Effect of diphenylhydantion on cortical epileptogenic foci in the rat

In acute experiments we studied the effect of diphenylhydantoin (DPH, 60 mg/kg i.p.) on the activity of cortical penicillin foci in 81 male rats. DPH reduced the discharge frequencies (measured by means of histograms of the intervals between adjacent discharges) and limited the projection of the discharges into non-primary cortical areas. The results for the administration of DPH before formation and after stabilization of the focus were qualitatively the same. DPH statistically significantly slowed down synchronization of the activity of two symmetrical cortical foci, but did not affect the progress of the synchronization of two asymmetrical foci, which was also very slow in the controls. DPH did not inhibit the possibility of triggering focal discharges by peripheral nerve stimulation. A detailed evaluation of focal activity allows the anti-epileptic effect of DPH to be demonstrated even in a model as potent as the penicillin focus in animals without general anaesthesia.     

Influence of clonazepam on cortical epileptogenic foci in the rat

The antiepileptic action of clonazepam was studied on epileptogenic foci induced by penicillin in sensorimotor cortex in acute experiments in rats. Clonazepam (1 mg/kg intraperitoneally) only moderately decreased the frequency of interictal discharges of single cortical focus and delayed the propagation of discharges into the ipsilateral occipital region. On the contrary, clonazepam failed to influence the callosal projection of interictal discharges in single unilateral as well as in two symmetrical foci. Spontaneous transition of interictal discharges into ictal phases regularly seen when two symmetrical foci were formed was only delayed but not blocked by clonazepam. It may be concluded that clonazepam exhibits only a weak anticonvulsant action against cortical foci and against secondary generalization of epileptic activity.     

Quality of life in childhood epilepsy with lateralized epileptogenic foci

Background  

Measuring quality of life (QOL) helps to delineate mechanisms underlying the interaction of disease and psychosocial factors. In adults, epileptic foci in the left temporal lobe led to lower QOL and higher depression and anxiety as compared to the right-sided foci. No study addressed the development of QOL disturbances depending on the lateralization of epileptogenic focus. The objective of our study was to examine QOL in children with lateralized epileptiform discharges.     

Effect of phenobarbital on cortical epileptogenic foci in the rat

The activity of epileptogenic foci was studied in acute experiments on adult male rats without general anaesthesia; the animals first received an intraperitoneal injection of phenobarbital [40 mg/kg] and 30 min later a cortical focus was induced by the local application of penicillin. These foci, which were induced in the sensorimotor area, had a lower discharge frequency than in the controls and the formation of projected discharges was delayed. In two symmetrical and asymmetrical cortical foci, activity was synchronized significantly more slowly after phenobarbital than in the controls. The cortical interhemispheric response was not influenced by the administered dose of phenobarbital. In these experiments, phenobarbital had an anti-epileptic effect both on the primary focus and on the spread of epileptic activity from this focus.     

Electrocorticographic development of epileptogenic foci in the occipital region of the rat cerebral cortex

The development of cortical penicillin foci in the occipital region was studied in rats whose ages ranged from five days up to the adult age. The local application of penicillin induced the formation of an epileptogenic focus for the first time at the age of seven days. With advancing age, the amplitude of focal discharges increased, the duration of the individual components of the discharge shortened, its originally negative-positive configuration changed to a triphasic form and in the third week of life initial positivity, for a time, become the dominant component of the discharge. Projection of the discharges to the contralateral hemisphere was found to be inconstant in the second postnatal week, but appeared regularly from the age of 14 days. Synchronization of the discharges of two symmetrical foci was very poor in 7-day-old young, but improved noticeably by the 14th day; it was never complete, however, even in adulthood. The activity of symmetrical foci changed spontaneously to ECoG seizures, which were most common in 7-day-old young (in which ictal activity was usually not generalized, however) and were least frequent in 14-day-old animals. Focal discharges could not be reliably triggered by electrical stimulation of the contralateral cortex until the age of 18 days and later. The occipital part of the cortex develops somewhat later than the sensorimotor, frontal region, and during its development there also appeared phenomena which are not present in the frontal cortex.     

A simple and objective method for reproducible resting state network (RSN) detection in fMRI

Spatial Independent Component Analysis (ICA) decomposes the time by space functional MRI (fMRI) matrix into a set of 1-D basis time courses and their associated 3-D spatial maps that are optimized for mutual independence. When applied to resting state fMRI (rsfMRI), ICA produces several spatial independent components (ICs) that seem to have biological relevance - the so-called resting state networks (RSNs). The ICA problem is well posed when the true data generating process follows a linear mixture of ICs model in terms of the identifiability of the mixing matrix. However, the contrast function used for promoting mutual independence in ICA is dependent on the finite amount of observed data and is potentially non-convex with multiple local minima. Hence, each run of ICA could produce potentially different IC estimates even for the same data. One technique to deal with this run-to-run variability of ICA was proposed by [1] in their algorithm RAICAR which allows for the selection of only those ICs that have a high run-to-run reproducibility. We propose an enhancement to the original RAICAR algorithm that enables us to assign reproducibility p-values to each IC and allows for an objective assessment of both within subject and across subjects reproducibility. We call the resulting algorithm RAICAR-N (N stands for null hypothesis test), and we have applied it to publicly available human rsfMRI data (http://www.nitrc.org). Our reproducibility analyses indicated that many of the published RSNs in rsfMRI literature are highly reproducible. However, we found several other RSNs that are highly reproducible but not frequently listed in the literature.     

Effect of acupuncture on the activity of experimental epileptogenic foci in the hippocampus of rabbits

Experiments were performed on rabbits with electrochemotrodes implanted into the left and right dorsal hippocamp. The evidence was obtained for the first time as to the marked inhibitory effect of acupuncture on epileptogenic foci created by penicillin microinjections into the hippocamp. The most effective was stimulation of the Min-Men point. The antiepileptic effect was potentiated on combined stimulation of the Min-Men and Yao-Yan-Guan points. The efficacy of the procedure was significantly decreased on stimulation of the points of another acupunctural canal. The epileptiform activity was potentiated by affecting the knowingly inactive points. The antiepileptic effect of acupuncture was significantly reduced with an increase in the number of acupunctures. This might be connected with the development of tolerance to enkephalins by which the effect of acupuncture is most likely mediated.     

Decreased acetylcholinesterase activity in the area of epileptogenic foci created by met-enkephalin in the hippocampus of rats

Experiments on rats with electrochemotrodes implanted in the left and right hippocamp have shown that in epileptogenic foci created by microinjections of met-enkephalin or D-ala-2-met-enkephalin into the hippocamp, acetylcholinesterase activity (AChE) was diminished. It is assumed that reduction in AChE activity is an adaptive mechanism by which the excitability of hippocampal inhibitory basket cells, which are sensitive to acetylcholine, is increased.     

基于fMRI的脑功能整合数据分析方法综述

脑功能成像在人脑信息处理和认知活动的神经关联中发挥了不可轻视的作用.从大脑功能整合出发,可以将脑功能成像数据分析方法分为探测大脑功能整合的功能连接和有效连接两方面,功能连接探究空间远离的两个脑区之间的连接,有效连接研究一个脑区对另一个脑区作用的大小.根据这两个概念,相应地可以将功能磁共振数据分析方法分为两大类.本文着重...     

Using an agent-based model to analyze the dynamic communication network of the immune response

Background  

The immune system behaves like a complex, dynamic network with interacting elements including leukocytes, cytokines, and chemokines. While the immune system is broadly distributed, leukocytes must communicate effectively to respond to a pathological challenge. The Basic Immune Simulator 2010 contains agents representing leukocytes and tissue cells, signals representing cytokines, chemokines, and pathogens, and virtual spaces representing organ tissue, lymphoid tissue, and blood. Agents interact dynamically in the compartments in response to infection of the virtual tissue. Agent behavior is imposed by logical rules derived from the scientific literature. The model captured the agent-to-agent contact history, and from this the network topology and the interactions resulting in successful versus failed viral clearance were identified. This model served to integrate existing knowledge and allowed us to examine the immune response from a novel perspective directed at exploiting complex dynamics, ultimately for the design of therapeutic interventions.     

Using network theory to survey for

Pathogens are well known to spread through networks of conveyors. The resulting distribution and progress of disease is often quite different to expected distributions made by compartmental models (natural spread). This paper outlines the use of network theory to target risk sites for surveillance of Candidatus Liberibacter solanacearum. Results are presented together with a discussion on the likely role that the conveyor network for Candidatus Liberibacter solanacearum has played in the spread of the disease and its vector within New Zealand and on-going implications.     

A biologically inspired neural network for dynamic programming

An artificial neural network with a two-layer feedback topology and generalized recurrent neurons, for solving nonlinear discrete dynamic optimization problems, is developed. A direct method to assign the weights of neural networks is presented. The method is based on Bellmann's Optimality Principle and on the interchange of information which occurs during the synaptic chemical processing among neurons. The neural network based algorithm is an advantageous approach for dynamic programming due to the inherent parallelism of the neural networks; further it reduces the severity of computational problems that can occur in methods like conventional methods. Some illustrative application examples are presented to show how this approach works out including the shortest path and fuzzy decision making problems.     

Imaging Conditioned Fear Circuitry Using Awake Rodent fMRI

Functional magnetic resonance imaging (fMRI) is a powerful method for exploring emotional and cognitive brain responses in humans. However rodent fMRI has not previously been applied to the analysis of learned behaviour in awake animals, limiting its use as a translational tool. Here we have developed a novel paradigm for studying brain activation in awake rats responding to conditioned stimuli using fMRI. Using this method we show activation of the amygdala and related fear circuitry in response to a fear-conditioned stimulus and demonstrate that the magnitude of fear circuitry activation is increased following early life stress, a rodent model of affective disorders. This technique provides a new translatable method for testing environmental, genetic and pharmacological manipulations on emotional and cognitive processes in awake rodent models.     

利用功能磁共振研究记忆功能的研究进展

功能磁共振成像(fMRI)作为一种无创伤,可反复实验的成像技术,已被广泛地应用于各项脑功能的研究。用fMRI进行脑功能研究的主要依据是血流敏感性和BOLD对比增强原理。记忆是人脑的高级功能,其过程分为编码加工、固化、存储和提取几个阶段。大脑皮质、海马、乳头体、丘脑是参与记忆的主要解剖结构。记忆的刺激方式对各个脑区的激活是具有差异性的,记忆功能的测量和分析方法也在不断的改进。年龄和性别的不同都会对记忆能力产生影响,同时激活的脑区也会有相应的改变。此外,情感和记忆的关系正越来越受到人们的关注。本文阐述利用功能磁共振成像研究记忆功能的最新进展。     

Using insect sniffing devices for detection

Emerging information about the ability of insects to detect and associatively learn has revealed that they could be used within chemical detection systems. Such systems have been developed around free-moving insects, such as honey bees. Alternatively, behavioral changes of contained insects can be interpreted by sampling air pumped over their olfactory organs. These organisms are highly sensitive, flexible, portable and cheap to reproduce, and it is easy to condition them to detect target odorants. However, insect-sensing systems are not widely studied or accepted as proven biological sensors. Further studies are needed to examine additional insect species and to develop better methods of using their olfactory system for detecting odorants of interest.