"The aim of this project is to understand the fundamental computation that underlies normalization in cortical sensory circuits. Neuronal responses during sensory processing depend on the statistical properties of the sensory stimuli as well as on the macroscopic organization of the cortical network that together facilitate the functional interplay between neurons within the network in order to perform complex computations. One such important computation that has been shown to operate in various neural systems is normalization. Normalization is the process in which the response of a neuron is modulated by the activity of a pool of neurons. A key question concerns the mechanism that results in normalization. Specifically, how the functional connectivity and interplay between excitatory and inhibitory neurons within a network facilitates this complex computation.Using two-photon microscopy, I will image calcium or voltage responses from a large population of neurons in the visual cortex of mice, and quantitatively characterize the evoked response of every neuron (excitatory vs. inhibitory, simple vs. complex, etc.). Then, I will make slices of the imaged areas and identify the active neurons in the slices by registering images obtained in vivo and in vitro. Finally, I will map the connectivity between the neurons using photo-stimulation, by sequentially evoking action potentials in every neuron while simultaneously measuring the postsynaptic activity of the rest of the neurons in the slice.This study will reveal the design principles of the functional connectivity of a sensory cortex and provide new insights into the relation between the connectivity and the functionality involved in processing sensory information in the cortex."