Voxelwise Encoding Models Show That Cerebellar Language Representations Are Highly Conceptual

Abstract

There is a growing body of research demonstrating that the cerebellum is involved in language understanding. Early theories assumed that the cerebellum is involved in low-level language processing. However, those theories are at odds with recent work demonstrating cerebellar activation during cognitive tasks. Using natural language stimuli and an encoding model framework, we performed an fMRI experiment on 3 men and 2 women, where subjects passively listened to 5 h of natural language stimuli, which allowed us to analyze language processing in the cerebellum with higher precision than previous work. We used these data to fit voxelwise encoding models with five different feature spaces that span the hierarchy of language processing from acoustic input to high-level conceptual processing. Examining the prediction performance of these models on separate BOLD data shows that cerebellar responses to language are almost entirely explained by high-level conceptual language features rather than low-level acoustic or phonemic features. Additionally, we found that the cerebellum has a higher proportion of voxels that represent social semantic categories, which include “social” and “people” words, and lower representations of all other semantic categories, including “mental,” “concrete,” and “place” words, than cortex. This suggests that the cerebellum is representing language at a conceptual level with a preference for social information.