兔笼类型对肉兔屠宰性能和宰后肉质的影响

【目的】通过测定单层大笼和三层兔笼饲养肉兔的屠宰性能和宰后肌肉成熟过程中肉质的变化,为肉兔养殖圈舍建设中兔笼的选择和兔肉加工消费提供参考。【方法】选择分别用单层大笼和三层兔笼饲养在同一栋兔舍内的70日龄、健康、接近群体平均体重的加利福尼亚肉兔各10只（公母各半）,按家兔屠宰方法屠宰后测定其屠宰性能和肌肉成熟过程中的pH、肉色、剪切力、蒸煮损失和失水率。【结果】相同日龄下,两种兔笼饲养对肉兔的屠宰重影响不显著;单层大笼饲养的肉兔和三层兔笼饲养的肉兔相比,全净膛中段的百分率显著降低（P<0.05）,而后段的百分率显著增加（P<0.05）,腹腔脂肪率极显著降低（P<0.01）,全净膛率和半净膛率均显著降低（P<0.05）;单层大笼饲养肉兔的股骨重、径骨重和后腿肌肉率较高,而三层兔笼饲养肉兔的肝重和肾重较高。三层兔笼饲养肉兔肌肉L*值在成熟的第2天达到最大值,单层大笼饲养的肉兔在第3天达最大值;三层兔笼饲养肉兔的肌肉L*值在第6天显著高于单层大笼饲养肉兔（P<0.05）,第7天极显著高于单层大笼肉兔（P<0.01）;但在成熟的前3天,单层大笼饲养肉兔的肌肉L*值高于三层兔笼饲养肉兔。单层大笼饲养肉兔的肌肉a*值在成熟的第2、3和5天显著高于三层兔笼饲养的肉兔（P<0.05）,在第4天极显著高于三层兔笼饲养的肉兔（P<0.01）。成熟过程中,三层兔笼饲养肉兔的肌肉b*值比单层大笼饲养肉兔的高,在第1天极显著高于单层大笼饲养的肉兔（P<0.01）。在兔肉成熟过程中的1-3 d,三层兔笼饲养肉兔的肌肉pH比单层大笼饲养的高,3天后比单层大笼饲养的低,整个成熟过程肌肉pH差异不显著。单层大笼饲养肉兔的肌肉剪切力在宰后和成熟的第1天和第3天显著高于三层兔笼饲养的肉兔（P<0.05）,第2天极显著高于三层兔笼饲养的肉兔（P<0.01）;第4天后,单层大笼饲养肉兔肌肉的剪切力低于三层兔笼饲养肉兔（P>0.05）。三层兔笼饲养肉兔的肌肉蒸煮损失在成熟过程中均大于单层大笼饲养的肉兔。兔肉在压力作用下的失水率情况和蒸煮损失一致。【结论】单层大笼饲养肉兔与三层兔笼饲养相比,能改变肌肉在胴体中的分布,改善兔肉肉质。     

The in vitro Classical Conditioning of the Gill Withdrawal Reflex of Aplysia californica

Associative learning has been demonstrated in a reduced siphon, mantle, gill, and abdominal ganglion preparation of Aplysia. The preparations learned to respond to a previously neutral stimulus as a consequence of training in a classical conditioning paradigm. Backward conditioning, presentation of the conditioned stimulus alone, or presentation of the unconditioned stimulus at some random interval after presentation of the conditioned stimulus failed to produce conditioning. This model system can be used to study the neural mechanisms underlying associative learning.     

Cerebellar LTD and learning-dependent timing of conditioned eyelid responses

Mammals can be trained to make a conditioned movement at a precise time, which is correlated to the interval between the conditioned stimulus and unconditioned stimulus during the learning. This learning-dependent timing has been shown to depend on an intact cerebellar cortex, but which cellular process is responsible for this form of learning remains to be demonstrated. Here, we show that protein kinase C-dependent long-term depression in Purkinje cells is necessary for learning-dependent timing of Pavlovian-conditioned eyeblink responses.     

Memory extinction, learning anew, and learning the new: dissociations in the molecular machinery of learning in cortex

The rat insular cortex (IC) subserves the memory of conditioned taste aversion (CTA), in which a taste is associated with malaise. When the conditioned taste is unfamiliar, formation of long-term CTA memory depends on muscarinic and beta-adrenergic receptors, mitogen-activated protein kinase (MAPK), and protein synthesis. We show that extinction of CTA memory is also dependent on protein synthesis and beta-adrenergic receptors in the IC, but independent of muscarinic receptors and MAPK. This resembles the molecular signature of the formation of long-term memory of CTA to a familiar taste. Thus, memory extinction shares molecular mechanisms with learning, but the mechanisms of learning anew differ from those of learning the new.     

Association of conditionability with degree of reactivity in psychiatric patients

A positive relationship exists between the number of times a subject responds with a psychogalvanic response to an orienting or alerting stimulus (tone) and the rate of learning in classical conditioning. This is seen by a correlation (p=.65 and .643 when corrected for ties) between the number of orienting responses and the resistance to extinction of the conditioned psychogalvanic response.     

Regenerating fish optic nerves and a regeneration-like response in injured optic nerves of adult rabbits

Regeneration of fish optic nerve (representing regenerative central nervous system) was accompanied by increased activity of regeneration-triggering factors produced by nonneuronal cells. A graft of regenerating fish optic nerve, or a "wrap-around" implant containing medium conditioned by it, induced a response associated with regeneration in injured optic nerves of adult rabbits (representing a nonregenerative central nervous system). This response was manifested by an increase of general protein synthesis and of selective polypeptides in the retinas and by the ability of the retina to sprout in culture.     

Epinephrine enables Pavlovian fear conditioning under anesthesia

Rats under Pavlovian defensive conditioning (noise paired with shock) while under general anesthesia. Peripheral administration of epinephrine (0.01 to 1.0 milligram per kilogram of body weight) during training resulted in the acquisition of conditioned fear, as shown 10 days later by conditioned suppression of water drinking. Analysis of heart rate and measurement of reflexes during training indicated that epinephrine did not lighten the state of anesthesia. These results indicate that epinephrine enables the learning of conditioned fear in the anesthetized brain.     

Qualitative versus directional cues in two forms of differentiation

Dogs given opportunities to base their instrumental conditioned responses in differentiation learning on either the quality of the auditory conditioned stimulus (for example, metronome versus buzzer) or the direction of its source (in front or behind) choose different cues in different tasks. In S(1)--> R(1), S(2)-->R(2) (left leg-right leg) differentiation they exclusively use directional cues and are almost unable to learn this task when only quality cues are available. When confronted with Pavlovian S +--> R, S ---> no R (go-no go) differentiation, however, they generally learn on the basis of quality cues, although some animals also attend to the directional cues. Thus an animal's success or failure in a given differentiation procedure depends not only on its ability to discriminate the stimuli but also on the task with which it is confronted.     

Retrograde amnesia: effects of handling and microwave radiation

Rats that were irradiated with microwaves immediately after the training trial in a one-trial shock-avoidance learning task retained the conditioned avoidance response 24 hours later. However, rats that were handled a few minutes each day for 3 days before the experiment did not retain the response, although they were capable of learning in a later test.     

Retrograde Amnesia from Conditioned Competing Responses

If electroconvulsive shock is given immediately after a learning trial, retrograde amnesia for that response occurs. The usual interpretation of such amnesia states that a neural engram, after a learning trial, requires a certain amount of time to consolidate, and electroconvulsive shock interferes with this consolidation, producing amnesia. Four studies are summarized which indicate that convulsive shock serves as an unconditioned stimulus producing a convulsive response, that takes precedence over other behavior, and part of which becomes conditioned to stimuli in the learning situation. The convulsive response competes with, and replaces, the previous response, resulting in the appearance of amnesia.     

Observational Learning in Octopus vulgaris

Untrained Octopus vulgaris (observers) were allowed to watch conditioned Octopus(demonstrators) perform the task of selecting one of two objects that were presented simultaneously and differed only in color. After being placed in isolation, the observers, in a similar test, consistently selected the same object as did the demonstrators. This learning by observation occurred irrespective of the object chosen by the demonstrators as the positive choice and was more rapid than the learning that occurred during the conditioning of animals. The task was performed correctly without significant errors and further conditioning for 5 days. These results show that observational learning can occur in invertebrates.     

Cues: their relative effectiveness as a function of the reinforcer

Two cues, either size or flavor of food pellet, were conditionally paired with either malaise induced by x-ray or pain induced by shock in four groups of rats. The combination of flavor and illness produced as conditioned decrement in consumption, but that of size and illness did not. Conversely, the combination of size and pain produced an inhibition of eating, but flavor and pain did not. Apparently, effective associative learning depends on central neural convergence of the paired afferent input.     

酸樱桃汁对D-半乳糖致衰老小鼠学习记忆功能的影响

目的检测酸樱桃汁对D-半乳糖致衰老小鼠模型学习记忆功能的影响.方法颈背部皮下注射D-半乳糖120 mg/（kg·d^-1）连续56 d建立亚急性衰老模型,同时灌胃给予不同剂量的酸樱桃汁进行治疗,治疗8周后,分别采用跳台实验、Morris水迷宫检测小鼠的学习记忆能力.结果跳台法检测结果显示：酸樱桃汁能延长D-半乳糖致衰老模型小鼠的潜伏期,减少错误次数;Morris水迷宫实验结果显示：酸樱桃汁能使D-半乳糖致衰老模型小鼠平均潜伏期明显缩短,跨过平台次数显著增加.结论酸樱桃汁能有效提高D-半乳糖致衰老小鼠的学习记忆能力.     

Aversive learning enhances perceptual and cortical discrimination of indiscriminable odor cues

Learning to associate sensory cues with threats is critical for minimizing aversive experience. The ecological benefit of associative learning relies on accurate perception of predictive cues, but how aversive learning enhances perceptual acuity of sensory signals, particularly in humans, is unclear. We combined multivariate functional magnetic resonance imaging with olfactory psychophysics to show that initially indistinguishable odor enantiomers (mirror-image molecules) become discriminable after aversive conditioning, paralleling the spatial divergence of ensemble activity patterns in primary olfactory (piriform) cortex. Our findings indicate that aversive learning induces piriform plasticity with corresponding gains in odor enantiomer discrimination, underscoring the capacity of fear conditioning to update perceptual representation of predictive cues, over and above its well-recognized role in the acquisition of conditioned responses. That completely indiscriminable sensations can be transformed into discriminable percepts further accentuates the potency of associative learning to enhance sensory cue perception and support adaptive behavior.     

四君子汤对FCIR大鼠大脑皮质神经保护作用的实验研究

目的 探讨四君子汤对局灶性脑缺血再灌注（focal cerebral ischemia-reperfusion,FCIR）大鼠大脑皮质神经保护作用的机制。方法 将48只SD雄性大鼠随机分成对照组、模型组、尼莫地平组（10.80 mg/kg）、四君子汤组（6 g/kg）,每组12只。运用大脑中动脉栓塞法制备大鼠FCIR模型,对照组和模型组给予生理盐水,其它各组则用相应药物连续灌胃14 d。运用Zea-Longa 5级评分法评定FCIR大鼠神经功能,免疫组化检测层粘连蛋白（laminin,LN）、组织金属蛋白酶抑制剂1（tissue inhibitor of matrix metalloproteinases 1,TIMP1）和基质金属蛋白酶9（matrix metalloproteinases 9,MMP9）表达。结果 与对照组比较,模型组神经功能评分显著增加（P<0.01）;与模型组比较,四君子汤组、尼莫地平组神经功能评分均明显减少（P<0.01）,且四君子汤组、尼莫地平组组间差异无统计学意义（P>0.05）。模型组大脑皮质LN阳性表达明显低于对照组（P<0.01）,四君子汤和尼莫地平组LN阳性表达明显高于模型组（P<0.01）。模型组大脑皮质TIMP1、MMP9阳性表达明显高于对照组（P<0.01）。四君子汤和尼莫地平组TIMP1阳性表达明显高于模型组（P<0.01）,而MMP9阳性表达明显低于模型组（P<0.01）。结论 四君子汤可能通过促进LN和TIMP1表达,抑制MMP9表达,减轻大鼠的神经功能症状,进而对FCIR大鼠大脑皮质起到神经保护作用。     

Brain aging correlates: retardation by hormonal-pharmacological treatments

Mid-aged rats were either adrenalectomized and chronically maintained, or left intact and treated daily for a 9- to 10-month period with a potent analog of the peptide adrenocorticotropin (residues 4 to 9), which has some stimulant properties, or with the neural stimulant pentylenetetrazole. All three treatments reduced hippocampal morphologic correlates of brain aging (neuronal loss, glial reactivity). The pentylenetetrazole and peptide treatments also improved reversal learning. These results suggest that certain endogenous peptides, with stimulant properties, may also exert long-term, trophic effects on brain structure and function.     

Cleaning symbiosis provides a positive reinforcer for fish

Chaetodon auriga, a conun7won marine fish in Hawaii, can be conditioned by presentation of a moving model of a cleaner fish as a positive reinforcement on an instrumental schedule. Reinforcement is probably through tactile stimulation and might help to shape the response of fish to cleaners. Tactile stimulilation night serve as a valuable reinforcer in studies of fish learning.     

正确认识年龄损害记忆——动物学研究

年龄相关性学习记忆能力减退是从人到啮齿类动物的常见现象.但因受到支持的记忆系统不同,各种类型的记忆形式受到年龄影响各不相同.并非所有形式的记忆都受损.受损的记忆消失也并非同时出现,且受损程度不同,以空间性记忆受损最早最重.衰老过程中,不同形式的记忆可能此消彼长,有些形式的记忆甚至可能增强.因此,在研究年龄相关性学习记忆能力减退时最好使用多个任务进行记忆评估.     

Learning in normal and mutant Drosophila larvae

Adult Drosophila melanogaster have previously been conditioned with shock to avoid various odors. In these experiments, larvae also sensed airborne odorants, responded to electric shock, and learned. Larval behavior paralleled adult behavior for (i) a mutant, smellblind, which failed to respond to odorants; (ii) three mutants, dunce, turnip, and cabbage, which were deficient in olfactory learning ability; and (iii) a mutant heterozygote, turnip/+, which learned but also forgot rapidly.     

Differential classical conditioning of a defensive withdrawal reflex in Aplysia californica

The defensive siphon and gill withdrawal reflex of Aplysia is a simple reflex mediated by a well-defined neural circuit. This reflex exhibits classical conditioning when a weak tactile stimulus to the siphon is used as a conditioned stimulus and a strong shock to the tail is used as an unconditioned stimulus. The siphon withdrawal component of this reflex can be differentially conditioned when stimuli applied to two different sites on the mantle skin (the mantle shelf and the siphon) are used as discriminative stimuli. The differential conditioning can be acquired in a single trial, is retained for more than 24 hours, and increases in strength with increased trials. Differential conditioning can also be produced within the field of innervation of a single cluster of sensory neurons (the LE cluster) since two separate sites on the siphon skin can serve as discriminative stimuli. The finding that two independent afferent inputs that activate a common set of interneurons and motor neurons can be differentially conditioned restricts the possible cellular loci involved in the associative learning.