EOG Pod

The ML317 EOG Pod is a signal conditioner designed to record horizontal and vertical eye position and movement. In the human the EOG Pod can be used in the measurement of saccadic and pursuit eye movements. It is ideal for use in undergraduate teaching laboratories. The device features a manual DC offset and is supplied with three shielded lead wires with snap-on connectors.


System Compatibility:

The EOG Pod connects to any PowerLab hardware units with Pod ports (8-pin DIN inputs). PowerLab and MacLab (except 4s, 8s and 16s) units without Pod ports require the ML305 Pod Expander.

The EOG Pod is supported by the following versions of LabChart and Scope software:

WINDOWS

• LabChart v3.4.8 or later

• Scope v3.6.3 or later

MACINTOSH

• LabChart v3.6.3 or later

• Scope v3.6.3 or later

Note: Earlier software versions do not support Pods.

Theory of Operation:

The EOG Pod is a DC coupled biopotential amplifier with a fixed low-pass filter (500 Hz) to remove high frequencies. On the front of the Pod, an offset knob is provided to remove DC drift. The offset control provides ±15 mV of offset range (at input) for all range selections. The EOG Pod utilizes the steady corneal-retinal potential in the detection of eye movement and position. This steady dipole may be used to measure eye position by placing surface electrodes to the left and right of the eyes. When the gaze is straight ahead, the steady dipole is symmetrically placed between the two electrodes, and the EOG output is approximately zero. When the gaze is shifted to the left, the positive cornea comes closer to the left electrode, which becomes more positive. There is an almost linear relationship between horizontal angle of gaze and EOG output (approximately ±30° of arc). Electrodes can also be placed above and below the eye to record vertical eye movements and using two EOG Pods, simultaneous vertical and horizontal eye movements can be measured.

Stacking and Unstacking Pods:

Pods stack by clicking into place on top of each other. To separate stacked Pods, push the top Pod towards the back and then pull them apart from the back.

The ML317 EOG Pod is supplied with three snap-on connector shielded lead wires which snap connect to conductive (Ag/AgCl) adhesive electrodes (MLA1010).