Common and unique structural plasticity after left and right hemisphere stroke

Strokes to the left and right hemisphere lead to distinctive behavioral profiles. Are left and right hemisphere strokes (LHS and RHS) associated with distinct or common poststroke neuroplasticity patterns? Understanding this issue would reveal hemispheric neuroplasticity mechanisms in response to brain damage. To this end, we investigated poststroke structural changes (2 weeks to 3 months post-onset) using longitudinal MRI data from 69 LHS and 55 RHS patients and 31 demographic-matched healthy control participants. Both LHS and RHS groups showed statistically common plasticity independent of the lesioned hemisphere, including 1) gray matter (GM) expansion in the ipsilesional and contralesional precuneus, and contralesional superior frontal gyrus; 2) GM shrinkage in the ipsilesional medial orbital frontal gyrus and middle cingulate cortex. On the other hand, only RHS patients had significant GM expansion in the ipsilesional medial superior and orbital frontal cortex. Importantly, these common and unique GM changes post-stroke largely overlapped with highly-connected cortical hub regions in healthy individuals. Moreover, they correlated with behavioral recovery, indicating that post-stroke GM volumetric changes in cortical hubs reflect compensatory rather than maladaptive mechanisms. These results highlight the importance of structural neuroplasticity in hub regions of the cortex, along with the hemispheric specificity, for stroke recovery.

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Dorsolateral and ventrolateral prefrontal cortex structural changes relative to suicidal ideation in patients with depression

Acta Neuropsychiatrica ◽

10.1017/neu.2019.45 ◽

2020 ◽

Vol 32 (2) ◽

pp. 84-91

Author(s):

Ran Zhang ◽

Shengnan Wei ◽

Miao Chang ◽

Xiaowei Jiang ◽

Yanqing Tang ◽

...

Keyword(s):

Prefrontal Cortex ◽

Suicidal Ideation ◽

Structural Changes ◽

Gray Matter Volume ◽

Major Depressive ◽

Left Dlpfc ◽

Healthy Control ◽

Left And Right ◽

And Gender ◽

The Right

AbstractThe prefrontal cortex (PFC) is enormously important in suicide and major depressive disorder (MDD). However, little is known about the structural alterations in the brains of people with MDD and suicidal ideation. We examined the gray matter volume (GMV) of the PFC of individuals with MDD and suicidal ideation to determine if PFC volumetric differences contribute to suicidal ideation in patients with MDD. Thirty-five subjects with MDD and suicidal ideation, 38 subjects with MDD but without suicidal ideation, and 43 age- and gender-matched healthy control (HC) subjects underwent T1-weighted imaging. A voxel-based morphometric analysis was conducted to compare the PFC GMVs of the three groups. Further GMV reductions in the left and right dorsolateral PFC (DLPFC) and right ventrolateral PFC (VLPFC) were detected in the MDD with suicidal ideation group compared with those in the HC group and the MDD without suicidal ideation group, whereas the MDD without suicidal ideation group only exhibited significant differences in the left DLPFC relative to the HC group. Our findings demonstrated that left DLPFC reductions were associated with MDD and suicidal ideation, and diminished GMV reductions in the right DLPFC and right VLPFC were only associated with suicidal ideation. These results help us better understand the neuropathological changes in MDD with suicidal ideation.

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A transcallosal fiber system between homotopic inferior frontal regions supports complex linguistic processing

10.1101/079244 ◽

2016 ◽

Author(s):

Philipp Kellmeyer ◽

Magnus-Sebastian Vry ◽

Tonio Ball

Keyword(s):

Right Hemisphere ◽

Diffusion Tensor ◽

The Body ◽

Canonical Model ◽

Stroke Recovery ◽

Linguistic Processing ◽

Fiber System ◽

Affective Prosody ◽

Left And Right ◽

The Right

AbstractInferior frontal regions in the left and right hemisphere support different aspects of language processing. In the canonical model, left inferior frontal regions are mostly involved in processing based on phonological, syntactic and semantic features of language, whereas the right inferior frontal regions process paralinguistic aspects like affective prosody.Using diffusion tensor imaging (DTI) based probabilistic fiber tracking in 20 healthy volunteers, we identify a callosal fiber system connecting left and right inferior frontal regions that are involved in linguistic processing of varying complexity. Anatomically, we show that the interhemispheric fibers are highly aligned and distributed along a rostral to caudal gradient in the body and genu of the corpus callosum to connect homotopic inferior frontal regions.In light of converging data, taking previous DTI-based tracking studies and clinical case studies into account, our findings suggest that the right inferior frontal cortex not only processes paralinguistic aspects of language (such as affective prosody), as purported by the canonical model, but also supports the computation of linguistic aspects of varying complexity in the human brain. Our model may explain patterns of right hemispheric contribution to stroke recovery as well as disorders of prosodic processing. Beyond language-related brain function, we discuss how interspecies differences in interhemispheric connectivity and fiber density, including the system we described here, may also explain differences in transcallosal information transfer and cognitive abilities across different mammalian species.

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Abstract 177: Brain-Wide Circuit Dynamics of Post-Stroke Recovery After Optogenetic Stimulation

Stroke ◽

10.1161/str.51.suppl_1.177 ◽

2020 ◽

Vol 51 (Suppl_1) ◽

Author(s):

Michelle Y Cheng ◽

Shahabeddin Vahdat ◽

Arjun V Pendharkar ◽

Sean Harvey ◽

Terrance Chiang ◽

...

Keyword(s):

Artery Occlusion ◽

Stroke Recovery ◽

Behavioral Recovery ◽

Post Stroke ◽

Optogenetic Stimulation ◽

Thalamic Projections ◽

Group 5 ◽

Layer V ◽

Cerebral Artery Occlusion ◽

Magnetic Response Imaging

Background: Post-stroke optogenetic stimulations have been shown to promote functional recovery. However, the cellular and circuit mechanisms underlying such recovery remain unclear. Elucidating key neural circuits in post-stroke recovery will be invaluable for translation of neuromodulation for stroke. Here we used optogenetic functional magnetic response imaging (ofMRI) to examine brain-wide circuit dynamics induced by optogenetic stimulation treatment (OST). Method: Male mice expressing channelrhodopsin (ChR2) in ipsilesional M1 (iM1) layer V excitatory neurons were used. ofMRI were performed on pre-stroke and post-stroke days (PD) 3, 15 and 29. OST were given daily from PD5-15. Sensorimotor tests were conducted one day prior to each ofMRI session. Mice underwent transient middle cerebral artery occlusion (intraluminal suture model, 30 minutes). Two groups were assigned: stim group (mice with 10 days of OST, n=9) and no stim group (mice without OST, n=9). Activation maps were compared between stim and no stim groups to reveal key brain circuits recovered by OST. The expression of plasticity marker GAP43 was examined using western blot. Result: Our results show that 1) Optogenetic excitatory neuronal stimulations in iM1 promotes motor function at PD 14 (P<0.01). 2) At pre-stroke, iM1 stimulations activate expected network including ipsilesional M1, M2, S1, striatum, thalamus, contralateral M1 and cerebellum. 3) At PD3, all mice exhibit a depressed response throughout the brain. 4) At PD15, ipsilesional thalamus and S1 circuits are significantly recovered by OST. Moreover, restoration of thalamic activation is correlated with behavioral recovery in the stim group. 5) At PD15, stimulated mice exhibited higher level of plasticity marker (GAP43) in the ipsilesional thalamus (P<0.05). 6) At PD29, iS1 activation remains stronger in the stim group when compared to no stim group. Conclusion: Our findings revealed key circuits underlying stimulation-induced post-stroke recovery. We found that restoration of cortico-thalamic projections is important in stimulation-induced recovery at early phase post-stroke, while sustained strengthening of ipsilesional cortico-cortical connections may be critical in the later phase of recovery.

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Perceived stress and depression in left and right hemisphere post-stroke patients

Neuropsychological Rehabilitation ◽

10.1080/09602011.2013.811087 ◽

2013 ◽

Vol 23 (6) ◽

pp. 783-797 ◽

Cited By ~ 14

Author(s):

Jacqueline S. Laures-Gore ◽

Lauren C. DeFife

Keyword(s):

Perceived Stress ◽

Right Hemisphere ◽

Stroke Patients ◽

Post Stroke ◽

Left And Right

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Human CA1 and subiculum activity forecast stroke chronicity

10.1101/2020.01.19.20017996 ◽

2020 ◽

Author(s):

Diogo Santos-Pata ◽

Belén Rubio Ballester ◽

Riccardo Zucca ◽

Carlos Alberto Stefano Filho ◽

Sara Regina Almeida ◽

...

Keyword(s):

Structural Damage ◽

Structural Changes ◽

Brain Activity ◽

Stroke Recovery ◽

Whole Brain ◽

Neuronal Reorganization ◽

Left And Right ◽

The Brain ◽

Activity Forecast ◽

Shed Light

ABSTRACTFollowing a stroke, the brain undergoes a process of neuronal reorganization to compensate for structural damage and cope with functionality loss. Increases in stroke-induced neurogenesis rates in the dentate gyrus and neural migration from the hippocampus towards the affected site have been observed, suggesting that the hippocampus is involved in functionality gains and neural reorganization. Despite the observed hippocampal contributions to structural changes, the hippocampal physiology for stroke recovery has been poorly characterized. To this end, we measured resting-state whole-brain activity from non-hippocampal stroke survivors (n=13) during functional MRI scanning. Analysis of multiple hippocampal subregions revealed that the voxel activity of hippocampal readout sites (CA1 and subiculum) forecast the patient’s chronicity stage stronger than early regions of the hippocampal circuit. Furthermore, we observed hemispheric-specific contributions to chronicity forecasting, raising the hypothesis that left and right hippocampus are functionally dissociable during recovery. In addition, we suggest that in contrast with whole-brain analysis, the monitoring of segregated and specialized sub-networks after stroke potentially reveals detailed aspects of stroke recovery. Altogether, our results shed light on the contribution of the subcortical-cortical interplay for neural reorganization and highlight new avenues for stroke rehabilitation.

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Production of Korean Idiomatic Utterances Following Left- and Right-Hemisphere Damage: Acoustic Studies

Journal of Speech Language and Hearing Research ◽

10.1044/2015_jslhr-l-15-0109 ◽

2016 ◽

Vol 59 (2) ◽

pp. 267-280 ◽

Cited By ~ 8

Author(s):

Seung-yun Yang ◽

Diana Van Lancker Sidtis

Keyword(s):

Right Hemisphere ◽

Native Speakers ◽

Hemispheric Specialization ◽

Acoustic Measures ◽

Right Hemisphere Damage ◽

Task Effect ◽

Healthy Control ◽

Left And Right ◽

Acoustic Analyses ◽

Highly Correlated

Purpose This study investigates the effects of left- and right-hemisphere damage (LHD and RHD) on the production of idiomatic or literal expressions utilizing acoustic analyses. Method Twenty-one native speakers of Korean with LHD or RHD and in a healthy control (HC) group produced 6 ditropically ambiguous (idiomatic or literal) sentences in 2 different speech tasks: elicitation and repetition. Utterances were analyzed using durational and fundamental-frequency (F0) measures. Listeners' goodness ratings (how well each utterance represented its category: idiomatic or literal) were correlated with acoustic measures. Results During the elicitation tasks, the LHD group differed significantly from the HC group in durational measures. Significant differences between the RHD and HC groups were seen in F0 measures. However, for the repetition tasks, the LHD and RHD groups produced utterances comparable to the HC group's performance. Using regression analysis, selected F0 cues were found to be significant predictors for goodness ratings by listeners. Conclusions Using elicitation, speakers in the LHD group were deficient in producing durational cues, whereas RHD negatively affected the production of F0 cues. Performance differed for elicitation and repetition, indicating a task effect. Listeners' goodness ratings were highly correlated with the production of certain acoustic cues. Both the acoustic and functional hypotheses of hemispheric specialization were supported for idiom production.

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