Ride The Ca^2+ Wave

Successive images (250ms interval) using a false color map depict the emergence and spread of an intracellular Ca2+ signal (green, black arrow) along the dendrite of a ventral horn neuron in the lamprey spinal cord. The images were generated using a CCD camera mounted on a fluorescent microscope. The cell was filled with a Ca2+-sensitive dye using whole cell patch clamp technique (frame 1: baseline fluorescence). A stimulating electrode was then used to excite nearby interneurons. Neurotransmitter released into the synapse opens ion channels on the filled cell, allowing Ca2+ to enter, causing the dye to fluoresce (frame 2). The wave that spreads vertically may be indicative of further release of Ca2+ from internal stores (frames 3-7). This experiment intended to demonstrate that synaptic activity induces local increases in Ca2+ specific to dendrites as opposed to a change over the entire cell. Ventral horn neurons govern the output of the spinal cord, causing coordinated muscle contraction, leading to rhythmic swimming behavior. Ca2+ fluctuation is intimately involved with the rhythmic excitation of cells in the spinal cord. A demonstration that Ca2+ increases occur in dendrites provides a role for synaptic plasticity and modification of locomotor output. Black scale bar = 40m.