Archives of Physical Medicine and Rehabilitation
Special communicationNeurobiology of Language Recovery After Stroke: Lessons From Neuroimaging Studies
Section snippets
Imaging Language Networks in the Healthy Brain
A profound understanding of language organization in the healthy human brain is mandatory for the interpretation of activation changes due to reorganizational mechanisms in patients with brain damage. While early models of language organization were solely based on behavioral deficits in patients with brain lesions (eg, Broca2 and Wernicke3, see Shalom and Poeppel 4 for a review), a new decade of studies on language organization in the human brain has started with the advent of modern
Voxel-Based Lesion Studies of Language
Since the days of Broca and Wernicke in the second half of the 19th century, research aims at defining functional-anatomic models of language organization in the human brain. While the modularity assumption (ie, discrete anatomical modules deal with different cognitive functions) of the classical lesion-deficit approach has frequently been criticized (eg,21, 22 for reviews), the recent advent of new techniques offers a complementary approach to the use of imaging studies in healthy volunteers.
Dynamics of Language Reorganization in 3 Phases
In a behavioral study, Pedersen et al37 tested 330 patients with acute aphasia at admission as well as weekly during the hospitalization period (6–12wk poststroke) and 6 months after stroke. The authors found that the highest dynamic of language recovery can be observed in the first 2 weeks after onset, while in the later course, recovery proceeded more prolonged. These different dynamics of functional improvement suggest that different mechanisms contribute to language recovery after stroke.
Imaging Treatment-Induced Plasticity
The results of the longitudinal fMRI study on language recovery from Saur et al43 implicated that aphasic patients may be able to resort to normative learning mechanisms in the chronic phase after stroke. Consequently, it can be assumed that model-based therapeutic strategies may be best applied in the chronic phase.
Overall, it has been demonstrated that the efficacy of language therapy depends on treatment intensity. Various studies showed that high-intensive short-term interventions can
Future Directions
Within the last years, the use of functional imaging techniques has substantially increased our knowledge about brain organization, loss of functions after brain damage, and reorganizational processes. It should be noted, however, that the results from functional imaging studies are correlative in nature and do not allow for any causal conclusions. Thus, the use of a multimodal approach combining different methods, such as functional and/or structural imaging with transcranial stimulation
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Cited by (100)
Efficacy of repetitive transcranial magnetic stimulation in treating stroke aphasia: Systematic review and meta-analysis
2022, Clinical NeurophysiologyCitation Excerpt :Although these findings are encouraging, the results are inconsistent and highly variable across individuals. These data suggest that multiple and overlapping mechanisms of neuroplasticity may underlie stroke recovery and that different individuals may benefit from different rTMS approaches (Hartwigsen and Saur, 2019; Saur and Hartwigsen, 2012). Accordingly, previous research identified several clinical factors that influence stroke recovery, including lesion size, location, time post stroke, and aphasia symptoms (Jarso et al., 2013; Saur et al., 2006).
How does hemispheric specialization contribute to human-defining cognition?
2021, NeuronCitation Excerpt :We propose that functional specialization within each hemisphere and functional competition between both hemispheres shapes compensation when recovering from brain damage. Following tissue damage to the language network in the left hemisphere, recruitment of ipsilesional regions is usually associated with better recovery of function than recruitment of homologous regions in the right hemisphere (Winhuisen et al., 2005; see also Hartwigsen and Saur, 2019; and Saur and Hartwigsen, 2012, for review). The role of the non-dominant hemisphere in stroke recovery remains debated (e.g., Hartwigsen and Volz, 2021; Turkeltaub et al., 2011; Volz and Grefkes, 2016).
Are transcranial brain stimulation effects long-lasting in post-stroke aphasia? A comparative systematic review and meta-analysis on naming performance
2019, Neuroscience and Biobehavioral Reviews
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