Aphasia Neuroplasticity Review

Sharp et al. (2004)

Reference

AuthorsSharp DJ, Scott SK, Wise RJ
TitleRetrieving meaning after temporal lobe infarction: the role of the basal language area
ReferenceAnn Neurol 2004; 56: 836-846
PMID15514975
DOI10.1002/ana.20294

Participants

LanguageUK English
Inclusion criteriaLesion in vicinity of L STG; no extensive frontal damage; no inferior temporal damage; able to perform tasks
Number of individuals with aphasia9
Number of control participants18
Were any of the participants included in any previous studies?No
Is age reported for patients and controls, and matched?Yes (median 58 years, range 39-72 years)
Is sex reported for patients and controls, and matched?Yes (males: 8; females: 1)
Is handedness reported for patients and controls, and matched?Yes (right: 9; left: 0)
Is time post stroke onset reported and appropriate to the study design?Yes (mean 45 months, range 14-145 months)
To what extent is the nature of aphasia characterized?Severity only
Language evaluationSubtests from CAT, subtests from PALPA, Action for dysphasic adults, TROG, PPT
Aphasia severityMild
Aphasia typeNot stated
First stroke only?Yes
Stroke typeNot stated
To what extent is the lesion distribution characterized?Lesion overlay
Lesion extentNot stated
Lesion locationLesion in vicinity of L STG; no extensive frontal damage; no inferior temporal damage
Participants notes

Imaging

ModalityPET (rCBF)
Is the study cross-sectional or longitudinal?Cross-sectional
If longitudinal, at what time point(s) were imaging data acquired?
If longitudinal, was there any intervention between the time points?
Is the scanner described?Yes (Siemens HR++ 966)
Is the timing of stimulus presentation and image acquisition clearly described and appropriate?Yes
Design typePET
Total images acquired16
Are the imaging acquisition parameters, including coverage, adequately described and appropriate?Yes (whole brain)
Is preprocessing and intrasubject coregistration adequately described and appropriate?Yes
Is first level model fitting adequately described and appropriate?Yes
Is intersubject normalization adequately described and appropriate?Yes
Imaging notes

Conditions

Are the conditions clearly described?Yes
ConditionResponse typeRepetitionsAll groups could do?All individuals could do?
semantic decisionWord (overt)aphasia: 8; control: 4YesYes
syllable count decisionWord (overt)aphasia: 8; control: 4YesYes
semantic decision (noise vocoded) (control only)Word (overt)4 (control)YesYes
syllable count decision (noise vocoded) (control only)Word (overt)4 (control)YesYes
Conditions notesSeems the response was a spoken word, but this is not stated explicitly; assuming all individuals could do the tasks because this was an inclusion criterion and behavioral data supports

Contrasts

Are the contrasts clearly described?Yes

Contrast 1: semantic decision vs syllable count decision

Language conditionSemantic decision
Control conditionSyllable count decision
Are the conditions matched for visual demands?Yes
Are the conditions matched for auditory demands?Yes
Are the conditions matched for motor demands?Yes
Are the conditions matched for cognitive/executive demands?Yes
Is accuracy matched between the language and control tasks for all relevant groups?No, different
Is reaction time matched between the language and control tasks for all relevant groups?No, different
Behavioral data notes
Are control data reported in this paper or another that is referenced?Somewhat
Does the contrast selectively activate plausible relevant language regions in the control group?Somewhat
Are activations lateralized in the control data?Yes
Control activation notesThe control data provided also include the noise vocoded conditions; only ventral temporal activations are shown, which are L-lateralized
Contrast notes

Analyses

Are the analyses clearly described?No* (moderate limitation) (see specific limitation(s) below)

Voxelwise analysis 1

First level contrastSemantic decision vs syllable count decision
Analysis classCross-sectional aphasia vs control
Group(s)Aphasia vs control (clear speech)
Covariate
Is the second level contrast valid in terms of the group(s), time point(s), and measures involved?Yes
Is accuracy matched across the second level contrast?Appear mismatched
Is reaction time matched across the second level contrast?Yes, matched
Behavioral data notesInteraction of group by task not reported for accuracy
Type of analysisVoxelwise
Search volumeWhole brain
Correction for multiple comparisonsSmall volume correction
SoftwareSPM99
Voxelwise pFWE p < .05 with SVC in fusiform gyri, temporal poles, L IFG, L orbitofrontal and L SFG
Cluster extent
Statistical details
Findings↓ L posterior inferior temporal gyrus/fusiform gyrus
Findings notes

Voxelwise analysis 2

First level contrastSemantic decision vs syllable count decision
Analysis classCross-sectional correlation with language or other measure
Group(s)Aphasia
CovariateSemantic decision accuracy
Is the second level contrast valid in terms of the group(s), time point(s), and measures involved?Yes
Is accuracy matched across the second level contrast?Accuracy is covariate
Is reaction time matched across the second level contrast?Unknown, not reported
Behavioral data notes
Type of analysisVoxelwise
Search volumeWhole brain
Correction for multiple comparisonsSmall volume correction
SoftwareSPM99
Voxelwise pFWE p < .05 with SVC in fusiform gyri, temporal poles, L IFG, L orbitofrontal and L SFG
Cluster extent
Statistical detailsFixed effects; this analysis is not clearly described
Findings↑ R posterior inferior temporal gyrus/fusiform gyrus
Findings notesPatients who were more accurate had more activity in R anterior fusiform gyrus

ROI analysis 1

First level contrastSemantic decision vs syllable count decision
Analysis classCross-sectional aphasia vs control
Group(s)Aphasia vs control (clear speech)
Covariate
Is the second level contrast valid in terms of the group(s), time point(s), and measures involved?Yes
Is accuracy matched across the second level contrast?Appear mismatched
Is reaction time matched across the second level contrast?Yes, matched
Behavioral data notesInteraction of group by task not reported for accuracy
Type of analysisRegion of interest (ROI)
ROI typeAnatomical
How many ROIs are there?1
What are the ROI(s)?L fusiform gyrus
How are the ROI(s) defined?Probabilistic brain atlas
Correction for multiple comparisonsOne only
Statistical details
Findings↓ L posterior inferior temporal gyrus/fusiform gyrus
Findings notes

ROI analysis 2

First level contrastSemantic decision vs syllable count decision
Analysis classCross-sectional aphasia vs control
Group(s)Aphasia vs control (noise vocoded)
Covariate
Is the second level contrast valid in terms of the group(s), time point(s), and measures involved?Yes
Is accuracy matched across the second level contrast?No, but attempt made
Is reaction time matched across the second level contrast?Yes, matched
Behavioral data notesPatients were more accurate on semantic decisions than syllable decisions, whereas controls were less accurate on noise vocoded semantic decisions than clear syllable decisions (which were the baseline for this analysis)
Type of analysisRegion of interest (ROI)
ROI typeAnatomical
How many ROIs are there?1
What are the ROI(s)?L fusiform gyrus
How are the ROI(s) defined?Probabilistic brain atlas
Correction for multiple comparisonsOne only
Statistical details
FindingsNone
Findings notesThis analysis suggests that the difference between groups in the L fusiform gyrus disappears when the controls perform a semantic task that is similarly challenging

Notes

Excluded analyses(1) combined analysis of patients and controls (Figure 4); (2) correlation with syllable decision making not described in sufficient detail