Counter conditioning in an operant conflict situation.
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Animals↗
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Results for “Conditioning, Operant”
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Transfer of Pavlovian differential conditioning to an operant discrimination.
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Animals↗
Electrical activity of the dorsal hippocampus in rats operantly trained to lever press and to lick.
One group of four rats was operantly conditioned in a Sidman avoidance procedure to lever press during one discriminative stimulus and to lick during another discriminative stimulus. Another group of four rats was conditioned in a similar manner in order to receive positive reinforcements. More dorsal hippocampal rhythmic slow activity (RSA) occurred during lever pressing than during operant licking. It was also found that dorsal hippocampal RSA accompanied walking and that dorsal hippocampal large irregular activity occurred during periods of immobility, during normal drinking and grooming and during the intense saliva spreading and grooming that were induced by exposure to a 40 degrees C environmental temperature. The data suggested that hippocampal RSA is related to type of response rather than to sensory, motivational, or learning processes. Furthermore, the data suggested that RSA is not related to the operant role of response or to relative vigor of response.
Animals↗
Sludge conditioning characteristics of copper chemical mechanical polishing wastewaters treated by electrocoagulation.
Treatment of copper chemical mechanical polishing (Cu-CMP) wastewaters by batch electrocoagulation was found effective in simultaneously removing the very fine metal oxide particles, copper ion and organic pollutants in the previous investigations. In the present work, the continuous electrocoagulation tests were performed to explore their treatment efficiencies and to identify the optimum operating conditions. Inherently, this electrocoagulation process, in either batch or continuous operating mode, generates a significant amount of sludge that needs to be properly disposed. In this study, the freeze/thaw conditioning of sludge obtained from this process was investigated in an aim to greatly reducing the sludge volume. Experimental tests were conducted to identify proper freeze/thaw operating conditions. Several fundamental aspects, such as the moisture bonding energy estimated using DSC test data, were examined to elucidate the conditioning results.
Copper↗
Environmental enrichment decreases responding for visual novelty.
Previous research has demonstrated that rats reared in an enriched condition (EC) with novel objects and social partners self-administer less amphetamine compared to rats raised in an isolated condition (IC). However, it is unclear if the enrichment-induced decrease in stimulant self-administration generalizes to non-drug rewards such as those provided by novel environmental stimuli. In the current study, EC, IC, and social condition (SC) rats were raised from 21 to 51 days of age before being tested in a two-lever operant conditioning chamber in which responding on one lever (active lever) resulted in illumination of a cue light. In Experiment 1, rats were initially assessed for baseline responding (no contingency) and then the contingent light was introduced. EC rats responded less than IC rats for the contingent light stimulus; however, EC rats also displayed a lower rate of baseline responding. In Experiment 2, rats were trained initially to lever press for a sucrose reward to decrease differences in baseline responding. While sucrose pretraining decreased baseline response differences between groups, EC rats still responded less for the contingent light stimulus than IC or SC rats. These results suggest that environmental enrichment decreases the incentive value of visual novelty.
Analysis of Variance↗
Microbiologic effects of atmospheric conditions used in operative laparoscopy.
We tested whether the atmospheric conditions used in operative laparoscopy were responsible for its low infection rate. A plexiglass chamber was used to recreate the atmospheric conditions in an operative laparoscopic procedure with CO2 pneumoperitoneum, including a CO2 atmosphere, gas flow and temperature control. Staphylococcus aureus and Escherichia coli were exposed to this atmosphere and their growth compared to that on control plates exposed to standard culture conditions. The ratio of colony growth on experimental versus control plates was 1.08 +/- 0.19 SD for Staphylococcus and 1.13 +/- 0.66 SD for E coli. We noted no direct inhibitory effect of the pelviscopic atmosphere upon microbiologic growth. The factors responsible for pelviscopy's low infection rate remain obscure.
Atmosphere Exposure Chambers↗
Human teeth exposed to argon laser irradiation: determination of power-time-temperature working conditions.
OBJECTIVE: This study was conducted to establish the operating parameters of the argon laser without thermal damage to the pulp tissue for clinical applications. SUMMARY BACKGROUND DATA: Previous studies have mainly compared the temperature modifications of the pulp chamber in a very limited situation, where a complete view of the thermal history cannot be obtained nor even extrapolated to new applications. METHODS: We used samples of molar and premolar tooth where a class V cavity was prepared and illuminated with an argon laser at different power levels, fixing the exposition area for all cases. Situations including open cavity and teeth restoration were analyzed. High-precision thermistors were placed in four different positions, one of which was inside the pulp chamber. The temperature evolution was monitored continuously by an interfaced computer during all laser exposure. Special attention was paid to the intrapulpal temperature variation because it is considered the most vulnerable thermal region. The temperature time evolution allowed the determination of the operating conditions (power-time-temperature variation) in which the use of the argon laser causes no pulpal damage. As a function of temperature variation, we divided the whole parameter space (power-time-temperature) into zones and the optimum zone of operation was determined. CONCLUSIONS: We created a diagram called power-time-temperature (PTT) where zones of temperature increased under laser irradiation allow the verification of which condition is safe for clinical laser application. The results have a broad use when this type of analysis is applicable.
Argon↗
[The reflection in the neuronal activity of the brain of the systemic mechanisms of instrumental behavior].
Changes of unit activity in the somatosensory, associative, and visual cortical areas were studied in cats during the conditioned operant feeding behaviour. Comparative analysis showed that 71.4% of the neurons in the associative cortical area increased their activity when a conditioned stimulus was switched on; 75.8% of the visual cortex neurons were activated as the cat pressed the lever; 82.5% of the cells in the somatosensory and 75.8% of the cells in the visual cortical areas increased their discharge activity at the moment when milk appeared in the cup; 75.8% of the cells in the visual cortical area lowered their activity during lapping. Reorganization of the discharge activity of the studied neurons reflected the integration that assembled during the preliminary training of the animal. Patterns of spike activity of the cells during the realization of the program of action and achieving the reinforcement were determined by perception of the parameters of the intermediate and end results.
Animals↗
Effect of fermentation conditions in the enzymatic activity and stereoselectivity of crude lipase from Candida rugosa.
Different fed-batch cultures of Candida rugosa were carried out using oleic acid as the only carbon source. The crude lipases obtained under several operational conditions and downstream processes showed different catalytic activity and isoenzymes ratio. This fact implied that the performance of the lipase produced could be modulated by using different operational fermentation conditions. These powders were compared with commercial lipase from Sigma (St. Louis, MO) in hydrolysis and synthesis reactions. Especially interesting was the fact that the enantioselectivity of a crude lipase was higher than that observed with commercial lipase in the resolution of racemic Ketoprofen. In addition, response of both lipases in the presence of water was different.
Journal Article↗
Asymmetries of brain dopamine metabolism related to conditioned paw usage in the rat.
Concentrations of dopamine, serotonin, and some of their metabolites were analyzed by means of high-performance liquid chromatography in brain samples obtained from rats operantly conditioned to use one paw for water-reinforced lever pressing. In the first experiment, the side of paw usage was determined by physical constraint (forced-handedness condition), whereas in the second experiment the side of paw usage was not restricted (paw-preference condition). Differences in dopamine metabolism were detected between brain samples from the hemispheres located ipsi- and contralaterally to the side of paw usage. A higher dopamine metabolism (indicated by higher metabolite/transmitter ratios) was found in the amygdala ipsilateral to the paw used both under the forced-handedness and paw-preference condition. A higher level of dopamine in the contralateral septum was found in rats sacrificed immediately after 15 min of forced-handedness and an ipsilateral increase was found in rats analyzed 2 h after performance of this task. In addition, a higher dopamine metabolism in the ventral striatum, dorsal striatum, and amygdala was found in the forced-handedness and yoked controls groups than in rats analyzed 2 h after lever pressing. In the second experiment, rats in the paw preference group had a lower dopamine metabolism in the ventral and dorsal striatum, septum, and substantia nigra than did their yoked controls. These results show that changes in dopamine metabolism during conditioned lever pressing can be asymmetrical with respect to the side of paw usage, indicating that the dopamine neurons in the two brain hemispheres are asymmetrically involved in such behavioral tasks.
3,4-Dihydroxyphenylacetic Acid↗
Effects of a pyrethroid type II pesticide on conditioned behaviors of rats.
Our present work investigated the effect of fenvalerate, a pyrethroid type II pesticide, on conditioned behaviors of rats. Pre-training administration of the pesticide did not modify passive avoidance but decreased active avoidance responses and operant conditioned responses; pre-training or pre-test administration of fenvalerate induced a facilitatory effect on passive avoidance task; pre-training and/or pre-test treatments reduced active avoidance responses of rats which received the pesticide before test; and post-training treatments were not capable of modifying both active and passive avoidance responses. Increased emotionality produced by the action of fenvalerate on the sympatho-adrenal system could be responsible for the differences observed between active and passive avoidance responses.
Animals↗
Conditioning of leg position in normal and mutant Drosophila.
Individual Drosophila melanogaster, with or without heads, can be trained to lift their legs to avoid electric shock. This behavior is similar to the operant conditioning previously demonstrated in intact and headless cockroaches. More than 90% of headless wild-type flies learned to our criterion. In contrast, three mutants (dunce, cabbage, and turnip), originally selected for failure to learn in an olfactory discrimination paradigm, tended to perform poorly in this new learning situation. The difference in learning behavior between normal and mutant flies is distinguishable in individuals and may be useful for mosaic analysis.
Animals↗
Behavioural effects of chronic manipulations of dietary choline in senescent rats.
1. Senescent rats were maintained on choline-deficient and choline-enriched diets. The modifications in rat behaviour caused by the chronic manipulations of dietary choline were studied in two schedules of operant conditioning. 2. In the "periodic conditioning" test, the schedule of reinforcement, in a 100 min trial, was changed from a fixed ratio to a fixed interval schedule. In the "reversal" test the contingency for food delivery was switched four times from one lever to the other in a two lever Skinner box. 3. In the "periodic conditioning" test, the choline enriched group (430 mg/Kg/day) showed the same reduction of responses/reinforcement as controls, from the beginning to the end of trial; in the same group the time course reduction of responses/reinforcement became significant earlier than in the control group. The deficient-choline group in the last 40 min of "periodic conditioning" trial gave a reduction of responses/reinforcement greater than controls and one rat in the group did not learn the change of experimental schedule and extinguished its operant behaviour. 4. In the "reversal" test, the choline-enriched diet (320 mg/Kg/day) improved the reinforced responses in the IV reversal; one rat of the deficient-choline group could not learn the new operant schedule since the first reversal and continued to respond on the same lever during the whole of the test.
Animals↗
A proposal for a conditioning model of eye movement desensitization treatment for posttraumatic stress disorder.
Although eye movement desensitization (EMD) was introduced as a specific treatment for traumatic memories, a satisfactory explanation of the therapeutic mechanism underlying the method has not been offered. This article describes a model of traumatic memories and EMD based primarily on principles of respondent conditioning, emotional interference with learning, and operant conditioning. A method for evaluating the conditioning model is briefly described.
Attention↗
Mediated amperometric biosensors for lactic acid based on carbon paste electrodes modified with baker's yeast Saccharomyces cerevisiae.
Carbon paste electrodes modified with baker's yeast Saccharomyces cerevisiae (a source of flavocytochrome b(2)) were investigated as amperometric biosensors for lactic acid. Phenazine methosulphate was used as a mediator. The optimal operational conditions of the electrodes were: an operating potential 0.0 V, solution pH 7.2, concentration of phenazine methosulphate in solution 0.2 mM. A linear range in the dependence of the current responses on the concentration of lactic acid was up to 1 mM. The suitability of the electrodes for determination of lactic acid in milk and dairy products such as kefir and yoghurt was tested. The yeast cells in the paste remained viable at least for 1 month.
Biological Assay↗
Ultrafiltration of wastewater: effects of particles, mode of operation, and backwash effectiveness.
The effects that wastewater quality and mode of operation have on the performance of an asymmetric, hollow fiber, polysulfone, ultrafiltration (UF) membrane with a molecular weight cutoff of 100,000 Daltons were investigated. Performance was assessed through monitoring membrane flux, transmembrane pressure, effluent biochemical oxygen demand, and operational cost of the experimental system while treating filtered secondary, secondary, and filtered primary effluents. Fluxes achieved for filtered secondary (129-173 l/m2 h), secondary (101-158 l/m2 h), and filtered primary (20-41 l/m2 h) effluents were compared to those obtained at three other locations where similar UF systems were operated. A conceptual model of the impact of an insufficient backwash and of operating the UF system at constant flux on membrane performance is presented to explain the differences in fluxes. Employing pre-membrane granular filtration to remove a portion of the problematic particles in secondary effluent prior to UF led to optimal operational conditions. The costs associated with the operation of pre-membrane granular filtration were offset by the increase in production achieved. Although the use of recirculation could increase maintainable flux when treating a concentrated feed (e.g., filtered primary effluent), the associated costs were high. Improved UF performance was found to result from allowing flux to decline naturally, rather than using a constant flux mode of operation. The effluents produced when filtered secondary and secondary effluents were the feeds would be equivalent to an oxidized, coagulated, clarified, and filtered wastewater as per Title 22 California Wastewater Reclamation Criteria.
Equipment Design↗
A capillary electrophoretic reactor with an electroosmosis control method for measurement of dissociation kinetics of metal complexes
The solvolytic dissociation rate constants of 1:2 complexes of Al3+ and Ga3+ with an azo dye ligand, 2,2'-dihydroxyazobenzene-5,5'-disulfonate (DHABS, H2L2-), have been evaluated with a capillary electrophoretic reactor (CER) system. This CER system is based on the fact that metal complexes encounter an overwhelming force to dissociate when apart from the ligand by CE resolution. Treatment of a capillary with a slightly acidic buffer solution, e.g., pH 5, reduces the double-layer potential (zeta) of the inner silica wall. Owing to slow relaxation of the deprotonation equilibria of superficial silanol groups known as the pH hysteresis, this zeta potential can be actually retained during the electrophoresis of the metal complexes in question with a neutral buffer at pH 7.0. This method enables one to manipulate migration times, namely, residence times in a capillary tube, from 5 to 90 min, depending on the prescribed conditioning pH, without changing any other operation conditions such as buffer composition and electric field strength. The excellent performance of the CER is exemplified by the accurate estimation of the dissociation degree of the complexes. The dissociation degree-time profiles for the complexes are quantitatively described using both internal and external standards; the very inert complex of [Co(III)L2]5- for the peak signal standardization and methyl orange for the injection volume correction. The solvolytic dissociation rate constants of the 1:2 complexes of Al3+ and Ga3+ ions with DHABS [AlL2]5- and [GaL2]5- into the 1:1 ones have been determined as (4.9+/-1.0) x 10(-4) and (3.7+/-0.3) x 10(-3) s(-1) at 303 K, respectively.
Journal Article↗
Solid acids as fuel cell electrolytes.
Fuel cells are attractive alternatives to combustion engines for electrical power generation because of their very high efficiencies and low pollution levels. Polymer electrolyte membrane fuel cells are generally considered to be the most viable approach for mobile applications. However, these membranes require humid operating conditions, which limit the temperature of operation to less than 100 degrees C; they are also permeable to methanol and hydrogen, which lowers fuel efficiency. Solid, inorganic, acid compounds (or simply, solid acids) such as CsHSO4 and Rb3H(SeO4)2 have been widely studied because of their high proton conductivities and phase-transition behaviour. For fuel-cell applications they offer the advantages of anhydrous proton transport and high-temperature stability (up to 250 degrees C). Until now, however, solid acids have not been considered viable fuel-cell electrolyte alternatives owing to their solubility in water and extreme ductility at raised temperatures (above approximately 125 degrees C). Here we show that a cell made of a CsHSO4 electrolyte membrane (about 1.5 mm thick) operating at 150-160 degrees C in a H2/O2 configuration exhibits promising electrochemical performances: open circuit voltages of 1.11 V and current densities of 44 mA cm-2 at short circuit. Moreover, the solid-acid properties were not affected by exposure to humid atmospheres. Although these initial results show promise for applications, the use of solid acids in fuel cells will require the development of fabrication techniques to reduce electrolyte thickness, and an assessment of possible sulphur reduction following prolonged exposure to hydrogen.
Journal Article↗