Sensory input from the nose in mammals is carried by the olfactory nerve first to a brain structure called the olfactory bulb, and then relayed to various parts of the cortex of the brain. A major area for olfaction is called the anterior piriform cortex. In contrast to our knowledge about how inputs are integrated from the two eyes or the two ears, we know very little about how the olfactory cortex integrates input from the two nostrils, or nares, on each side of the nose. It is possible that the bilateral input (from both sides) is important for signal amplification, or for redundancy, or bilateral access to olfactory memories. Recent studies have shown that single nerve cells, or neurons, in the anterior piriform cortex are usually about equally responsive to odors in either naris. This new study builds on current ideas that bilateral stimulation is important to form and maintain the connections in certain local circuits among neurons in the brain. Anatomical and physiological techniques will be used to measure cellular features and trace the connections in this olfactory system during development under conditions of unilateral deprivation, so that only one side of the nose receives odors. The results should reveal some of the anatomical and physiological mechanisms for experience-dependent plasticity, in which responsiveness is partly determined by coordinated spatial and temporal patterns of input. This work addresses very important questions about the organization of olfactory cortex, about which we still know little, and will also have an impact on studies of development, plasticity and learning. A major part of this work also involves the training of a graduate student with breadth across the areas of neurophysiology, anatomy, development and learning.
