Microneurography
Overview:
Microneurography is a technique that uses metal electrodes record neural traffic of both myelinated and unmyelinated axons in efferent and afferent neurons of the skin and muscle. Therefore, it can provide information of the neurophysiology of nerve fibers in the peripheral nervous system.
Electrodes of various metals have been used in the past to improve the signal-to-noise ratio. Platinum-iridium was found to be too soft and steel was too brittle. Finally tungsten, which was hard and non-brittle, was used and it was found that an electrode tip (5-10 µm) provided acceptable records of nerve activity. An epoxy-based varnish was also found to provide an acceptable electrode coating.
Microneurography applications include:
- Observing single action potentials from unmyelinated axons
- Studying neural control autonomic effector organs
- Understanding receptive fields of mechanoreceptors
Method:
Microneurography is a wired (tethered) method of recording the activity of peripheral nerves, which are essentially bundles of axons (whole nerve recordings). The electrode (usually silver wire) is placed in contact with the nerve in question.
Microneurography can be performed using the ADInstruments Neuro Amp EX together with a PowerLab data acquisition system. The Neuro Amp EX is a low noise and high gain amplifier which has a wide range of filters and is supplied with the Neuro Amp EX Headstage. The device is certified safe for human connection. Note: The Neuro Amp EX is NOT suitable for intracellular recording. Microelectrodes are NOT supplied by ADInstruments
The Neuro Amp EX in conjunction with PowerLab and LabChart provides:
- Full electrical isolation from power-line (mains) circuitry to guarantee subject safety
- A low-noise, high-gain differential amplifier specifically designed for recording extracellular potentials
- Software-controlled low-pass, high-pass, notch and mains filters to remove unwanted signal frequencies for particular uses
- Audio output to listen to neural signals
For more information see:
- Sympathetic Nerve Activity application page
Software:
The LabChart Advantage:
(may require additional Modules and Extensions)
- Sample up to 200,000 Hz in a single channel (up to 400,000 Hz aggregate) using the 35 series PowerLabs
- Smoothing, Absolute Value, Integration and RMS Arithmetic calculations for quantification of neural activity
- Scope View for spike-triggered averaging and the overlay of evoked responses
- Spike Histogram Module for discrimination analysis of extracellular data
- Peak Analysis Module for analysis of peak heights, half-widths, latency periods, population spike heights, rise times and areas
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 and LabChart Extensions are free for download from the website for existing LabChart users.
Spike Histogram Module
The Spike Histogram Module (Windows or Macintosh) in conjunction with our PowerLab systems provides the capability to record and analyze extracellular spike data in real-time and offline.
Features and benefits include:
- Provides easy to use spike discrimination and spike-sorting using easy to use amplitude and width discrimination, or semi-automated template matching
- Performs auto-correlograms and cross-correlograms analysis
- Saves data in a .nex format for easy transfer to NeuroExplorer software for further analyses (Windows only)
Peak Analysis Module
The Peak Analysis Module (Windows) automatically detects and analyses multiple, non-overlapping peaks in recorded waveforms.
Features and benefits include:
- View automatically detected peaks with highlighted parameter markers, values and peak areas in the Peak Analysis View.
- Log calculated peak parameters to a table and easily export parameters from the table into other programs.
- Select from the default analysis settings available for general and specific signal types. For example, the Population Spike analysis detects and analyses extracellular evoked responses consisting of a spike population superimposed on an excitatory postsynaptic potential.
- Customizable detection and calculation settings to suit your application or waveform.
Scope View
Scope View (LabChart Windows) provides the features of a digital oscilloscope to facilitate recording and viewing consecutive sweeps of data. These sweeps, or pages, can be overlaid and averaged within LabChart. The signal averaging functions are necessary to extract the evoked response from background noise.
There are several powerful features in Scope View that enhance analysis and display including:
- Create pages or sweeps from Comments in Chart View in addition to block mode and Event Mode.
- 3D Depth and Saturation Overlay feature in the Scope Overlay Options to help distinguish overlaid traces.
- Alter the active trace and overlay trace colors.
- Change the display background to black for better contrast.
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.
Hardware:
PowerLab Data Acquisition Systems
The PowerLab is a high-performance data acquisition unit capable of recording at speeds of up to 400,000 samples per second continuously to disk (aggregate). PowerLab units are compatible with instruments, signal conditioners and transducers supplied by ADInstruments, as well as many other third-party companies. In addition to standard single-ended BNC inputs, 4 differential Pod ports are also available for direct connection of Pod signal conditioners and appropriate transducers. Research PowerLab units include:
- PL3504 PowerLab 4/35 - 4 Channels
- PL3508 PowerLab 8/35 – 8 Channels
- PL3516 PowerLab 16/35 – 16 Channels
Signal Conditioners
The FE185 Neuro Amp EX is a low noise and high gain device which makes it suitable for all recording environments requiring a wide bandpass (100 Hz – 5 kHz) and a high signal to noise ratio. It provides a gain of 100x with a 10Hz High Pass filter. The cable shielding is directly connected to the casing, limiting the need for additional shielding at the input terminals. The device is certified safe for human connection with the supplied MLT185 Neuro Amp EX headstage. Also supplied are six male Amphenol connectors for customization of microelectrode adapters (microelectrodes are not supplied). Note: Only a single Neuro Amp EX may be connected to a single PowerLab.
Sympathetic neural responses to mental stress: responders, nonresponders and sex differences
Carter J R and Ray C A, American Journal of Physiology: Heart and Circulatory Physiology, H847-H853, 2009
Hypercapnic vs. hypoxic control of cardiovascular, cardiovagal, and sympathetic function
Steinback C D, Salzer D, Medeiros P J, Kowalchuk J, Shoemaker
J K, American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, R402–R410, 2009
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.
