Basic characterization of a synaptic pathway includes the estimation of specific potentials and currents during synaptic activity. In particular, we collect data on the reversal potential of a synapse, the voltage at which there is no net flow of ions through the membrane, the peak PSP and PSC, and the coefficient of variation (CV) of the peak PSC.

Reversal potential

PSP amplitude

PSC amplitude

PSC shows a specific rise and decay which depends on the synapse and the set of synaptic receptors. The rise time are usually measured as the time taken by the PSC trace to go from 10% to 90% of its amplitude, while the time constant of the decay (tau decay) is estimated fitting an exponential decay function (e-t/decay) after the PSC peak and identifying its time constant. When slow receptors (i.e. NMDA and GABAB) are inactive or blocked in the experiments, the measures are due to mainly the fast receptors, AMPA or GABAA, respectively for excitatory or inhibitory synapses.

PSC rise time

PSC tau decay

Excitatory synapses have two types of ionotropic receptors, AMPA and NMDA. Contribution of NMDA receptors to the synaptic response is expressed as a ratio between peak conductance of NMDA and AMPA (NMDA/AMPA ratio). NMDA has slower kinetics and rise and decay time constants are usually computed by fitting exponential rise (et/rise) and decay (e-t/decay) functions.

NMDA/AMPA ratio

NMDA tau decay

NMDA tau rise