Relationships between regional cerebellar volume and sensorimotor and cognitive function in young and older adults

Abstract

The cerebellum has been implicated in both sensorimotor and cognitive function, but is known to undergo volumetric declines with advanced age. Individual differences in regional cerebellar volume may therefore provide insight into performance variability across the lifespan, as has been shown with other brain structures and behaviors. Here, we investigated whether there are regional age differences in cerebellar volume in young and older adults, and whether these volumes explain, in part, individual differences in sensorimotor and cognitive task performance. We found that older adults had smaller cerebellar volume than young adults; specifically, lobules in the anterior cerebellum were more impacted by age. Multiple regression analyses for both age groups revealed associations between sensorimotor task performance in several domains (balance, choice reaction time, and timing) and regional cerebellar volume. There were also relationships with working memory, but none with measures of general cognitive or executive function. Follow-up analyses revealed several differential relationships with age between regional volume and sensorimotor performance. These relationships were predominantly selective to cerebellar regions that have been implicated in cognitive functions. Therefore, it may be the cognitive aspects of sensorimotor task performance that are best explained by individual differences in regional cerebellar volumes. In sum, our results demonstrate the importance of regional cerebellar volume with respect to both sensorimotor and cognitive performance, and we provide additional insight into the role of the cerebellum in age-related performance declines.

Figure 1

A) Lobules of the cerebellum as defined by the SUIT atlas presented on coronal (left), mid-saggital (center) and axial (right) slices. Labels are only included on the right hemisphere and vermis, though analysis was completed on both hemispheres. B) Anatomical imaging post processing stream. Masks created using the SUIT atlas (left) were then warped to individual subject's high-resolution anatomical images (center), resulting in subject-specific masks for each individual (right). Individual masked overlays for Right Crus I are presented for a representative young (red) and older adult (green).

Figure 2

Age differences in cerebral tissue types (YA: black bars; OA: gray bars). There was no significant main effect of age, though there was a significant age by tissue type interaction. Follow-up t-tests indicated significant age differences in gray matter and CSF volume (**p<.01; ***p<.001). Error bars represent the standard error of the mean.

Figure 3

Age differences in lobular volume (YA: black bars; OA: gray bars). There are significant main effects of age (F_(1,51)=20.17, p<.001) indicating that older adults have smaller cerebellar gray matter volume. There is also a main effect of lobule (F_{(4.26,217.14)}=1985.66, p<.001), along with a significant age by lobule interaction (F_{(4.26,217.14)}=9.07, p<.001). *Indicates significant age differences in lobular volume as assessed using follow-up pairwise t-tests, corrected for multiple comparisons (p<.002). Error bars represent the standard error of the mean. Lobules are labeled using roman numerals. L: left hemisphere; R: right Hemisphere; V: vermis; CRI: Crus I; CRII: Crus II.

Figure 4

Hemispheric differences in gray matter volume (%TIV) of motor and cognitive regions of the cerebellum (YA: black bars; OA: gray bars). The three-way repeated measures age by hemisphere by region interaction was nearly significant when using a Greenhouse-Geiser correction for sphericity (F_{(1.51, 78.39)}=3.02, p=.068). We further conducted follow-up analyses to investigate the effect of hemisphere on the motor and cognitive regions. These analyses indicate significant effects of hemisphere for all three regions (in all cases, F_(1,52)>8, p<.005), and are indicated with an asterisk. Error bars represent the standard error of the mean.

Figure 5

PCA components in the young adults were used to define sub-regions of the cerebellum for additional analysis. Overlays are presented on the right hemisphere only on both a coronal (left) and axial (right slice), to allow for comparison to the left hemisphere, though analysis was conducted on both hemispheres. Lobules not included in a component (left and right lobule X and right Crus II) were included in the posterior grouping given their anatomical location. Red: anterior cerebellum, corresponding to component two; Green: posterior cerebellar grouping corresponding to component one; Blue: Crus I, corresponding to component four; Yellow: cerebellar vermis corresponding to component three.

Figure 6

Correlations with age and regional cerebellar volume (% TIV). A) right anterior cerebellum (r=−.64), B) left posterior cerebellum (r=−.38), C) right Crus I (r=−.41), and D) the vermis (r=−.47). Additionally, there were significant negative correlations with the left anterior cerebellum (r=−.64) and left Crus (r=−.48), though just the right hemisphere is presented here for the sake of parsimony. These linear relationships indicate differences in cerebellar volume across adulthood.

Figure 7

Differential relationships between regional cerebellar volume (%TIV) and performance in young and older adults. Differential relationships were seen between A) Grooved pegboard performance and right Crus I volume, B) Choice reaction time and the volume of the right posterior cerebellum, and C) Choice reaction time and the volume of the vermis, and D) 1500 msec timing and right Crus I volume, YA: black circles. OA: Gray Squares.