Abstract
Repetitive task performance can lead to faster, more accurate performance, a phenomenon known as priming. One example is priming of pop-out visual search. In this task, participants identify a conspicuous singleton in a search array by shifting gaze to the singleton. This singleton is defined by a pop-out feature such as color (e.g. red among green). With repetition of the singleton feature participants become faster and more accurate. We investigated further what neural processes could yield the observed behavioral effects. Performance monitoring signaling seems a likely neural contributor as priming occurs concurrently with improved performance. We hypothesized that the modulation of performance monitoring signals contributes to behavioral changes observed during visual priming. Earlier work has demonstrated that an area known as the Supplementary Eye Field (SEF), a medial frontal cortical area, contributes to performance monitoring in visual search. This intersection provides a neural location in which we can investigate priming of pop-out. To test our hypothesis, two monkeys performed a priming of pop-out search task. During task performance, microelectrodes recorded from SEF simultaneously with EEG recorded extracranially to monitor an index of performance monitoring known as the error related negativity (ERN). Bayesian analysis demonstrated that whereas spike rates show no modulation with visual priming, the ERN did modulate with visual priming. This is particularly interesting as it has been shown previously that spiking in SEF contributes to the generation of the ERN. It is not entirely unexpected, however. SEF spiking does not reliably represent ongoing visual search processing, such as discrimination of target and distractors. The absence of stimulus-specific and spatially distinct visual information may be important to priming. Based on the dissociation between SEF spiking and EEG, we conclude that performance monitoring does play a role in priming of pop-out, but the signal source is not localized to SEF.
Acknowledgement: R01EY019882, R01EY08890, R01EY027402, P30EY008126, T32EY007135, U54HD083211, E. Bronson Ingram Chair in Neuroscience