Abstract
Selective attention is the mechanism that enables the selection of behaviorally relevant inputs to be prioritized at the expense of irrelevant inputs. Evidence suggests that this process is not static; instead, it ebbs and flows in an oscillatory manner. Here, we investigate oscillatory interactions with feature and space-based attention. Previously, we used steady-state visual evoked potentials (SSVEPs) to extract high temporal resolution information about stimulus orientation based on the spatiotemporal pattern of EEG responses across the scalp (Garcia et al., 2013). In the present study, subjects viewed a high frequency (20Hz) flickering grating (Experiment 1) and checkerboard (Experiment 2) while they search for occasional targets. We reconstructed either the attended feature (E1) or the attended spatial location (E2) using the SSVEP signal across all EEG electrodes. In Experiment 1, the phase of the intrinsic alpha cycle modulates the orientation response profile, such that responses are larger at a trough of the alpha cycle and attenuated at an alpha peak. In Experiment 2, the magnitude of spatially selective responses increases and decreases as a function of both intrinsic theta and alpha phase. Interestingly, modulations within the theta band display an interaction with stimulus type (attended vs ignored), suggesting a key role in the deployment of spatial attention, whereas modulations within the alpha band are more generally related to overall response amplitude. Together, these results suggest that attention modulates the fidelity of population codes for stimulus information in an oscillatory manner that depends upon the types of feature (space or orientation) attended.
Meeting abstract presented at VSS 2014