Squid Giant Axon Membrane Potential

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This data set, its source, and the methods used to generate it, are described in

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.

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.
Bod’ová K, Paydarfar D, Forger DB, Characterizing Spiking in Noisy Type II Neurons. Journal of Theoretical Biology 365:40-54, 2015.

When referencing this material, please include at least one of the citations above, and also include the standard citation for PhysioNet:

Goldberger AL, Amaral LAN, Glass L, Hausdorff JM, Ivanov PCh, Mark RG, Mietus JE, Moody GB, Peng C-K, Stanley HE. PhysioBank, PhysioToolkit, and PhysioNet: Components of a New Research Resource for Complex Physiologic Signals. Circulation 101(23):e215-e220 [Circulation Electronic Pages; http://circ.ahajournals.org/cgi/content/full/101/23/e215]; 2000 (June 13).

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.

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.

Icon  Name                    Last modified      Size  Description
[PARENTDIR] Parent Directory                             -   
[   ] DOI                     2016-04-26 14:07   20   
[TXT] Irms.txt                2016-04-16 16:19  2.6K  
[   ] MD5SUMS                 2016-04-16 16:19  224   
[   ] RECORDS                 2016-04-16 16:19  1.7K  list of record names
[   ] Recording-Info.ods      2016-04-16 16:19   54K  
[   ] SHA1SUMS                2016-04-16 16:19  264   
[   ] SHA256SUMS              2016-04-16 16:19  384   
[DIR] raw/                    2016-04-16 16:20    -

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Updated Friday, 28 October 2016 at 16:58 EDT
PhysioNet is supported by the National Institute of General Medical Sciences (NIGMS) and the National Institute of Biomedical Imaging and Bioengineering (NIBIB) under NIH grant number 2R01GM104987-09.