Volume 17, Number 24,
Issue of December 15, 1997
pp. 9675-9685
Lobular Patterns of Cerebellar Activation in Verbal
Working-Memory and Finger-Tapping Tasks as Revealed by Functional
MRI
Received May 27, 1997; revised Sept. 29, 1997; accepted Oct. 2, 1997.
John E. Desmond1,
John
D. E. Gabrieli1,
Anthony D. Wagner1,
Bruce L. Ginier2, and
Gary H. Glover3
Departments of 1 Psychology and
3 Radiology, Stanford University, Stanford, California
94305, and 2 Radiology Department, Saint Agnes Medical
Center, Fresno, California 93720
The lobular distributions of functional activation of the
cerebellum during verbal working-memory and finger movement tasks were
investigated using functional magnetic resonance imaging (fMRI).
Relative to a rest control, finger tapping of the right hand produced
ipsilateral-increased activation in HIV/HV [Roman numeral designations
based on Larsell's () nomenclature] and HVI
and weaker activation in HVIII that was stronger on the ipsilateral
side. For a working-memory task, subjects were asked to remember six
(high load) or one (low load) visually presented letters across a brief
delay. To assess the motoric aspects of rehearsal in the absence of
working memory, we asked the subjects to repeatedly read subvocally six
or one letters at a rate that approximated the internally generated
rehearsal of working memory (motoric rehearsal task). For both tasks,
bilateral regions of the superior cerebellar hemispheres (left superior HVIIA and right HVI) and portions of posterior vermis (VI and superior
VIIA) exhibited increased activation during high relative to low load
conditions. In contrast, the right inferior cerebellar hemisphere
(HVIIB) exhibited this load effect only during the working-memory task.
We hypothesize that HVI and superior HVIIA activation represents input
from the articulatory control system of working memory from the frontal
lobes and that HVIIB activation is derived from the phonological store
in temporal and parietal regions. From these inputs, the cerebellum
could compute the discrepancy between actual and intended phonological
rehearsal and use this information to update a feedforward command to
the frontal lobes, thereby facilitating the phonological loop.
Key words:
cerebellum;
verbal working memory;
cognition;
brain
mapping;
functional magnetic resonance imaging;
finger tapping