For comments, questions and suggestions or to report a bug contact: Paul Kullmann (pkullman@pitt.edu)

most recent version: G-clamp 2.1.1

System requirements: LabVIEW-RT 8.0 (or higher), DAQmx

Download:

• G-clamp v2.1.1 Software
• G-clamp v2.1.1 User Manual

An update on possible hardware configurations:

1) When G-clamp was originally developed (as described in J. Neurophysiol. 91:542-554, 2004) the only available platform for embedded real-time controllers was the PXI-system. Since then National Instruments has introduced other platforms for real-time targets of which the PC-based solution is a possible alternative for G-clamp. In this case, instead of using a PXI controller running under a real-time operating system (together with the PXI version of the data acquisition board), a conventional PC (equiped with the PCI version of the data acquisition board) is booted into the real-time operating system and serves as the embedded controller for G-clamp (for details see "NI Real-Time Hardware" and "Requirements for a Desktop PC as a Real-Time Target"). Both systems use the same internal bus architecture (PCI) to transfer data between system components. The extended features of the PXI system (PXI stands for 'extended PCI') are additional bus lines to synchronize multiple PXI modules within a PXI chassis. As a typical G-clamp PXI system has only one module - the data acquisition board - these enhanced synchronization features are not required and not used. Thus, a PC (together with the license for the real-time operating system) is now a more cost-efficient alternative to what could be done a few years ago only with a PXI system.

2) Also, when G-clamp was originally developed (as described in J. Neurophysiol. 91:542-554, 2004) the data acquisition boards of choice from National Instruments for intracellular electrophysiological applications were the E-series multifunction (analog/digital input and output) boards. Since then, National Instruments has introduced a new family of multifunction boards ('M-series') which offer enhanced features and improved performance at similar or even less cost. Because the driver software (DAQmx) handles both board types, G-clamp can be used with either type.

Revision history of G-clamp 2

Feb. 15, 2008: G-clamp v2.1.1

• Fixes a bug in the single-point data acquisition procedure used in the dynamic clamp feedback loop to result in an error and to return no data. This bug was encountered under a specific set of conditions (LabVIEW-RT 8.2, DAQmx 8.3 and M-series data acquisition board) and it is not clear which of these conditions is the actual culprit.

Jan. 25, 2008: G-clamp v2.1

• Triggering/gating an external device now possible when using Model 2400 or MultiClamp 700B amplifier
• Support for the use of an additional amplification stage after the recording amplifier added

Oct. 19, 2007: G-clamp v2.0.1

• Amplifier module for MultiClamp 700B added
• Automatic updating of memory usage information of the embedded controller now after every experiment.
• Changes to event file specifications:
• Events do not have to be sorted in ascending order anymore
• Events specified to start at identical times now start simultaneously and not any more in subsequent cycles of the dynamic clamp loop
• Fixed Bug: Real-time performance of Threshold-g_syn and Synaptic Gain modules could break down under certain specific conditions
• Fixed Nuisance: After long (>10 sec) recordings with the Synaptic Gain module G-clamp remained unresponsive for some time after transferring the data to the host computer

Feb. 1, 2007: First release of G-clamp v2.0

• Plug-in architecture for experiment modules on embedded controller and host computer facilitates modification of existing and addition of new experiment modules 
• Integrated seal and membrane test functions similar to PClamp plus integrated bridge test function
• Simulation mode to test the kinetic behavior of a voltage dependent conductance with a model cell and running the amplifier in voltage clamp
• Logging of experimental settings to an ASCII text file
• Adaptable to different recording amplifiers by using amplifier-specific plug-in modules, therefore capable of using telegraph-feature of recording amplifier (amplifier modules available for AxoClamp 2B and A-M Systems Model 2400)
• Template files for patterns of synaptic activity have been replaced with event files that specify the timing of virtual synaptic events with the kinetic of virtual synaptic events now user-selectable
• Threshold-g_syn and Synaptic Gain module can now use either only a single or multiple event files with user-settable reversal potentials for each individual event file
• Integrated monitoring of memory usage on the embedded controller

Site last updated: Jan. 25, 2008