EOG
Overview:
The electro-oculogram (EOG) records eye movements via a voltage difference between the cornea and retina. As the eye moves, the vector of this electric field changes with respect to a reference electrode. At least 2 biopotential channels are required when recording eye movements to assist in distinguishing eye movement potentials from other signal artifacts.
Method:
Eye movements may occur slowly or rapidly, thereby requiring DC or AC-coupled amplifiers, respectively. Slow-tracking eye movements occur at 30-40 Hz (a feature used in humans to track distant moving objects and slow-moving near objects). The tracking movements of the eye become rapid (900 Hz) and the eye moves back and forth very quickly when the object is moving rapidly.
These bioelectrical signals are typically very small in amplitude (µV) and an amplifier is required to accurately record, display and analyze the EOG. Depending on the hardware and software used, the biological amplifier serves not only to amplify the signal but also to apply a range of filtering options for the removal of unwanted signal artifacts. ADInstruments offer a range of Bio Amplifiers suitable for use with animals as well as units certified safe for use with humans. A PowerLab data acquisition system can be used with other brands and models of amplifier to record the EOG, provided they have a suitable analog output (Maximum ± 10V).
Electrode Configurations
Two Channel Configuration
In this configuration, one electrode is placed slightly above the outer canthus of the right eye, whilst the other is placed slightly below the outer canthus of the left eye. Reference electrodes are placed at the contralateral (opposite) ear or mastoid processes. Because eye movements are largely binocularly synchronous in both sleeping and awake subjects, this electrode configuration will provide out-of-phase deflections for most types of eye movements. However, it does not permit differentiation between horizontal and vertical eye movements and provides no information about the direction and size of eye movements.
Four Channel Configuration
A four channel configuration is recommended when the researcher wishes to obtain information about the direction and size of eye movements. This requires that electrodes are placed horizontal to the outer canthi as well as infraorbital and supraorbital, with all electrodes paired with a similar ear, mastoid or supranasion electrode.
Specific information about eye positions requires a DC-coupled recording. The ADInstruments ML317 EOG Pod is an electrically isolated DC-coupled device that provides additional information about eye movement direction and is useful for the investigation of tracking, saccadic movements and nystagmus. Two EOG Pods will be required for recording both vertical and horizontal eye movements. This device is intended more for teaching applications, and thus limited for long-term research applications.
Note: ADInstruments multi-channel amplifiers will provide out-of-phase deflections (depending on electrode configuration) for most types of eye movements as they are AC-coupled recordings.
For more information see the ERG (Electroretinogram) application page.
Software:
LabChart
LabChartsoftware (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.
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:
Bio Amplifiers
The biopotentials are typically very small in amplitude (µV). Therefore accurate recording, display and analysis of an EOG require a suitable bioamplifier. ADInstruments offer a range of Bio Amplifiers that when connected to a PowerLab data acquisition unit are certified safe for use with humans or used with animals. These bioamplifiers are fully software-controlled using LabChart or Scope. The following ADInstruments' biological amplifiers are fully isolated for connection to human or animal subjects:
Human EOG
The following ADInstruments' biological amplifiers are independently certified to comply with international safety standards and are fully isolated for connection to human subjects:
ML132 Bio Amp
- A single channel, differential amplifier that is suitable for recording a range of biopotentials such as EEG, ECG, EMG or EOG.
- Supplied with a MLA2340 3 Lead Shielded Bio Amp Cable
- Supplied with MLA2503 Shielded Lead Wires (3 snap-on)
- A dual channel, differential amplifier that is suitable for recording 2 independent biopotentials that share a common ground.
- Supplied with an MLA2540 5 Lead Shielded Bio Amp Cable
- Supplied with MLA2505 Shielded Lead Wires (5 snap-on)
- A dual channel, differential amplifier that also includes an isolated stimulator suitable for mild electrical stimulation of human subjects (i.e. Evoked EMG studies).
- Supplied with an MLA2540 5 Lead Shielded Bio Amp Cable
- Supplied with MLA2505 Shielded Lead Wires (5 snap-on)
- Supplied with MLADDB30 Recording Bar Electrode
The Bio Amp, Dual Bio Amp and Dual Bio Amp/Stimulator are manufactured for use with PowerLab data acquisition systems and are fully software-controlled by LabChart or Scope. These Bio Amps cannot be used for recording 3 or more biopotentials on a single subject; however, they may be used for multiple subjects that have separate grounding leads. For recording more than 3 biopotentials from a single subject see below:
Multiple-Channel EOG Recordings
ADInstruments also provides multiple channel bioamplifiers that connect directly to PowerLab data acquisition systems. These units are also fully-isolated, and independently certified, for connection to human subjects.
ML138 Octal Bio Amp
- A differential amplifier that consists of eight electrically isolated differential input AC amplifiers
- A shared ground connection across all eight inputs.
- Supplied with two packets of MLA0310 Lead Wires (1.8 m, 10 snap on)
- A fully isolated, 16 channel stand-alone biological amplifier that consists of 8 modules, with each module containing two channel amplifiers that share a common ground input
- Suitable for unipolar and bipolar recordings
- Electrodes are NOT supplied and must be ordered separately
- Suitable electrodes and lead wires include the:
- MLAWBT9 Flat EEG Electrodes for recording ECG, EEG, EOG and EMG
- MLA0315 Lead Wires (unshielded, 5 snap on)
- MLA1010B Disposable ECG Electrodes
Animal EOG
The following ADInstruments' biological amplifiers for use with animals (i.e. pithed toad, or anaesthetized rat/mouse) only:
ML136 Animal Bio Amp
- An isolated, high performance and software-controlled differential amplifier
- Has three 2mm input sockets allow the direct connection of electrodes to this amplifier
- Supplied with MLA1215 Animal Bio Lead Wires
- Also suitable for use with
Pods
ML317 EOG Pod
- Use in the detection of eye movement and position.
- Electrically isolated
- Supplied with MLA2503 Shielded Lead Wires (3 snap-on) that connects to the MLA1010B Disposable ECG Electrodes.
- Plugs directly into any PowerLab Pod port or the ML305 Pod Expander
Accessories
Bio Amp cables:
- MLA1340 3 Unshielded Lead Bio Amp Cable
- MLA1540 5 Unshielded Lead Bio Amp Cable
- MLA2340 3 Shielded Lead Bio Amp Cable
- MLA2540 5 Shielded Lead Bio Amp Cable
Leads compatible with both shielded (MLA2340 & MLA2540) and unshielded (MLA1340 & MLA1540) cables:
- MLA1505 Unshielded Lead Wires (5 alligator clip)
- MLA0311 Unshielded Lead Wires (1 m, 10 Snap on)
- MLA0310 Unshielded Lead Wires (1.8 m, 10 snap on)
- MLA1203 Needle Electrodes (29 gauge, 5)
Leads compatible with shielded cables (MLA2340 & MLA2540) only:
- MLA1605 Shielded Lead Wires (5 alligator clip, 25 cm)
- MLA1610 Shielded Lead Wires (5 Micro-Hooks)
- MLA1615 Shielded Lead Wires (5 Alligator Clip, 100 cm)
Leads that directly connect to the Dual Bio Amp
Leads that directly connect to the Animal Bio Amp
Electrodes:
Consumables:
Feature-specific electrophysiological correlates to texture segregation
M Fahle; T Quenzer; C Braun and K Spang, Vision Research, 7-19, 2003
Menstrual cycle effects on postural stability but not optokinetic function
C L Darlington; A Ross; J King and P F Smith, Neuroscience Letters, 147-150, 2001
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.
