Generalized Role for the Cerebellum in Encoding Internal Models: Evidence from Semantic Processing

Abstract

The striking homogeneity of cerebellar microanatomy is strongly suggestive of a corresponding uniformity of function. Consequently, theoretical models of the cerebellum's role in motor control should offer important clues regarding cerebellar contributions to cognition. One such influential theory holds that the cerebellum encodes internal models, neural representations of the context-specific dynamic properties of an object, to facilitate predictive control when manipulating the object. The present study examined whether this theoretical construct can shed light on the contribution of the cerebellum to language processing. We reasoned that the cerebellum might perform a similar coordinative function when the context provided by the initial part of a sentence can be highly predictive of the end of the sentence. Using functional MRI in humans we tested two predictions derived from this hypothesis, building on previous neuroimaging studies of internal models in motor control. First, focal cerebellar activation-reflecting the operation of acquired internal models-should be enhanced when the linguistic context leads terminal words to be predictable. Second, more widespread activation should be observed when such predictions are violated, reflecting the processing of error signals that can be used to update internal models. Both predictions were confirmed, with predictability and prediction violations associated with increased blood oxygenation level-dependent signal in the posterior cerebellum (Crus I/II). Our results provide further evidence for cerebellar involvement in predictive language processing and suggest that the notion of cerebellar internal models may be extended to the language domain.

The role of the supplementary motor area for speech and language processing

“…Furthermore, the role of cortico-cerebellar circuits seems to be out of question with respect to speech motor control. However, there is increasing evidence that the cerebellum also contributes to top-down mechanisms during speech perception by serving predictive functions (Moberget et al, 2014). In this respect, the SMA seems to play a coordinative role between procedural memory traces, on the one hand and cognitive structures such as syntax and grammar, on the other (Ullman, 2004).…”

The impact of cerebellar transcranial direct current stimulation (tDCS) on learning fine-motor sequences

“…This hypothesis is based on many studies that have found cerebellar involvement in more cognitive tasks [27] and the uniform microanatomy throughout the cerebellum that suggest similar computations in both motor and cognitive domains [28]. Probably more relevant to sequence learning and generalization, the cerebellum is involved in cognitive functions such as applying rules that constrain responses [29] and language [30].…”

Patients with focal cerebellar lesions show reduced auditory cortex activation during silent reading

“…Consistent with this hypothesis, in a recent fMRI study using healthy young controls, the BOLD response in lateral posterior cerebellum to the final word of a sentence was stronger when the sentence established a strong semantic expectancy, compared to when the final word was not predictable (Moberget, Gullesen, Andersson, Ivry, & Endestad, 2014). Especially pronounced activations were observed when the final word violated the semantic prediction, consistent with the hypothesis of error-based learning in the cerebellum (Doya, 1999; Ito, 2006; Ramnani, 2006).…”

“…The data for nine of these participants were included in our original report (Moberget et al, 2014). Control participants were self-reported as right-handed and reported no neurological or current psychiatric problems.…”