Background. Electro- and magneto-encephalographic (EEG/MEG) responses to a stimulus are systematically attenuated? by up to 80%? if the same stimulus was presented less than 8-12 seconds ago. This dynamic modulation of response amplitude to identical stimuli is one of the most striking and fundamental properties of the EEG/MEG signal. The proposed work will test the hypotheses (1) that the attenuation of EEG/MEG amplitude to repeated identical stimuli is caused by short-term synaptic depression at cortical synapses and (2) that the manifestation of synaptic depression at the micro- and meso-scopic level critically depends on local circuit and network architecture leading to a complex but systematic relationship between macroscopic modulation of EEG/MEG responses and several micro- and mesoscopic measures of neural function.
The goal of the proposed research is to understand the meso- and microscopic events that underlie the dynamic changes of EEG/MEG amplitude to identical auditory stimuli in humans. We will study this phenomenon in three model systems and at five levels of observation to understand how the effect is enhanced, attenuated or otherwise altered while transitioning from synapse to single cell, from cell to local circuit, from circuit to individual brain region and from brain region to macroscopic EEG/MEG.
