ASL MRI informs blood flow to chronic stroke lesions in patients with aphasia

Introduction: Response to post-stroke aphasia language rehabilitation is difficult to anticipate, mainly because few predictors can help identify optimal, individualized treatment options. Imaging techniques, such as Voxel-based Lesion Symptom Mapping have been useful in linking specific brain areas to language behavior; however, further development is required to optimize the use of structural and physiological information in guiding individualized treatment for persons with aphasia (PWA). In this study, we will determine if cerebral blood flow (CBF) mapped in patients with chronic strokes can be further used to understand stroke-related factors and behavior.Methods: We collected perfusion MRI data using pseudo-Continuous Arterial Spin Labeling (pCASL) using a single post-labeling delay of 2,200 ms in 14 chronic PWA, along with high-resolution structural MRI to compute maps of tissue damage using Tissue Integrity Gradation via T2w T1w Ratio (TIGR). To quantify the CBF in chronic stroke lesions, we tested at what point spatial smoothing should be applied in the ASL analysis pipeline. We then related CBF to tissue damage, time since stroke, age, sex, and their respective cross-terms to further understand the variability in lesion CBF. Finally, we assessed the feasibility of computing multivariate brain-behavior maps using CBF and compared them to brain-behavior maps extracted with TIGR MRI.Results: We found that the CBF in chronic stroke lesions is significantly reduced compared to its homologue grey and white matter regions. However, a reliable CBF signal (although smaller than expected) was detected to reveal a negative relationship between CBF and increasing tissue damage. Further, the relationship between the lesion CBF and age, sex, time since stroke, and tissue damage and cross-terms suggested an aging-by-disease interaction. This relationship was strongest when smoothing was applied in the template space. Finally, we show that whole-brain CBF relates to domain-general visuospatial functioning in PWA. The CBF-based brain-behavior maps provide unique and complementary information to structural (lesion-based) brain-behavior maps.Discussion: Therefore, CBF can be detected in chronic stroke lesions using a standard pCASL MRI acquisition and is informative at the whole-brain level in identifying stroke rehabilitation targets in PWAs due to its relationship with demographic factors, stroke-related factors, and behavior

Relationships Between Ambiguity Tolerance and Well-Structured vs. Ill-Structured Problems

Problem Solving can be divided between two types of tasks: well-structured problems and ill-structured problems (Collins, Gookin, & Sibthorp, 2016). Well-structured problems (WSP) typically offer one solution or one pathway to the solution as well as clear rules and constraints that lead to the correct answer (e.g. simple math problems). Ill-structured problems (ISP) are lacking in one or more of these conditions. Given the differences between ISP and WSP, this study examined potential relationships between individuals\u27 experiences when solving both types of problems and their general ambiguity tolerance. A person with a high tolerance for ambiguity is comfortable with uncertainty (McLain, 2009). On the contrary, those with a low tolerance for ambiguity are more likely to perceive ambiguous situations as threatening and are therefore less likely to be confident in negotiating such tasks. To examine the relations between ambiguity tolerance and individuals’ experiences while solving both ISP and WSP, participants completed various tangram puzzles in this quasi-experimental mixed research design. Participants reflected on their stress (Spielberger\u27s State-Trait Anxiety Inventory) and enjoyment ( I would enjoy solving problems like this in the future. ) immediately after completing each problem solving task. Participants also reported their general levels of ambiguity tolerance (Multiple Stimulus Types Ambiguity Tolerance Scale-II) and their general problem solving confidence (Problem Solving Confidence Questionnaire) at the end of the session. Participants with high ambiguity tolerance experienced lower anxiety than those with low ambiguity tolerance while completing both the ISP and WSP. However, those with higher ambiguity tolerance only feel significantly greater enjoyment when completing the ISP. Finally, we discovered that overall problem solving confidence mediates the relationship between ambiguity tolerance and anxiety during the WSP