Aphasia Neuroplasticity Review

Zahn et al. (2004)

Reference

AuthorsZahn R, Drews E, Specht K, Kemeny S, Reith W, Willmes K, Schwarz M, Huber W
TitleRecovery of semantic word processing in global aphasia: a functional MRI study
ReferenceCogn Brain Res 2004; 18: 322-336
PMID14741318
DOI10.1016/j.cogbrainres.2003.10.021

Participants

LanguageGerman
Inclusion criteriaGlobal aphasia in the first three months; some improvement of comprehension within 6-12 months
Number of individuals with aphasia7
Number of control participants14
Were any of the participants included in any previous studies?No
Is age reported for patients and controls, and matched?Yes (range 29-67 years)
Is sex reported for patients and controls, and matched?Yes (males: 6; females: 1)
Is handedness reported for patients and controls, and matched?Yes (right: 7; left: 0)
Is time post stroke onset reported and appropriate to the study design?Yes (range 6 months-4 years)
To what extent is the nature of aphasia characterized?Comprehensive battery
Language evaluationAABT, AAT
Aphasia severityTT percentile range 28-63
Aphasia type3 global, 2 Broca's, 2 unclassifiable; all had been global initially
First stroke only?Yes
Stroke typeNot stated
To what extent is the lesion distribution characterized?Lesion overlay
Lesion extentNot stated
Lesion locationL MCA
Participants notes

Imaging

ModalityfMRI
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 (Philips ACS NT Gyroscan 1.5 Tesla)
Is the timing of stimulus presentation and image acquisition clearly described and appropriate?No* (moderate limitation) (insufficient blocks per experimental condition (3) because blocks were too long (44 s))
Design typeBlock
Total images acquired198
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?N/A—no intersubject normalization
Imaging notes

Conditions

Are the conditions clearly described?Yes
ConditionResponse typeRepetitionsAll groups could do?All individuals could do?
phonetic decision (reversed words vs sounds)Button press3YesNo
lexical decision (words vs reversed words)Button press3YesYes
semantic decisionButton press3YesNo
restNone9N/AN/A
Conditions notes

Contrasts

Are the contrasts clearly described?No (see specific limitation(s) below)

Contrast 1: semantic decision vs phonetic decision and lexical decision (conjunction)

Language conditionSemantic decision
Control conditionPhonetic decision and lexical decision (conjunction)
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?Appear similar
Is reaction time matched between the language and control tasks for all relevant groups?Unknown, not reported
Behavioral data notesTasks were matched in controls, but no statistics reported for patients
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?Yes
Are activations lateralized in the control data?Yes
Control activation notesL-lateralized frontal activation, as well as temporal and parietal to a lesser extent
Contrast notesConjunction of baseline conditions not described in sufficient detail

Analyses

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

ROI analysis 1

First level contrastSemantic decision vs phonetic decision and lexical decision (conjunction)
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, no test
Is reaction time matched across the second level contrast?Unknown, not reported
Behavioral data notesRelative performance on language and control tasks unclear
Type of analysisRegion of interest (ROI)
ROI typeLaterality indi(ces)
How many ROIs are there?1
What are the ROI(s)?Language network LI
How are the ROI(s) defined?
Correction for multiple comparisonsOne only
Statistical detailsConjunction analyses not clearly described; in two patients, a different conjunction was used (lexical decision vs phonetic decision & semantic decision vs phonetic decision)
FindingsNone
Findings notesLI > 0 in 12 out of 14 controls and 5 out of 7 patients; no significant difference

Notes

Excluded analysesIndividual patient analyses