Squid Giant Axon Membrane Potential

Abstract

The SGAMP database contains single-unit neuronal recordings of North Atlantic squid (Loligo pealei) giant axons in response to stimulus currents. The membrane potential and stimulus current are given for a total of 170 trials across 8 different axons.

Data Desciption

The applied stimulus current profiles can be divided into two groups: Stochastically summated polysynaptic currents (PSCs), and individual current pulses. Refer to the original publication for technical details, and see the Recording-Info.ods spreadsheet for information about each trial. In addition, the Irms file contains the root mean squared stimulus current values in uA/cm2. This only applies to stochastic current records when the stimulation is on; current pulse records are marked 'PULSE'.

The files in the raw directory contain the original raw values captured by the DATAQ Instruments capturing device (translated into MIT format). Both channels are given in volts, and have not been calibrated or translated into their physical units. In order to convert the raw recorded values into physical units:

1. For the membrane potential channel (1), multiply the values by 0.1 to remove the instrumentation gain. This gives the membrane potential in volts.
2. For the stimulus current channel (2), apply the physical unit conversion, 1V = 5uA/cm2 to get the stimulus current in uA/cm2. Note that current recordings may have a DC offset due to the recording instrumentation, which does not reflect an offset of applied current. When the stimulation current is off, the baseline should be zero.

File names are in the form aXtY, where X is the axon number and Y is the trial number for that axon. Each record lasts in the order of several seconds and is sampled at 125KHz.

References

The data set is also used in

• Forger DB, Paydarfar D, Clay JR, Optimal Stimulus Shapes for Neuronal Excitation.PLoS Computational Biology 7(7):e1002089, 2011.
• Clay JR, Forger DB, Paydarfar D, Ionic Mechanism Underlying Optimal Stimuli for Neuronal Excitation: Role of Na+ Channel Inactivation. PLoS One 7(9):e45983, 2012.
• Bod’ová K, Paydarfar D, Forger DB, Characterizing Spiking in Noisy Type II Neurons. Journal of Theoretical Biology 365:40-54, 2015.