High-Frequency Local Field Potential Oscillations May Modulate Aggressive Behaviors in Mice.

Aggressive behavior is one of congenital social behaviors in many species, which could be promoted by social neglect or isolation in the early stages of life. Many brain regions including the medial prefrontal cortex (mPFC), medial amygdala (MeA) and ventromedial hypothalamus (VMH) are demonstrated to relate to aggressive behavior; however, the dynamic patterns of neural activities during the occurrence of this behavior remain unclear. In this study, 21-day-old male CD-1 mice were reared in social isolation conditions and cohousing conditions for two weeks. Aggressive behaviors of each subject were estimated by the resident-intruder test. Simultaneously, the local field potentials of mPFC, MeA and VMH were recorded for exploring differences in the relative power spectra of different oscillations when aggressive behaviors occurred. The results showed that the following: (1) Compared with the cohousing mice, the socially isolated mice exhibited more aggression. (2) Regardless of "time condition" (pre-, during- and post- attack), the relative power spectra of beta band in the cohousing mice were significantly greater than those in the socially isolated mice, and inversely, the relative power spectra of gamma band in the cohousing mice were significantly smaller than those in the socially isolated mice. (3) The bilateral mPFC exhibited significantly smaller beta power spectra but greater gamma power spectra compared with other brain areas regardless of rearing patterns. (4) For the right VMH of the socially isolated mice, the relative power spectra of the gamma band during attacks were significantly greater than those before attack. These results suggest that aggressive behaviors in mice could be shaped by rearing patterns and that high-frequency oscillations (beta and gamma bands) may engage in mediating aggressive behaviors in mice.

Dynamics of electroencephalogram oscillations underlie right-eye preferences in predatory behavior of the music frog.

Visual lateralization is a typical characteristic of many vertebrates; however, its underlying dynamic neural mechanism is unclear. In this study, predatory responses and dynamic brain activities were evaluated in the Emei music frog (Nidirana daunchina) to assess the potential eye preferences and their underlying dynamic neural mechanism, using behavioral and electrophysiological experiments, respectively. To do this, when the prey stimulus (live cricket and leaf as control) was moved around the frogs in both clockwise and anticlockwise directions at constant velocity, the number of predatory responses were counted and electroencephalogram (EEG) absolute power spectra for each band were measured for the telencephalon, diencephalon and mesencephalon. The results showed that: (1) no significant differences in the number of predatory responses could be found for the control (leaf), but the number of predatory responses for the right visual field (RVF) was significantly greater than that for the left visual field (LVF) when the live cricket was moved into the RVF clockwise; (2) compared with no stimulus in the visual field and stimulus in the LVF, the power spectra of each EEG band were greater when the prey stimulus was moved into the RVF clockwise; and (3) the power spectra of the theta, alpha and beta bands in the left diencephalon were significantly greater than those of the right counterpart for the clockwise direction, but similar significant differences presented for the delta, theta and alpha bands in the anticlockwise direction. Together, the results suggested that right-eye preferences for predatory behaviors exist in music frogs, and that the dynamics of EEG oscillations might underlie this right eye/left hemisphere advantage.

Research on Handwashing Techniques of Peritoneal Dialysis Patients From Yiwu, Southeast China.

The aim of the present study was to evaluate handwashing technique, bacteriology, and factors influencing handwashing technique of 86 stable chronic peritoneal dialysis (PD) patients from Yiwu City in Southeast China. Based on the "Hygienic standard for disinfection in the hospital", we also performed sampling for bacteriology from PD operators after they washed their hands. We compared their clinical features including the pathogenic bacteria of their previous peritonitis episodes and their handwashing evaluation results according to their bacteriologic sampling results. 65% of patients turned off the tap by bare hand, and 74% did not follow the six-step handwashing method. Dialysis duration longer than 6 months (P = 0.04) and lower income (P = 0.05) were independent risk factors for higher handwashing error scores. The overall rate of appropriate handwashing, according to the "hygienic standard for disinfection in the hospital" was 26%. The bacteriologic sampling results showed that the most common pathogenic bacterium was Staphylococcus aureus (92%). PD operators whose hand bacteria culture was qualified contained a lower proportion of participants with advanced age (P = 0.07). Patients with repeated peritonitis occurrence had a significantly higher score on handwashing error (P < 0.01) and were more likely to develop Staphylococcus infection. We found that in Yiwu city patients on dialysis for more than 6 months, were of low income and had multiple prior episodes of PD peritonitis had poor handwashing compliance. Elderly patients had higher rates of positive bacterial culture (Staphylococcus) from their hands.

Left hemisphere predominance of pilocarpine-induced rat epileptiform discharges.

BACKGROUND: The left cerebral hemisphere predominance in human focal epilepsy has been observed in a few studies, however, there is no related systematic study in epileptic animal on hemisphere predominance. The main goal of this paper is to observe if the epileptiform discharges (EDs) of Pilocarpine-induced epileptic rats could present difference between left hemisphere and right hemisphere or not. METHODS: The electrocorticogram (ECoG) and electrohippocampogram (EHG) from Pilocarpine-induced epileptic rats were recorded and analyzed using Synchronization likelihood (SL) in order to determine the synchronization relation between different brain regions, then visual check and cross-correlation analysis were adopted to evaluate if the EDs were originated more frequently from the left hemisphere than the right hemisphere. RESULTS: The data show that the synchronization between left-EHG and right-EHG, left-ECoG and left-EHG, right-ECoG and right-EHG, left-ECoG and right-ECoG, are significantly strengthened after the brain functional state transforms from non-epileptiform discharges to continuous-epileptiform discharges(p < 0.05). When the state transforms from continuous EDs to periodic EDs, the synchronization is significantly weakened between left-ECoG and left-EHG, left-EHG and right-EHG (p < 0.05). Visual check and the time delay (tau) based cross-correlation analysis finds that 10 out of 13 EDs have a left predominance (77%) and 3 out of 13 EDs are right predominance (23%). CONCLUSION: The results suggest that the left hemisphere may be more prone to EDs in the Pilocarpine-induced rat epilepsy model and implicate that the left hemisphere might play an important role in epilepsy states transition.

[Detrended fluctuation analysis of epileptic rat EEG].

Detrended fluctuation analysis (DFA) is a new technique used to characterize the long-range temporal correlation (LRTC) structure of non-stationary time series, which has been applied in electroencephalographic (EEG) oscillations and diseases such as Alzheimer and stroke. In this paper, DFA is used to study the scaling exponents of intracranial EEG recordings of Pilocarpine-induced epileptic rat. It was found that when the brain functional status changed from non-epileptiform discharges to continuous-epileptiform discharges and to period-epileptiform discharges, the average scaling exponents of four brain regions (left cortex and left hippocampus, right cortex and right hippocampus) changed from 0.97 to 0.82 and to 0.94, and a statistically significant difference between the brain functional states was shown by paired T test (P < 0.05), thus suggesting that the local neuronal network dynamics of the three brain function states may be different. But in regard to the three brain function states, there is no statistically significant difference between the four brain regions(P >0.05).

[Synchronization analysis of ECoG and EHG from eplieptiform discharges rats].

The mechanisms leading to the occurrence of seizures in humans are still poorly understood. It is widely accepted, however, that the process of seizure generation is closely associated with an abnormal synchronization of neurons. In order to investigate this process, we have studied synchronization between different regions of the brain from intracranial EEG recordings of Pilocarpine-induced epileptic rat by Synchronization likelihood (SL). It was found that during the state of transition from non-epileptiform discharges to continuous-epileptiform discharges, synchronization between left-ECoG and left-EHG was significantly strengthened, and similar change had taken place between right-ECoG and right-EHGd; left-ECoG; and right-ECoG and left-EHG and right-EHG (P < 0.05). During the state of transition from continuous-epileptiform discharges to period-epileptiform discharges, the synchronization was significantly weakened between left-ECoG and left-EHG, and similar change was noted between left-EHG and right-EHG (P < 0.01). The results showed that SL might be used to assess the dynamics of synchronization and it might be helpful to understanding the mechanisms involving the origin of epileptiform discharge.