Human speech processing in Broca’s area across neuronal scales

• Applicant: Professor Dr. Simon N. Jacob
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 532521431

Speech and language are among the most formidable functions of the human brain. While the regions in the frontal, temporal and parietal lobe that comprise the cortical language network have already been identified, the fundamental principles that govern how the human brain organizes and orchestrates neural processing in the speech and language network are largely unknown. In this project, we will investigate the mechanisms of human vocal communication in a key node of the speech and language network, Broca’s area (BA 44) in the left inferior frontal gyrus (LIFG), across neuronal scales. We will intraoperatively record directly from Broca’s area in neurosurgical patients undergoing awake brain surgery for the removal of left-hemispheric tumors. We will combine electrocorticography (ECoG), intracortical microelectrode array recordings and ultrahigh-density measurements of single-unit activity across cortical layers to explore both the collective dynamics and the microcircuitry processing of individual neurons that in concert control our ability to verbalize thoughts, intentions and emotions. At the macroscale, we will explore which modular organization and which neural dynamics in the language-selective and domain-general subdivisions of the LIFG control the planning, production and composition of human speech sounds. At the mesoscale, we will investigate how neuronal population activity in cortical patches of Broca’s area is orchestrated for the preparation and production of speech. At the microscale, we will determine how elementary speech sounds and phonetic constructs are encoded at the single-neuron level and how neuronal population patterns contribute to temporal integration and combinatorial processes during speech production.

• DFG Programme: Research Units
• Subproject of: FOR 5768: Neural basis of vocal communication