Nonlinear coupling between occipital and motor cortex during motor imagery: a dynamic causal modeling study.

摘要: We demonstrate the capacity of dynamic causal modeling to characterize nonlinear coupling among cortical sources that underlie time-frequency modulations in MEG data. Our experimental task involved mental rotation hand drawings ten subjects used decide if it was a right or left hand. Reaction times were shorter when stimuli presented with small angle (fast responses) compared large (slow responses). The grand-averaged data showed both cases performance accompanied by marked increase gamma activity occipital areas and concomitant decrease alpha beta power motor regions. Modeling directed (cross) frequency interactions between two regions revealed after stimulus induced regions, area served attenuate these modulations. difference fast slow behavioral responses manifest as an altered strength forward backward connections, which led less pronounced attenuation for more difficult reaction time) trials. This mediated (backwards) from till sources, whereas other mainly within same frequency. Results are consistent theory predictive coding suggest during imagery, influence on cortex co-determines performance. study illustrates benefit terms generative model can disentangle contributions intra-areal vis-a-vis inter-areal connections