Differential Effects of Slowing on
Orthographic, Phonological and Semantic Processing in
Children with Specific Language Impairment
Aimee L. Arnoldussen1; Julia L. Evans2; Mark S. Seidenberg1,3
Neuroscience Training Program1; Department of Communicative Disorders2; Department of Psychology3
University of Wisconsin-Madison
Introduction
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).
C A -M atch
SLI
R ead-M atch
90
80
70
60
50
40
30
20
10
-Woodcock Reading Mastery Test (WRMT)
CLPT
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.
Orthography
NowordRep
SLI children
performed worse
on reading
measures than CA
children, but
similarly to
younger RM
children.
100
C A -M atch
S LI
R e a d- M a t c h
90
80
70
Age-Matched
60
50
SLI
Reading-Matched
Voxel-wise p<.005, map-wise p<.05. All three groups show similar
activation profiles along the left visual cortex and fusiform gyrus.
40
30
20
Phonology
10
0
Exceptio ns
No nwo rds
PAT
fMRI Task Performance
The SLI children
were slower than
the CA group but
faster than the
RM group.
Functional MRI:
Tasks:
Accuracy
100
Percent Correct
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.
Age-Matched
SLI
ReadingMatchedp<.005, map-wise p<.05. Looking at the 2 non-SLI groups, there
Voxel-wise
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
CA-Match
SLI
Read-Match
95
90
85
80
75
70
65
Orth
Phon
Sem
Speed:
Summary
Conclusions about speed deficits in SLI depend on which
group the SLI children 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).
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.
fMRI Activity:
Reading
-Competing Language Processing Task (CLPT)
-Nonword Repetition (Nonword Rep)
-Exception Word Reading (Exceptions)
-Nonword Reading (Nonwords)
-Phonological Awareness Test (PAT)
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.
fMRI Results
0
Methods
Behavioral Measures:
The SLI group
performed
significantly worse
than CA children,
but similarly to
younger RM
children.
1 00
Percent Correct
Participants
Verbal Working Memory
Pe rce nt Corre ct
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.
Behavioral Measures
Match
Age-Matched
SLI
Reading-Matched
Voxel-wise p<.005, map-wise p<.05. 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.
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.
Conclusions:
We have reported preliminary findings from a study
for which additional analyses are being conducted. To this point the
results underscore the importance of:
1. Comparing SLI children to both same-aged and younger
reading/language matched children
2. Assessing performance on multiple components of language
3. Examining behavioral (speed, accuracy) and fMRI data together
The SLI children were consistently slower and less accurate than sameaged 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 to pattern more closely with the younger RM
group. Moreover, the imaging data suggest that the SLI children do not
fit on the normal developmental trajectory defined by RM and CA
groups. The SLI children were comparable to the other groups on the
orthography task but not phonology or semantics, producing greater
activity than even the younger subjects.
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).