Synaptic Plasticity - Post-Tetanic Potentiation

In this study, g-PRIME was used to simultaneously stimulate the nerve upstream of the muscle (it had been severed to disconnect it from it's tonic activity source) and record intracellularly from the superficial flexor muscle. Post synaptic potentials (PSPs) for a given spike can be visualized and their corresponding amplitude increase can be measured in response to a tetanic stimulus.

Post-tetanic potentiation illustrates one type of short term synaptic plasticity visible in most synaptic junctions. It is a product of increased calcium concentration to a rapid stimulus. The cell can not fully expell the calcium influx from the previous action potential so the result is an increase in neurotransmitter release (and thus an increased PSP size).

Raw Data Files

• ptp.daq - 10 seconds of intracellular recordings from a muscle during which the nerve innervating the muscle was stimulated in a regular fashion.

The max amplitude of these specific window regions corresponds to the peak of the post synaptic potential. Note how the post tetanic PSP peak at approximately 6 seconds is considerably larger than the initial peak at the beginning of the tetanus even though the membrane potentials are at identical voltages for both.

Here is the event capture regime. The large stimulus artifact is used to trigger the analysis window (negative threshold). Since the window only includes the negative stimulus artifact and the PSP, the max amplitude value returns the peak value of the post synaptic potential and can be used to measure potentiation.

1. Load ptp.daq into the analysis window. Select channel 0 and trigger 1.
2. Select 0% from the window center on threshold menu in the analysis menu
3. Activate threshold 1 and set it to -0.9V (trigger off the negative sweep of the stimulus artifact
4. hit calculate and select a display of the max amplitude of the window vs time