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The basal forebrain (BF) constitutes a major neuromodulatory center, providing extensive cholinergic and non-cholinergic projections to the entire forebrain. Mounting evidence demonstrates that these projections play a key role in cognitive functions, including learning and memory, and damage or deterioration of the BF leads to severe cognitive impairments, such as dementia and executive dysfunction. Despite the association of the BF with higher cognitive functions and a host of disease states, surprisingly little is known about how it accomplishes its intricate tasks. Importantly, it is not known when cholinergic or non-cholinergic neurons are recruited during behavior and how their activity might support different aspects of cognition. We used optogenetic identification to record cholinergic and GABAergic neurons in mice performing an auditory detection task. We found that central cholinergic neurons responded phasically to primary reward and punishment with remarkable speed and precision (18±2 ms), whereas GABAergic neurons showed slower and more sustained responses to the auditory cues. Cholinergic responses to reward were scaled by reinforcement surprise, raising the possibility that the cholinergic system also conveys cognitive information. These results suggest that cholinergic neurons form a rapid, reliable and temporally precise signaling route for reinforcement feedback that can mediate fast cortical activation, plasticity and learning.