Spatio-Temporal Progression of Cortical Activity Related to Continuous Overt and Covert Speech Production in a Reading Task.
Level 4 - case-series / case-control
Case-series / observational intracranial electrophysiology study in human subjects
PubMed 27875590 · doi:10.1371/journal.pone.0166872
What was done
Electrocorticography (ECoG) signals were recorded directly from the brain surface of human subjects during a reading task. Participants repeated continuous sentences aloud (overt speech) or silently (covert speech) while researchers mapped sub-second cortical population-level activity relative to speech output across multiple brain regions.
What was found
The abstract reports no numerical data, effect sizes, or statistical values. It describes a spatio-temporal sequence of cortical activation that initiates in frontal-motor areas and terminates with auditory feedback monitoring in the superior temporal gyrus. Direct comparison showed a shared network of brain regions active during both overt and covert speech conditions.
Why it matters
This work provides electrophysiological mapping of continuous, fluent speech at sub-second resolution and demonstrates that overt and covert speech rely on a shared cortical substrate.
Limits
The abstract omits the sample size, participant demographics, clinical indications for electrode placement, and all quantitative metrics. Coverage of brain regions via ECoG is inherently constrained by clinical necessity.
Cited by
- supports Expressing thoughts externally by writing them down or speaking them to another person engages distinct brain processes and error-checking mechanisms compared to internal thinking.