Abstract
Understanding the mechanisms by which long-term synaptic plasticity is expressed remains an important objective in neuroscience. From a physiological perspective, the strength of a synapse can be considered a consequence of several parameters including the probability that a presynaptic action potential (AP) evokes the release of neurotransmitter, the mean number of quanta of transmitter released when release is evoked, and the mean amplitude of a postsynaptic response to a single quantum. Various methods have been employed to estimate these quantal parameters from electrophysiological recordings; such “quantal analysis” has been used to support competing accounts of mechanisms of expression of long-term plasticity. Because electrophysiological recordings, even with minimal presynaptic stimulation, can reflect responses arising at multiple synaptic sites, these methods are open to alternative interpretations. By combining intracellular electrical recording with optical detection of transmission at individual synapses, however, it is possible to eliminate such ambiguity. Here, we describe methods for such combined optical and electrical monitoring of synaptic transmission in brain slice preparations and illustrate how quantal analyses thereby obtained permit more definitive conclusions about the physiological changes that underlie long-term synaptic plasticity.
Key Questions and Answers
What is optical quantal analysis?
Optical quantal analysis is a technique that uses optical methods to detect and measure the release of neurotransmitters at synapses. By combining optical detection with electrical recording, researchers can accurately assess synaptic activity and plasticity.
Why is combining optical and electrical monitoring important?
Combining optical and electrical monitoring allows for simultaneous measurement of synaptic transmission, providing a more comprehensive understanding of synaptic function. This dual approach helps eliminate ambiguities that might arise from using either method alone.
How does this method contribute to understanding synaptic plasticity?
By enabling precise quantal analyses, this method allows researchers to observe and measure the physiological changes that underlie long-term synaptic plasticity. This contributes to a deeper understanding of how synaptic connections strengthen or weaken over time.
