017; Jacobs et al, 2018). Despite the striking uniformity of cerebellar cellular organisation, the anterior-posterior functional continuum from motor to cognitive regions and the unique cortico-limbic connectivity patterns of each cerebellar lobule suggest non-uniformity of age and pathological effects across this brain region (Bernard, Leopold, Calhoun, & Mittal, 2015; Buckner et al, 2011; Koppelmans et al, 2017; Ramanoël et al, 2018).…”