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Intracellular Recordings
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| Intracellular amplifiers and headstages with PowerLab systems are ideal for recording intracellular potentials. |
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 Electrophysiology is the study of the electrical properties of biological cells and tissues. It involves measurements of voltage change or electrical current flow on a wide variety of scales from single ion channel proteins to whole tissues like the heart. In neuroscience, it includes measurements of the electrical activity of neurons, and particularly action potential activity. Intracellular recordings involves voltage or current measurements across a membrane of a cell.
Intracellular recordings involve measuring voltage and/or current across the membrane of a cell. There are many intracellular recording techniques including: - Voltage Clamp – measures the ionic current across a cell's membrane when the membrane potential is held at a constant
- Current Clamp - measures the membrane potential changes when injecting a constant current into a cell through the recording electrode.
- Patch Clamp – measures voltage or current across ion channels using a blunt a micropipette
- Sharp Electrode Technique – measures the potential inside the cell membrane with a sharp electrode (glass micropipette with a smaller pore)
PowerLab data acquisition systems and Dagan Corporation provide complete solutions that allow researchers to record and analyze intracellular recordings. Note: Equipment supplied by Dagan Corporation is NOT suitable for connection to human subjects. For more information on various applications please visit:
LabChart
LabChart software (for Windows and Macintosh) combines the familiar simplicity of a traditional strip chart recorder with the powerful analysis features of a digital acquisition system. LabChart software and a PowerLab data acquisition unit provide data integrity, easy selection of hardware settings, powerful online and offline analysis, procedure automation, seamless extraction of experimental data and flexible display options. Acquisition and analysis capabilities can be further increased with LabChart Extensions and LabChart Modules. LabChart Modules are available as part of LabChart Pro.
LabChart software is also suitable for evoked potential recordings that do NOT require waveform averaging or if more than two recording channels are required. The triggering option within LabChart is extremely useful to synchronize recordings with a stimulus, while the analog or digital outputs on the PowerLab may be used to control a third-party stimulator. The LabChart software can be used to identify the specific waveform components such as amplitude and latency. LabChart Extensions are free for download from the website for existing LabChart users and they include:
- Event Manager (Win Only): Allows the user to monitor user defined events online using different criteria, and to perform a variety of user defined actions.
- Export Axon (Win Only): Allows the user to save LabChart files in the ABF (Axon binary format) which can be read by pClamp.
- Evoked Response (Mac Only): This extension analyzes physiological responses to a stimulus (evoked response experiments). A number of response parameters can be measured and logged to the Data Pad. This process can be automated to analyze a series of stimuli/response cycles. Physiological responses of neurons to stimuli can be measured include value, latency, peak height, half-width, latency to peak, slope, population spike height and population spike area.
- Peak Parameters (Win or Mac): Allows the user to determine a number of parameters for an individual peak. Parameters calculated include peak height, width, slope and various time parameters. It is useful for determining parameters of action potentials such as cardiac potentials, EPSP and IPSP.
- Read Scope (Mac Only): Read Scope is a LabChart extension which allows LabChart for Mac to read Scope for Mac files directly.
- Export Matlab(Win only): Allows LabChart for Windows files to be saved and exported as MATLAB compatible files. MATLAB is a flexible data analysis program available from The Mathworks Inc. (www.mathworks.com).
- Translate Binary (Win only): Translate Binary is a LabChart extension which allows LabChart for Windows files to be saved and exported in a simple binary format. Translate Binary can import documents that have either been exported from LabChart, or generated by another application.
- Translate EDF (Win only): Allows LabChart to save data as an EDF file, and to read EDF files. Translate EDF does not support the EDF+ format.
- Telegraph (Win only): Makes use of the gain-telegraph output from an electrophysiological amplifier to continue to display data at the correct scale after a gain change. The Telegraph Extension uses the gain telegraph voltage from the amplifier to automate the display of electrophysiological data in LabChart, so that the correct units and scale are used.
Scope
Scope software, supplied with PowerLab systems, provides powerful display, recording and analysis features to transform your computer into a two-channel storage oscilloscope, XY plotter or Power Spectrum (FFT) analyser. Scope is used commonly to measure any high-frequency signal that is time-locked to a stimulus such as action potentials and evoked responses. For analyzing Evoked Potentials, the Scope Software is recommended because it provides signal averaging functions that are necessary to extract the evoked response from background noise.
This software:
- Provides the ability to record, display and analyze any high frequency signal that is time-locked to a stimulus
- Synchronizes sweeps with recorded or built-in stimulation patterns
- Provides a range of real-time and offline analysis features
- Generate stimuli of differing intensities and waveform structures (i.e. single-pulse, multiple pulse, simple ramps) and control an external stimulator using the analog output on the front of the PowerLab.
Therefore, Scope is an ideal software program for recording any type of evoked potential because each successive stimulus and evoked potential may be recorded in a single sweep and the results of multiple sweeps may be superimposed or averaged to minimize signal noise and isolate the evoked potential. Scope is useful in signal averaging techniques to improve the signal-to-noise ratio and minimize artifacts induced by related events such as the blink-response. Using features in Scope such as filtering and spectral analysis, may be used to identify oscillating potentials. The analog output of the PowerLab data acquisition system may be used to control a stroboscopic flash unit (with suitable inputs) for presentation of the light stimuli.
GLP and 21 CFR Part 11
For those researchers working within a laboratory requiring GLP and 21 CFR Part 11 compliance the GLP Client and GLP Server are available for use with LabChart (Windows only) and PowerLab data acquisition systems. For more information, visit the Good Laboratory Practice application page or contact your nearest ADInstruments representative.
Data Recording and AnalysisPowerLab data acquisition systems and LabChart/Scope software are ideal for intracellular recordings due to their ability to record at high sampling rates. The high frequency of neuronal firing rates greatly exceeds the frequency of most other physiological signals. Sampling rates of 40 kHz to 200 kHz are recommended for most intracellular recordings. They include: Intracellular Recording SystemML870B71 Intracellular Recording System includes: Two Electrode Voltage Clamp SystemML870B72 Two Electrode Voltage Clamp System includes: Preamplifiers and Accessories Stimulators
| The relay of high-frequency sensory signals in the whisker-to-barreloid pathway |
| M Deschenes, E Timofeeva and P Lavallee, Journal of Neuroscience, 6887-6787, 2003 |
| Adult rats (250–300 gm) were used to investigate whisker-evoked EPSPs in anesthetized animals………Extracellular and/or intracellular recordings were obtained from VPM and PR5 neurons and from primary afferent axons in the vicinity of the PR5 nucleus. Cells were recorded using glass micropipettes (tip diameter, 0.5 m; DC resistance, 30–40 m ) filled with a K-acetate solution (0.5 M). Once an intracellular recording had been established, EPSPs evoked by manual deflection of individual whiskers were sampled over a 2–10 min period. Then the piezoelectric stimulator was positioned to deflect the principal whisker in different directions with bursts of 10 cycle stimuli. Most VPM and PR5 cells strongly responded to one whisker and more weakly to one to three adjacent whiskers, whereas other cells robustly reacted to the motion of four to eight whiskers; latter units were classified as multiwhisker cells. After the tests, electrical stimulation of the whisker follicle was attempted by inserting two tungsten microelectrodes on each side of the follicle to determine conduction velocity in the pathway. Signals were amplified and low-pass-filtered at 3 kHz by conventional means. Analog signals were digitized at 20 kHz (Powerlab; AD Instruments, Castle Hill, Australia), stored on hard disks, and analyzed off-line using commercially available software (Chart 4.0; AD Instruments; Excel; Microsoft, Redmond, WA). |
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| Micro-opioid receptor agonist effects on medullary respiratory neurons in the cat: evidence for involvement in certain types of ventilatory disturbances |
| P M Lalley, American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, R1287-R1304, 2003 |
| adult cats (3.0–5.7 kg) were anesthetized with halothane in a chamber (5% halothane in oxygen, 5 l/min gas flow) followed by administration through a mask (2.5–3.5%, 2–3 l/min), and then pentobarbital sodium (Abbott Laboratories, North Chicago, IL), 30 mg/kg iv, was given during gradual withdrawal of halothane, thereby maintaining anesthesia………The head of the animal was ventroflexed to allow wide exposure of the dorsal surface of the medulla by occipital craniotomy. The dura and arachnoid membranes were reflected, and patches of pia membrane were removed to allow insertion of fine-tipped glass microelectrodes. A pressure foot was placed gently on the surface of the medulla over the site of microelectrode insertion. A cervical laminectomy (C2–C4 ) was performed, and the dura was cut and reflected for insertion of stimulating electrodes…………Intracellular recordings were obtained with fine-tipped glass micropipettes filled with 2 M K-methylsulfate. DC resistances of the microelectrodes ranged from 50 to 80 M?. Membrane potentials were recorded in bridge or discontinuous single-electrode current-clamp mode with amplifiers for intracellular recording (Bandwidth, DC-10, 000 Hz; SEC 05; npi, Tamm, Germany or Dagan 8500, St. Paul, MN). Neuron input resistance measurements were made by injecting 60- or 80-ms negative-going constant-current pulses through the microelectrode in current-clamp mode and measuring the resulting hyperpolarizing voltage drop across the cell membrane. Electrophysiological data were also acquired and stored on computer and CD with PowerLab hardware and software (AD Instruments, Castle Hill, NSW, Australia). |
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The material on this page is provided in good faith and believed accurate at the time of writing. No responsibility will be taken, or liability accepted, for damages arising from the use of information herein. Readers are urged to check with respective manufacturers the accuracy of all product related information.
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