An important function of the nervous system is to transform information about the environment into a succession of neural codes that the brain can process into memories and behaviors. Odors are detected by a large assortment of receptor neurons, each with different sensitivities. These neurons respond to odors by firing simple patterns of action potentials that are conveyed to a brain structure called the olfactory bulb (in vertebrates) or the antennal lobe (in insects). There, interactions between excitatory and inhibitory neurons broadly distribute olfactory information across large populations of cells, add to the complexity of the firing patterns with sequences of excitation and inhibition, and synchronize responsive cells into oscillatory waves of spiking. This information is then sent to deeper brain areas including the piriform cortex (in vertebrates) or the mushroom body (in insects), where the broadly distributed, synchronized input is transformed into sparse patterns of spiking distributed across huge numbers of neurons, a format ideal for comparison and memorization. Less is known about gustatory coding;analyses of this process have been fraught with disagreement and controversy. Our lab investigates both odor and taste coding in parallel with similar methods, focusing on relatively simple species in which experiments can be performed in intact, awake animals, and neural circuits can be traced from point to point from the periphery to the brain. Our recent results show the gustatory system is organized and functions very much like the olfactory system. We are pursuing this analysis with the goal of understanding how the nervous system processes essential and complex forms of information.

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