Hippocampal ripples correlate with memory performance in humans.

Memory performance evaluation has generally been based on behavioral tests in the past decades. However, its neural correlates remain largely unknown, particularly in humans. Here we addressed this question using intracranial electroencephalography in patients with refractory epilepsy, performing an episodic memory test. We used the presurgical Wechsler Memory Scale (WMS) test to assess the memory performance of each patient. We found that hippocampal ripples significantly exhibited a transient increase during visual stimulation or before verbal recall. This increase in hippocampal ripples positively correlated with memory performance. By contrast, memory performance is negatively correlated with hippocampal interictal epileptic discharges (IEDs) or epileptic ripples in the memory task. However, these correlations were not present during quiet wakefulness. Thus, our findings uncover the neural correlates of memory performance in addition to traditional behavioral tests.

The role of voltage-gated chloride channels in the epileptogenesis of temporal lobe epilepsy.

BACKGROUND: Temporal lobe epilepsy (TLE) is the most common intractable epilepsy in adults, and elucidation of the underlying pathological mechanisms is needed. Voltage-gated chloride channels (ClC) play diverse physiological roles in neurons. However, less is known regarding their functions in the epilepogenesis of TLE. METHODS: ClC-mediated current and the spontaneous inhibitory synaptic currents (sIPSC) in hippocampal neurons of epileptic lesions were investigated by electrophysiological recording. The EEG data were analyzed by Z-scored wavelet and Fourier transformations. The expression of ClC-3, a member of ClC gene family, was detected by immunostaining and western blot. FINDINGS: ClC-mediated current was increased in the hippocampal neurons of chronic TLE mice. Application of chloride channel blockers, NPPB (5-Nitro-2- [3-phenylpropylamino] benzoic acid) and DIDS (4,4'-Diisothiocyanato-2,2'-stilbenedisulfonic acid disodium salt) reduced ClC-mediated current and increased inhibitory synaptic transmission in TLE mice. NPPB and DIDS reduced the seizure frequency and the average absolute power of ictal high-frequency oscillations (HFOs, 80-500 Hz) in TLE mice. In addition, both drugs induced outwardly rectified currents, which might be tonic inhibitory currents in the hippocampal neurons of TLE patients. Furthermore, the expression of ClC-3 was increased in the hippocampus of TLE mice and patients and positively correlated with both the absolute power and number of ictal HFOs per seizure in the sclerotic hippocampus. INTERPRETATION: These data suggest that ClC participate in the epilepogenetic process of TLE and the inhibition of ClC may have anti-epileptic effect. FUNDING: This work was supported by National Natural Science Foundation of China (No. 81601143, No. 81771217).

Comparison of Neuronavigation and Frame-Based Stereotactic Systems in Implanting Epileptic Depth Electrodes.

AIM: To investigate the application of neuronavigation in the implantation of depth electrodes in patients with epilepsy. MATERIAL AND METHODS: Thirty-six patients with epilepsy who were implanted with depth electrodes using neuronavigation were assessed for accuracy of implantation and associated complications. RESULTS: In the imaging navigation group, patients were implanted with 2-14 depth electrodes. The average number of implantations was 4.8 electrodes/case. The average implantation error was 2.03 ± 0.98 mm, exhibiting no significant difference compared to the frame-based stereotactic group. In the imaging group, an average of 19.4 min was required to implant each electrode, which was significantly shorter than the time required in the frame group (34.5 min). The temporal lobe was elucidated as the factor that affects electrode implantation accuracy. One patient in the imaging group exhibited a small amount of bleeding, and one suffered from cerebrospinal fluid leakage; however, the overall complication rate in the imaging group was lower than that in the frame group. CONCLUSION: Imaging navigation provides better means of depth electrode implantation; its implantation accuracy is similar to that of the frame-based stereotactic method and it is less time consuming and causes less complications, and is especially suitable for stereoelectroencephalography, which requires multiple depth electrodes.

[Ligustrazine fought against cisplatin induced ototoxicity in guinea pigs].

OBJECTIVE: To study the protective effect of Ligustrazine Injection (LI) against cisplatin-induced ototoxicity and to explore its mechanism. METHODS: Thirty healthy adult guinea pigs were randomly divided into three groups, 10 in each group, i.e., the normal control group, the cisplatin group, and the LI group. Guinea pigs in the normal control group were intraperitoneally injected with normal saline at 3 mL/kg for 7 consecutive days. Those in the cisplatin group were intraperitoneally injected with cisplatin at 3 mg/kg for 7 consecutive days. Those in the LI group were intraperitoneally injected with LI at 140 mg/kg for 7 days, but cisplatin (3 mg/kg) was intraperitoneally injected from the opposite side starting from the 4th day. Brainstem auditory evoked potential (BAEP) was performed in all animals before and after injection. All animals were sacrificed after the final testing under anesthesia and their cochleas collected. Half the cochleas of each group were collected for silver nitrate staining of cochlear basilar membrane stretched. The other half the cochleas of each group made into paraffin sections to observe the apoptosis of cochlea cells by TUNEL method and the expression levels of c-Jun detected by immunohistochemistry. RESULTS: There was no statistical difference in the difference of BAEP threshold among the 3 groups before injection (P > 0.05), but the BAEP threshold increased in the cisplatin group and the LI group (P < 0.05). Besides, it was higher in the cisplatin group (P < 0.05). In the cisplatin group, most hair cells were missing, spiral ganglion cells obviously decreased, more TUNEL positive cells occurred, and the expression of c-Jun was stronger. But the aforesaid impairment in the LI group was obviously lessened (P < 0.05). CONCLUSIONS: LI showed certain antagonist effect on cisplatin-induced ototoxicity. Its mechanism might be associated with scavenging oxygen radicals of the cochlea tissue, improving the microcirculation, and fighting against apoptosis.

[Preventive effects of cerebro cellular growth peptide on gentamycin-induced inner ear damage in guinea pigs].

AIM: To investigate the preventive effects of the cerebro cellular growth peptide (CCGP) on gentamycin-induced inner ear damage in guinea pigs, and to clarify its mechanism. METHODS: The hypoacusis severity and enzymatic activity in the cochlear hair cells were examined by brainstem auditory evoked potential (BAEP) and histochemistry, respectively. The damaged hair cells was counted in three groups. RESULTS: CCGP reduced the elevated BAEP reaction thresholds. It protected activities of mitochondrial succinate dehydrogenase and lysosome acid phosphatase in the cochlear hair cells. The number of damaged hair cells in the CCGP group was less than that in the gentamycin (GM) group. CONCLUSION: CCGP can reduce GM ototoxicity. The mechanism may be associated with the protective activity of mitochondrial enzyme, the maintenance of lysosome intactness, energy metabolism of the cochlear hair cells, and reduction of autolysis of hair cells induced by hydrolase over flowing from lysosome.