Jake Westerberg

Certain stimuli have an uncanny ability to draw our attention. These stimuli are characterized by their salience and “pop-out” from their surroundings. Take for instance the vibrant color of a bright red apple hanging from a leafy green tree branch. In this talk, I will discuss how these pop-out stimuli are represented and selected for early in the visual processing stream of macaque monkeys. To investigate this, we introduced linear multielectrode arrays into mid-level visual cortical area V4. We recorded the laminar population spiking activity, local field potentials, and the overlying EEG signal during pop-out visual search. I will share findings that suggest attentional selection for pop-out stimuli occurs rapidly, in the feedforward visual response. I will also show how the priming of popout stimuli leads to changes in visual cortical feature maps, thereby allowing for more rapid selection when the pop-out feature is behaviorally pertinent. Lastly, I will share how this attentional selection process in visual cortex leads to the production of electrical fields that comprise the N2pc, a commonly used EEG index of attention and bridge between nonhuman primate and human cognitive neuroscience research.