The study describes a behavioral task and electrophysiological recordings in rats and monkeys to investigate the neural mechanisms underlying perceptual learning. In the behavioral task, rats were trained to lick a spout for rewards of sucrose solution or ICSS (intermittent conditioned sensory stimulation). The threshold for maintaining licking behavior with ICSS was determined to be between 65 and 110 μA. The licking frequency varied depending on the reward method, with higher frequencies for liquid rewards and lower frequencies for ICSS. In the cued operant task, tones and lights signaled the availability of rewards. Electrophysiological recordings were conducted to study the neural responses in the posterior thalamus and visual cortex. Neurons were classified based on their response to cues, and their tuning characteristics were analyzed. The study found that trained neurons showed specific changes in their orientation tuning curves, particularly at the trained orientation, leading to improved neuronal performance in orientation discrimination tasks. These changes were not observed in naive neurons or those responding to untrained orientations. The increase in slope of the tuning curves at the trained orientation was significant and was predicted by a computational model of orientation learning. The study also compared the performance of trained and naive neurons in a Bayesian analysis, showing that trained neurons had significantly better discrimination abilities around the trained orientation. The observed changes in neuronal performance were consistent with the improvement in psychophysical performance, suggesting that learning leads to specific and efficient increases in neuronal sensitivity in primary visual cortex.The study describes a behavioral task and electrophysiological recordings in rats and monkeys to investigate the neural mechanisms underlying perceptual learning. In the behavioral task, rats were trained to lick a spout for rewards of sucrose solution or ICSS (intermittent conditioned sensory stimulation). The threshold for maintaining licking behavior with ICSS was determined to be between 65 and 110 μA. The licking frequency varied depending on the reward method, with higher frequencies for liquid rewards and lower frequencies for ICSS. In the cued operant task, tones and lights signaled the availability of rewards. Electrophysiological recordings were conducted to study the neural responses in the posterior thalamus and visual cortex. Neurons were classified based on their response to cues, and their tuning characteristics were analyzed. The study found that trained neurons showed specific changes in their orientation tuning curves, particularly at the trained orientation, leading to improved neuronal performance in orientation discrimination tasks. These changes were not observed in naive neurons or those responding to untrained orientations. The increase in slope of the tuning curves at the trained orientation was significant and was predicted by a computational model of orientation learning. The study also compared the performance of trained and naive neurons in a Bayesian analysis, showing that trained neurons had significantly better discrimination abilities around the trained orientation. The observed changes in neuronal performance were consistent with the improvement in psychophysical performance, suggesting that learning leads to specific and efficient increases in neuronal sensitivity in primary visual cortex.