Electroretinogram Recording in Mice

ERGs were recorded using the Espion E² system (Diagnosys LLC, Littleton, MA) according to published protocols (Saszik et al., 2002 (link)). 8-12 week old mice were dark-adapted overnight and prepared for recordings in darkness using infrared goggles. Mice were anesthetized by intraperitoneal injection of a ketamine/xylazine mixture (75/10 mg/kg). Pupils were dilated with 1% cyclopentolate-HCl, 2.5% phenylephrine (~2.8 mm in diameter). A drop of the Gonak solution (Akorn, Buffalo Grove, IL) was placed on the cornea. Recordings were performed simultaneously from both eyes with silver loop electrodes supplemented with contact lenses to keep the eyes immersed in Gonak solution. This prevented eyes from drying and cataract development during recording periods of up to 60 min. The reference electrode was a toothless alligator clip wetted with Gonak and attached to the mouse cheek. Mouse body temperature was maintained at 37°C using a Deltaphase Isothermal Pad (Braintree Scientific, Braintree, MA). ERG signals were sampled at 1 kHz and recorded with 0.15 Hz low frequency and 500 Hz high frequency cut-offs.