Neural temporal dynamics of facilitation and suppression in top-down guided feature-based attention

点击翻译按钮获取中文摘要

The proposed project sets out to investigate basic neural dynamics of facilitation and suppression in feature-based attention (FBA). A central question in the field of attention is whether visual processing is a strictly limited resource, which must be selectively and frugally allocated by selective attention. If this were the case, attentional enhancement of one stimulus should invariably lead to suppression of unattended distracter stimuli. However, in our previous studies in which we investigated the temporal dynamics of attentional shifts in FBA, we constantly found a biphasic process, with fast facilitation of the to-be-attended feature (color) followed by suppression of the to-be-ignored feature (color) with a time delay in the range of about 120-140 ms. Here, we will propose a new unified framework of temporal neuronal dynamics of attentional shifting that integrates the basic neural principles of neural gain, competition and suppression in FBA. While we replicated that biphasic process several times, some reviewers were asking some critical questions during the respective publication process that need experimental attention to exclude alternative explanations. These questions revolved around the usage of frequency-tagged stimuli and mainly the restriction to focus the analysis to steady state visual evoked potentials (SSVEPs). In the suggested project, we intend to run 3 studies extending our research to behavioral data employing a probe design and concurrently analyze ERPs that are elicited by events that comprise the task and probe stimuli. We are convinced that such a multi-modal approach will significantly strengthen our suggestion for an alternative framework for the allocation of attentional resources of attentional shifts in FBA. In further explorative studies, we intend to test the time course and the time point of suppression when selection is driven by top-down selection or driven by hard-wired center surround suppression. A further explorative study intends to test our idea that early gain modulation and the subsequent competitive interactions are not independent of each other, but instead, that initial amplification gain needs to reach a critical level before it triggers suppression. If suppression comes into play, we want to test whether facilitation and suppression result in a reciprocal relationship in that competitive interaction. We are convinced that these findings would enrich existing models of attention, and thus, should also be of highest interest to computational models and the way amplification and suppression are implemented in the respective algorithms.