New insights into the neural network mediating reading processes provided by cortico-subcortical electrical mapping

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neurolinguistics

Background:

• Reading is a complex cognitive function relying on intricate neural networks.
• Understanding the precise brain regions and pathways involved in reading is crucial for diagnosing and treating reading impairments.

Purpose of the Study:

• To elucidate the neural underpinnings of reading by employing intraoperative electrostimulation.
• To map the functional connectivity of reading processes within the human brain.

Main Methods:

• Intraoperative electrical mapping of reading processes in seven patients undergoing awake surgery for left occipitotemporal gliomas.
• Integration of diffusion tensor imaging (DTI)-based white matter atlases with surgical resection cavity data.
• Correlation of resection site location with observed reading impairments (regular, irregular, pseudowords).

Main Results:

• Stimulation of the left posterior inferior temporal cortex (ITCp) and anterior visual word form area (VWFA) induced reading disturbances.
• Disruption of the VWFA-arcuate fascicle (AFp) connection impaired phonological processing for irregular and pseudowords.
• Resection of the posterior inferior longitudinal fascicle (ILFp) led to long-term global reading deficits, highlighting its role in visual input to the VWFA.

Conclusions:

• The visual word form area (VWFA) exhibits a posterior-to-anterior hierarchical coding of letter strings.
• The left inferior longitudinal fascicle (ILFp) is essential for transmitting visual information to the VWFA.
• The arcuate fascicle posterior (AFp) appears to mediate an interactive feedback system for processing complex word types.