The effects of phencyclidine and chlordiazepoxide on target biting of confined male mice

Target-biting of confined mice increases following delivery of tail shock and decreases during a tone that precedes the shock. Both phencyclidine and chlordiazepoxide reduced biting (dose dependently) following shock and had no effect on biting during the tone. These observations are discussed in reference to previous reports, which infer that the effects of phencyclidine and chlordiazepoxide on aggression might depend upon the baseline rate of the behavior.     

重症感染非抗感染措施的思考

近年来严重感染与感染性休克治疗策略的主要进展是对强化血糖控制、糖皮质激素等疗法的再评价。同时,也出现了诸如血管加压素、他汀类药物、选择性口腔/肠道脱污染等新的治疗措施,并取得了一定成果。本文对相关研究进展进行综述,以阐明集束化策略和管理水平的提高可能是最终降低重症感染病死率的关键。     

男女两性在文化震荡、心理健康及其关系中的差异比较

采用自编问卷对1555名30岁及以上被试受文化震荡的影响程度及其心理健康进行调查,分别探讨不同生活环境和环境相同但受教育程度不同的男女两性在两变量及其关系中的差异。结果表明:(1)总体上,男性报告的文化事件的主观影响明显比女性更积极,但其心理健康水平却明显低于女性;男女两性在文化震荡与心理健康之间均存在显著正相关,但具有不同特点。(2)不同生活环境和同一生活环境中不同受教育程度的男女两性在文化震荡、心理健康中均存在不同程度的差异;在这两变量间也均存在不同方面的显著正相关。     

Facing Ourselves

At the time of this writing, a widely publicized, waived-consent trial is underway. Sponsored by Northfield Laboratories, Inc. (Evanston, IL) the trial is intended to evaluate the emergency use of PolyHeme^®, an oxygen-carrying resuscitative fluid that might prevent deaths from uncontrolled bleeding. The protocol allows patients in hemorrhagic shock to be randomized between PolyHeme^® and saline in the field and, still without consent, randomized between PolyHeme^® and blood after arrival at an emergency department. The Federal regulations that govern the waiver of consent restrict its applicability to circumstances where proven, satisfactory treatments are unavailable. Blood—the standard treatment for hemorrhagic shock—is not available in ambulances but is available in hospitals. The authors argue that the in-hospital stage of the study fails to meet ethical and regulatory standards.     

Biobehavioral effects of extended salt loading and conflict stress in intact baboons.

Behavioral stressors may inhibit sodium excretion, potentially increasing plasma volume and elevating blood pressure during chronic exposure. Blood pressure regulation may be especially deranged during manipulations that further challenge the kidney, such as a diet high in salt content. The effects on blood pressure and other variables of combined behavioral stress (food/shock conflict) and dietary salt (12 g NaCl per day; 218 mEq Na+ per day) were examined in adult male baboons over the course of 1 year. Mean arterial pressure was not significantly elevated over baseline after 5 months of high dietary salt alone (6 +/- 5 mmHg) but was maximally elevated by an average of 17 (+/- 3 SEM) mmHg after 5 months of combined salt and conflict stress. Control baboons showed no significant trends in mean arterial pressure across the same time period. Individual subjects whose blood pressure was "salt+stress resistant" or "salt+stress sensitive" were differentiated by their degree of pressure diuresis and natriuresis, urinary free cortisol, and a behavioral index of stress sensitivity. The data indicate additive effects of chronic high dietary salt intake and behavioral stressors on blood pressure in nonhuman primates that are dependent on renal function and pituitary-adrenocortical activity.     

Reduction of shock duration as negative reinforcement in free-operant avoidance

Rats were trained on a free-operant procedure in which shock duration was controlled by responses within a limited range of interresponse times. Shocks of 1.6-mA intensity occurred randomly with average density of 10 shocks per minute. As long as interresponse times were 15 seconds or less, any shocks received were at the briefer of two durations (.3 second). Whenever interresponse times exceeded 15 seconds, any shocks received were at the longer duration (1.0 second). For six of eight animals, avoidance responding developed quickly and reached levels of better than 90%. Four yoked animals stopped responding within the first few sessions. Shock duration reduction without change in shock probability or intensity was sufficient for the acquisition and maintenance of avoidance responding.     

Negative reinforcement with shock-frequency increase

Two avoidance-conditioning experiments in which responding delayed shocks are reported. Rats receiving an average of two shocks per minute (imposed condition) could produce, by pressing a bar, a 3-min alternate condition. Six (Experiment I) or more (Experiment II) shocks occurred in the alternate condition. All shocks in the alternate condition were delayed and delivered at 1-sec intervals. With long delays, all subjects produced the alternate condition and spent a large percentage of each session in the alternate condition. The first experiment demonstrated that the longer the delay from onset of the alternate condition to onset of the shocks, the more session time spent in the alternate condition. The second experiment indicated that despite increased shock frequency, behavior is acquired and maintained when responding leads to sufficient delay. Individual subjects produced the alternate condition by bar pressing in essentially one of two patterns. One pattern, termed postshock, involved bar pressing immediately after shock; the other, termed posttransition, involved responding immediately after the transition from the alternate to the imposed condition. These results indicate that shock-frequency reduction is not necessary for avoidance conditioning; delay to shock onset is sufficient.     

Punishment of responding under schedules of stimulus-shock termination: effects of d-amphetamine and pentobarbital.

Responding maintained in squirrel monkeys under 5-min fixes-interval schedules of either food presentation or termination of a visual stimulus associated with electric-shock delivery was suppressed by presenting an electric shock for every thirtieth response (punishment). In monkeys responding under the schedule of food presentation, d-amphetamine sulfate only further decreased punished responding, and pentobarbital sodium markedly increased punished responding, as expected from previous reports. In monkeys responding under the schedule of stimulus-shock termination, however, the effects of the two drugs were opposite: d-amphetamine markedly increased punished responding, whereas pentobarbital only decreased responding. Thus, the effects of these drugs on punished responding were different depending on the type of event maintaining responding. These and previous results indicate that it may be misleading and inaccurate to speak of the effects of drugs on "punished responding" as though punishment were a unitary phenomenon. As with any behavior, the effects of drugs and other interventions on punished responding cannot be accurately characterized independently of the precise conditions under which the behavior occurs.     

Integrated delays to shock as negative reinforcement

Rats were shocked at the rate of two per minute until they pressed a lever. In Experiment I, shocks were delivered at variable-time intervals averaging 30 sec; in Experiment II, shocks were delivered at fixed-time intervals of 30 sec. A response produced an alternate condition for a fixed-time period. The shock frequency following a response, calculated over the whole alternate condition, was two per minute. The pattern of shocks in the alternate condition was controlled so that the first shock occurred at the same time as it would have occurred had the response not been emitted; the remaining shocks were delayed until near the end of the alternate condition. Bar pressing was acquired in both experiments. This finding is not explained by two-factor theories of avoidance and is inconsistent with the notion that overall shock-frequency reduction is necessary for negative reinforcement. The data imply that responding is determined by the integrated delays to each shock following a response versus the integrated delays to shock in the absence of a response.     

Response-shock delay as a reinforcer in avoidance behavior

After rats received preliminary training to avoid shock on a discrete-trial retractable-bar avoidance procedure, the procedure was changed such that responses retracted the lever but did not affect the rate of shock. Responses only delayed the onset of shock. About half of the animals under these procedures responded consistently on almost 100% of the discrete-trial cycles over days. When short latencies maximized the response-shock delay, animals tended to make short-latency responses. When long latencies maximized the response-shock delay, animals tended to make long-latency responses. When all response latencies produced the same response-shock delay, animals made differing average-latency responses. And, when responses did not delay shock, most of the animals primarily engaged in shock-elicited responding while the other animals engaged in preshock responding.