Spatial Processing Enhancement in Prefrontal Cortex for Rapid Detection of Valuable Objects

It is recently shown that objects with long-term reward associations can be efficiently located during visual search. The neural mechanism for valuable object pop-out is unknown. In this work, we recorded neuronal responses in the ventrolateral prefrontal cortex (vlPFC) with known roles in visual search and reward processing in macaques while monkeys engaged in efficient vs inefficient visual search for high-value fractal objects (targets). Behavioral results and modeling using multi-alternative attention-modulated drift-diffusion (MADD) indicated that efficient search was concurrent with enhanced processing for peripheral objects. Notably, neural results showed response amplification and receptive field widening to peripherally presented targets in vlPFC during visual search. Both neural effects predict higher target detection and were found to be correlated with it. Our results suggest that value-driven efficient search independent of low-level visual features arises from reward-induced spatial processing enhancement of peripheral valuable objects. Significance Statement Rapid detection of rewarding objects can be essential for survival and reproduction in real life. However, finding valuable objects, among many others, can be time-consuming and slow. In this work, we reveal reward-related changes in the receptive fields of neurons within the prefrontal cortex of macaque monkeys that help them find valuable objects more efficiently. Such reward-related plasticity is shown to develop slowly for objects that are consistently associated with reward and challenges current theories of efficient search based on low-level visual features alone.