Evidence for identified dopamine motor neurons to the gill of Aplysia

Dopamine (DA) is present in the gill of Aplysia in considerable quantity. We have investigated the possibility that DA may be an excitatory neuromuscular transmitter. Perfusion of DA through the gill elicits contraction of the same muscles as are activated by the identified motor neurons L₇ and L₉. The cholinergic motor neuron LDG₁ activates different muscles. The contractions induced by DA and three L₉ neurons but not that of L₇ are blocked by ergometrine. These results are consistent with the possibility that the neurons L₉, L_9-A and L_9-P are dopaminergic motor neurons.     

Quel(s) impact(s) de la vie hormonale féminine dans les troubles bipolaires ?

Estrogens and progesterone are involved in many aspects of brain function (modulation of neurotransmissions, neuronal survival, synaptic plasticity). In addition, some biomarkers involved in bipolar disorder are thought to be influenced by sex hormones. The links between the different hormonal periods of women's lives (pubertal, premenstrual syndrome, perinatal period, menopause) and the evolution of bipolar disorders are explored and some new lines of research presented.     

A randomised controlled multimodal intervention trial in patients with ischaemic stroke in Shandong,China: design and rationale

Background

Stroke is the leading cause of death and disability in China and has conferred a huge economic and societal burden. The effectiveness of primary prevention of stroke by targeting major vascular or cardiometabolic risk factors (eg, smoking, hypertension, diabetes) has been well established. This study aims to investigate whether a personalised, multimodal, multilevel intervention programme is effective in modifying unhealthy lifestyle and improving control of major cardiometabolic risk factors in patients with ischaemic stroke, and thus in reducing the risk of recurrent stroke and associated complications (functional disability, cognitive impairment).

Towards a comprehensive model of stereotypy: integrating operant and neurobiological interpretations

The predominant models on the emergence and maintenance of stereotypy in individuals with developmental disabilities are based on operant and neurobiological interpretations of the behavior. Although the proponents of the two models maintain largely independent lines of research, operant and neurobiological interpretations of stereotypy are not mutually exclusive. The paper reviews the two models of stereotypy and proposes an integrated model using recent findings on the neurobiology of reinforcement. The dopaminergic system and the basal ganglia are both involved in stereotypy and in reinforcement, which provides a potential link between the models. Implications of the integrated model for future research are discussed in terms of improving the assessment and treatment of stereotypy in individuals with developmental disabilities.     

精神病高危综合征的研究进展

精神病高危综合征主要指以下三种情形：遗传风险和功能减退综合征;弱化阳性症状综合征;短暂间歇性精神病综合征。本文从它的诊断、流行病学、神经生物学及伦理学方面进行现状综述。     

Repeated administration of triiodothyronine (T3) to rats enhances nigrostriatal and mesolimbic dopaminergic behavioural responses

A once daily injection to rats of triiodothyronine (T₃; 100 μg/kg s.c.) for 10 days enhanced the locomotor responses of rats pretreated with tranylcypromine (5 mg/kg) to an injection into the nucleus accumbens of dopamine (5 μg bilaterally), when tested 24 hr after the last T₃ administration. This treatment did not, however, alter the control responses of tranylcypromine-pretrealed rats to injection of saline (1 μl bilaterally). Injection of T₃ for 10 days enhanced the circling responses of unilateral nigrostriatal-lesioned rats to apomorphine (0.5 mg/kg) but not to methamphetamine (0.5 mg/kg). The probable explanation for the latter result was the finding that repeated T₃ administration lowered basal striatal dopamine concentrations. The treatment also produced a trend towards reduced dopamine concentrations in the n. accumbens, although the difference did not reach statistical significance. These data suggest that repeated T₃ injection causes an increased post-synaptic function of both the nigrostriatal and mesolimbic dopamine systems in rat brain.     

Silicon neuron simulation with SPICE: tool for neurobiology and neural networks

The paper deals with computer simulations of ‘silicon neurons’, which are assemblies of CMOS circuits that generate the equivalents of the ionic currents and of the action potentials of real (biological) neurons. The circuit simulation program SPICE is used to simulate the generation of action potentials by a silicon neuron. Moreover, the equivalent circuits of silicon synapses are described and the behaviours of simple two- and three-neuron networks are analysed. Implications for the areas of neurobiology and formal neural networks are briefly considered.     

Aging effects on spatial tuning of hippocampal place cells in mice

One reason the electrophysiological correlates of hippocampal neurons are of interest is the possibility that they reflect their representational properties, presumably spatial/relational ones. Stable spatial representations, based on activity of ensembles of hippocampal place cells, initially develop through a series of short-episodic spatial tunings. Hence these short-episodic spatial tunings are important for understanding the establishment of stable place fields. Studies of age-related changes in place cell activities traditionally focus on place fields. In the present study, we characterized the short-episodic spatial tunings (1-min bins) of hippocampal CA1 place cells of freely moving mice in a familiar cylinder arena, and compared these functions in young and old mice. Spatial tuning was expressed by spatial selectivity, which we found fluctuated across a 16-min recording session in both young and old mice. High spatial selectivity, which is mainly due to the low firing of a place cell out of the place field in young mice, was significantly higher in old mice. The high firing rate out of the place field was the main factor contributing to significantly lower spatial selectivity in old mice. In addition, young mice showed a broad peak in the spatial selectivity between 4 and 10 min. In contrast old mice showed no peak in the spatial selectivity during this time period. The stability of place fields after a 24-h interval was also lower in old mice than in young mice. The low spatial tuning and unstable place fields suggest that a hippocampal-based spatial representation was impaired in the old mice. Furthermore, we speculate that the age-related impairment in hippocampal inhibition system may be involved in the impaired spatial representation of hippocampal CA1 place cells in old mice. Electronic Publication     

合谷穴与面口部特异性联系的神经生物学机制研究

面口合谷收是经脉体表与体表之间联系的重要体现,从神经生物学角度阐释针刺合谷穴对面口部影响的机制可能是研究面口合谷收理论内涵的重要突破口之一。文章中作者针刺合谷穴,以后溪、外关作为对照,观察其对面口部痛阈、肌电活动、唾液分泌和脑中枢功能网络响应的影响,从不同层面揭示合谷穴与面口部特异性联系的神经生物学机制,以期为面口合谷收理论提供更丰富的科学依据。