The circuitry of the human brain includes a trillion neurons and a quadrillion synapses and its connectivity underlies all human perception, thought, emotion, and behavior. During the past years, studies in various species have illustrated that the overall structure of the nervous system is genetically hard-wired but that neural circuits undergo extensive sculpting and rewiring in response to a variety of stimuli. The process of experience-dependent changes in synaptic connectivity is named synaptic plasticity. The hypothesis synaptic plasticity and memory (SPM) is not identified with any one individual scientist. It is an idea that has come forward in various guises over the years.
Fig.1 Function of synaptic plasticity.
Function of Synaptic Plasticity
Synaptic plasticity manipulates how two neurons communicate with each other effectively. The strength of communication between two synapses can be compared to the volume of a conversation. The synaptic strength is not static but can change in the short term and/or long term. Synaptic plasticity refers to these changes in synaptic strength. In detail, short-term synaptic plasticity refers to changes in synaptic strength that occur on a sub-second timescale. A rapid down or up adjustment of the volume control helps determine how vital that connection is to the ongoing conversation, but which reverts to “normal” soon afterward. On the other hand, long-term synaptic plasticity lasts anywhere from minutes to hours, days, or even years. Long-term plasticity is the dominant model for how the brain stores information.
Imaging Synaptic Plasticity
Over the past years, advances in optical imaging techniques, combined with the use and development of fluorescent biosensors, have advanced our understanding of synaptic plasticity by offering an unparalleled spatiotemporal resolution of molecular events at synapses. Most researches focus on the presynaptic expression of long-term potentiation (LTP), postsynaptic expression of LTP, and the spatiotemporal dynamics of plasticity-related signaling.
- Presynaptic expression of LTP - FM dyes, Ca2+ sensitive dyes
- Postsynaptic expression of LTP - Single particle tracking, pH lourins
- Synaptic signaling - FRET/FLIM, Photoactivation
Future Research Directions
With the development of molecular, electrophysiological, cell biological proteomic approaches and combinational solutions, Creative Biolabs believes that the next few decades will bring further clarification of the detailed molecular mechanisms underlying the major forms of synaptic plasticity. The use of advanced genetic and molecular manipulations will simultaneously facilitate the examination of the neural circuit basis of behavior.