Transcript No Slide Title

Performance Matching: Comparing Children with Specific Language
Impairment to Younger Children with Similar Abilities using fMRI
Aimee L. Arnoldussen; Julia L. Evans; Mark S. Seidenberg
Waisman Center, University of Wisconsin-Madison
Several competing hypotheses have been proposed
concerning the bases of Specific Language
Impairment (SLI). One is that SLI is secondary to
general slowing in the processing of information (Kail
1994; Miller, Kail, Leonard & Tomblin 2001). Our
study investigated the speed of orthographic,
phonological and semantic processing in children with
and without language impairments and brain activity
measured by fMRI.
Participants
Behavioral Measures
Verbal Working Memory
100
Percent Correct
Introduction
CA-M atch
80
SLI
Read-M atch
60
40
20
0
CLPT
Nonword Rep
The SLI group performed significantly worse than CA
children, but similarly to younger RM children.
fMRI Task Performance
90
80
S LI
R e a d- M a t c h
70
60
50
40
10
0
Exceptions
Nonwords
3500
3000
2500
CA-Match
SLI
Read-Match
Left-lateralized over-activity SLI>RM>NC
Age-Matched
2000
1500
1000
500
0
Orth
Phon
Sem
Match
Tasks:
SLI
Reading-Matched
Looking at the 2 non-SLI groups, there is a
developmental trend with younger RM showing more
activation than older CA children. The SLI children
depart from this pattern with additional activation in left
MFG, IFG, precentral gyrus, fusiform gyus and visual
cortex.
Semantics
The SLI children were slower than the CA group but
faster than the RM group.
Accuracy
Percent Correct
100
90
80
Age-Matched
60
50
Orth
Phon
Sem
Match
SLI children were less accurate than CA children across
all tasks. They were similar to RM accuracy for all
tasks except phonology, where the SLI group
performed poorest.
SLI
The typical developmental trend from younger RM to
older NC children is marked by a reduction in the size of
the overall left hemisphere activation. SLI children fall
beyond this developmental trend: more left activity than
the RM children who were equated by skill/performance.
Summary
Speed: Conclusions about children with SLI depend
on which group they are compared to. They are slower
than same aged non-SLI children (CA) but faster than
younger non-SLI children with similar
reading/language abilities (RM).
CA-Match
SLI
Read-Match
70
1. Comparing SLI children to both sameaged and younger reading/language
matched children
2. Assessing performance on multiple
components of language
3. Examining behavioral (speed, accuracy)
and fMRI data together
Phonology
PAT
Reaction Time
RT (ms)
We have reported preliminary findings from a study for
which additional analyses are being conducted. To this
point the results underscore the importance of:
Age-Matched
SLI
Reading-Matched
All three groups show similar activation profiles along the left
visual cortex and fusiform gyrus.
30
20
Behavioral Measures:
Children were instructed to choose the word that spelled,
rhymed or was in the same category as the picture as
quickly and accurately as possible. A nonlinguistic shape
matching control task was also included. All children
received practice in order to confirm task understanding.
Performance was assessed by reaction time and accuracy.
Conclusions
C A -M atch
Methods
Percent Correct
Orthography
Overall more voxels of activity SLI>RM>NC
SLI children performed worse on reading measures than
CA children, but similarly to younger RM children.
Functional MRI:
fMRI Activity: In the two non-SLI groups, there is a
developmental trend: younger, less skilled RM children
produce more activation than older, more skilled CA
children. The SLI group does not fall on this
developmental continuum. Rather, they exhibited the
largest amount of activity, even more than the RM group
to whom they were matched on reading/language ability.
These findings are consistent with other research
showing greater brain activity for more difficult tasks
and for clinical populations with relevant behavioral
impairments.
3T whole brain images were acquired from 26 axial
slices taken every 3 seconds. After motion correction, a
boxcar reference function comparing blocks in each task
versus control was convolved with a blood flow response
model. Images were transformed into Talairach space
and smoothed with a 4mm blur before computing group
statistics: Voxel-wise p<.005, map-wise p<.05.
Reading
100
11 SLI children ages 9;8-13;4 were compared to two
nonimpaired groups: 11 chronological age-matched
(CA ages 9;11 - 13;1) and 11 younger children (7;0 8;9) with similar reading abilities as the SLI group
(reading-matched, RM). All children tested within the
normal range on IQ. Those with SLI were identified
as having expressive and/or receptive language
abilities more than 1.5 standard deviations from
normal. Reading matches were based on performance
on the Woodcock Word Reading Mastery Test (1998).
-Woodcock Reading Mastery Test (WRMT)
-Competing Language Processing Task (CLPT)
-Nonword Repetition (Nonword Rep)
-Exception Word Reading (Exceptions)
-Nonword Reading (Nonwords)
-Phonological Awareness Test (PAT)
fMRI Results
Reading-Matched
Similar developmental trend. Among non-SLI,
increase in skill is associated with less activation. The
SLI group produced additional activation compared to
both normal groups, in the left frontal and
visual/fusiform areas to a greater degree than either
normal group.
Accuracy: Conclusions also depend on comparisons.
SLI children were less accurate than CA children across
all tasks, but performed as well as the younger RM
children on the orthography, semantics, and matching
tasks. They showed a particular deficit on the
phonological task, performing more poorly than even
the RM group.
The SLI children were consistently slower and less
accurate than same-aged non-SLI children, consistent
with a generalized slowing hypothesis. However,
comparisons to the RM children and performance on
the different tasks yield a more complex picture. If the
language impairment in SLI merely reflected
generalized slowing we would have expected the SLI
children's performance and fMRI activity to pattern
more closely with the younger RM group. Instead, the
imaging data suggest that the SLI children do not fit on
the normal developmental trajectory defined by RM
and CA groups.
Although the data from this study continue to be
analyzed, the results to this point suggest that slowing is
a consequence of another type of underlying
impairment (e.g., one related to phonological
processing) rather than the proximal cause of language
delay.
Special thanks to Lisbeth Simon for help in subject recruiting and
clinical assessments. We also wish to thank Jeff Binder consultation
on the imaging component. This research was supported by NIDCD
R01DC005650 (Evans) and NICHD RO1MH29891 (Seidenberg).