Creation Of Caudate Putamen-hippocampal Epileptic Network And Its Behavioral Expression

The electrographic and behavioral kindling effects were induced by chronic tetanization of the right caudate-putamen (CPu) or the right hippocampus (HPC) to study the target-behavior expression involved in the CPu or HPC network abnormalities. Experiments were performed on 58 SD rats weighing 45~65 g. Tetanization (60Hz, 0.4~0.6mA, 2s) was delivered into the CPu or into the HPC, once a day, for 7~12 days. Animal behaviors were observed every day and CPu or HPC depth electrographs were recorded at the beginning or at the end of the experiments. Results demonstrated that the CPu or the HPC network abnormalities might be induced by chronic tetanization: (1) rhythmic sharp waves occurred in the CPu and paroxysmal epileptiform events were observed in the HPC electrographs on the ipsilateral side. Seizure-like network oscillations with changeable frequency and amplitude were recorded in the right CPu. Kindling effects were observed in the contralateral CPu or HPC electrographs. (2)evoked primary behavioral seizures, secondary behavioral seizures, and kindling effects included wet dog shakes(WEDS), rearing, face wash, immobility, chewing and head nodding. WEDS emerged first, then other behavioral manifestations were observed. (3)compared with HPC-tetanized rats, much lighter primary WEDS (P<0.01) and much severer secondary WEDS (P<0.01) happened in the CPu-tetanized rats. (4) the peak of secondary WEDS rate was at the 4 th stimulating day. (5) much longer silent period of behavioral seizures before kindling appeared in the CPu-tetanized rats. The results suggest that kindling effects in the CPu-tetanized rats resembles those in the HPC-tetanized rats. The CPu might participate in the origin of epileptic focus and be involved in reestablishment of limbic epileptic networks, which may be responsible for the target-behavioral seizures.