Relating resting-state hemodynamic changes to the variable language profiles in post-stroke aphasia

Abstract

Linking both structural lesions and the functional integrity of remaining brain tissue to patients' behavioural profile may be critical in discovering the limits of behavioural recovery post stroke. In the present study, we explored the relationship between temporal hemodynamic changes and language performance in chronic post-stroke aphasia. We collected detailed language and neuropsychological data for 66 patients with chronic (>1 year) post-stroke aphasia. We used principal component analysis to extract their core language-neuropsychological features. From resting-state fMRI scans in 35 patients, we calculated the lag in the time-course of the intact brain voxels in each patient. Finally, variation across the language-cognitive factors was related to both the patients' structural damage and the time-course changes in each patient's intact tissue. Phonological abilities were correlated with the structural integrity of the left superior temporal, angular gyrus, supramarginal gyrus and arcuate fasciculus regions and hemodynamic advance in the left intra-parietal sulcus. Speech fluency related to integrity of premotor regions, plus hemodynamic advance in the left middle/superior temporal gyrus, left middle occipital gyrus, and right angular gyrus. Semantic performance reflected a combination of medial ventral temporal lobe status and hemodynamic delay in the left posterior middle temporal gyrus. Finally, executive abilities correlated with hemodynamic delay in the left middle/inferior frontal gyrus, right rolandic operculum, bilateral supplementary motor areas/middle cingulum areas, and bilateral thalamus/caudate. Following stroke, patients' patterns of chronic language abilities reflects a combination of structural and functional integrity across a distributed network of brain regions. The correlation between hemodynamic changes and behaviours may have clinical importance.

Functional anomaly mapping reveals local and distant dysfunction caused by brain lesions

“…But signal elsewhere could reflect any difference in the patient relative to the control group. These differences could arise from negative biological effects of the stroke on surviving tissue, such as diaschisis (i.e., distant dysfunction due to network level disruption) (Carrera and Tononi, 2014;Feeney and Baron, 1986;von Monakow, 1914), hemodynamic differences (Bonakdarpour et al, 2007;Siegel et al, 2016;Zhao et al, 2018), maladaptive disinhibition (Allred et al, 2010;Ferbert et al, 1992;Johansen-Berg et al, 2002;Letzkus et al, 2015), or atrophy due to deafferentation of cell bodies in otherwise spared regions of the brain (Bonilha and Fridriksson, 2009;Bonilha et al, 2014). Other differences in anatomically intact brain regions could reflect negative behavioral consequences of stroke, such as learned disuse (Levin et al, 2009;Taub et al, 2006), or maladaptive behavioral compensation (Levin et al, 2009;Takeuchi and Izumi, 2012).…”

“…A number of studies have also used task-based fMRI to demonstrate functional disturbances distant from the lesion (Corbetta et al, 2005;Saur et al, 2006;Ward et al, 2003), but such task-based approaches are limited because they only measure dysfunctional neural processes associated with one specific experimental paradigm (Carter et al, 2012). More recent work has relied on resting state fMRI connectivity (Boes et al, 2015;He et al, 2007;Nair et al, 2015;Park et al, 2011;Yourganov et al, 2018), or hemodynamic lag at rest (Zhao, Lambon Ralph, & Halai, 2018) to examine remote effects of lesions, but these approaches have not yielded maps of brain-wide functional integrity in individual patients.…”

Cerebral perfusion of the left reading network predicts recovery of reading in subacute to chronic stroke

“…Future studies may be able to shed light on the role of such areas in recovery using voxelwise (Zhao, Lambon Ralph, & Halai, 2018), or region of interest analyses. Future studies may be able to shed light on the role of such areas in recovery using voxelwise (Zhao, Lambon Ralph, & Halai, 2018), or region of interest analyses.…”

“…Likewise, although we compared global perfusion differences between the right and the left hemispheres, we did not consider the contribution of specific brain areas outside of the reading network to behavioral recovery. Future studies may be able to shed light on the role of such areas in recovery using voxelwise (Zhao, Lambon Ralph, & Halai, 2018), or region of interest analyses. Although we followed the current recommendations for pulsed ASL implementation in clinical patients (Alsop et al, 2015), we may not have captured hypoperfusion present at long delay intervals due to the limited window provided by the pulsed ASL technique.…”

Auditory beat perception is related to speech output fluency in post-stroke aphasia

“…Individuals with PSA were at least one year post left hemispheric stroke (either ischaemic or haemorrhagic), pre-morbidly right-handed and part of a larger cohort of 76 stroke survivors recruited from community groups throughout the North West of England for whom extensive neuropsychological and imaging data was available. A number of the participants with PSA have been included in previous publications (Halai et al, 2017;Zhao et al, 2018). Controls were recruited from the volunteer panel of the MRC Cognition and Brain Sciences Unit, were right handed and had no history of neurological injury.…”