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PubMed1982

Distribution of cardiac output during static exercise in the conscious cat.

Blood flows to major organs were measured in conscious cats to study the changes in the distribution of cardiac output during voluntary static (isometric) exercise. Five animals were operantly conditioned to hold a bar against a fixed resistance for 30 s. Organ flows were measured during rest and exercise by injecting 25-micrometer radioactive microspheres into the left atrium or left ventricle. Increases were observed during exercise in heart rate (18%), mean arterial pressure (25%), left ventricular systolic pressure (17%), and rate of left ventricular development (26%). Static exercise produced significant changes in flow (ml . min-1 .g-1) to the kidneys (-1.09 +/- 0.24), spleen (-0.85 +/- 0.21), and exercising muscles (+0.13 +/- 0.08), while flows to liver, heart, brain, and nonexercising muscle were not significantly changed from control levels. Denervation of the left kidney abolished the decrease in flow to that kidney during exercise. Thus, static exercise appears to produce a significant increase in blood flow to exercising muscles and significant reductions in blood flow to spleen and kidneys. The reduction in renal blood flow is mediated by a neural mechanism.

Animals↗

PubMed1986

Learned control of heart rate during dynamic exercise in nonhuman primates.

The purpose of this study was to describe an animal model to test the relationships among the cardiovascular, pulmonary, and somatomotor command systems during exercise. Using operant conditioning, three chronically chaired monkeys (Macaca mulatta) were trained to exercise (to lift weights repeatedly), to attenuate their heart rate responses, and finally, both conditions were combined so that the animals were required to exercise and attenuate their heart rates. Heart rate, systolic and diastolic blood pressure, rate-pressure product, O2 and CO2 concentration in expired air, and number of weight lifts were recorded and compared between the two conditions, i.e., exercise only and combined exercise and heart rate slowing. In all animals heart rate increases in response to exercise were significantly less (P less than 0.05) during combined conditions than during exercise only: the mean heart rate increase was 41 beats/min less during combined sessions than during exercise only sessions for monkey 1, 13.5 beats/min less for monkey 2, and 9 beats/min less for monkey 3. Rate-pressure product showed a consistent difference across animals paralleling the heart rate differences. This acquired response did not involve other cardiovascular and pulmonary parameters, which did not change systematically across animals. However, the pattern of cardiovascular reactivity in relation to O2 consumption (linear regression of heart rate and systolic or diastolic blood pressure on change in O2 consumption over many experiments) was attenuated during combined sessions relative to exercise only experiments. The relative attenuation of heart rate during combined sessions also remained significant when both experimental conditions were equated on the basis of work done. Therefore, this animal model shows a dissociation of cardiovascular, somatomotor, and pulmonary effects of central command.

Animals↗

PubMed2003

Control and quantitation of voluntary weight-lifting performance of rats.

The present paper describes an exercise model that produces a voluntary hindlimb weight-lifting response. Each rat was operantly conditioned to enter a vertical tube, insert its head into a weighted ring (either 70 g or 700 g), lift the ring until its nose interrupted an infrared detector, and then lower the ring. Load cells measured the external force generated, and displacement transducers measured the vertical displacement of the ring during each lifting and lowering movement. The apparatus and training procedures were computer automated. Peak force, velocity, work, and power were calculated for each movement. Rats in both groups easily acquired the task after 12-15 training sessions, on average, conducted 5 days/wk. Once rats were trained, the lifting patterns were quite stable during several more weeks of posttraining exercise; however, the lighter 70-g load gave rise to more variable performances across rats. Results demonstrate the utility of quantitating the biomechanics of volitional movements and suggest that the present model can establish and maintain controlled repetitive movements necessary for studies of adaptation and/or injury in muscles, tendon, and bone.

Animals↗

PubMed2004

Sound-localization performance in the cat: the effect of restraining the head.

In oculomotor research, there are two common methods by which the apparent location of visual and/or auditory targets are measured, saccadic eye movements with the head restrained and gaze shifts (combined saccades and head movements) with the head unrestrained. Because cats have a small oculomotor range (approximately +/-25 degrees), head movements are necessary when orienting to targets at the extremes of or outside this range. Here we tested the hypothesis that the accuracy of localizing auditory and visual targets using more ethologically natural head-unrestrained gaze shifts would be superior to head-restrained eye saccades. The effect of stimulus duration on localization accuracy was also investigated. Three cats were trained using operant conditioning with their heads initially restrained to indicate the location of auditory and visual targets via eye position. Long-duration visual targets were localized accurately with little error, but the locations of short-duration visual and both long- and short-duration auditory targets were markedly underestimated. With the head unrestrained, localization accuracy improved substantially for all stimuli and all durations. While the improvement for long-duration stimuli with the head unrestrained might be expected given that dynamic sensory cues were available during the gaze shifts and the lack of a memory component, surprisingly, the improvement was greatest for the auditory and visual stimuli with the shortest durations, where the stimuli were extinguished prior to the onset of the eye or head movement. The underestimation of auditory targets with the head restrained is explained in terms of the unnatural sensorimotor conditions that likely result during head restraint.

Acoustic Stimulation↗

PubMed2003

Effects of learning on smooth pursuit during transient disappearance of a visual target.

Previous research has demonstrated learning in the pursuit system, but it is unclear whether these effects are the result of changes in visual or motor processing. The ability to maintain smooth pursuit during the transient disappearance of a visual target provides a way to assess pursuit properties in the absence of visual inputs. To study the long-term effects of learning on nonvisual signals for pursuit, we used an operant conditioning procedure. By providing a reinforcing auditory stimulus during periods of accurate tracking, we increased the pursuit velocity gain during target blanking from 0.59 in the baseline session to 0.89 after 8 to 10 daily sessions of training. Learning also reduced the occurrence of saccades. The learned effects generalized to untrained target velocities and persisted in the presence of a textured visual background. In a yoked-control group, the reinforcer was independent of the subjects' responses, and the velocity gain remained unchanged (from 0.6 to 0.63, respectively, before and after training). In a control group that received no reinforcer, gain increased slightly after repetition of the task (from 0.63 to 0.71, respectively, before and after training). Using a model of pursuit, we show that these effects of learning can be simulated by modifying the gain of an extra-retinal signal. Our results demonstrate that learned contingencies can increase eye velocity in the absence of visual signals and support the view that pursuit is regulated by extra-retinal signals that can undergo long-term plasticity.

Acoustic Stimulation↗

PubMed1999

Kinematics of eye movements of cats to broadband acoustic targets.

Operant conditioning was used to train cats with their heads immobilized to localize sound by directing their eyes to the location of the sources. The kinematics of those eye movements were studied and compared with eye movements to visual targets at the same locations. The main finding of this study is that eye movements to broadband long-duration acoustic targets have two components: an initial slow phase of variable duration and a fast, normal saccade. The slow component is characterized by a persistent, shallow velocity ramp, while the saccadic component of the response falls on the main sequence computed from eye movements to visual targets. The slow component was shorter before saccades to long-duration stimuli performed under the delayed-saccade task and practically absent before saccades to transient acoustic stimuli. The results suggest that the initial slow component is used by cats to deal with uncertainty associated with the location of long-duration broadband targets and that the input to the saccade integrator(s) is similar under both visual and acoustic conditions.

Acoustic Stimulation↗

PubMed2000

Enhanced behavioral recovery from sensorimotor cortex lesions after pyramidotomy in adult rats.

Unilateral transection of the bulbar pyramid, performed before the ablation of the ipsilateral sensorimotor cortex, has been shown to facilitate the recovery of operantly conditioned reflexes and compensatory processes in rats. Such enhanced behavioral recovery was absent when only the sensorimotor cortex was ablated. This phenomenon is explained by the switching of motor activity under the control of the cortico-rubrospinal system. Switching of the descending influences is accomplished through the following loop: cortico-rubral projection-red nucleus-inferior olive-cerebellum-thalamus-cerebral cortex. This suggests that a preliminary lesion of the peripheral part of the system, represented by a descending spinal projection, facilitates the recovery processes to develop during the subsequent destruction of its central part.

Animals↗

PubMed2001

Lack of reinforcing effect of the benzodiazepine and tricyclic antidepressant combination of diazepam and dothiepin.

Fixed combinations of a tricyclic antidepressant (TCA) with a benzodiazepine (BZD) for the treatment of depressive syndromes enjoy remarkable acceptance among patients and prescribing physicians. In order to investigate if the widespread use of one such fixed TCA-BZD combination might be due to its high positive reinforcing effect, we tested each drug alone and in combination in an operant conditioning paradigm (fixed ratio 1 time-out 150 s) of intravenous self-administration in rats and compared their reinforcing effects to that of cocaine. Diazepam proved to be of only moderate reinforcing strength. Dothiepin alone was ineffective as a reinforcer but essentially abolished the reinforcing effect of diazepam when given in combination with it. These data indicate that the widespread acceptance of the fixed diazepam-dothiepin combination by the therapeutic community is not due to an increase in the positive reinforcing effect of diazepam by dothiepin but that, in contrast, addition of dothiepin might even decrease diazepam's moderately positive reinforcing effect.

Animals↗

PubMed1995

Visual resolution during growth in a cichlid fish: a morphological and behavioural case study.

The spatial resolution of the visual system during growth of the cichlid fish Haplochromis argens was deduced from the cone density according to two models of possible connectivity patterns. The models include a convergency type of 5 cones per visual unit and a divergency type of 1.25 cones per visual unit. The minimum separable angle in this species was measured during ontogeny using operant conditioning in a two choice discrete trial situation. As a consequence of the moderate performances of the juveniles, the behavioural study showed a greater change of visual resolution than was predicted by the morphology. The minimum separable angle of the adult fishes was accurately predicted by the 'divergency model', which led to rejection of the other morphological model. It is argued that the high resolution as found in some other fish species by authors using the same technique may be due to imperfect calculations.

Animals↗

PubMed1983

An animal model to detect learning deficits following treatment of the immature brain. Studies using radiation and methotrexate.

Learning deficits have been noted in children with acute leukemia given methotrexate (MTX) with and without cranial irradiation (RT) for prophylaxis. A rat model has been developed to assess treatment effects on learning. The test used was altered performance of a simultaneous discrimination task in a standard operant conditioning box, employing the mean number of days needed to score 80% correct responses as the criterion. An illustrative experiment distributed suckling rats among four groups: (1) 36 controls; (2) 14 cranial RT (1,000 R); (3) 14 MTX (5 mg/kg i.p.); (4) 36 RT + MTX 24 h later, and (5) 12 undernourished controls (to match poor weight gain patterns of treated animals). Survivors were tested 10-12 weeks later: values for groups 1-5 in order were 3.9, 4.1, 4.7, 5.0 and 4.0 days. Only group 4 results were significantly different from group 1 (p = less than 0.05).

Age Factors↗

PubMed1982

External contingency management for chronic pain: critical review of the evidence.

The use of operant conditioning to treat chronic pain has grown rapidly in the past 10 years. It usually occurs in a multidisciplinary inpatient setting with patients for whom nearly everything else has failed. The author reviews the theoretical rationale for this application of contingency management and evaluates the evidence for its efficacy. Although the evidence indicates considerable promise, particularly in improving physical functioning and reducing analgesic use, more definitive conclusions about the role of these methods in treatment of chronic pain are precluded by the methodological limitations of research in this area.

Back Pain↗

PubMed2001

Sevoflurane drawover anaesthesia with two Oxford Miniature Vaporizers in series.

The output of sevoflurane from a drawover system utilizing two Oxford Miniature Vaporizers (OMVs) in series has been shown in bench-testing to be predictable. We have shown that adequate anaesthesia can be achieved with one vaporizer in most situations if an intravenous induction is used. Occasionally a second vaporizer is necessary to deepen the level of anaesthesia. For an inhalational technique to be successful it is necessary to use both vaporizers from the outset. Under these conditions, adequate operating conditions are easily produced. The method could be useful in field or military applications.

Anesthesiology↗

PubMed2003

The use of positive reinforcement training techniques to enhance the care, management, and welfare of primates in the laboratory.

Handled frequently and subjected to a wide range of medical procedures that may be particularly invasive, nonhuman animals in a laboratory setting have unique needs. To produce the most reliable research results and to protect and enhance the well-being of the animals, it is desirable to perform these procedures with as little stress for the animals as possible. Positive reinforcement training can use targeted activities and procedures to achieve the voluntary cooperation of nonhuman primates. The benefits of such work include diminished stress on the animals, enhanced flexibility and reliability in data collection, and a reduction in the use of anesthesia. Training also provides the means to mitigate social problems, aid in introductions, reduce abnormal behavior, enhance enrichment programs, and increase the safety of attending personnel. This article describes the application of operant conditioning techniques to animal management.

Animal Husbandry↗

PubMed2003

Positive reinforcement training as a technique to alter nonhuman primate behavior: quantitative assessments of effectiveness.

Many suggest that operant conditioning techniques can be applied successfully to improve the behavioral management of nonhuman primates in research settings. However, relatively little empirical data exist to support this claim. This article is a review of several studies that discussed applied positive reinforcement training techniques (PRT) on breeding/research colonies of rhesus macaques (Macaca mulatta) and chimpanzees (Pan troglodytes) at The University of Texas M. D. Anderson Cancer Center and measured their effectiveness. Empirical analyses quantified the amount of time required to train rhesus monkeys to come up, station, target, and stay. Additionally, a study found that time spent affiliating by female rhesus was changed as a function of training low affiliators to affiliate more and high affiliators to affiliate less. Another study successfully trained chimpanzees to feed without fighting and to come inside on command. PRT is an important behavioral management tool that can improve the care and welfare of primates in captivity. Published empirical findings are essential for managers to assess objectively the utility of positive reinforcement training techniques in enhancing captive management and research procedures.

Animal Husbandry↗

PubMed2003

Training nonhuman primates to cooperate with scientific procedures in applied biomedical research.

This report provides a brief overview of aspects of training nonhuman primates who have been, and continue to be, used in this laboratory. The research context involves applied behavioral studies in which animals are trained to perform complex operant behavioral sequences, often in their homecage environment. In such studies, animals have freedom to choose whether to engage in appetitively reinforced behavioral tests that employ neither food deprivation nor fluid management. This background of operant conditioning has provided an insight to, and a context for, animal training both as an adjunct to general laboratory management and as a way to expedite scientific procedures. Thus, training has potential implications for both well-being and scientific quality, although it must be considered an adjunct to the provision of socialization with conspecifics in high quality diverse housing systems and not as an alternative to such provision. The importance of discussion and consideration of alternative procedures cannot be overemphasized.

Animal Husbandry↗

PubMed1979

Operant control of single neurons in monkey motor cortex.

This article reviews three points. Monkeys may be trained by operant conditioning to control the firing rate and pattern of single neurons in the precentral cortex. Recent data provide an explanation of how this control is mediated and an accounting of various factors that influence it. Using this technique to study cortical physiology, researchers have generated new insights into the pathophysiology and clinical effects of epilepsy.

Animals↗

PubMed2003

Forgetting and the extension of memory in Lymnaea.

Aerial respiratory behaviour in Lymnaea stagnalis was operantly conditioned using a procedure that results in long-term memory (LTM) persisting for 1 but not 3 days. By manipulating the snails' post-training environment, i.e. preventing Lymnaea from performing aerial respiratory behaviour, memory persistence was significantly extended. Memory retention, however, is only extended if snails are prevented from performing aerial respiration in the same context in which they were trained. Snails trained in the 'standard' context but prevented from performing aerial respiration in the 'carrot-odor' context (and vice versa) did not extend their memory. These data are consistent with the hypothesis that forgetting is due to interfering events, that occur following learning and memory consolidation.

Animals↗

PubMed2003

Intermediate and long-term memories of associative learning are differentially affected by transcription versus translation blockers in Lymnaea.

Aerial respiratory behaviour in the pond snail, Lymnaea stagnalis, can be operantly conditioned. This associative learning then undergoes consolidation into a long-lasting memory which, depending on the training procedure used, causes intermediate-term memory (ITM; lasting 3 h) or long-term memory (LTM; lasting >6 h) to be formed. We determined the differential susceptibility of these two forms of memory to translation and transcription blockers. The injection of a translation blocker, Anisomycin, 2.5 h before training prevents the establishment of both ITM and LTM. On the other hand, injection of the transcription blocker Actinomycin D, 2.5 h before training, did not prevent the establishment of ITM, but did, however, prevent LTM formation. Thus in Lymnaea, following associative learning, both ITM and LTM are dependent on new protein synthesis. ITM appears to be dependent on protein synthesis from preexisting transcription factors, whilst LTM is dependent on protein synthesis from new transcription messages.

Animals↗