Perception and neural representation of intermittent odor stimuli in mice

Odor cues in nature are sparse and fluctuating due to turbulent transport. To investigate how animals perceive these intermittent cues, we developed a behavioral task in which mice made binary decisions based on the total number of discrete odor pulses presented stochastically over several seconds. Mice quickly learned this task, placing higher perceptual weight to stimuli arriving during inhalation than exhalation, a phase dependency that strongly correlated with the magnitude of responses in olfactory sensory neurons. Neurons in the anterior piriform cortex responded to odor pulses with varying degrees of dependence on respiration phase. Single cortical neurons responded stochastically and transiently to odor pulses, leading to a representation that carries signatures of sensory evidence, but not its accumulation. Our study reveals that mice can integrate intermittent odor signals across dozens of breaths and that respiratory modulation imposes limits on sensory information acquisition that cortical circuits cannot overcome to improve behavior.