What is Intracellular Recording?
We have already published an article demonstrating how the NeuroLog System can be used for extracellular recording in vivo and in vitro, but now we turn our attention to how it may be employed for intracellular recording. Intracellular recording is a widely used electrophysiological technique which allow investigators to measure voltage or current across an individual cell membrane. Standard intracellular recordings are made possible through the use of sharp glass micro-electrodes, filled with an electrolyte and connected to a specialist DC voltage-following amplifier of high input impedance and low noise characteristics. The target cell is impaled by the glass micro-electrode, usually under precision micro-manipulator control, allowing the intracellular potential to be continuously monitored by the amplifier throughout an experiment.
Recording with the NeuroLog System NL102G
Many intracellular amplifiers, including our own NeuroLog System DC pre-amplifier module, offer current injection capabilities which allow the intracellular potential and therefore the excitability of the cell to be artificially manipulated. The NL102G DC PRE-AMPLIFIER also features capacitance neutralization, low leakage current and low DC drift. It is particularly suitable for intracellular recording through fluid filled micro-electrodes mentioned above. Electrode attachment to the dedicated compact pre-amplifier headstage is made via our NL111-x ELECTRODE CHAMBERS.
Other features of the NL102G include electrode impedance check, calibrator, stimulus bridge balance, DC level adjustment (±2V) and current injection/monitor. A maximum current injection of up to ±100nA is possible through the front panel control or from an external analogue input.
Current injection occurs either when the toggle switch is moved to the DEP or HYPER positions or in response to an input at the TTL GATE IN socket and/or EXT. STIM. IN socket. Electrode impedance checking and output calibration features can be easily accessed using the controls on the right hand side of the of the NL102G. The timing of these functions can be controlled by other modules or a computer controlled data acquisition interface via the TTL GATE IN socket.
In the setup illustrated above, which would be housed in the NL900D Case & Power Supply Unit, the impedance checking/calibration functions are controlled by a 50ms gating pulse which is generated by other NeuroLog modules once every 200ms. The first NL405 WIDTH/DELAY module delays the pulse from the NL304 PERIOD GENERATOR while the second NL405 gives the duration of the pulse. However, such pulses could possibly be provided by your chosen data acquisition interface/software, making these additonal modules unecessary.
Please note that all newly supplied NL102G DC PREAMPLIFIERS now include a handheld NL412 PULSE unit. This provides a remote BUZZ control which activates the capacitance compensation circuitry briefly in order to facilitate micro-electrode cell penetration.
Find Out More More
The NeuroLog System has been used extensively for research studies involving intracellular recording and you can download related publications from Google Scholar. Please contact us to request the latest copy of the Life Science Product Guide or download it from our website.