Database Open Access

Squid Giant Axon Membrane Potential

Published: April 15, 2016. Version: 1.0.0

When using this resource, please cite the original publication:

Paydarfar D, Forger DB, Clay JC. Noisy Inputs and the Induction of On–Off Switching Behavior in a Neuronal Pacemaker. Journal of Neurophysiology, 96:3338-3348, 2006.

Please include the standard citation for PhysioNet: (show more options)
Goldberger, A., Amaral, L., Glass, L., Hausdorff, J., Ivanov, P. C., Mark, R., ... & Stanley, H. E. (2000). PhysioBank, PhysioToolkit, and PhysioNet: Components of a new research resource for complex physiologic signals. Circulation [Online]. 101 (23), pp. e215–e220.


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.


The data set is also used in


Access Policy:
Anyone can access the files, as long as they conform to the terms of the specified license.

License (for files):
Open Data Commons Attribution License v1.0

Corresponding Author
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Total uncompressed size: 901.7 MB.

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Folder Navigation: <base>
Name Size Modified
Irms.txt (download) 2.6 KB 2016-04-16
RECORDS (download) 1.7 KB 2016-04-16
Recording-Info.ods (download) 54.1 KB 2016-04-16
SHA256SUMS.txt (download) 26.5 KB 2019-02-20