Language function in the brain, once thought to be highly localized, is now appreciated as relying on a connected but distributed network. The semantic system is of particular interest in the language domain because of its hypothesized integration of information across multiple cortical regions. Previous work in healthy individuals has focused on group-level functional connectivity (FC) analyses of the semantic system, which may obscure interindividual differences driving variance in performance. These studies also overlook the contributions of white matter networks to semantic function. Here, we identified semantic network nodes with a semantic decision fMRI task in 53 typically-aging adults, characterized network organization using structural connectivity (SC), and quantified the segregation and integration of the network using FC. Hub regions were identified in left inferior frontal gyrus. The individualized semantic network was composed of three interacting modules: 1) default-mode module characterized by bilateral medial prefrontal and posterior cingulate regions and also including right-hemisphere homotopes of language regions; 2) left frontal module extending dorsally from inferior frontal gyrus to pre-motor area; and 3) left temporoparietal module extending from temporal pole to inferior parietal lobule. FC within Module3 and integration of the entire network related to a semantic verbal fluency task, but not a matched phonological task. These results support and extend the tri-network semantic model (Xu et al., 2017) and the controlled semantic cognition model (Chiou et al., 2018) of semantic function..

Background and ObjectivesA prominent theory proposes that neuroplastic recruitment of perilesional tissue supports aphasia recovery, especially when language-capable cortex is spared by smaller lesions. This theory has rarely been tested directly, and findings have been inconclusive. Here, we test the perilesional plasticity hypothesis using two fMRI tasks in two groups of patients with prior aphasia diagnosis.MethodsTwo cohorts totaling 82 chronic left-hemisphere stroke patients with prior aphasia diagnosis, and 82 control participants underwent fMRI using either a naming task or a reliable semantic decision task. Individualized perilesional tissue was defined by dilating anatomical lesions, and language regions were defined using meta-analyses. Mixed modeling examined differences in activity between groups. Relationships with lesion size and aphasia severity were examined.ResultsPatients exhibited reduced activity in perilesional language tissue relative to controls in both tasks. Although a few cortical regions exhibited greater activity irrespective of distance from the lesion, or only when distant from the lesion, no regions exhibited increased activity only when near the lesion. Larger lesions were associated with reduced language activity irrespective of distance from the lesion. Using the reliable fMRI task, reduced language activity related to aphasia severity independent of lesion size.DiscussionWe find no evidence for neuroplastic recruitment of perilesional tissue in aphasia beyond its typical role in language. Rather, our findings are consistent with alternative hypotheses that changes in left-hemisphere activation during recovery relate to normalization of language network dysfunction and possibly recruitment of alternate cortical processors. These findings clarify left-hemisphere neuroplastic mechanisms supporting language recovery after stroke.

Group treatment is an integral part of speech-language pathology (SLP) practice. The majority of SLP literature concerns group treatment provided in outpatient settings. This article describes the goals, procedures, and benefits of providing quality SLP group therapy in the comprehensive inpatient rehabilitation (CIR) setting. Effective CIR groups must be designed with attention to type and severity of communication impairment, as well physical stamina of group members. Group leaders need to target individualized patient goals while creating a challenging, complex, and dynamic group context that supports participation by all group members. Direct patient-to-patient interaction is fostered as much as possible. Peer feedback supports goal acquisition by fellow group members. The rich, complex group context fosters improved insight, initiation, social connectedness, and generalization of communication skills. Group treatment provides a unique type of treatment not easily replicated with individual treatment. SLP group treatment in a CIR is an essential component of an intensive, high-quality program. Continued advocacy for group therapy provision and research into its efficacy and effectiveness are warranted.