Extracellular Recordings

Overview:

Electrophysiology is the study of the electrical properties such as voltage change or electrical current flow on a wide variety of scales from single ion channel proteins to whole organs, such as the brain. In neurophysiology, it includes measurements of the electrical activity of neurons and particularly action potential activity.


 

Method:

Extracellular Recording

Extracellular recordings involve recording potentials outside the cell, i.e. in the extracellular fluid. However, by definition, this is not limited to the extracellular fluid. Extracellular recordings include:

• Single Unit Recording – records the electrical activity of a single one neuron with a small tip electrode
• Multi-Unit Recording – records electrical activity generated by several neurons
• Whole Nerve Recordings - records the activity of peripheral nerves, which essentially are bundles of axons. Recording techniques include:
  • Wired – An electrode (usually silver wire) is placed in contact with the nerve of interest. ADInstruments NeuroAmp EX can be used for whole nerve recordings in animals and humans (certified safe for human connection).
  • Telemetry – The sympathetic nerve activity (SNA) series of transmitters and receiver by Telemetry Research (TR) enable recording of nerve activity in conscious freely moving animals.
• Field Potentials - represent the integration of synaptic current within a local volume surrounding a single electrode tip. Field potentials are characterised by their slow frequency (< 200 Hz). Because the signals reflect a spatiotemporal sum of membrane currents, it is a useful technique for measuring the degree of synchronicity among neurons in small areas. With high-pass filtering it is possible to measure the much faster action potentials within the signal (e.g., > 300 Hz). Spike-sorting algorithms can also be used to determine individual neuronal contribution to the signal.
  • EEG – Consists of a set of field potential recordings for measuring the degree of cortical synchronicity over large areas.

For more information on various applications please visit:

• Intracellular Recordings application page
• Patch & Voltage Clamping application page
• Evoked Potentials application page
• Microneurography application page

Software:

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.

Useful LabChart Extensions

• Event Manager (Win): Allows the user to monitor user defined events online using different criteria, and to perform a variety of user defined actions..
• Evoked Response (Mac): 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 (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.
• Export MATLAB (Mac or Win): Allows LabChart for Windows files to be saved and exported as MATLAB compatible files.
• Translate Axon (Win): Allows the user to save LabChart files in the ABF (Axon binary format) which can be read by pClamp
• Translate Binary (Win): 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): Allows LabChart to save data as an EDF file, and to read EDF files. Translate EDF does not support the EDF+ format.
• Telegraph (Win): 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.

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.
• Events in Blood Pressure and ECG Module can be used to generate pages in Scope View.
• 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

Research Systems

PL3508B73 Extracellular Recording System includes:

• PL3508 PowerLab 8/35 (LabChart software)
• MLS260 LabChart Pro software
• MLA190 19" Rack Adapter
• DP-311 Differential Amplifier with Active Headstage
• ESW-F15N E Series Electrode Holder (Str, Ag Wire, 1.5 mm)

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.

Instruments

Extracellular Amplifiers

• DP-301 Single Channel Differential Amplifier
• DP-304-V Four Channel Differential Amplifier
• DP-311 Single Channel Differential Amplifier with Active Headstage
• AM3000H AC/DC Differential Amplifier (teaching)
• 2400A Extracellular Preamplifier

Note: With a suitable extracellular headstage an intracellular amplifier can also be used to make extracellular recordings.

Intracellular Amplifiers/Voltage Clamp

• IX1 Single Channel Intracellular Preamplifier

Stimulators

• STG4004 4 Channel Stimulus Generator
• STG4008 8 Channel Stimulus Generator 
• ML1001 Electronic Stimulator
• ML1101 Stimulus Isolator

Transducers and Accessories

Electrode Holders

For the complete range of electrode holders click here:

• ESW-F10N E Series Electrode Holder (Str, Ag Wire, 1.0 mm)
• ESW-F10V E Series Electrode Holder (Str, Vent, Ag Wire, 1.0 mm)
• ESW-F12N E Series Electrode Holder (Str, Ag Wire, 1.2 mm)
• ESW-F12V E Series Electrode Holder (Str, Vent, Ag Wire, 1.2 mm)
• ESW-F15N E Series Electrode Holder (Str, Ag Wire, 1.5 mm)
• ESW-F15V E Series Electrode Holder (Str, Vent, Ag Wire, 1.5 mm)
• ESW-F20N E Series Electrode Holder (Str, Ag Wire, 2.0 mm)
• ESW-F20V E Series Electrode Holder (Str, Vent, Ag Wire, 2.0 mm)
• ESW-M10P E Series Electrode Holder (Str, Port, Ag Wire, 1.0 mm)
• ESW-M12P E Series Electrode Holder (Str, Port, Ag Wire, 1.2 mm)
• ESW-M15P E Series Electrode Holder (Str, Port, Ag Wire, 1.5 mm)
• ESW-M20P E Series Electrode Holder (Str, Port, Ag Wire, 2.0 mm)

Note: Selection is based on the outer diameter of user’s glass electrode

Extracellular Headstages

• MLT185 Neuro Amp EX headstage (for FE185 Neuro Amp EX)
• 3110W Headstage (for DP-311 Differential Amplifier)
• 2410A Capacitance Compensation Probe (for 2400A Extracellular Preamplifier)
• 8024-15 Extracellular Headstage (for use with intracellular amplifiers such as IX1)
• 8024-7001 Dual Intracellular & Extracellular Headstage (for use with intracellular amplifiers such as IX1)

Cables

• PJ2-5 2 mm Jack Uninsulated for DP-311 (pack of 5)
• IC-2S Input Cable set for DP-304-V (2 pack)
• IC-4M Input Cable set w/alligator clip for DP-304-V (2 pack)

Identification of functional intramuscular rectal mechanoreceptors in aganglionic rectal smooth muscle from piebald lethal mice
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Anterograde transneuronal viral tract tracing reveals central sensory circuits from white adipose tissue
Song C K, Schwartz G J, Bartness T J, American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, R501–R511, 2009

Activation of Lumbar Spinal Wide-Dynamic Range Neurons by a Sanshool Derivative
Sawyer C M, Iodi Carstens M, Simons C T, Slack J, McCluskey T S, Furrer S, Carstens E, Journal of Neurophysiology, 1742–1748, 2009