Intermittent Photic Stimulation in Rabbit Model: A Technique to Induce Epileptic Seizures and Simultaneously Record Multisystem Parameters

Photic stimulation is a technique where intermittent light flashes elicit a seizure response in epilepsy patients. Since the cardiac activity of rabbits is comparable to that of humans, they are an ideal model for epilepsy research.

Begin with a rabbit secured in a restrainer with EEG and ECG electrodes attached. A restrainer helps acquire readings in a conscious state, omitting the need for anesthesia. Attach a pulse oximeter to the rabbit's ear and mask with capnography tubing over its mouth. These instruments capture respiratory activity to continuously assess oxygenation and ventilation.

Next, place an appropriate light source at the rabbit's eye level. Use mirrors on either side of and behind the rabbit's head to ensure light enters its eyes. Now, flash the light of a low frequency and maximum intensity. Expose the rabbit to light with its eyes open. Then cover the rabbit's face to simulate eye closure, triggering photosensitivity to seizures.

Repeat the experiment by gradually increasing the frequency and then decreasing it. Record the corresponding changes in cerebral and cardiac functions using video EEG and ECG techniques. Subsequently, remove the electrodes and return the rabbit to its home cage for routine care.

For photic stimulation, place a light source with a circular reflector 30 centimeters in front of the rabbit at eye level, with the flash intensity set to the maximum, and place two mirrors on each side of the head, and one mirror behind the rabbit so that the light enters the rabbit's eyes. Attach the light to a controller with an adjustable rate, intensity, and duration.

With the photic stimulator set to 1 Hertz and the flash on, record the response for 30 seconds. Cover the rabbit's eyes with a mask to simulate or cause eye closure and stimulate for another 30 seconds. After recording the eyes-open and eyes-closed response at each frequency, turn off the photic stimulator for 30 seconds and set the controller to the next frequency setting.

After recording for 60 seconds at each frequency from 1 to 25 Hertz in 2 Hertz intervals, decrease the frequency from 60 to 25 Hertz in 5 Hertz increments and record for 30 seconds with the eyes open and 30 seconds with the eyes closed. At the end of the experiment, remove the EEG and ECG leads from the rabbit and return the animals to their home cages for routine care by the husbandry staff.