Aphasia Neuroplasticity Review

Connor et al. (2006)

Reference

AuthorsConnor LT, DeShazo Braby T, Snyder AZ, Lewis C, Blasi V, Corbetta M
TitleCerebellar activity switches hemispheres with cerebral recovery in aphasia
ReferenceNeuropsychologia 2006; 44: 171-177
PMID16019040
DOI10.1016/j.neuropsychologia.2005.05.019

Participants

LanguageUS English
Inclusion criteriaL IFG, possibly extending to neighboring regions
Number of individuals with aphasia8
Number of control participants14
Were any of the participants included in any previous studies?Yes (re-analysis of data from Blasi et al. (2002))
Is age reported for patients and controls, and matched?No (mean 48.6 years; patients and controls not closely matched for age, unclear if difference significant)
Is sex reported for patients and controls, and matched?Yes (males: 2; females: 6)
Is handedness reported for patients and controls, and matched?Yes (right: 8; left: 0)
Is time post stroke onset reported and appropriate to the study design?No (> 6 months; actual TPO not stated)
To what extent is the nature of aphasia characterized?Comprehensive battery
Language evaluationWAB or BDAE
Aphasia severityAQ range 66.5-89.0 in 6 participants, BDAE aphasia severity of 4 in 1 participant, no formal evaluation in 1 participant
Aphasia type3 anomic, 3 transcortical motor, 1 Broca's, 1 not stated; most were Broca's or global acutely
First stroke only?Yes
Stroke typeIschemic only
To what extent is the lesion distribution characterized?Individual lesions
Lesion extentNot stated
Lesion locationL IFG and operculum, extending to adjacent cortex and white matter in several cases
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 (Siemens Vision 1.5 Tesla)
Is the timing of stimulus presentation and image acquisition clearly described and appropriate?Yes
Design typeEvent-related
Total images acquired1024
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?
word stem completion (novel items)Word (covert)196YesUnknown
word stem completion (repeated items)Word (covert)196YesUnknown
restNoneimplicit baselineN/AN/A
Conditions notesNovel items were presented in runs 1, 6, 7, and 8; repeated items were presented in runs 2, 3, 4, and 5; of the four repeated runs, only run 5 was analyzed.

Contrasts

Are the contrasts clearly described?Yes

Contrast 1: word stem completion (novel items) vs word stem completion (repeated items)

Language conditionWord stem completion (novel items)
Control conditionWord stem completion (repeated items)
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?Yes, matched
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?Unknown
Are activations lateralized in the control data?Somewhat
Control activation notesNo whole brain analysis of this contrast, but somewhat lateralized in the sense that L but not R frontal areas showed a learning effect
Contrast notesThe only contrast analyzed in this paper is the "learning" contrast which corresponds to contrast 2 in Blasi et al. (2002)

Analyses

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

Voxelwise analysis 1

First level contrastWord stem completion (novel items) vs word stem completion (repeated items)
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?Yes, matched
Is reaction time matched across the second level contrast?Yes, matched
Behavioral data notesCovert task but overt data acquired separately; no interaction of group by practice for accuracy or RT
Type of analysisVoxelwise
Search volumeCerebellum
Correction for multiple comparisonsNo direct comparison
Softwarenot stated
Voxelwise p
Cluster extent
Statistical detailsQualitative comparison on p. 174; Monte Carlo-based thresholding not described; rather than fitting a HRF, the authors looked at the shape of the signal in the 8 volumes following each stimulus
Findings↑ L cerebellum
↓ R cerebellum
Findings notes

ROI analysis 1

First level contrastWord stem completion (novel items) vs word stem completion (repeated items)
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?Yes, matched
Is reaction time matched across the second level contrast?Yes, matched
Behavioral data notesCovert task but overt data acquired separately; no interaction of group by practice for accuracy or RT
Type of analysisRegion of interest (ROI)
ROI typeFunctional
How many ROIs are there?1
What are the ROI(s)?L cerebellum
How are the ROI(s) defined?L cerebellar region with a learning effect in the patients
Correction for multiple comparisonsOne only
Statistical detailsCircular because ROIs defined in one group; rather than fitting a HRF, the authors looked at the shape of the signal in the 8 volumes following each stimulus
Findings↑ L cerebellum
Findings notes

Notes

Excluded analyses(1) analysis of frontal changes is excluded since it appears to be identical to Blasi et al. (2002); (2) the analyses involving mirrored cerebellar regions are excluded since the groups were not compared directly