成年雄性斑胸草雀前脑与中脑对习得性发声控制的侧别差异

成年雄性鸣禽的习得性发声信号——长鸣(long call)和鸣唱(song)是由前脑高级发声中枢启动,以及由前脑最后一级输出核团弓状皮质栎核(robust nucleus of the arcopallium,RA)整合输出.RA投射神经元与位于中脑的基本发声中枢丘间复合体背内侧核(dorsomedial nucleus of the intercollicular,DM)形成突触连接.该文采用电损毁与声谱分析相结合的方法,通过依次损毁成年雄性斑胸草雀(Taeniopygia guttata)单侧RA和DM核团,探讨了前脑和中脑对习得性发声的影响.结果提示,RA核团与DM核团共同参与了对雄性斑胸草雀习得性声音的调控,而且这种控制具有右侧优势.     

Mother-infant separation leads to hypoactive behavior in adolescent Holtzman rats

This is the first study of the effects of mother-infant separation (MS) on adolescent behavior of Holtzman (HO) rats. Different rat strains, such as Harlan Sprague-Dawley and HO, share a common origin. However, MS may lead to hypoactive behavioral effects in HO rats because of their greater susceptibility to show depressive-like responses to stress. Sixty HO pups were divided into three groups at postnatal day 2 (P2). For 10 days, the MS group was separated 6h daily and the early handled (EH) group 15 min daily. A standard facility reared (SFR) group was not separated. Animals were tested for novel open-field activity (P28), defensive withdrawal in a light-dark (LD) apparatus (P29) and familiar open-field (P30). Behavioral measures were classified into general activity (ambulatory and short movement time), orienting (rearing time) and risk-taking (velocity and exposed zone time). MS rats displayed reductions in general activity and risk-taking, and increases in orienting time. In contrast, EH favored risk-taking behavior, which may be consistent with previous findings implicating early handling as beneficial in coping with stress. Sex differences in these behaviors were limited. This study suggests a genetic predisposition in HO rats for predominantly hypoactive/anxiety-like behaviors when exposed to an early life stressor.     

Pyrrolizidine alkaloid deters ant predators of Utetheisa ornatrix eggs: effects of alkaloid concentration,oxidation state,and prior exposure of ants to alkaloid-laden prey

To examine the chemical defense of lepidopteran eggs towards ant predators, eggs of the arctiid moth Utetheisa ornatrix were offered to laboratory colonies of the ant Leptothorax longispinosus. The ants rapidly devoured Utetheisa eggs produced by parents reared on an alkaloid-free diet, but left eggs that had been endowed with parental alkaloid largely unmolested. That defense can be attributed directly to the presence of a pyrrolizidine alkaloid since topical application of monocrotaline in either its free base or N-oxide state conferred protection on otherwise palatable eggs. The N-oxide and free base were not equally effective in conferring protection however; free-base treated eggs were subject to greater predation than N-oxide treated eggs after 24 h. The emergence of differential alkaloid effectiveness only after prolonged exposure is consistent with the notion that chemical protection is seldom absolute. That difference was resolved only when the otherwise food-deprived ants exceeded a certain threshold of hunger. The efficacy of applied monocrotaline as a predator deterrent increased with increasing concentration of N-oxide, but was lowest for eggs treated with an intermediate concentration of free base. The latter concentration effect likely represents an artefact of the behaviour of the ant colonies offered eggs treated with an intermediate concentration, as those colonies were the most voracious predators in reference tests with palatable eggs. In addition to the immediate deterrent value of pyrrolizidine alkaloid, ant colonies that had been exposed to alkaloid-laden eggs subsequently avoided even palatable, unprotected eggs offered 33 days later. Our data provide the first demonstration of such long-term avoidance of chemically protected lepidopteran prey by an invertebrate. The discovery of a mechanism promoting learned avoidance on the part of ant predators has important ramifications to egg-laying strategies of female Utetheisa, both in terms of the dispersion of eggs, and the extent to which eggs are provisioned with alkaloid.     

Compensatory Limb Use and Behavioral Assessment of Motor Skill Learning Following Sensorimotor Cortex Injury in a Mouse Model of Ischemic Stroke

Mouse models have become increasingly popular in the field of behavioral neuroscience, and specifically in studies of experimental stroke. As models advance, it is important to develop sensitive behavioral measures specific to the mouse. The present protocol describes a skilled motor task for use in mouse models of stroke. The Pasta Matrix Reaching Task functions as a versatile and sensitive behavioral assay that permits experimenters to collect accurate outcome data and manipulate limb use to mimic human clinical phenomena including compensatory strategies (i.e., learned non-use) and focused rehabilitative training. When combined with neuroanatomical tools, this task also permits researchers to explore the mechanisms that support behavioral recovery of function (or lack thereof) following stroke. The task is both simple and affordable to set up and conduct, offering a variety of training and testing options for numerous research questions concerning functional outcome following injury. Though the task has been applied to mouse models of stroke, it may also be beneficial in studies of functional outcome in other upper extremity injury models.     

The comparison of immobility time in experimental rat swimming models

Rat swimming models have been used in studies about stress and depression. However, there is no consensus about interpreting immobility (helplessness or adaptation) in the literature. In the present study, immobility time, glucose and glycogen mobilization, corticosterone and the effect of desipramine and diazepam were investigated in two different models: swimming stress and the forced swimming test. Immobility time was lower in swimming stress than in the forced swimming test. Both swimming models increased corticosterone levels in comparison with control animal levels. Moreover, swimming stress induced higher corticosterone levels than the forced swimming test did [F(2,14)=59.52; p<0.001]. Liver glycogen content values differed from one another (swimming stress相似文献   

综述: 习得性无助行为研究进展

近年来,习得性无助行为(learned helplessness)作为抑郁症的动物模型之一,得到越来越广泛并深入的研究.通过利用多种动物模型,包括狗、啮齿类和果蝇等建立的行为范式,对习得性无助的行为表现和神经回路等方面的理解也更加深入和全面.本文通过回顾习得性无助行为的发现,总结了其在啮齿类动物模型和果蝇模型中的研究成果,并对未来的研究方向进行了展望,便于读者把握相关领域的全貌.     

Pathological withdrawl of refugee children seeking asylum in Sweden

Between 2001 and 2006 there was an ‘epidemic’ of complete withdrawal from daily life among numerous children in refugee families seeking asylum in Sweden. It became embedded in many distinct controversies, including the politics of immigration, and acrimonious disagreements between pediatricians dealing with individual families, and government-employed sociologists commissioned to report on what was going on. Most of the cases resolved themselves when an amnesty was agreed in 2006, although there remain many doubts about the statistics. After describing this phenomenon, the paper proposes a (non-exclusive) model called Imitation & Internalisation. Most of the children may have begun by imitating others who had fallen ill, but soon internalized it to the extent that it became an integral part of their psychophysical and social constitution. The model can be applied to phenomena as diverse as hypnotism, the placebo effect, and catching faith by association with believers (Pascal’s wager).     

研究报告：果蝇习得性无助影响空间位置记忆

目的 习得性无助（learned helplessness）是指动物经历了不可逃避性刺激后而产生的无助状态。它对随后实验动物的运动能力、生理状态等多方面都会产生影响,也是人类抑郁症的有效动物模型之一。目前已在多种动物模型中建立了研究习得性无助神经机制的行为实验范式,包括黑腹果蝇（Drosophila melanogaster）。之前的研究发现,经历过不可逃避高温惩罚的果蝇在活跃程度等方面有显著改变。然而,果蝇的习得性无助状态是否也影响学习认知能力,目前仍然未知。本文对果蝇空间位置学习能力是否受到习得性无助状态影响进行了研究。方法 此研究中,我们完善实验范式,分别检测果蝇在新范式中的空间位置学习行为和习得性无助行为,以及经过长时程随机刺激后果蝇空间位置学习能力的变化。结果 野生型果蝇可在此范式中展现空间位置学习能力与习得性无助状态,而经过长时程不可逃避刺激训练的果蝇,空间位置记忆有显著下降。结论 此研究完善了果蝇习得性无助行为实验范式,实验结果表明习得性无助对果蝇空间位置记忆存在影响。这将对进一步加深对动物习得性无助行为的理解,进而其发生机制研究起到推进作用。     

Habituation of unconditioned fear can be attenuated by the presence of a safe stimulus: assessment using the neophobic response of the rat

Protection from extinction of conditioned fear has been demonstrated when a conditioned inhibitor of fear is presented during extinction treatment. The present study assessed if similar results could be obtained during the analogous habituation of unconditioned fear. The neophobic response typically elicited by the presentation of a novel flavor was used as a model of unconditioned fear. Consumption by rats was used to ascertain the impact of nonreinforced exposure to a novel flavor either alone, in compound with another novel flavor, or in compound with a safe flavor (i.e., a flavor previously trained as a conditioned inhibitor for illness). The presentation of the novel flavor alone in the absence of illness reduced neophobia. However, exposure to the novel flavor in compound with the safe flavor reduced habituation of neophobia. This effect was not observed when the novel flavor was exposed in compound with another novel flavor. These results suggest that removing safe stimuli from the therapeutical environment might improve the effectiveness of exposure therapy in the treatment of unconditioned fear.     

Stress increases dynorphin immunoreactivity in limbic brain regions and dynorphin antagonism produces antidepressant-like effects

Rats exposed to learned helplessness (LH), an animal model of depression, showed a recovery following an intracerebroventricular injection of nor-binaltorphimine dihydrochloride (norBNI; a kappa-opioid antagonist). To investigate the potential role of dynorphin A and dynorphin B, we examined the effects of different stress/depression models on dynorphin A and dynorphin B immunoreactivity in hippocampus and nucleus accumbens (NAc). Immobilization stress (3 h) caused an increase in levels of dynorphin A and dynorphin B immunoreactivity in the hippocampus and the NAc. Forced swim stress also temporally increased dynorphin A levels in the hippocampus. Furthermore, exposure to LH produced a similar increase in dynorphin A and dynorphin B in the hippocampus and NAc. Infusions of norBNI into the dentate gyrus or CA3 regions of hippocampus and into the shell or core regions of NAc produced antidepressant-like effects in the LH paradigm. The degrees of norBNI's effects were stronger in the CA3 region and NAc shell and less effective in the dentate gyrus of hippocampus and NAc core. These results indicate that both dynorphin A and dynorphin B contribute to the effects of stress, and suggest that blockade of kappa-opioid receptors may have therapeutic potential for the treatment of depression.