User: Pascal Steiner, a postdoc in the lab of Harvard University neuroscientist Bernardo Sabatini.
Project: Imaging changes in spine morphology over time at the neuronal synapse.
Problem: Steiner images in 400-µm hippocampal slices in order to capture the 3D branching complexity of neurons. Imaging at the synapse also requires superior spatial resolution.
Solution: Two-photon imaging is the only technique that can penetrate the tissue beyond about 100 µm. However, spatial resolution is noticeably lower than with confocal techniques. "When I image," says Steiner, "what I see is the [dendritic] spines, and I assume there is a synapse." (In hippocampus, excitatory synapses are on the spines and inhibitory synapses are on the shaft of the dendrites.) But researchers studying new synapse formation must confirm the presence of a synapse with physiology or electron microscopy.
While most confocal microscopes use one or many pinholes to scatter unfocused light from the sample, two-photon ...
