Natural sleep modifies the rat electroretinogram.

Abstract

We show here electretinograms (ERGs) recorded from freely moving rats during sleep and wakefulness. Bilateral ERGs were evoked by flashes delivered through a light-emitting diode implanted under the skin above one eye and recorded through electrodes inside each orbit near the optic nerve. AdditI electrodes over each visual cortex monitored the brain waves and collected flash-evoked cortical potentials to compare with the ERGs. Connections to the stimulating and rdng ruments through a plug on the head made data collection posslble at any time without physically disturbing the annl. The three major n gs are (A) Rivers in 1900 (10). If the center exists, nothing is known about its functions, perhaps because these are not likely to be displayed by unanesthesized mamma s, and because it is difficult to deliver quantifiable visual stimuli to an animal free to move its eyes. We believe we have solved both of these problems in rats by implanting a recording electrode behind the eyeball and a small light-emitting diode (LED) beneath the skin above the eye; rats tolerate both of these implants well and have consistently delivered similar b-waves for as long as 3 months. MATERIALS AND METHODSThe LED Stimulus. The implanted LED is a transparent plastic cylinder 5 mm in diameter and 8 mm long (BI-B6334 SQD; Bright LED Electronics, Budapest). It emits red light measuring 300 mcd at its saturation current (2 mA). Its calibration curve (see Fig. 3A) shows its output to be proportional over 3 log units to log duration ofa 4-V square pulse delivered to it. The stimuli used in the experiments were of 3 or 5 msec duration.Implantations. Implants were placed during halothane (1% in air) anesthesia. Electrodes were stainless steel screws (1 x 5 mm) turned into the skull. The ERG electrodes entered the skull about 10 mm rostral to the bregma; they were directed laterally, and at one autopsy the tip was found within the orbit dorsal and anterior to the optic nerve. The visual cortex screws were positioned about 2 mm from the midline and 1 mm rostral to the lambdoid suture. Some animals had additional frontal and auditory cortex electrodes. The reference electrode was placed over the cerebellum %2 mm off the midline and behind the lambdoid suture. The LED was inserted under the skin over the left eye and fixed in place with dental cement. Insulated wires from the LED and electrodes were soldered to leads in a socket attached to the skull in the midline with dental cement.

Temporal distribution of the ganglion cell volleys in the normal rat optic nerve

“…Furthermore, the implanted LEDs radiate photons in all directions (the rat's entire head glows red), which means unquantifiable numbers reach unknowable retinal regions by unknown paths. The LED flash illuminated both retinas about equally in control experiments, and through skull and sclera rather than pupil (1). Responses change for several days after implantation, then stabilize.…”

“…To gain further insights into how information is transferred from retina to brain in such situations, we have been studying behaving rats with light-emitting diodes (LED) attached to the skull and electrodes implanted at the anatomical beginning, middle, and end of the visual system. Flashes of light from the LED, which appear to activate the entire retina (1), are varied in duration to simulate natural exposures such as a lightning flash, or the fixation at the end of a saccade, or an attempt to stare at an object without moving the eyes. We present here four simple experiments in which changes in stimulus parameters are correlated with the responses produced throughout the system.…”

Sleep modifies retinal ganglion cell responses in the normal rat

“…Published details (1,2) can be briefly summarized. Young male Wistar rats, under halothane anesthesia and in a stereotaxic device, are implanted with stainless steel electrodes on the cornea, over each visual cortex, and, for sleep-staging, over the parietal cortex.…”

“…e have been studying the visual system of normal, behaving rats stimulated by a light-emitting diode (LED) permanently attached to the skull (1,2). The red LED flashes activate the entire retina from behind the eyeball and evoke responses at electrodes implanted on the corneal surface of the eye, in the optic chiasm, and at the cortical terminal of the pathway.…”

Using the Electroretinogram to Assess Function in the Rodent Retina and the Protective Effects of Remote Limb Ischemic Preconditioning

“…Neuromuscular blockers and anaesthetic agents are used in ERG experimentation to achieve an unconscious and motionless state. There have only been five reports of awake ERG recordings in rats [16][17][18][19][20] . In these studies, electrodes were surgically pre-implanted into the skull and two of these studies tested the effect of anaesthesia on the ERG 17,20 .…”