Test of a Non-Motor Sequencing Hypothesis for a Frontal-Cerebellar Circuit: Implications for Epilepsy
Abstract number :
1.239
Submission category :
Year :
2000
Submission ID :
1396
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Joseph I Tracy, Scott S Fargo, Feroze Mohamed, Mark Pinsk, Ryan Tiver, Alex Pines, Peter Bandettini, Thomas Jefferson Univ, Philadelphia, PA; MCP Hahnemann Univ, Philadelphia, PA; National Institute of Health, Lab of Brain Cognition, Bethesda, MD; Ursinu
RATIONALE: The importance of the cerebellum to the efficient sequencing, timing and coordinating of motor responses suggests a specialization for these operations in general. If so, cerebellar involvement should be evident in non-motor tasks that demand these operations as part of instantiation of a larger cerebellar/thalamic/prefrontal circuit. This project tested a non-motor "sequencing" hypothesis for the cerebellum by examining activation during a non-motor sequencing task. METHODS: Healthy normals (n= 4) served as participants. Cognitive stimulation at 1.5 Tesla involved a non-motor, sequencing (Months) task and a non-motor, non-sequencing experimental control (Covert Reading). BOLD signal associated with each task was acquired in separate fRMI runs that included resting baseline conditions administered in a "blocked" design. Normals were predicted to show heightened task-related activation in the key nodes of this circuit (prefrontal, thalamic, cerebellar). RESULTS: Subject-specific statistical contrasts reflecting brain activation associated with the Months task were conjoined. The sample showed right medial cerebellar activation in addition to left dorsolateral prefrontal cortex activity, providing strong evidence for two key nodes of the hypothesized prefrontal-thalamic-cerebellar circuit. Data from normals suggested a role for two additional cerebellar regions (right posterior medial; right posterior lateral). Prefrontal and inferior parietal areas were also active. CONCLUSIONS: Data provide support for the hypothesis that the cerebellum contributes to the efficient sequencing and ordering of symbolic (non-motor) information. Thus, the cerebellum's involvement in motor sequencing may reflect a broader expertise in the implementation of sequencing behavior. Implications for frontal lobe epilepsy involve the role sequencing plays in the efficient organization of behavior, both motor and non-motor, as well as providing grounds to understand potential disruptions of focal frontal deficits to large brain circuits.