Dynamics of excitatory and inhibitory circuits in piriform cortex and its modulation

NOEL FEDERMAN; ANTONIA MARIN BURGIN

Mar del Plata

Congreso; Sociedad Argentina de Neurociencias; 2015

The piriform cortex (PC) serves as point of anatomical convergence for olfactory bulb output neurons, conveying information about distinct odorant features extracted from the periphery. The spiking of pyramidal neurons can be driven directly by afferent inputs from the lateral olfactory tract (LOT), by intrinsic associational fiber inputs (ASSN), or the combination of both. Activity arriving from LOT or ASSN not only produces excitation but also recruits inhibitory circuits. The contribution of each of these pathways on the population activity is not known in detail. We test if the response of Layer II neurons depends on the differential contribution of ASSN and LOT inputs through differential recruitment of inhibitory circuits, in PC slices. In addition, we use optogenetics to stimulate afferents coming from other brain regions as the basolateral amygdale (BLA) and study the modulation of the excitation/inhibition dynamics in PC neurons. Preliminary results show that the relationship between E/I under LOT stimulation is quite linear for different stimulation intensities but with a slope on which outweighs inhibition. Something similar happens with ASSN. Stimulation of BLA primarily produce inhibition in PC. Interestingly, simultaneous stimulation LOT + BLA generates similar excitatory currents as LOT stimulation only, but inhibitory currents summate in an arithmetic manner, indicating that the population of inhibitory interneurons that recruits LOT and BLA are different.