Investigating neural mechanisms of visual spatial attention by means of the steady-state visual evoked potential
The steady-state visual evoked potential (SSVEP) can be used as a powerful tool to analyze temporal mechanisms of visual spatial attentional shifting. In addition, neural mechanisms of spatial orienting can be investigated. In one of our studies, we have shown that shifting of attention to a peripheral stimulus cued by an endogenous attention direction cue is a rather slow cortical process which lasts up to 600 ms. In addition, we found no sign of an inhibition of the SSVEP to the unattended stimuli. Furthermore, we investigated the time course of attentional shifting to an exogenous cue, which is hypothesized to trigger a much faster shifting of attention and (b) a studied neural mechanisms of attentional shifting in schizophrenic patients. In a last experiment we asked the still controversingly discussed question whether the beam of the attentional spotlight works like an unitary focus or can be devided among spatially noncontiguous zones.