Brain network topology influences response to intensive comprehensive aphasia treatment

Recent imaging studies indicate that aphasia is associated with large-scale reorganization of brain networks. Today, neuroimaging studies show that various brain connectivity properties, as measured by resting state fMRI, can partially explain different behavioral symptoms in and across various patient groups. Despite these observations, the neural networks underlying the progress and recovery of aphasia following intensive treatment remains relatively obscure.

To examine the role of brain network properties in determining recovery of aphasia following intensive therapy in stroke patients.

We studied eight patients with left hemispheric lesions who completed an intensive comprehensive aphasia program (ICAP). Language and cognition were assessed before and after four weeks of intensive treatment. In addition, all patients underwent resting state fMRI prior to and after treatment. We used graph theory analysis to evaluate relationships of baseline brain network properties, such as efficiency, modularity, and connectivity to clinical improvements.

We found global properties such as efficiency and interhemispheric connectivity could partially explain recovery. More importantly, we identified two unique brain networks that are significantly associated with improvement in language and attention related behavior.

These results suggest baseline brain functional properties play a key role in determining responsiveness of patients with aphasia to intensive comprehensive aphasia treatment. Furthermore, these results indicate that brain mechanisms underlying language comprehension and processes are different from those involved in spatial attention.