When a near-threshold stimulus is presented, a sensory percept may or may not be produced. The unpredictable outcome of such perceptual judgment is believed to be determined by the activity in early sensory cortex. My colleagues and I analyzed the responses of neurons in primary somatosensory cortex and downstream areas, recorded while monkeys judged the presence or absence of threshold stimulus. We observed that the responses in the somatosensory cortex did not covary with the monkeys’ perceptual reports. In contrast, the activity of frontal lobe neurons did covary with trial-by-trial judgments. Further control and microstimulation experiments indicated that frontal lobe neurons are closely related to the monkeys’ subjective experiences during sensory detection. Surprisingly, an actor not considered before is the midbrain dopamine system in coding the subjective sensory experience and uncertainty of perceptual decisions. I will presence the evidence that it codes the subjective magnitude of a conscious sensory experience and the uncertainty associated with a perceptual judgment about the presence or absence of a vibrotactile stimulus.  Therefore, in addition to their well-known role in reward prediction, midbrain dopamine neurons code subjective sensory experience and uncertainty arising internally from perceptual decisions.