fMRI study of regular and irregular past tense (fwd)

[david gohre]

This may be of interest to FUNKNETTERS

---------- Forwarded message ----------
Date: Thu, 15 May 1997 16:19:46 +0100
From: Michael Ullman <michael at giccs.georgetown.edu>
To: info-childes at andrew.cmu.edu
Subject: fMRI study of regular and irregular past tense


My colleagues and I have recently carried out a
functional Resonance Magnetic Imaging (fMRI) study
of regular and irregular past tense production,
which may be of interest to some of you.

Five right-handed male native English speakers were shown the
stems of regular verbs (look) and irregular verbs (dig) on a screen,
and were asked to silently produce their past tense forms.
Twenty seconds of regulars (10 verbs) were followed by
20 seconds of fixation, 20 seconds of irregulars (10 verbs),
and 20 seconds of fixation.  This was repeated,
for a total of 80 regulars and 80 irregulars.
Signed Kolmogorov-Smirnov statistics were calculated for
three comparisons:  Regular vs. Fixation, Irregular vs. Fixation,
and Irregular vs. Regular.

We found overlapping as well as distinct patterns of brain activation
for the regular and irregular conditions.  Activation differences between
conditions were confirmed with time-course analyses.

For both the regular and irregular conditions, activation increases
were observed in inferior frontal cortex and the
basal ganglia (caudate nucleus).

However, a left prefrontal region was associated with an
activation increase for irregulars, but a decrease for regulars.
In contrast, left temporal and temporo-parietal regions were
associated with an activation decrease for irregulars, but
not for regulars. While the specific causes of these activation
decreases remain to be investigated, the double dissociations
between the frontal and temporal regions, for activation
decreases of regulars and irregulars, suggest that the two
types of past tense form are subserved by partially distinct
sets of brain structures, which may be linked to these two regions.

My colleagues and I are presenting these findings at the
Third International Conference on Functional Mapping
of the Human Brain in Copenhagen, on May 23.
The authors are Michael Ullman, Ruth Bergida, and Kathleen O'Craven.


Best,

Michael Ullman


************************************************
Michael Ullman
Assistant Professor
Institute for Cognitive and Computational Sciences
Georgetown University
3970 Reservoir Road NW
Washington, DC 20007
Phone: 202-687-6896
Fax: 202-687-0617
Email: michael at brain.georgetown.edu
************************************************




Michael Ullman
GICCS
3970 Reservoir Rd, NW
Georgetown University
Washington DC 20007
michael at giccs.georgetown.edu
tel: 202-687-6896
fax: 202-687-0617