刺激家兔杏仁复合体对听皮层声反应影响的研究

实验在40只三碘季铵酚麻痹的家兔上进行。使用记录诱发电位以及单个神经元放电的方法,观察了刺激杏仁复合体对Woolsey AⅠ AⅡ以及嗅鼻沟后缘听区皮层声反应的影响。实验结果表明,刺激杏仁外侧核和基底核可以对皮层的声反应产生易化或抑制性影响。这种影响的潜伏期一般为10—25ms,时程为20—115ms,在1例动物上也观察到了2ms的最短潜伏期。这些结果表明杏仁核群对于听区皮层的抑制影响主要是经过多突触环路传递的,但也有可能经由单突触途径实现兴奋性影响。本文对杏仁复合体影响的意义作了讨论。     

大鼠杏仁核5-HT_3受体参与免疫调制

实验通过大鼠侧脑室和杏仁核给予 5 HT3受体激动剂 1 phenylbiguanide (PBG) ,用 3H TdR掺入法测定脾细胞丝裂原 (concanavalinA ,ConA和lipopolysaccharide ,LPS)刺激增殖效应 ,用活化脾细胞增殖法测定IL 2生成 ,MTT法测定自然杀伤 (naturalkiller,NK)细胞活性和用放射免疫测定血浆皮质酮水平 ,以探讨大鼠杏仁核 5 HT3受体在免疫调控中的作用。结果表明 :5 HT3受体拮抗剂granisetron (GNT ,0 1～ 0 4mg/kgip)剂量依赖地增强ConA和LPS刺激的脾细胞增殖 ,作用在连续给药 5d最明显 ;双侧脑室给予PBG ( 5 μg/side)可增强ConA和LPS刺激的脾细胞增殖效应 ,作用在连续给药 3d最明显 ;双侧和单侧中央杏仁核给予PBG 0 5 μg均增强ConA刺激的脾细胞增殖和IL 2生成 ;底内侧杏仁核给予同剂量PBG仅增强LPS刺激的脾细胞增殖效应 ,不影响ConA刺激的脾细胞增殖和IL 2生成 ;中央杏仁核给予PBG升高血浆皮质酮的作用较底内侧杏仁核给予等量PBG引起的升高血浆皮质酮作用明显 (P <0 0 1)。侧脑室、中央杏仁核和底内杏仁核给予PBG对丝裂原刺激的脾细胞增殖效应影响不同 ,但均被同时同部位给予GNT所拮抗 ,提示杏仁核中央核和底内侧核的 5 HT3受体可能以不同方式参与ConA或LPS刺激的脾细胞增殖效应的调制     

杏仁中央核在躯体传入冲动抑制中枢性升压反应中的作用

目的:阐明电刺激腓深神经(DPN)对下丘脑室旁核(PVN)兴奋后的心血管反应的调节作用及杏仁中央核(CeA)在此作用中的地位。方法:电刺激SD大鼠中枢核团PVN,或用核团(CeA)内微量注射法注射L-谷氨酸钠(L-Glu)或红藻氨酸(KA)。同时记录大鼠股动脉血压、平均动脉压(MAP)、心电图及心率(HR)曲线。结果:电刺激一侧PVN后,MAP升高,HR变化不一,以下降为主。电刺激腓深神经对PVN兴奋诱发的升压反应有抑制作用。在同侧CeA微量注射0.02mol/L的KA100nl,10min后刺激PVN,血压升高(13.8±3.2)mmHg,较注射KA前削弱了(6.6±1.6)mmHg(P<0.05),DPN对刺激PVN的升压反应的抑制百分比也从51.5%降为32.0%。结论:杏仁中央核部分介导了PVN兴奋后引起的升压反应。DPN传入冲动对PVN中枢性升压反应有抑制作用,其机制可能与杏仁中央核有关。     

Expression of FOS, EGR-1, and ARC in the amygdala and hippocampus of female rats during formation of the intromission mnemonic of pseudopregnancy

Pseudopregnancy (PSP) in the female rat is a neuroendocrine condition that is induced by repeated and intermittent vaginocervical stimulation received during mating and involves the expression of bicircadian prolactin surges and cessation of normal estrous cyclicity for 10-12 days postmating. The temporal patterning and number of intromissions received by the female are critical for PSP initiation, and thus, short-term encoding of VCS occurs during transduction of intromissions into PSP. In this experiment, we characterized and compared the mating-induced neural activation patterns within amygdalar and hippocampal regions using expression of the immediate early genes FOS, EGR-1, and ARC. Cycling female rats mated on proestrus received 15 or 5 intromissions under paced or nonpaced mating conditions. High numbers of intromissions during nonpaced mating or low numbers received during paced mating are sufficient to induce PSP, while five nonpaced intromissions and mounts without intromission are insufficient. Here we demonstrate that the CA1 region of the hippocampus was selectively sensitive to PSP-sufficient but not PSP-insufficient mating stimulation by showing significant effects of paced mating for all three IEGs. Paced mating also stimulated the expression of ARC within the basolateral, cortical, and central nuclei of the amygdala. The posterodorsal medial amygdala also showed selective EGR-1 responses to PSP-sufficient mating stimulation. There was no effect of hemisphere on IEG expression. The postmating expression profiles of these IEGs provide evidence that limbic areas involved in encoding and consolidation of memory are involved in initiating the neuroendocrine memory of PSP.     

Rat brain TRH receptors: kinetics, pharmacology, distribution and ionic effects

Optimal conditions for measuring receptor binding for thyrotropin-releasing hormone (TRH) in the rat central nervous system (CNS) have been determined using 3H-labelled [3-Me-His2]TRH [( 3H]MeTRH). Binding assays conducted at 0 degree C for 5-6 h using sodium phosphate- and/or Hepes-buffered tissue resuspensions, with subsequent filtration through Whatman GF/B filters, yielded the best results. Association and dissociation of [3H]MeTRH binding to amygdala membranes were time and temperature dependent. Dissociation kinetics appeared biphasic. Progressive reduction in receptor affinity and capacity and increased radioligand breakdown were observed at elevated temperatures. Bacitracin (25-1000 microM) prevented peptide degradation but inhibited receptor binding (8-37%). Detailed competition experiments using MeTRH and other drugs yielded a pharmacological profile similar to that observed previously in other tissues indicating TRH receptor identification. Highest density of TRH receptors was observed in the retina and numerous limbic areas. Monovalent and divalent cations modulated [3H]MeTRH binding by reducing apparent receptor number.     

Amygdala, an important regulator for food intake

Amygdala plays a critical role in the regulation of emotional behavior and food intake. Neuropeptides are short chains of amino acids secreted by neurons as intercellular messengers, which regulate different functions such as emotion, food intake, learning and memory. In this review, we summarize the recent progress on the regulation of food intake by amygadala, which is mediated by those neuropeptides known to be critical in the regulation of this process.     

Lower Brainstem Pathways Regulating Sympathetically Mediated Changes in Cutaneous Blood Flow

1. When the individual is alerted by painful or salient stimuli, there is a vigorous sympathetically mediated constriction of the cutaneous vascular bed. We investigated central pathways mediating this response using chronically implanted Doppler ultrasonic probes to measure cutaneous blood flow in the rabbit ear pinna and in the rat tail.2. Blockade of neuronal function in the amygdala prevents cutaneous vasoconstriction elicited by salient stimuli, but does not prevent the response to painful stimuli. Blockade of neuronal function in raphe magnus/pallidus and the parapyramidal region in anesthetized rabbits prevents cutaneous vasoconstriction elicited by painful stimuli. A similar region of the medullary raphe regulates tail artery vasoconstriction in rats. Inhibition of neuronal function in this region reverses cutaneous vasoconstriction induced by cooling the animal.3. Bulbospinal presympathetic neurons in the rostral medullary raphe region appear to regulate cutaneous blood flow responses occurring as part of the response to painful or dangerous environmental events and as part of the regulation of body temperature.     

The amygdala and ventromedial prefrontal cortex: functional contributions and dysfunction in psychopathy

The current paper examines the functional contributions of the amygdala and ventromedial prefrontal cortex (vmPFC) and the evidence that the functioning of these systems is compromised in individuals with psychopathy. The amygdala is critical for the formation of stimulus-reinforcement associations, both punishment and reward based, and the processing of emotional expressions. vmPFC is critical for the representation of reinforcement expectancies and, owing to this, decision making. Neuropsychological and neuroimaging data from individuals with psychopathy are examined. It is concluded that these critical functions of the amygdala and vmPFC, and their interaction, are compromised in individuals with the disorder. It is argued that these impairments lead to the development of psychopathy.     

GABA参与兔杏仁体抑制内膝体神经元电活动

本文采用多管微电极胞外记录技术观察了短纯音引起兔内膝神经元的声反应及刺激杏仁体对声反应的影响,并在此基础上观察电泳ＧＡＢＡ及其拮抗剂Ｂｉｃｕｃｕｌｌｉｎｅ的效应。实验结果表明：ＧＡＢＡ可以抑制ＭＧＢ神经元的声反应及自发放电活动,而ＧＡＢＡＡ拮抗剂Ｂｉｃｕｃｕｌｌｉｎｅ的作用则相反;电泳ＧＡＢＡ对ＭＧＢ神经元产生同刺激杏仁体一样的抑制产应,并且这种影响可被Ｂｉｃｕｃｕｌｌｉｎｅ翻转;嗅鼻沟后缘听区农     

The Emotional Brain, Fear, and the Amygdala

1. Considerable progress has been made over the past 20 years in relating specific circuits of the brain to emotional functions. Much of this work has involved studies of Pavlovian or classical fear conditioning, a behavioral procedure that is used to couple meaningless environmental stimuli to emotional (defense) response networks.2. The major conclusion from studies of fear conditioning is that the amygdala plays critical role in linking external stimuli to defense responses.3. Before describing research on the role of the amygdala in fear conditioning, though, it will be helpful to briefly examine the historical events that preceded modern research on conditioned fear.     

Genetic inactivation of prohormone convertase (PC1) causes a reduction in cholecystokinin (CCK) levels in the hippocampus, amygdala, pons and medulla in mouse brain that correlates with the degree of colocalization of PC1 and CCK mRNA in these structures in rat brain

Prohormone convertase (PC1) is found in endocrine cell lines that express cholecystokinin (CCK) mRNA and process pro CCK to biologically active products. Other studies have demonstrated that PC1 may be a one of the enzymes responsible for the endoproteolytic cleavages that occur in pro CCK during its biosynthesis and processing. Prohormone convertase 1 (PC1) has a distribution that is similar to cholecystokinin (CCK) in rat brain. A moderate to high percentage of CCK mRNA-positive neurons express PC1 mRNA. CCK levels were measured in PC1 knockout and control mice to assess the degree to which loss of PC1 changed CCK content. CCK levels were decreased 62% in hippocampus, 53% in amygdala and 57% in pons-medulla in PC1 knockout mice as compared to controls. These results are highly correlated with the colocalization of CCK and PC1. The majority of CCK mRNA-positive neurons in the pyramidal cell layer of the hippocampus express PC1 mRNA and greater than 50% of CCK mRNA-positive neurons in several nuclei of the amygdala also express PC1. These results demonstrate that PC1 is important for CCK processing. PC2 and PC5 are also widely colocalized with CCK. It may be that PC2, PC5 or another non-PC enzyme are able to substitute for PC1 and sustain production of some amidated CCK. Together these enzymes may represent a redundant system to insure the production of CCK.     

Rhesus Macaques (Macaca mulatta) Use Posture to Assess Level of Threat From Snakes

Once prey animals have detected predators, they must make decisions about how to respond based on a cost‐benefit analysis of their risk level. The threat sensitivity hypothesis predicts that prey animals match their response to the level of risk, with high‐risk predator encounters eliciting stronger evasive responses than low‐risk encounters. Primates are known prey of snakes, yet they vary their responses toward snakes. We predicted that primates match their response to the threat level from snakes by assessing posture, with striking postures indicating greater risk than coiled postures and coiled postures indicating greater risk than extended sinusoidal postures. We tested this prediction in a series of experimental trials in which captive rhesus macaques (Macaca mulatta) were exposed to snake models in those postures. Results supported the predictions: macaques responded more strongly to a snake model in a striking posture than in a coiled posture and more to a snake model in a coiled posture than to an extended sinusoidal snake model. We also examined responses of macaques to a partially exposed snake model to mimic the condition of incomplete information, as snakes are often occluded by vegetation. The occluded snake model evoked a response comparable to that of the striking snake. These findings support the threat sensitivity hypothesis. Rhesus macaques use the posture of snakes as a cue in threat assessment, responding more intensely as threat increases, and they also behave as if risk is elevated when their information about snakes is incomplete.     

Cocaine

Cocaine HCl (0, 10, or 50 mg/kg) was injected into adult male ICR mice ip. Thirty minutes later, the brains were removed, and nine regions were isolated: olfactory bulbs, olfactory tubercles, prefrontal cortex, septum, striatum, amygdala, hypothalamus, hippocampus, and thalamus. Using high-performance liquid chromatography, concentrations of norepinephrine, dopamine, serotonin, and their major metabolites and the metabolite/neurotransmitter ratios were determined as an indicator of utilization. Serotonergic systems responded most dramatically. 5HIAA/5-HT decreases were seen in all the brain regions, except the septum, hippocampus, and olfactory bulbs. In most instances, the alterations were dose-dependent. The most profound changes were seen in the amygdala, prefrontal cortex, hypothalamus, and thalamus. For noradrenergic systems, significant responses were seen only in the amygdala, prefrontal cortex, and hypothalamus, but then only at the lower dose. The dopaminergic responses were more complex and not always dose-dependent. The DOPAC/DA ratio was decreased only in the amygdala and striatum at the lower dose, and the olfactory tubercles at the higher dose. It was increased in the septum. The HVA/DA ratios were decreased in the amygdala, prefrontal cortex, and hypothalamus, but only at the lower dose (like MHPG/NE). The 3MT/DA ratio was decreased in the thalamus at the lower dose and in the olfactory tubercles at the higher dose, whereas it was increased in the prefrontal cortex at the lower dose. The HVA and DOPAC routes of degradation were both utilized only by the amygdala. Thus, cocaine produced its most comprehensive effects in this nucleus, as well as the greatest absolute percentage changes for all three of the monoamine systems studied.     

OFF-transient alpha RGCs mediate looming triggered innate defensive response

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Response of shoaling fish to the threat of aerial predation

Synopsis Many species of shoaling fish are preyed upon by aerial predators. However, to date there has been no analysis of the evasive response of a group of shoaling fish to an aerial threat or attack. The response of a shoal of fish encompasses a suite of behaviors starting with a startle response. Shoals of golden shiner, Notemigonus crysoleucas, responded to the threat of aerial predation from a kingfisher model with a startle response, an increase in shoal depth, an increase in polarity, swimming in the opposite direction under the model predator, shoal compression along the depth axis, and shoal expansion on the plane perpendicular to the depth axis. It was hypothesized that shoal compression along the depth axis serves to increase predator confusion by placing more fish in the predator's visual field. This compression was termed the ‘plane of confusion’.     

Cellular processes in the amygdala: gates to emotional memory?

The amygdala is considered a core structure of the so-called limbic system and has been implicated in a variety of functions, including emotional interpretation of sensory information, emotional arousal, emotional memory, fear and anxiety, and related clinical disorders. Despite the clinical and functional importance of the amygdala, it is only recently that some general principles of intra-amygdaloid mechanisms of signal processing that are relevant for fear behavior and memory have emerged from behavioral, anatomical, electrophysiological, and neurochemical studies performed in the amygdala of various mammalian species in vivo, in situ and in vitro.     

Triage: How do we prioritize health care for landscapes?

Summary We explore the potential use of health care as a metaphor for landscape-scale conservation. In human health-care provision, a range of care options is generally available to cover the various levels of treatment required and the degree of urgency of that treatment. The concept of triage is frequently used in emergency situations where many people may be injured and decisions have to be made on the relative urgency of treatment for different individuals versus the relative likelihood of the success of that treatment. Indeed, the need to decide on level and type of care extends throughout health-care provision, and the array of health-care options available can be displayed on a grid that considers relative level of need or threat and the probability of recovery. A similar grid can be constructed for landscape management, which considers level of threat and the probability of system persistence or recovery. The grid differentiates between a variety of scenarios ranging from the need for prompt management action to protect or restore important habitat through to preventative threat minimization. We suggest that the broad concept of triage goes beyond the simple allocation of patients, landscapes or species into urgent, not urgent, and terminal categories and, instead, offers a rational basis for considering allocation of appropriate levels of management to different situations. We also suggest that the practice of restoration has much to learn from health care, where decisions are made daily on the allocation of appropriate levels of care.