Photosensitive response mouse model: A potential tool for studying mechanisms of photosensitive epilepsy and initial screening of anti-epileptic drugs.

Numerous studies have investigated the mechanisms underlying photosensitive epilepsy, yet they remain poorly understood. Progress in this field has been substantially hampered by the scarcity of valid animal models and the difficulty in establishing them. Here we presented flashing lights at varying frequencies to head-fixed mice while recording local field potentials (LFPs) in the primary visual cortex (V1). We identified approximately 5 Hz as the resonant frequency for eliciting photosensitive responses. By modulating the luminance within the behavioural chamber we found that the response amplitude diminished with reduced stimulus contrast. Dual-region LFP recordings revealed that the photosensitive response propagated to the medial prefrontal cortex (mPFC), with the response in V1 being both stronger and earlier than those in the mPFC. Acute treatment with pentylenetetrazole (PTZ) enhanced the photosensitive response in V1, whereas chronic PTZ treatment did not. Furthermore we demonstrated that several anti-epileptic drugs effectively attenuated the photosensitive response in both V1 and mPFC. Collectively our findings establish a murine photosensitivity model as a promising platform for the investigation of the mechanisms underlying photosensitive epilepsy and for the initial screening of potential antiepileptic therapeutics. KEY POINTS: The resonant frequency of the photosensitive response in mice is approximately 5 Hz. Photosensitive response decreases as the stimulus contrast reduces, and its response to red light is weaker than that to white light. The photosensitive response can propagate to the medial prefrontal cortex (mPFC) region but does not induce clinical epileptic seizures. Some anti-epileptic drugs can alleviate the photosensitive response.