Using Manganese Enhanced MRI to Reveal Active Olfactory Circuitry in Response to Odorant Stimuli
Chuang K, Koretsky A, Lee J, Belluscio L, Silva A
National Institutes of Health
To investigate the circuitry activated by odorants in the mammalian olfactory bulb (OB) we adapted a functional imaging technique known as manganese-enhanced MRI (MEMRI). A functional map of the odorant in the OB can be detected by quantifying regional signal enhancement as manganese traces from active olfactory neurons in the nose and enters the OB. Odor maps of the glomerular layer for three different odorants were obtained. Furthermore, activation of a single glomerulus could be observed by comparing MEMRI maps to specific glomeruli that were visualized with green fluorescent protein. The ability of manganese to trace trans-synaptically should enable depicting the organizational pattern of the signal transduced to deeper parts of the OB and into the brain.