Abstract
Under identical physical stimulus conditions, sometimes visual events are detected whereas at other times these same visual events can go unnoticed. Using both metacontrast masking and transcranial magnetic stimulation (TMS) of the primary visual cortex to induce visual suppression, we have been examining the neural mechanisms underlying this variability in perception. Our results indicate that the timing of arrival of visual events in primary visual cortex with respect to ongoing oscillatory activity and feedback signals play an important role in dictating whether a visual event is detected or not. Furthermore, experiments manipulating visual stimulus salience suggest that the strength of only feedforward signals, but not feedback signals in primary visual cortex is affected by manipulations of saliency. Taken together, our studies shed some insight into the nature and variability of the neural signals that support conscious visual perception.