A corollary discharge circuit in human speech

Area of Science:

• Neuroscience
• Speech Motor Control
• Auditory Processing

Background:

• The brain differentiates self-generated from external sounds, a function supported by corollary discharge signals in animals.
• The precise origin and timing of corollary discharge in humans have remained largely unknown.
• Understanding this signal is crucial for speech production and auditory perception.

Purpose of the Study:

• To identify the neural source and temporal dynamics of the corollary discharge signal in humans during speech production.
• To investigate the relationship between corollary discharge and auditory cortex suppression.

Main Methods:

• Electrocorticographic (ECoG) recordings were obtained from neurosurgical patients during speech tasks.
• A connectivity analysis framework utilizing Granger causality was employed to map neural communications.
• Multiple speech production paradigms were used to ensure reproducibility.

Main Results:

• A reproducible source of corollary discharge was identified in the ventral speech motor cortex, preceding speech articulation.
• The strength of the corollary discharge signal predicted the degree of auditory cortex suppression.
• This provides direct evidence for the role of the ventral speech motor cortex in generating corollary discharge.

Conclusions:

• The study reveals the human corollary discharge source and its timing, offering critical insights into speech motor control.
• Findings have significant implications for understanding the neural basis of auditory hallucinations in psychosis.
• This work advances our knowledge of how the brain processes self-generated auditory information.