Are networks for residual language function and recovery consistent across aphasic patients?

Area of Science:

• Neuroscience
• Neurology
• Speech and Language Pathology

Background:

• Aphasia, a language disorder following stroke, presents significant challenges for recovery.
• Understanding neuroplastic changes in aphasia is crucial for developing effective treatments.

Purpose of the Study:

• To meta-analyze functional neuroimaging studies on chronic aphasia to identify consistent patterns of brain activity.
• To determine if neuroplasticity in aphasia follows stereotyped mechanisms that could guide noninvasive brain stimulation.

Main Methods:

• A meta-analysis of 105 functional neuroimaging studies in chronic aphasia patients and 129 controls was conducted.
• Activation Likelihood Estimation (ALE) was used to identify consistent brain activation areas.
• Functional homology between patient and control networks was assessed under similar language tasks.

Main Results:

• Controls consistently activated left hemisphere language networks.
• Aphasic patients showed consistent activation in spared left hemisphere areas, new left hemisphere regions, and homologous right hemisphere areas.
• Right inferior frontal gyrus recruitment was more prominent in patients with left inferior frontal lesions.

Conclusions:

• The brain network recruited for language in aphasia is largely consistent across studies.
• Recovery involves persistent function, compensatory recruitment, and potentially maladaptive activation.
• Findings support the development of brain stimulation protocols tailored to common patient attributes.