Processing Stages of Visual Stimuli and Event-Related Potentials, in "The NeuroComp/KEOpS’12 workshop

Event-evoked potentials (ERP) in electroencephalograms reflect various visual processing stages according to their latencies and loca-tions. Thus, ERP components such as the N100, N170 and the N200 which appears 100, 170 and 200 ms after the onset of a visual stim-ulus correspond respectively to a selective attention, the processing of color, shape and rotation (e.g. processing of human faces) and a degree of attention. Event Related Potential (ERP) Event-Related Potentials (ERPs) are electrical changes in electroencephalo-graphic (EEG) recordings that are time-locked with sensory or cognitive events. These deflections in the signal are more vlongnamesfirst isible when responses are averaged. The ERP components (figure 1) are a useful tool to track the temporal brain dynamics to understand the neural processing. The ERP components are peaks whose names are designated by their nega-tive (N) or positive (P) polarity and their approximate latency in ms. Thus the P100 component reflects a positive deflection of the signal with a peak approximatively around 100 ms. Until now it is unclear how ERPs are generated. Two hypotheses are the most suitable. The first one establishes that ERPs are generated due to an event-related activation of neural assemblies with the stimulus (evoked re-sponse) [1], meaning that the ERP is added to the ongoing EEG. The second hypothesis states that ERPs are generated by “phase resetting”, meaning 1 ha l-