Operant conditioning of cortical unit activity

The activity of single neurons in precentral cortex of unanesthetized monkeys (Macaca mulatta) was conditioned by reinforcing high rates of neuronal discharge with delivery of a food pellet. Auditory or visual feedback of unit firing rates was usually provided in addition to food reinforcement. After several training sessions, monkeys could increase the activity of newly isolated cells by 50 to 500 percent above rates before reinforcement.     

Rats' preference for earned in comparison with free food

Rats were trained to eat free food from a dish, then trained to press a lever for similar food. The free food was then presented while subjects were pressing on several reinforcement schedules. Subjects continued to press for reinforcement when one or two presses were required for reinforcement, and ate little free food. When ten presses were required for reinforcement, rats preferred free food and pressed little or not at all. It was concluded that, when work demands are not too high, rats prefer earned food to free food.     

Control of vocal responding in chickens

Schedules of reinforcement were shown to control the rate of chirping bychickens in the same way as other motor responses in subhumans. Under a discrimination procedure, chickens responded selectively to the visual stimulus associated with food reinforcement for chirping. Control experiments demonstrated that food influenced the rate of responding because it was presented dependent on the chick's vocalizing and not because it had an innate eliciting or "emotionalizing" power.     

Classical conditioning of a complex skeletal response

The pigeon's so-called "arbitrary" response of pecking an illuminated disk can be established and maintained by procedures resembling those of classical conditioning. This phenomenon was shown to be independent of the specific signaling relationships between illumination of the pecking disk and presentation of food; it will appear as long as the key is differentially associated with food. When a nondifferential condition is introduced, pecking "extinguishes" even if it has previously been established and even when the new condition involves as much reinforcement as the old one. Reinstating differential conditions reestablishes pecking. The initial conditions determine the speed and apparently the asymptote of pecking rates in the differential condition; initial exposure to a nondifferential procedure retards subsequent acquisition, possibly quite permanently. These findings are discussed in the context of mechanisms of adaptive learning, not involving reward and punishment, which lead to selection of effective behaviors on a nonarbitrary basis.     

Bacterioplankton: a sink for carbon in a coastal marine plankton community

Recent determinations of high production rates (up to 30 percent of primary production in surface waters) implicate free-living marine bacterioplankton as a link in a "microbial loop" that supplements phytoplankton as food for herbivores. An enclosed water column of 300 cubic meters was used to test the microbial loop hypothesis by following the fate of carbon-14-labeled bacterioplankton for over 50 days. Only 2 percent of the label initially fixed from carbon-14-labeled glucose by bacteria was present in larger organisms after 13 days, at which time about 20 percent of the total label added remained in the particulate fraction. Most of the label appeared to pass directly from particles smaller than 1 micrometer (heterotrophic bacterioplankton and some bacteriovores) to respired labeled carbon dioxide or to regenerated dissolved organic carbon-14. Secondary (and, by implication, primary) production by organisms smaller than 1 micrometer may not be an important food source in marine food chains. Bacterioplankton can be a sink for carbon in planktonic food webs and may serve principally as agents of nutrient regeneration rather than as food.     

Conditioned reinforcement in the goldfish

Goldfish were trained to press a lever on a 10:1 fixed-ratio schedule of reinforcement. They were extinguished under three conditions. Responding was followed by (i) solenoid noise and water delivery formerly associated with food reinforcement, (ii) solenoid noise only, or (iii) nothing. The number of extinction responses was largest in condition 1, less in condition 2, and smallest in condition 3, thus providing evidence for conditioned reinforcement in goldfish.     

Wolves, moose, and tree rings on isle royale

Investigation of tree growth in Isle Royale National Park in Michigan revealed the influence of herbivores and carnivores on plants in an intimately linked food chain. Plant growth rates were regulated by cycles in animal density and responded to annual changes in primary productivity only when released from herbivory by wolf predation. Isle Royale's dendrochronology complements a rich literature on food chain control in aquatic systems, which often supports a trophic cascade model. This study provides evidence of top-down control in a forested ecosystem.     

Behavioral regulation of the milieu interne in man and rat

In regulating the internal homeostatic environment mammals, by necessity, employ behavioral strategies that differ from the tactics used in coping with contingencies in the external environment. When an animal consumes a meal, the palatability of that meal is automatically adjusted in accordance with the ultimate internal effects of that meal. If the meal causes toxicosis, the animal acquires an aversion for the taste of the meal; conversely, if recuperation follows ingestion of the meal, the taste of that meal is enhanced. Unlike the learning that occurs when externally referred visual and auditory signals are followed by punishment in the form of peripheral pain or reward in the form of food in the mouth, conditioning to the homeostatic effects of food can occur in a single trial and rarely requires more than three to five trials, even though the ultimate effects of the meal are delayed for hours. Paradoxically, the animal need not be aware of the ultimate internal effect in the same sense that it is aware of external contingencies. For example, an aversion can be acquired even if the animal is unconscious when the agent of illness is administered. Thus, the way in which food-effects are stored in memory may be fundamentally different from the way in which memories of specific time-space strategies devised for external contingencies are stored. This separation of function is indicated by limbic lesions which disrupt conditioning to a buzzer that is followed by shock and facilitate conditioning to a taste that is followed by illness. Operationally speaking, one can describe both aversion conditioning and buzzer-shock conditioning in the spacetime associationistic terms of classical conditioning. However, psychologically speaking, one must realize that in aversion conditioning the animal does not act as if it were acquiring an "if-then" strategy. It acts as if a hedonic shift, or a change in the incentive value of the flavor were taking place. Such hedonic shifts are critical in regulation of the internal milieu. When an animal is in need of calories, food tends to be more palatable; as the caloric deficit is restored, food becomes less palatable. If the animal's body temperature is below optimum, a warm stimulus applied to the skin is pleasant. When body temperature is too high, the converse is true. In this way, homeostatic states monitored by internal receptors produce changes in the incentive values of external stimuli sensed by the peripheral receptors, and guide feeding behavior. In mammals at least, the gustatory system, which provides sensory control of feeding, sends fibers to the nucleus solitarius. This brainstem relay station also receives fibers from the viscera and the internal monitors of the area postrema. Ascending fibers bifurcate at the level of the pons and project toward the feeding areas of the hypothalamus and the cortex. The olfactory system which primarily projects to the limbic system does not play a primary role in adjusting food incentives. Rather, it plays a secondary role in the activation of feeding, as do other external sensory systems. This specialized conditioning mechanism, which specifically adjusts gustatory hedonic values through delayed visceral feedback, is widespread among animals, including man and rat. These two species are remarkably similar in their thresholds and preferences for gustatory stimuli. The behavioral similarities are based on the animals' having similar gustatory systems, similar convergence of gustatory and internal afferents to the nucleus solitarius, and similar midbrain regulatory mechanisms. Thus, it is not surprising that the feeding of obese rats with internal hypothalamic damage resembles the feeding of obese human beings insensitive to the internal signs of this caloric state. Obviously, man has a highly specialized form of symbolic communication and the rat does not, yet man's cognitive specialization does not prevent him from developing aversions to food consumed before illness even when he knows that his illness was not caused by food (43).     

Discrimination of tones during reinforcing brain stimulation

Hungry animals were trained to press a lever for brain stimulation. Different tones were presented concurrently with the stimulation. A second lever delivered food only during critical tone periods. Animals were able to discriminate tones presented concurrently with rewarding intracranial stimulation, and they also interrupted self-stimulation behavior to respond appropriately under other reinforcements.     

乌鲁木齐市动物源性食品中兽药残留分析与评价

为了解乌鲁木齐市动物源性食品中的兽药残留情况,采用高效液相色谱法(HPLC)对14种兽药在动物源性食品中的残留量进行检测.结果表明:伊维菌素、呋喃唑酮、磺胺嘧啶、磺胺间甲氧嘧啶、磺胺二甲嘧啶、磺胺甲基异口恶唑均有不同程度的残留量,其余未见检出.检出率依次为89;、30;、28;、4;、70;和22;.其中磺胺类药物与呋喃唑酮残留问题较突出,超标率分别为66;和30;,将其作为乌鲁木齐市兽药残留监控的主要药物是很必要的.     

Natural occurrence of malaria in rhesus monkeys

A tone ending in unavoidable electric shock was periodically presented to pigeons while they pecked a key for food. When pecking was completely disrupted by tone, shock was disconnected, and the training tone and tones having new frequencies were presented. Initially the gradient of generalization was broad; as testing proceeded, however, the gradient narrowed severely.     

Control of their environment reduces emotionality in rats

Rats reared from birth in a "contingent environment" in which they controlled lighting conditions and the delivery of food and water were compared as adults to rats reared in an environment in which they received the same food, water, and lighting conditions, but without control over their occurrence. Rats reared in the contingent environment were less emotional, as judged by activity and defecation scores in open-field testing.     

Conditioned Approach and Contact Behavior toward Signals for Food or Brain-Stimulation Reinforcement

When presentation of a retractable lever always preceded food delivery, rats licked or gnawed the lever. They also approached but seldom orally contacted a lever signaling brain-stimulation reinforcement; instead, subjects sniffed, pawed, or "explored" the lever. Therefore, a Pavlovian conditioned stimulus evoked directed skeletal responses whose specific form depended on the forthcoming unconditioned stimulus.     

TECHNIQUE FOR SUSTAINING BEHAVIOR WITH CONDITIONED REINFORCEMENT

Pigeons were intermittently reinforced with food for pecking at one key. Concurrent pecking at a second key intermittently produced conditioned reinforcers (the set of stimuli that accompanied food reinforcement, but not the food). Under these conditions, responding on the second key was maintained indefinitely. Rates and patterns of responding on the second key were a function of the schedule of conditioned reinforcement.     

Steady potential correlates of positive reinforcement: reward contingent positive variation

A positive reinforcement with food produced high-voltage bursts of alpha activity over the posterior marginal gyrus in a cat deprived of food and water. This synchronization was always associated with a large (180 to 300 microvolt), positive steady potential shift comparable to that occurring during the onset of sleep. Since this shift was contingent upon the relative appropriateness and desirability of food reward, it was termed reward contingent positive variation.     

Continuous compensatory tracking by a cebus monkey

A cebus monkey was trained to hold a continuously moving voltmeter needle on-target for 60 seconds to obtain a food-pellet reinforcement. The task confronting the animal was relatively complex in that the high-frequency error voltage fed to the voltmeter needle was nulled by the animal by means of a joystick physically separated from the stimulus display.     

Dr. Guthrie and Felis domesticus or: tripping over the cat

The principal reactions described in Guthrie and Horton's classic learning monograph appear to have been caused by the mere presence of the experimenters. Neither escape nor food reinforcement is necessary for the establishment of such responses. They are species-typical "greeting" reactions, readily elicited by the sight of human observers.     

Depressive disorders: toward a unified hypothesis

Our scientific understanding of psychiatric syndromes, including the phenomena of depression, has been hampered because of: (i) the use of metapsychological concepts that are difficult to test; (ii) methodological and linguistic barriers that prevent communication among psychoanalysts, behaviorists, experimental psychologists, and psychiatrists; and (iii) the reluctance of psychiatrists to accept animal models as possible approximations of certain aspects of human psychopathology. We have attempted to demonstrate that the animal models simulate some of the central features of clinical depression (for example, helplessness and object loss), thereby allowing one to rigorously investigate them from developmental, behavioral, and biochemical perspectives. The object loss model, as a concrete version of a metapsychological-psychoanalytic concept, has enabled primatologists to study the disruption of an attachment bond. The behavioral model accommodates this concept to a broader generalization: loss of reinforcement or loss of control over reinforcement. We have reviewed the evidence that these processes involve the diencephalic centers of reward or reinforcement, thereby permitting integration of the psychoanalytical and behavioral formulations with the biochemical hypotheses. Also, we have presented data strongly suggesting that the breaking of an attachment bond in the primate represents significant loss of reinforcement that induces helplessness and disrupts motivated behavior. Finally, we have argued that the depressive syndrome could be caused by interactions of genetic, chemical, developmental, and interpersonal factors, all of which impinge on the diencephalic centers of reinforcement.     

广西反刍动物饲料和动物源性饲料产品中牛羊源性成分监测

为了监测广西反刍动物饲料和动物源性饲料产品中的牛羊源性成分,掌握动物饲料安全情况,农业部饲料质量监督检验测试中心（南宁）于2005～2009年,应用实时荧光PCR和PCR对广西南宁、柳州、防城港、北海、钦州、桂林等市974批反刍动物饲料及动物源性饲料产品进行牛羊源性成分的抽样检测。结果表明,2005～2006年共有12批产品被检出含有牛羊源性成分,其涉及所有抽检产品类别和饲料生产、经营、使用3个环节;2007—2009年的抽检合格率均达100％。说明广西的反刍动物饲料和动物源性饲料的牛羊源性成分呈现下降趋势,反刍动物饲料逐步转向安全生产及使用的方向发展。     

上海市预包装食品营养标签现状调查

采用食品标签和预包装调查(FLAPS)的方法,在上海市4家大型超市以拍照、抄写或购买的方式获取营养标签信息;应用SPSS20.0软件进行统计分析,并且同2008年上海市调查结果进行统计学比较。结果表明,共调查7大类1 102件大陆预包装食品,营养标签标示率为45.8%,较《规范》实施前(2008年调查)的标示率(35.4%)有显著提高;营养成分表中能量和4项核心营养素的标示率均高于98%,饱和脂肪、反式脂肪、铁的标示率较低,分别为9.7%、5.3%和9.5%。该调查结果为完善我国营养标签管理,充分发挥其在合理选择食物中作用,食品生产企业、消费者和政府职能部门应该共同努力。