The top-down function of prestimulus EEG alpha activity

As Brain Makes Mind, Mind Makes Brain (Byoung-Kyong Min) - The functional dynamics of prestimulus alpha activity and its relation to mental events were investigated through this work. For this purpose, participants were categorized according to either the amount or the dominance of prestimulus alpha activity. Study 1 demonstrated the existence of an additive power after stimulation irrespective of the amount of prestimulus alpha activity, while Study 2 provided substantial evidence (dominance-dependency) in favor of phase-resetting of ongoing alpha activity in ERP-generation. Taken together, both models for ERP-generation are evenly plausible within a single framework and able to coexist. Both Study 1 and Study 2 also suggested that prestimulus alpha activity, which presumably reflects a functional state of the brain prior to stimulation, might influence poststimulus information processes. In agreement with this view, Study 3 proposed that prestimulus alpha activity probably reflects top-down inhibitory processing in advance of stimulation and modulates subsequent poststimulus responses. Within this framework, a paradoxical increase of alpha activity can be understandable.