Aphasia Neuroplasticity Review

Specht et al. (2009)

Reference

AuthorsSpecht K, Zahn R, Willmes K, Weis S, Holtel C, Krause BJ, Herzog H, Huber W
TitleJoint independent component analysis of structural and functional images reveals complex patterns of functional reorganisation in stroke aphasia
ReferenceNeuroImage 2009; 47: 2057-2063
PMID19524049
DOI10.1016/j.neuroimage.2009.06.011

Participants

LanguageGerman
Inclusion criteria
Number of individuals with aphasia12
Number of control participants12
Were any of the participants included in any previous studies?No
Is age reported for patients and controls, and matched?No (mean 49 + 14 years, range 30-71 years; controls were younger)
Is sex reported for patients and controls, and matched?Yes (males: 9; females: 3)
Is handedness reported for patients and controls, and matched?No
Is time post stroke onset reported and appropriate to the study design?No (mean 1.9 ± 1.4 years, range 0.2-3.7 years; one non-chronic patient is included)
To what extent is the nature of aphasia characterized?Comprehensive battery
Language evaluationAAT
Aphasia severityNot stated
Aphasia type3 global, 3 Wernicke's, 2 amnestic, 2 Broca's, 2 unclassified
First stroke only?Not stated
Stroke typeNot stated
To what extent is the lesion distribution characterized?Lesion overlay
Lesion extentNot stated
Lesion locationL MCA, with greatest overlap in the posterior STG
Participants notes15 controls were scanned but 3 were randomly excluded to match group sizes for jICA.

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 (CTI-Siemens HR+)
Is the timing of stimulus presentation and image acquisition clearly described and appropriate?Yes
Design typePET
Total images acquired9
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?
lexical decision (words vs pseudowords)Button press3YesYes
lexical decision (words vs reversed foreign words)Button press3YesYes
tone decisionButton press3YesYes
Conditions notesBehavioral data was lost, but it is clearly stated that all participants could perform all tasks above chance; the tone decision task is not described in sufficient detail, but since it is not used in any contrast of interest, the conditions are coded as being clearly described

Contrasts

Are the contrasts clearly described?Yes

Contrast 1: lexical decision (words vs pseudowords) vs lexical decision (words vs reversed foreign words)

Language conditionLexical decision (words vs pseudowords)
Control conditionLexical decision (words vs reversed foreign words)
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?Unknown, not reported
Is reaction time matched between the language and control tasks for all relevant groups?Unknown, not reported
Behavioral data notes
Are control data reported in this paper or another that is referenced?Yes
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 contrast activated a ventral part of the L IFG, along with L anterior cingulate and L DLPFC
Contrast notes

Analyses

Are the analyses clearly described?Yes

Voxelwise analysis 1

First level contrastLexical decision (words vs pseudowords) vs lexical decision (words vs reversed foreign words)
Analysis classCross-sectional aphasia vs control
Group(s)Aphasia vs control
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?Unknown, not reported
Is reaction time matched across the second level contrast?Unknown, not reported
Behavioral data notes
Type of analysisVoxelwise
Search volumeWhole brain
Correction for multiple comparisonsClusterwise correction based on arbitrary cluster extent
SoftwareSPM5
Voxelwise p.001
Cluster extent0.64 cc
Statistical details
Findings↑ R posterior STG
↑ R Heschl's gyrus
Findings notesActivation is 1105 voxels (> 8 cc) so quite convincing, but when the contrast was examined in the patient group, this region was not activated.

Complex analysis 1

First level contrastLexical decision (words vs pseudowords) vs lexical decision (words vs reversed foreign words)
Analysis classCross-sectional aphasia vs control
Group(s)Aphasia vs control
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?Unknown, not reported
Is reaction time matched across the second level contrast?Unknown, not reported
Behavioral data notes
Type of analysisComplex
Statistical detailsJoint ICA was performed on structural and functional contrast images using FIT 1.1b. Only 1 of the 8 components differed between groups in its loadings and was interpretable. The structural part of this component related to the patients' lesions. The functional part was thresholded at voxelwise p < .001 (CDT), arbitrary minimum cluster extent = 0.64 cc.
FindingsOther
Findings notesThe component that differed between groups showed more activation for patients than controls in the L anterior temporal lobe, L cerebellum, R posterior STG, R anterior temporal lobe, R posterior inferior temporal gyrus/fusiform gyrus, R cerebellum, and R brainstem, and less activation in patients than controls in the L IFG, L anterior temporal lobe, L occipital lobe, L anterior cingulate, L cerebellum, L thalamus, and R IFG.

Notes

Excluded analyses