Timing and location of speech errors induced by direct cortical stimulation

Area of Science:

• Neuroscience
• Neurosurgery
• Speech Production

Background:

• Direct electrocortical stimulation is the gold standard for mapping eloquent cortical regions during neurosurgery.
• Current methods lack specificity regarding the cognitive processes interrupted by stimulation.
• Understanding temporal dynamics of speech arrest can differentiate between speech planning and motor execution.

Approach:

• Retrospective observational study of 20 epilepsy patients undergoing intracranial EEG monitoring.
• Quantified latency between stimulation onset and speech arrest onset during an automatic speech task.
• Analyzed speech arrest latencies across peri-sylvian cortices to infer region-specific functional roles.

Key Points:

• Speech arrest latencies varied significantly across cortical regions.
• Shorter latencies in supramarginal gyrus and superior temporal gyrus suggest interference with motor execution.
• Longer latencies in inferior frontal gyrus and ventral sensorimotor cortex indicate disruption of higher-level speech planning processes.

Conclusions:

• Distinct temporal dynamics of speech arrest differentiate speech planning from motor execution.
• Inferior frontal gyrus and ventral sensorimotor cortex are implicated in speech planning.
• This latency mapping approach enhances understanding of speech production circuitry for neurosurgical guidance.