A single neuron from a rat’s hippocampus, an area of the brain essential for learning and memory. The bulbous part is the cell body. fluorescent color markers have been attached to specific proteins to allow researchers to assess the length and complexity of dendrites (green) and the number and size of dendritic spines (red). Each spine is part of a synapse, where this neuron receives incoming signals from other neurons. Photomicrograph courtesy Gary Wayman.