Perceptual training selectively strengthens top-down signaling to sensory cortex

Sensory cortical neurons adjust their responses to enhance the detection and discrimination of behaviorally relevant stimuli. Top-down signals from frontal cortical regions are thought to mediate these changes, and prior work has proposed that these signals may strengthen during perceptual learning. However, this hypothesis has not been tested directly. Here, we asked whether neurons in the orbitofrontal cortex (OFC), a higher-order brain region implicated in top-down control of sensory cortex, alter their activity during auditory perceptual learning and whether learning-related changes are transmitted to sensory cortex. We found that OFC neurons encode both trial outcome and stimulus-related information, and that the strength and sensitivity of these signals increase as animals learn to detect progressively weaker amplitude modulations. Notably, learning-related changes were conveyed to auditory cortex, but not visual cortex, indicating that perceptual learning selectively strengthens signaling within a task-relevant frontal-to-sensory cortical circuit. Together, these findings provide direct evidence that top-down cortical networks are modified during perceptual learning.