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Abstract:
Introduction: 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. This study measured cerebellar activation
during both motor and non-motor sequencing to test a non-motor
"sequencing" hypothesis for the cerebellum. Methods: Two cases are
reported (a normal control and a schizophrenia patient).
Alternating patterns of task activation and rest conditions were
run on four tasks (4 fMRI series at 1.5 Tesla) capturing all
permutations of sequenced/non-sequenced and motor/non-motor
experimental conditions. The key task (non-motor sequencing)
involved mentally ordering months of the year presented visually.
We predicted prefrontal and cerebellar activation during this
non-motor sequencing task. Results: Based on non-parametric (KS)
test comparisons, the primary finding was lateral cerebellar
activation during both the sequenced and non-sequenced motor tasks,
and the sequenced but not the non-sequenced non-motor task. The
primary difference between the schizophrenia patient and normal
control involved location of robust activation sites during the two
motor tasks. Conclusions: These data corroborate previous findings
regarding the cerebellum=s role in coordinated motor responses. It
also provides preliminary support for the hypothesis that the
cerebellum contributes to the efficient sequencing and ordering of
symbolic (non-motor) information.
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