TOUCH/TOUCH – Celeris

What is TOUCH/TOUCH

TOUCH/TOUCH protocols utilize Celeris's dual-function electrode-stimulators, allowing independent stimulation of each eye. This enables the unused eye to serve as a reference electrode, eliminating the necessity for a reference needle electrodes in the snout. This setup is faster, produces less baseline noise, and eliminates much of the variability caused by electrode placement.

TOUCH/TOUCH protocols

For the latest version of protocols, please contact Diagnosys Support.

Light Adapted ERG: Flashes of light on a light background test the cone pathway (ERG) and amacrine cell response oscillatory potentials (OPs)

Dark Adapted ERG: Flashes of light on dark background test the rod pathway (ERG)

Dark and Light Adapted ERG: Flashes of light on both light and dark backgrounds that test both rod and cone pathway function

Photopic Negative Response (PhNR): Green flashes on a white background to elicit retinal ganglion cell response

Flicker Frequency Series: Gradually increasing flicker frequencies starting from 0.5 to 30 Hz drive a cone-dominant response

C-wave: Flash of light on a dark background followed by a very long recording time to measure retinal pigmented epithelium (RPE) response

Scotopic Threshold Intensity Series: Extremely dim flashes of light on a dark background may be used to determine the light perception threshold. Note that this protocol requires dim flash range stimulators.

General tips

For optimal results, consider anesthesia, eye preparation, and animal positioning. For detailed instructions on positioning the electrode-stimulator, follow these instructions.

Electrode setup

The electrode setup for a TOUCH/TOUCH protocol is simple. All you need are the two stimulator-electrodes. Plug both eyes into channel 1.

Plug Right Eye into Channel 1+
Plug Left Eye into Channel 1-

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FAQs

Are there any exceptions for using a TOUCH/TOUCH protocol?

Yes. Intracranial stimulation may occur at very bright flash intensities. Intracranial stimulation occurs when light passes through the stimulated eye, traverses the brain tissue, and reaches the retina of the other eye. Therefore, TOUCH/TOUCH is not suitable for flash intensities that exceed approximately 10 cd.s/m2.

Will a TOUCH/TOUCH protocol take twice as much time as a traditional ERG?

No. It is standard to wait between 1-30 seconds between flashes, depending on stimulus intensity and light adaptation. It is during this period of time that the fellow eye is stimulated. For this reason, the TOUCH/TOUCH method does not significantly increase the duration of testing.

Is the TOUCH/TOUCH method reproducible?

Yes. We conducted an experiment on young, adult, pigmented mice to contrast a TOUCH/TOUCH setup with a traditional ERG Active/Reference/Ground configuration. The variability observed with the TOUCH/TOUCH protocol was approximately 4%, whereas the corresponding Active/Reference/Ground setup exhibited a variability of 15%. The graph below shows data from a TOUCH/TOUCH recording (top waveforms) alongside those measured with Active/Reference/Ground (bottom waveforms) on the same mouse, during the same recording session.

References