Test Environment and Room Setup

Sections in this Article:

• Electrical Environment
• Dark Room
• Animal Recovery Area
• Software

Electrophysiology is sensitive to various environmental factors. Please consider potential electrical interference from nearby electronics and machinery, as well as any sources of ambient light.

Electrical Environment

When conducting electrophysiology, be aware that all electronic devices emit electromagnetic radiation that can interfere with test results. If you notice a very regular sinusoidal frequency overlaying your graph, make every attempt to minimize the electrical noise coming from your testing area. To minimize the amount of electrical noise affecting your recording, check the following: 

Example of Electrical Noise

Mitigate Electrical Noise 

1. Plug the line cord of the Celeris and associated laptop directly into a grounded wall outlet, do not plug it into a power strip. Avoid lights with dimmer switches that often create 100 or 120 Hz noise. If possible, have the Celeris on a non-metallic tabletop. 

2. If possible, have the room on a separate circuit. Make sure the circuit is properly grounded. At a minimum, large electrical systems such as HVAC, cage washers, servers, elevators, etc should be as far away as possible. Any other medical devices in the same room should be powered off. 

3. Keep USB and power cords spaced apart. To avoid crosstalk, these cables should not overlap. Ferrite rings may also be used around USB cables to insulate the signal. 

4. If electrical noise persists, try enabling the 50/60 Hz line filter. 

Dark Room

Animals should be dark adapted overnight, or for a minimum of 3 hours.

Mice, rats, and rabbits are dichromatic animals that only have green and blue cones. Thus, red light can be used in dark rooms without jeopardizing dark adaptation. The graph below represents the light sensitivity curves of mice. Notice that mice can detect up to 630 nm of red light, while a wavelength of 670 nm is outside of their visual range. Therefore, dim, dark red lights are best suited for dark room condition.

Mouse Light Sensitivity Curves

Ensure the testing room is entirely dark when the main lights are off, using only the minimal red light necessary for the technician's visibility. Eliminate all sources of ambient light. To block light seeping in from under the door, install a door sweep or draft blocker. Cover any device indicator lights with black electrical tape. Computer monitors should be equipped with red filters and positioned away from the animals being tested.

Red light sources recommended by Diagnosys

• Bulb: https://www.amazon.com/dp/B07TDP67LR?th=1 
• Pen: https://www.amazon.com/gp/product/B07MCZHMMP 
• Stylus: https://www.amazon.com/gp/product/B00008BFS2?th=1
• Headlamp: https://www.blackdiamondequipment.com/en_US/product/flare-headlamp/ 
• Baseball cap: Diagnosys product D394
• Screen filter: Diagnosys product 15128

Animal Recovery Area

Animals recovering from anesthesia will need help with maintaining body temperature. Be aware that heating elements can generate electrical noise, so mindfully place them away from the testing area. Check the baseline of a recording to evaluate environmental noise. 

Software

ERG data recorded in the lab may be analyzed using a separate computer. Each Celeris purchase includes 2 additional software licenses, more may be purchased. Exporter software is also available for bulk exportation of data. https://info.diagnosysllc.com/software 

References

Peirson SN, Brown LA, Pothecary CA, Benson LA, Fisk AS. Light and the laboratory mouse. Journal of Neuroscience Methods. (2018) 26-36.