INVOLVMENT OF THE CEREBELLUM IN VERABL WORKING MEMORY AND PHONOLOGICAL JUDGMENT: EVIDENCE FOR A ROLE IN PREDICTIVE PHONOLOGICAL CODING

Within recent decades, researchers have found evidence that the cerebellum contributes to language processing, yet exactly how it contributes remains a mystery. Researchers have attempted to map functional zones within the cerebellar cortex in an effort to determine precisely how the cerebellum contributes to language with limited success. We predict that the cerebellum’s functional zones are not strictly divisible by cognitive domains such as “language” or “executive control” and are instead delineated by task demands not unlike cognitive regions in the cerebral cortex. Prior neuropsychological results indicate that rhyme judgment and verbal working memory tasks impose task demands that require the cerebellum for normal levels of performance. In an effort to localize this shared functional process in the cerebellum, we used a slow event-related design to study the hemodynamic response in participants (N=12) as they performed rhyme judgment task and then compared to the results to separate pool of the subjects who performed a verbal working memory task (N=12). We hypothesized that these two tasks share cognitive processes and thereby neural substrates; in other words, they will engage the same functional regions in the cerebellum. Secondly, we hypothesized that these functional regions would be most engaged during task components negatively impacted by concurrent articulation, i.e., the encoding period of verbal working memory tasks and judgments involving mismatched non-rhyme pairs, e.g. “tint” and “pint.” We found three potential clusters engaged in both tasks, with one region (located in Crus I) demonstrating the predicted response patterns across different task components. Based upon these findings and the cognitive literature on verbal working memory and rhyme judgments, we suggest that this region contributes to an internal speech-based process that involves phonological error prediction