8. Epileptic seizures in adult mice with partial cortical deafferentation

Traumatic brain injury is a major risk factor for epileptogenesis. Understanding and preventing trauma-induced epileptogenesis (TIE) will prevent epilepsy and therefore significantly increase the quality of life of patients. We aimed to test the age-dependency of TIE in a mouse model of cortical undercut. Because the efficacy of homeostatic plasticity processes decreases with age, we hypothesized that cortical trauma will induce epilepsy in adult, but not young animals. We performed undercut in the somatosensory area in C57/BL6 young (3 months) and adult (12–14 months) mice and implanted LFP electrodes in diverse cortical areas and EMG electrodes for chronic recordings. The electrographic activities were recorded continuously for at least two months. Almost all animals generated acute seizures of variable morphology within the first 10 h from lesion. In young animals only isolated interictal spikes were recorded afterwards. In the following weeks, all but one old mouse revealed recurrent seizure activities of different types. The most common type was 8–16 Hz spindle-like oscillation in frontal cortex accompanied with an increase in the muscle tone and either body freezing or rhythmic contractions. The lower frequency (3–6 Hz) seizures were generalized and accompanied by behavioral freezing and low muscle tone or by rhythmic muscle and body contractions. The low frequency (1.5–3 Hz) seizures were accompanied with rhythmic muscle contractions. We conclude that TIE is age-dependent and is likely due to an uncontrolled homeostatic up-regulation of excitation in adult animals. Supported by CIHR, NSERC, and FRQS