Decoding the role of the cerebellum in the early stages of reading acquisition

Abstract

Numerous studies have consistently reported functional activation of the cerebellum during reading tasks, especially in the right cerebellar hemisphere. However, it remains unclear whether this region is also involved in reading during the earliest stages of reading acquisition. Here, we investigated whether and how the cerebellum contributes to reading acquisition. We tested 80 5-6-year-old kindergarteners, who performed a visual word matching task during which functional MRI (fMRI) data were collected. We found that bilateral cerebellar hemispheres were significantly activated during visual word processing. Moreover, activation of left cerebellar lobule VII extending to lobule VIII negatively and significantly correlated with current reading ability, whereas activation of right cerebellar lobule VII extending to lobule VIII significantly and positively correlated with future reading ability. Functional decoding via functional connectivity patterns further revealed that left and right cerebellar lobules connected with different cerebral cortex regions. Our results suggest a division of labor between the left and right cerebellar lobules in beginning readers.

Keywords: Beginning readers; Cerebellum; Division of labor; Longitudinal; Reading.

Figure 1.

The distribution of reading performance at Time 1 and Time 2. Dot line represents LWID scores equal to 14. Scores under 14 indicate that the children were still in the alphabetic phase of reading acquisition and could not identify words. Blue dots represent children who returned for Time 2, red dots represent children who did not return for Time 2.

Figure 2.

Whole brain activation pattern and its relations with reading. (A) The topographic relations between activation region in the current study (lime color), the reading network established by Neurosynth (blue color), and the overlapping areas between the two (red). (B) The first 25 cognitive terms showing greater correlation with the whole brain activation map. The size of the font represents the strength of the correlation between the current activation map and term-based meta-maps generated by Neurosynth. The first five terms were colored orange and the remaining terms were colored black.

Figure 3.

Brain (Mean % signal change) and behavior (LWID) relationship. LWID = Woodcock-Johnson letter word identification subtest. Left T1CRBLM = regions in the left cerebellum that negatively and significantly correlated with reading ability at Time 1; Right T2CRBLM = regions in the right cerebellum that positively correlated with reading ability at Time 2. (A) locations of Left T1CRBLM and Right T2CRBLM. (B) Scatter plot to visualize the significant negative relationship between the mean % signal change of Left T1CRBLM and LWID score at Time 1 (n = 80, corresponding to statistical analysis in section 3.3). (C) Topographic relationship between the regions that significantly activated during the reading fMRI task (yellow), Left T1CRBLM (blue; overlap with activation shown in light blue), and Right T2CRBLM (red; overlap with activation shown in light red). (D) Scatter plot to visualize the significant positive relationship between the mean % signal change of Right T2CRBLM and LWID score at Time 2 (n = 43, corresponding to statistical analysis in section 3.4). Dot in the black circle was an extreme value with almost 4 standard deviations from the group mean.

Figure 4:

Topographic relationship between different analyses. (A) Regions in the cerebellum that show negative correlations with reading ability at Time 1 within the whole sample (n = 80) are shown in red, and within children who returned at Time 2 are shown in blue (n = 43). Overlapping regions are shown in pink. (B) Regions in the cerebellum that show positive correlations with reading ability at Time 2 are shown in red, and with reading gain across time are shown in blue. Overlapping regions are shown in pink.

Figure 5.

FC patterns during the task. FC = functional connectivity. L.MFG = left middle frontal gyrus, L.IFG = left inferior frontal gyrus, L.PostG = left postcentral gyrus; L.STG = left superior temporal gyrus; L.SPL = left superior parietal lobule; L.FG = left fusiform gyrus; L.IOG = left inferior occipital gyrus; R.SPL = right superior parietal lobule. (A) ROIs with reading network based on Murphy et al., (2019). Blue dots represent regions that had greater FC with Left T1CRBLM. Red dots represent regions that had greater FC with Right T2CRRBLM. (B) Visualization of the strength of FC between Left T1CRBLM and with Right T2 CRBLM and regions within the reading network. The value in each unit represents the difference between the FC from the cerebellum to a given ROI and the mean FC from the cerebellum to the remaining ROIs. This index indicates a cerebellar cluster to be relatively more connected to a given cerebral reading ROI relative to the remaining reading ROIs. Dots represent regions that showed significantly different FC with Left T1CRBLM and with Right T2CRBLM. ***p <.001, FDR corrected; **p <.01, FDR corrected; * p <.05, FDR corrected.

Figure 6.

FC patterns decoded by Neurosynth. Regions in the cerebral cortex that functionally connected with the peaks in the left and right cerebellum clusters, which correlated with reading ability at Time 1 and Time 2, respectively. R.AG = right angular gyrus; R.ITG = right inferior temporal gyrus; R.MFG = right middle frontal gyrus; R.IFG = right inferior frontal gyrus; R.IFS = right inferior frontal sulcus; R.SFG = right superior frontal gyrus. Threshold to identify these regions was set as voxel-level correlation coefficient larger than 0.2, cluster volume larger than 200 mm³.

Figure 7.

Overlap in FC patterns. FC = functional connectivity; Yellow regions in the cerebellum represent Left T1CRBLM, which positively correlated with yellow dot (R.SPL) in the cerebrum during the task. Green regions in the cerebellum represent Right T2CRBLM, which positively correlated with green dot (L.IFG) in the cerebrum during the task. The blue dot in the cerebellum represents the first peak of Left T1CRBLM, which demonstrated FC with blue regions in the cerebrum as decoded by Neurosynth. The red dot in the cerebellum represents the second peak of Right T2CRBLM, which demonstrated FC with red region in the cerebrum as decoded by Neurosynth. R.SPL = right superior parietal lobule; L.IFG = left inferior frontal gyrus.