Temporal lobe epilepsy animal model established by stereotaxic microinjection of kainic acid

BACKGROUND： Kainic acid can be used to induce a model of epilepsy by systemic injection, such as intraperitoneal or subcutaneous injection. Individual rats have different responses to kainic acid, therefore high doses of drug are required and the success rate of model induction is low. It is necessary to develop an improved method to establish a temporal lobe epilepsy （TLE） animal model. OBJECTIVE： To explore an economic, stable and efficient method of establishing a TLE animal model. DESIGN, TIME AND SETTING： A completely randomized, controlled study. The experiments were performed in the Cellular Function Laboratory of the Physiology Department, Anhui Medical University from March to July 2007. MATERIALS： Twenty adult male Wistar rats, weighing 230-260 g, were provided by the Experimental Animal Centre of Nanjing Medical University. Kainic acid was purchased from Sigma in USA. Type SN-2 stereotaxic apparatus was made by Narishge in Japan. METHODS： Wistar rats were randomly divided into a kainic acid （KA） group （n = 12） and a normal saline （NS） group （n = 8）. For intrahippocampal microinjection, a burr hole was drilled in the skull at the following stereotaxic coordinates： anteroposterior （AP） 4.1 mm caudal to bregma; lateral （ML） 4.2 mm right lateral to the midline. Rats in the KA group were injected with 2.5 μL KA （0.4 g/L） into the center of the CA3 region, while in the NS group the same volume of NS was injected into the same site. MAIN OUTCOME MEASURES： Both groups were monitored under a video capture system for 12 weeks to record spontaneous seizures. Intracranial eletroencepholograph （IEEG） recordings in vivo were performed after the behavioral observations. After the IEEG recordings, hippocampi were processed into coronal sections. Nissl and Timm stainings were then performed to observe and confirm pathology. RESULTS： Twenty rats were involved in the final analysis. Behavioral observations： the eadiest spontaneous onset of epilepsy appeared 2 weeks after injection of KA. Eight rats had spontaneous onset of epilepsy 3-12 weeks after treatment. None of rats in the NS group had spontaneous onset of epilepsy. IEEG recordings： Epileptic-form waves, such as sharp waves and spike waves, were calculated by artificial analysis The number of epileptic-form waves in the KA group increased significantly compared to those of the NS group （P 〈 0.01）. Morphology results： In the KA group, Nissl staining and Timm staining revealed typical pathology in the hippocampal temporosphenoid lobe. In the NS group, no pathology was observed. CONCLUSION： Intrahippocampal microinjection of KA is a reliable method to establish a temporal lobe epilepsy animal model, requiring low doses of kainic acid and giving a high rate of success.

Changes in the default mode network in the prefrontal lobe, posterior cingulated cortex and hippocampus of heroin users

The default mode network is associated with senior cognitive functions in humans. In this study, we performed independent component analysis of blood oxygenation signals from 14 heroin users and 13 matched normal controls in the resting state through functional MRI scans. Results showed that the default mode network was significantly activated in the prefrontal lobe, posterior cingulated cortex and hippocampus of heroin users, and an enhanced activation signal was observed in the right inferior parietal Iobule （P 〈 0.05, corrected for false discovery rate）. Experimental findings indicate that the default mode network is altered in heroin users.

A novel SSA-CCA framework for muscle artifact removal from ambulatory EEG

Background Electroencephalography(EEG)has gained popularity in various types of biomedical applications as a signal source that can be easily acquired and conveniently analyzed.However,owing to a complex scalp electrical environment,EEG is often polluted by diverse artifacts,with electromyography artifacts being the most difficult to remove.In particular,for ambulatory EEG devices with a restricted number of channels,dealing with muscle artifacts is a challenge.Methods In this study,we propose a simple but effective novel scheme that combines singular spectrum analysis(SSA)and canonical correlation analysis(CCA)algorithms for single-channel problems and then extend it to a few channel case by adding additional combining and dividing operations to channels.Results We evaluated our proposed framework on both semi-simulated and real-life data and compared it with some state-of-the art methods.The results demonstrate this novel framework's superior performance in both single-channel and few-channel cases.Conclusions This promising approach,based on its effectiveness and low time cost,is suitable for real-world biomedical signal processing applications.