Sensory acquisition functions of the cerebellum in verbal working memory

Jutta Peterburs,Yu Liang,Dominic T Cheng,John E Desmond

doi:10.1007/s00429-020-02212-5

Abstract

Several fMRI studies have shown that the superior cerebellum exhibits load-dependent activations during encoding of letters in a Sternberg verbal working memory (VWM) task. It has been hypothesized that the cerebellum regulates the acquisition of sensory data across all modalities, and thus, that VWM load activations may reflect high- vs low-load differences in sensory acquisition demands. Therefore, increased difficulty in sensory data acquisition should elicit greater activation in the cerebellum. The present fMRI study manipulated sensory acquisition in VWM by presenting visually degraded and non-degraded stimuli with high and low memory loads, thereby identifying load-dependent regions of interest in the cerebellum, and then testing if these regions showed greater activation for degraded stimuli. Results yielded partial support for the sensory acquisition hypothesis in a load-dependent region of the vermis, which showed significantly greater activation for degraded relative to non-degraded stimuli. Because eye movements did not differ for these stimulus types, and degradation-related activations were present after co-varying eye movements, this activation appears to be related to perceptual rather than oculomotor demands. In contrast to the vermis, load-sensitive regions of the cerebellar hemispheres did not show increased activation for degraded stimuli. These findings point to an overall function of association-based prediction that may underlie general cerebellar function, with perceptual prediction of stimuli from partial representations occurring in the vermis, and articulatory prediction occurring in the hemispheres.

Highlights

A growing body of evidence is demonstrating that the cerebellum is involved in motor coordination and motor learning, and in non-motor functions, such as linguistic processes, affective processing and emotional regulation (e.g., Lupo et al.2018; Jeremy Schmahmann 2019; Schmahmann and Sherman 1998), executive functions (Bellebaum and Daum 2007; Bürk et al 2003), working memory (e.g., Desmond et al 1997; Hayter et al 2007; Peterburs et al 2010; Ravizza et al 2006), and timing (Breska and Ivry 2016; Coull et al 2011; Ivry 1997)
The present study investigated whether cerebellar activations in a verbal working memory task were modulated by perceptual demands
In line with the a priori hypothesis, and in support of sensory acquisition as a general function of the cerebellum, load-dependent activations in vermis Crus II scaled with sensory acquisition demand and were increased for degraded relative to non-degraded stimuli

Summary

Introduction

A growing body of evidence is demonstrating that the cerebellum is involved in motor coordination and motor learning, and in non-motor functions, such as linguistic processes (for a review see Mariën and Borgatti 2018), affective processing and emotional regulation (e.g., Lupo et al.2018; Jeremy Schmahmann 2019; Schmahmann and Sherman 1998), executive functions (Bellebaum and Daum 2007; Bürk et al 2003), working memory (e.g., Desmond et al 1997; Hayter et al 2007; Peterburs et al 2010; Ravizza et al 2006), and timing (Breska and Ivry 2016; Coull et al 2011; Ivry 1997). Given that the cerebellum is characterized by a rather uniform neuroarchitecture, and given the existence of closed cerebro-cerebellar input–output loops (Middleton and Strick 1994; Strick et al 2009), the idea of uniform cerebellar computations and overarching functions is very enticing. This idea has recently been challenged by the proposal of multiple functionality, i.e.,. The debate about universal and multiple functionality illustrates that the question of how the cerebellum contributes to nonmotor functions warrants further investigation

Methods

Results

Conclusion