The primary focus of our research group is understanding how neuronal circuits encode and interpret sensory cues from environment, within and across sensory modalities, to generate behaviors. We use rodent olfaction as a model system and study the input-output transformations performed by the circuit as we modulate the sensory inputs or specific circuit elements in anesthetized and awake animals. In the olfactory bulb, numerous interneurons interact with the sensory afferents, as well as with the output neurons (mitral/tufted cells) and cortical or neuro-modulatory feedback fibers via short or long range connections. Their connectivity patterns and roles in olfactory processing remain however largely unknown. We are combining the recent advances in optogenetics with pattern illumination techniques to modulate activity of select neuronal populations in a controlled and reversible manner. In parallel, we monitor the effects of these manipulations on the output of the bulb network. We couple this with electrophysiological recordings in the olfactory cortex to map bulbar-cortical connections and understand cortical integration rules. Further, we combine our capacities of circuit manipulation and monitoring with head-fixed and freely moving behavioral paradigms. We perturb odor-triggered activity patterns in behaving animals by manipulating glomerular inputs and observe its direct effects on odor identification behavior.