Studying the role of the piriform cortex in an olfactory-contextual conditioning paradigm

NOEL FEDERMAN; LUCCA SALOMON; ANTONIA MARIN-BURGIN; SEBASTIÁN ALEJO ROMANO

CABA

Workshop; ISN School on portable fluorescent microscopy and Latin American Miniscope Workshop; 2022

ISN / Fundación Instituto Leloir

Increasing evidence indicates that representation of sensory stimuli in cortical areas is plastic and can be modified by experience. In particular, a unique feature of olfactory processing is its high dependence on past experience, context, and the animal’s internal state. To study contextual modulation of sensory learning we developed an olfactory-contextual conditioning paradigm in a virtual reality environment, in which animals learn to associate an odor with a water reward when presented in a particular visual context. To investigate how activity in the mice primary olfactory cortex is modulated by sensory and non-sensory variables, we recorded, during the task, neuronal responses from the piriform cortex (PC) in first session of training and expert animals. We found that neurons in the PC respond not only to odors but also to several task-relevant variables. Furthermore, the ability of neurons to encode more than one variable is acquired with learning. Last, to test the importance of the PC in the learned association we bilaterally silenced excitatory PC neurons using a chemogenetic approach. Interestingly, preliminary results show that silencing PC impaired the animal’s performance. We observed that the ability to distinguish odors was more affected than the one to discriminate visual contexts, indicating that the piriform cortex plays an important role in the studied task and that it may be linked to both olfactory and associative functions. In summary, this results show that associative learning dynamically modifies the representation in the PC to reflect experience. This suggests an adaptive coding in this primary sensory cortex useful to adjust behavior after learning.