Figure 6

Electrophysiological properties of neurons whose surrounding sympathetic fibers were examined before recording. A - D: arrowheads indicate examples of cells classified has having sympathetic baskets (A) or rings (B) (such cells were combined into a single group of "basket cells"); cells with nearby but less elaborated sympathetic fibers (C); and no nearby sympathetic fibers (D), based on observation of EGFP fluorescence during the recording session. B.V. in (D) indicates a blood vessel. Some small TH-positive neurons are also seen (see text). EGFP fluorescence is shown in green and is from combined layers of a confocal image. Neurons are not counterstained because the images are from live preps used for recording; however, a bright field images of the cells taken in a single plane is shown in the red channel. (E) Basket cells have much higher incidence of spontaneous activity, primarily of the bursting pattern. Overall incidence of spontaneous activity (left), as well as incidence of bursting (right), were significantly higher in basket cells compared to either cells with nearby sympathetic fibers but not making a basket/ring formation, or to cells without any nearby sympathetic fibers (Fisher's exact test). (F) Cells (left) with sympathetic basket formations have lower rheobase (F, top) and shorter AP duration (F, bottom) compared to cells with nearby fibers (not forming a basket or ring) or no nearby fibers; the difference in rheobase is still seen when only non-spontaneously active cells are considered. (ANOVA on ranks with Dunn's post test).