This glittering web is actually a live nerve cell, or neuron, in which its branches are labeled with glowing probes. Each dot reveals a potential junction between neurons—called a synapse—where chemicals are released allowing the cells to talk to each other. The red dots reveal inhibitory synapses—which silence electrical signals—whereas the green dots show the excitatory synapses that promote electrical signals.
The balance of inhibitory and excitatory pulses affects the behavior of the neuron. With this new labeling technique, NIH-funded researchers from the University of Southern California have given us a real time window into the complex microscopic anatomy of a neuron without interfering with its function. For a long time it has been thought that when a memory is stored, the pattern of synapses on individual neurons changes. Now we can watch in real time as that happens, both in healthy neurons and in neurons in animals where synapses do not change appropriately; for instance in animal models of autism, mental retardation, or Alzheimer’s disease.
 Recombinant probes for visualizing endogenous synaptic proteins in living neurons. Gross GG, Junge JA, Mora RJ, Kwon HB, Olson CA, Takahashi TT, Liman ER, Ellis-Davies GC, McGee AW, Sabatini BL, Roberts RW, Arnold DB. Neuron. 2013 Jun 19;78(6):971-85.
NIH support: National Institute of General Medical Science, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke