Brainstem control of spinal function: methods of fluorescence microscopy Almost everything we do and every sensation we perceive appears to be under the control of the brain. However, the mechanism by which this control is exerted is unclear. Our laboratory is interested in how the brainstem -- in particular, the serotonergic neurons of the lower brainstem -- controls the function of neurons in the spinal cord. Some, but not all, serotonergic neurons of the lower brainstem also contain other neurotransmitters -- chiefly, neuropeptides. We have examined the projections of these different types of serotonergic cells and found that there were distinct patterns of innervation: the cells containing neuropeptides predominantly innervated motor regions and the cells not containing neuropeptides innervated sensory regions. These differences suggest that these different types of serotonergic neurons have different functions. We are also localizing different types of serotonergic receptor to determine if different types of spinal neurons employ different receptors, i.e. if there is a functional organization at the level of receptors. The techniques that we employ include sophisticated types of optical microscopy, specifically, confocal microscopy, which allows tissue to be stained with several different fluorescent labels and "optically sectioned." In addition to our studies of receptor localization we combine molecular biological methods such as in situ hybridization with fluorescent neuronal labeling. Our research has required us to engineer several novel microscopic methods and doing so has been part of the job of this work.
