Biomechanics of the motor act following destruction of the somatic feedback connections

By means of cyclography method developed in detail by N.A. Bernstein for disclosing the changes in the physical parameters of jumps it was shown that as compared with intact animals, the speed of movements of the distal parts of the fore and hind limbs significantly decreases in animals with electro-coagulated medial lemnisci. The swing of flexion-extension in the ulnar and knee joints likewise diminishes, and the trajectory of the centre of gravity movement changes significantly. In the course of jumping from one platform to another the operated animal experiences difficulties in changing movement phases. It is suggested that the system of medial lemnisci exercises the function of internal somatic backward connection, which is necessary for the succession of micromovements within the general program of the motor act.     

Mechanisms of resurgence of an extinguished instrumental behavior.

Four experiments examined “resurgence” of an instrumental behavior after extinction. All experiments involved three phases in which rats were (1) trained to press one lever for food reward, (2) trained to press a second lever while the first leverpress was extinguished, and (3) tested under conditions in which neither leverpress was rewarded. In each experiment, the first leverpress recovered (resurged) in Phase 3, when the second leverpress was extinguished. The results demonstrated that resurgence occurred when the schedules of reinforcement employed in Phases 1 and 2 yielded either an upshift, downshift, or no change in the rate of reward delivery between those phases. They also demonstrated that initial training on the first lever was required to observe a robust increase in pressing at test (resurgence is thus an associative effect). Resurgence was shown to occur over a wide variety of schedules of reinforcement in Phase 2 (including ratio, interval, and leverpress-independent schedules). Finally, the results do not support the view that resurgence occurs because response competition suppresses leverpressing of the first lever during extinction. Overall, they are consistent with the view that resurgence is a renewal effect in which extinction of an instrumental behavior is specific to the context provided by rewarded leverpressing during the extinction phase. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The mechanism of movement instrumental learning in a Hopfield environment in the feline motor cortex

A model of the neuronal processes in the motor cortex is proposed, which provides the mechanism for instrumentalization (voluntary reproduction) of movements primarily evoked by stimulation of the parietal cortex. The main propositions of the model are as follows: the late NMDA-dependent response of the motor cortex neurons to stimulation of the parietal cortex reflects the discharges in the recurrent collaterals of the pyramidal cell axons; learning processes in the motor cortex are based on the long-term potentiation of the efficiency of the recurrent collaterals; the Hopfield's theory of neuronal nets is applied to the processes of motor learning in the cortex. The movement instrumentalization is viewed as the stable state formation in the collaterally linked neuronal structure; the voluntary reproduction of the previously learned movement in considered as the process of transition of the neuronal structure into the stable state. The data on acetylcholine and dopamine modulatory influences on the reactions of motor cortex neurons are discussed.     

Associations between an instrumental discriminative stimulus and multiple outcomes.

In 5 experiments, rats learned initial stimulus–outcome (S–O) associations in an instrumental training task. Exps 1 and 2 examined the effects on those S–O associations of subsequent or concurrent training of the stimulus with another outcome. Exps 3–5 examined the effects of subsequent nonreinforcement of the stimulus. In each case, the S–O association was assessed by its successful transfer to a different response that had earned the same outcome. In each experiment, additional training of the stimulus, either with another outcome or with nonreinforcement, had little effect on the original S–O association. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control of instrumental performance by Pavlovian and instrumental stimuli.

Two experiments used rats to examine the transfer of control of a stimulus to a new instrumental response. That transfer was successful to the degree that the stimulus and the response shared a common outcome. The transfer was more substantial, however, when the stimulus signaled the availability of that outcome for another instrumental response compared with signaling its occurrence in a Pavlovian manner. That result suggests that the stimulus–outcome associations formed during instrumental training are not reducible to a Pavlovian association. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Blood donation is an act of benevolence rather than altruism.

Objectives: Blood donation is described as an archetypal altruistic behavior, and recruitment/retention campaigns emphasize altruism. Here, a benevolence hypothesis for blood donation (both the donor and recipient benefit) rather than the altruism hypothesis (only the recipient gains) is proposed. Design: Three United Kingdom-based studies contrasted benevolence and altruism: (a) a 6-month prospective study of blood donor behavior (Study 1: N = 957), (b) a cross-sectional study of blood donors' intentions (Study 2: N = 333), and (c) an experimental study examining the effect of benevolent and altruistic messages on willingness to help across high- and low-cost helping behaviors for committed and noncommitted blood donors (Study 3: N = 200). Main Outcome: Donor behavior and intentions-willingness. Measures: Beliefs in personal and societal benefit (Time 1) and actual donations (Time 2) were assessed in Study 1; beliefs in benevolence, altruism, hedonism, and kinship along with donation intentions were assessed in Study 2; and empathy, donor commitment, and willingness to donate blood, money, fund-raise, and staff a telephone helpline were assessed in Study 3. Results: Beliefs in personal rather than societal benefit predicted actual future donation. A path model showed that only beliefs in benevolence were associated with intentions to donate. Committed blood donors were more willing to donate blood when exposed to a benevolent message rather than an altruistic one. This effect was not observed for other forms of helping. Conclusions: The benevolence hypothesis is supported, suggesting that blood donor motivation is partly selfish. Blood donation campaigns should focus on benevolent rather than purely altruistic messages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Caries prevention--based on evidence? Or an act of faith?

The era of evidence-based healthcare requires that dentists' actions are supported by scientific proof of effectiveness. In this paper, evidence regarding the impact of strategies for caries prevention is derived from epidemiology and from a systematic review of research papers.     

The role of cytokines in bacterial pneumonia: an inflammatory balancing act

The effect of 2 mM ethanol, a concentration indicative of daily alcohol consumption, was investigated on trichloroethylene (TRI) metabolism in perfused Wistar rat liver. The study consisted of two parts: The first part studied TRI administration with or without ethanol. In the second study chloral hydrate (CH), an intermediate in TRI metabolism, was administered in the absence or presence of ethanol to phenobarbital (PB) treated or non-PB-treated rats. The concentrations of the metabolites, total trichloroethanol (TCE), and trichloroacetic acid (TCA) were measured by gas chromatography and intracellular reduced pyridine nucleotides by surface fluorometry. In the first study, ethanol infusion significantly increased the TCE/TCA ratio, TCE production rate, and percentage of reduced pyridine nucleotides, and decreased TCA production rate without an associated change in the sum of TCE and TCA formation rates. In the second study, ethanol infusion in the absence or presence of PB produced similar significant increases in the TCE/TCA ratio, TCE production rate, and percentage of reduced pyridine nucleotides, accompanied by a decrease in TCA formation. The observed shift in TRI metabolism in the presence of ethanol, from oxidation to TCA to reduction to TCE, suggests that alcohol exerts alterations in hepatic intracellular oxidation-reduction (redox) states.     

Choice as an act of meaning: The case of social class.

Social class is one important source of models of agency--normative guidelines for how to be a "good" person. Using choice as a prototypically agentic action, 5 studies test the hypotheses that models of agency prevalent in working-class (WK) contexts reflect a normative preference for similarity to others, whereas models prevalent in middle-class (MD) contexts reflect a preference for difference from others. Focusing on participants' choices, Studies 1 and 2 showed that participants from WK relative to MD contexts more often chose pens that appeared similar to, rather than different from, other pens in the choice set, and more often chose the same images as another participant. Examining participants' responses to others' choices, Studies 3 and 4 demonstrated that participants from WK relative to MD contexts liked their chosen pens more when a confederate chose similarly and responded more positively when a friend chose the same car in a hypothetical scenario. Finally, Study 5 found that car advertisements targeting WK rather than MD consumers more often emphasized connection to, rather than differentiation from, others, suggesting that models of agency are reflected in pervasive cultural products. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neonatal hind-paw injury disrupts acquisition of an instrumental response in adult spinal rats.

The present study was designed to evaluate the impact of neonatal injury on adult spinal plasticity in rats. Subjects were randomly assigned to 1 of 4 experimental conditions: (a) hind-paw injury at Postnatal Day (PD) 2, (b) hind-paw injury at PD 5, (c) anesthesia exposure only on PD 2, or (d) anesthesia exposure only on PD 5. Subjects receiving a unilateral neonatal hind-paw injury showed decreased mechanical threshold (hyperalgesia) on the previously injured hind paw throughout development. This decrease in threshold survived spinal transection (at T2) at 12 weeks of age. Injured subjects also showed significant impairment in a spinal instrumental learning task performed by the previously injured hind paw. This disruption of learning indicates a disruption of spinal plasticity that may be due to induction of long-term changes in nociceptive processing within the spinal cord. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The optimization of instrumental hemofiltration

47 hemofiltration procedures were performed in 10 patients. A self-made balancer based on the volumic hydrodynamics dependent on substitute from filtrate was used. An APD-02 peritoneal dialysis machine served the source of the substitute. It provided change of the concentration and was used for prophylaxis of osmodisturbances, massive dehydration and for obtaining bicarbonate substitute. The technology for F-60 cartridges reuse has been elaborated and tested. One of the patients received the isolated hemofiltration programme for more than 2 months. Antiuremic efficacy of hemofiltration was studied.     

简析三相异步电动机绕组故障

我厂在修理三相异步电动机时,发现电动机绕组经常出现接地、短路、开路、接线错误等故障,给修理维护造成很大困难。本文将分别论述这些故障的产生时的现象、产生的原因以及检查、处理方法,希望能为电气维修人员提供一些参考。     

Non-invasive instrumental method in uncontrollable post-partum hemorrhage (an alternative to hemostatic hysterectomy)

A new non-invasive instrumental technique which is useful to stop the most severe post-partum haemorrhages is described. This technique is proposed as an alternative to more invasive methods such as the binding of uterine or hypogastric arteries, which is itself a trauma, not always effective and could promote the obstetric shock. The method proposed by the authors is not invasive, can be performed in a few minutes and performed without the help of anaesthesia. Very encouraging results were achieved and have allowed to avoid the use of the so-called "haemostatic" hysterectomy.     

Dissociating ventral and dorsal subicular dopamine D? receptor involvement in instrumental learning, spontaneous motor behavior, and motivation.

A series of experiments investigating the role of dopamine D? receptors in the ventral subiculum (vSUB) and dorsal subiculum (dSUB), 2 subregions of the hippocampal formation, found that D? receptor antagonism (3.0 nmol/0.5 μl SCH-23390 bilaterally) in the vSUB impaired instrumental learning and performance, reduced break point in progressive ratio (PR) tests, and produced an intrasession decline in responding during test sessions, but had no effect on spontaneous motor or food-directed behavior. In contrast, D? receptor blockade in the dSUB had no effect on instrumental learning, performance, PR break point, or food-directed behavior, but reduced spontaneous motor behavior. These results suggest a dissociation between the vSUB and dSUB with respect to the role of dopamine in various aspects of motivated and motor behavior. Further, D? activation in the vSUB may be a critical component of motivational arousal associated with learned contextual cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)