Understanding Epilepsy Through a New Mouse Model

Epilepsy affects most individuals with tuberous sclerosis complex (TSC), yet the link between small cortical abnormalities and seizure generation is not fully understood. A new study published in Frontiers in Molecular Neuroscience, coauthored by Noldus' Jason Rogers, asked a focused question: is a small, localized disruption in the frontal cortex enough to trigger epilepsy and related behavioral changes? The answer was yes — and the work shows how automated behavioral tracking can support this kind of research.

Modeling tuberous sclerosis and focal epilepsy

TSC is caused by mutations in the genes Tsc1 or Tsc2, which alter the mTOR pathway and affect cell growth. Many patients develop focal cortical lesions, known as tubers, that are strongly associated with seizures. It has been unclear whether such focal abnormalities alone are sufficient to create epileptic networks, or whether more widespread developmental changes are required. To test this directly, the team deleted Tsc2 in a very small area of the frontal cortex shortly after birth, isolating the effects of a discrete lesion without disrupting the rest of the brain.

The impact of a targeted Tsc2 deletion

Even though the lesion was small, its impact was significant:

• All mice with the focal Tsc2 deletion developed spontaneous seizures during EEG monitoring.
• The affected neurons were enlarged and showed hyperactivation of the mTOR pathway.
• Surrounding cortical tissue contained fewer inhibitory interneurons and showed increased microglial activation.

Connecting cellular changes to behavior

The team examined how the focal lesion influenced natural exploration. Mice were placed in an open field arena for thirty minutes while their movement was tracked with EthoVision. Mice with the Tsc2 deletion explored the arena but avoided the center, displaying high thigmotaxic behavior (staying close to the walls), often interpreted as increased anxiety. Importantly, the groups did not differ in total distance traveled — the shift in exploration strategy was not caused by reduced mobility but by a change in how the animals chose to explore the space.

How EthoVision contributed

EthoVision provided reliable, high-resolution movement data, letting the researchers quantify center time, thigmotaxis, and locomotor activity without manual scoring. Automated tracking is especially helpful in TSC and epilepsy research, where many behavioral changes are subtle and consistent quantification is important when linking behavior to cellular and network-level findings.

A model that supports future research

This focal TSC model brings together several important features of the disorder: seizures, altered inhibitory circuits, neuroinflammation, and changes in exploration. Because the lesion is small and well defined, the model can help researchers investigate how specific cortical disruptions lead to epileptic activity and behavioral consequences. By combining EEG, histology, and automated behavioral tracking, the researchers created a comprehensive picture of how focal pathology affects the whole animal.

Source: Noldus blog. Reference: McCoy et al. (2025), Focal postnatal deletion of Tsc2 causes epilepsy, Front. Mol. Neurosci. 18:1686023.