CONICET | Buscador de Institutos y Recursos Humanos

Sensory representations are typically thought as neuronal activity patterns that encode physical attributes of the outside world. However, increasing evidence is showing that as animals learned the association between a sensory stimulus and its behavioral relevance, stimulus representation in sensory cortical areas can change. Moreover, internal state as well as animal movements related to a particular task have been shown to modulate cortical activity. To study the dynamics of sensory cortex representations as behavior evolves, we developed a spatial context-olfactory task in which mice learn that an odor is rewarded when presented in a specific spatial context. We measured the activity of piriform cortex (PC) neurons in head-fixed mice running in a virtual reality environment. We find neurons not only responding to odors, but also to visual contexts and to water reward, indicating that the PC encodes information about relevant aspects of the task. Moreover, by analyzing the population activity dynamics using Principal Components Analysis (PCA), we find different population trajectories evolving through time that can discriminate aspects of different trial types. We then further dissected the contribution of different sensory and non-sensory variables to the modulation of PC activity at the level of individual trials, using a statistical approach based on Generalized Linear Models (GLMs). Our results show that, after animals have learnt the context-odor-reward association, animal position in the virtual environment is a spatial element of the task that has considerable weight on PC responses. Furthermore, we found that variables related to both sensory and non-sensory aspects of the task (e.g., odor, context, reward, licking, sniffing rate and running speed) differently modulate PC activity, suggesting that the PC may use information from other brain areas to adapt odor processing depending on experience and behavior.