Analysis-Code for the 'Neuronal Markers of Corollary Discharge' research project, conducted at the University of Oldenburg.
05.09.2024, Tim Dreßler, University of Oldenburg
The theory of internal forward models suggests that self-generated motor actions are accompanied by an 'efference copy', which is used to predict the sensory consequences of actions, leading to a 'corollary discharge' (CD) in the corresponding sensory areas. As a result of this mechanism, the neural response to self-generated stimuli is suppressed. In the auditory domain, this is often evidenced by a speech-induced suppression of the N1 component in the event-related potential (ERP). We aimed to identify another neural marker of the CD phenomenon in the auditory domain using a robust connectivity measure. Based on results from invasive work in humans, we hypothesized that there would be increased functional connectivity between frontal and temporal sites during active production of vocalizations compared to passive listening to vocalizations. During a 'talk/listen' paradigm, the neural responses of 38 individuals were recorded using a 64-electrode EEG system. The debiased weighted phase lag index (dwPLI) was used to estimate functional connectivity. We found a suppressed N1 ERP component in the ’talk’ condition as compared to the ’listen’ condition. However, contrary to our hypothesis, we did not observe increased functional connectivity during the 'talk' condition as indexed by the dwPLI. While the former finding adds to the evidence for the replicability of CD-related effects in the human brain, the latter however challenges previous results. The findings are discussed in the light of the potential influence of using different approaches to estimate functional connectivity, as well as the potential impact of using EEG rather than invasive measurements.
