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C L Cunningham

Publications and source records attributed to C L Cunningham.

72 records · Page 4Linked to original sources
PubMed1986

Handling-induced enhancement of alcohol's acute physiological effects.

A mild stressor (handling) exacerbated the acute effects of ethanol on heart rate and body temperature in rats. Although the tachycardia produced by the combination of ethanol and handling appeared to be due to a simple summation of the separate tachycardic effects of each condition, the thermal change represented a nonadditive combination of the separate effects. Specifically, although handling alone produced hyperthermia, it enhanced the hypothermia induced by ethanol. Blood and brain levels of ethanol were not altered by handling. Stress-induced enhancement of critical responses to ethanol may have important implications for the development of tolerance to and dependence on alcohol.

Alcoholic Intoxication↗
PubMed1986

Heart rate response to shock delivered via different implanted electrodes.

The heart rate reaction elicited by electric shock was studied in rats stimulated via implanted electrodes that were placed entirely beneath the skin (subcutaneous electrodes) or were passed under and through the skin (cutaneous electrodes). Cutaneous shock elicited greater cardioaccelerations than subcutaneous shock except at very low intensities. This finding may help to explain differences in conditioned heart rate responses when these two types of electrodes are used to deliver shock stimuli.

Animals↗
PubMed1985

Dissociation of tolerance to the hypothermic and tachycardic effects of ethanol.

Tolerance to the cardioacceleratory and hypothermic effects of ethanol was studied in unanesthetized, freely-moving rats surgically implanted with EKG electrodes and biotelemetric temperature sensors. Different groups received 0.0, 1,0 or 2.0 g ethanol/kg body weight in injections given every other day for a total of nine injections. Heart rate and body temperature were recorded for 1 hr before and 2 hr after each injection. Ethanol initially induced a monophasic dose-related cardioacceleration (80 bpm) and hypothermia (1.0 degrees C) that persisted throughout the 2-hr sample period. Tolerance developed to the hypothermic, but not to the tachycardic effect of ethanol. Assuming that tolerance depends on level of impairment in specific neuronal pathways, this outcome suggests that these two effects of ethanol are not mediated through a common autonomic mechanism (e.g., vasomotor depression) and/or that tolerance to the hypothermic effect is due to alterations in pathways unique to the thermoregulatory system. Overall, the finding is consistent with those of studies showing development of tolerance to depressant, but not to excitatory drug effects.

Animals↗
PubMed1982

Pavlovian conditioning with ethanol and lithium: effects on heart rate and taste aversion in rats.

Rats received paired injections of either ethanol or saline as the conditioned stimulus and lithium chloride as the unconditioned stimulus (US) in a Pavlovian differential conditioning paradigm. Lithium chloride evoked a large deceleration in heart rate (80-100 beats per minute) as an unconditioned response. As a result of 10 conditioning trials, the substance paired with LiCl elicited a lower average heart rate than that elicited by the unpaired substance. Moreover, animals that received ethanol-LiCl injections subsequently were more averse to the taste of ethanol than animals receiving saline-LiCl pairings. However, there were no differences in ethanol's ability to serve as the US to induce an aversion to a novel flavor solution (i.e., the Avfail phenomenon was not observed). The overall pattern of results underscores the value of using multiple indexes of learning in drug-drug conditioning paradigms.

Animals↗
PubMed1981

Spatial aversion conditioning with ethanol.

To determine whether dose level affected ethanol's ability to establish a preference or aversion for an associated spatial location, two groups of male albino rats each received five pairings of an IP injection of ethanol (1 or 2 g/kg) with exposure to a distinctive compartment for 15 min. On alternate days, each rat was exposed to a different compartment after a saline injection. A choice test indicated that aversions were established at both dose levels, and thus failed to confirm a previous report of conditioned location preference at the lower dose level.

Animals↗
PubMed1981

The paradox of persisting self-punitive behavior.

The paradox presented by the "masochist" who persists in behaviors that are followed contingently be seemingly aversive consequences is analyzed. Prototypical data from infra-human experiments are evaluated for their bearing on two theories of self-punitive actions, one based on traditional stimulus-response principles, the other on cognitive assumptions. Although the label "self-punitive" is widely used, a question remains as to whether animals that react so as to bring about so-called noxious outcomes are properly to be described as "punishing themselves." In an attempt to resolve this question, two major conceptions of punishment are evaluated as they apply to self-punitive studies. Neither conception is deemed adequate because of a lack of criteria for determining which events are aversive. A search for criteria of aversiveness eventuates in a completely relativistic view in which noxiousness and attractiveness are judged to be relational rather than absolute properties of events.

Animals↗
PubMed1981

Association between the elements of a bivalent compound stimulus.

Evidence that an association forms between the elements of a bivalent compound stimulus during inhibitory training was provided in four experiments with rats in a conditioned suppression task. This association occurred both in a conditioned inhibition paradigm, which intermixed A+ and AX- trials (Experiments 1 and 2), and in an extinction-inhibition paradigm, which presented A+ and AX- training sequentially (Experiments 3 and 4). The within-compound association appeared to be bidirectional inasmuch as excitatory changes in the value of either component affected responding to the associated component. After inhibitory training in Experiments 1-3, pairings of the inhibitory stimulus (X) with shock increased suppression to the associated excitatory stimulus (A). In Experiment 4, additional pairings of the excitatory stimulus (A) with shock after inhibitory training increased suppression to the associated inhibitory stimulus (X). These studies add to a growing body of evidence on within-compound associations and encourage the development of a conceptual framework that provides an integrated description of within-compound and stimulus-reinforcer learning.

Animals↗
PubMed1980

Paradoxical aversive conditioning with ethanol.

In three experiments with hooded rats, paired injections of ethanol and lithium chloride produced an aversion to the taste of ethanol, yet reduced ethanol's potency as an unconditioned stimulus during subsequent taste aversion conditioning with saccharin (i.e., saccharin leads to ethanol). Two of the experiments were designed to test an associative "blocking" account of the latter finding. In each of these experiments, an attempt was made to extinguish the aversion conditioned to a potential blocking stimulus after ethanol-lithium pairings, but before saccharin-ethanol conditioning. Nonreinforced exposure to intraperitoneally mediated ethanol taste cues did not eliminate the detrimental effect of ethanol-lithium pairings on subsequent saccharin-ethanol conditioning (Experiment 2), whereas nonreinforced exposure to handling-injection cues did (Experiment 3), thus providing support for the associative blocking interpretation. Implications of these findings for chemical aversion therapy are discussed.

Animals↗
PubMed1980

Conditioning and extinction of tolerance to the hypothermic effect of ethanol in rats.

The contribution of classical conditioning to tolerance to the hypothermic effect of ethanol was examined. During the tolerance acquisition phase, rats were exposed at 4-day intervals to a distinctive set of environmental cues paired with injections of ethanol (1.4 g/kg, ip). Interspersed between these drug trials were exposures to an alternate set of cues paired with injections of saline. In addition, three groups experienced different amounts of stimulation and activity during drug exposure in order to determine whether "behavioral augmentation" of tolerance would occur. In subsequent tests, the rats were tolerant only in the presence of cues previously paired with ethanol. Moreover, this environmentally specific tolerance was associated with a conditioned hyperthermic response to placebo (saline) injections in the drug environment. An extinction procedure designed to weaken tolerance mediated by classical conditioning was also found to be effective. Evidence for conditioned tolerance was weakest in animals experiencing low levels of activity during the initial drug exposure periods.

Animals↗
PubMed1979

Effects of concentration of ethanol injected intraperitoneally on taste aversion, body temperature, and activity.

Levels of ethanol-induced conditioned taste aversion and hypothermia were found to be directly related to the concentration of fixed amounts of ethanol injected i.p. in a range of doses (1.0--1.8 g/kg) and concentrations (8--32% v/v) commonly used in behavioral studies. No effect of ethanol concentration on locomotor activity was obtained. The results of blood-ethanol determinations indicate that a given dose of ethanol is absorbed more rapidly, and thus reaches greater peak levels, when injected in a higher concentration. Thus ethanol dosage might be better manipulated by varying the volume of a single concentration rather than by altering concentration. In this way, dose-response data will not be obscured by concentration-induced differences in absorption.

Animals↗
PubMed1979

Spatial contiguity facilitates Pavlovian second-order conditioning.

Two experiments investigated the effects of spatial contiguity upon the formation of second-order conditioning in pigeon subjects. Experiment 1 used an autoshaping procedure to pair two visual stimuli, S2 and S1, after S1 had previously been paired with food. The resulting second-order conditioning of S2 was superior when both stimuli appeared on the same response key within a trial, compared with their appearing on different keys. Experiment 2 found a similar importance of spatial contiguity between S2 and S1 in a conditioned suppression paradigm. In addition, consistently presenting S2 and S1 in the same spatial location produced superior conditioning compared with varying their spatial relation from trial to trial. The design of these experiments was such as to imply that spatial contiguity facilitates performance by improving the formation of association rather than by promoting stimulus generalization or pseudoconditioning. Moreover, the observation of a facilitative effect of spatial contiguity between S1 and S2 in two different paradigms that use qualitatively different unconditioned stimuli and evoke different responses implies some generality for these findings. Consequently, these results suggest that spatially contiguous stimuli are especially associable in Pavlovian conditioning paradigms.

Animals↗
PubMedDate not supplied

Effect of ingestion-contingent hypothermia on ethanol self-administration.

This study tested the hypothesis that ethanol intake and preference for ethanol-paired flavors are inversely related to the magnitude of hypothermia induced by ethanol. Fluid-deprived rats were given 15-min daily access to 7% ethanol in one of two flavored saccharin solutions. Consumption of one flavored ethanol solution (counterbalanced) was consistently followed by 6-hr placement in a room maintained at 32 degrees C, whereas, consumption of the other flavored ethanol solution was followed by maintenance at room temperature (21 degrees C). Animals experienced less hypothermia when ethanol was followed by exposure to 32 degrees C and eventually drank more of the flavored ethanol that preceded this exposure. Moreover, intermittent two-bottle choice tests revealed development of a preference for the flavor that preceded exposure to 32 degrees C. An "extinction" phase indicated that this preference was not due to association with the thermal environments, but depended on differences in ethanol-induced hypothermia. These results support the conclusion that oral intake of ethanol is modulated by ethanol-induced hypothermia, most likely through a conditioned taste aversion mechanism.

Alcohol Drinking↗
PubMedDate not supplied

Species difference in sensitivity to ethanol's hedonic effects.

Recent research suggests that rats and mice differ in their sensitivity to ethanol's rewarding effect in the place conditioning paradigm. However, these species have not previously been examined in a comparable manner. The present study compared genetically heterogeneous rats and mice using an identical place conditioning procedure. Each animal received four pairings of a distinctive tactile floor stimulus with injection of ethanol (1.5 g/kg); a different tactile stimulus was paired with saline injection. Ethanol suppressed activity in rats but elevated activity in mice. As in most previous studies with drug-naive animals, rats showed aversion whereas mice showed preference for the ethanol-paired stimulus. This difference cannot be attributed to differences in housing conditions, apparatus, stimuli, or temporal parameters. Rather, it appears to represent a species difference in initial sensitivity to ethanol's hedonic effects. If one assumes that ethanol is both rewarding and aversive, this outcome might be explained by a species difference in tolerance/sensitization, the time-course of the biphasic hedonic response to a single ethanol exposure, or selective association. Together with other recent studies from this laboratory, the present findings suggest the mouse may well be the species of choice for studying preferences conditioned by ethanol.

Animals↗
PubMedDate not supplied

Genetic differences in ethanol-induced conditioned taste aversion after ethanol preexposure.

The present studies examined the development of ethanol-induced conditioned taste aversion in C57BL/6J (B6) and DBA/2J (D2) mice with a history of ethanol preexposure. In Experiment 1, adult male B6 and D2 mice received four preexposure injections of either saline or 4 g/kg ethanol over an 8-day period. After preexposure, all mice were given five conditioning trials consisting of 1-h access to 0.15% w/v saccharin solution followed immediately by ethanol injections (4 g/kg, IP) on all but the last trial. Drug-naive D2 mice showed greater reductions in saccharin intake. Ethanol preexposure reduced the development of ethanol-induced taste aversion in each strain. However, B6 mice showed little taste aversion overall, hindering the characterization of genetic differences in ethanol's preexposure effect. To address this problem, the parameters for taste conditioning were changed in Experiment 2 to more closely match degree of taste aversion in drug-naive mice across both strains. B6 and D2 mice received four preexposure injections of either saline, 2 g/kg ethanol, or 4 g/kg ethanol, or 4 g/kg ethanol. Subsequently, mice received five conditioning trials consisting of 1-h access to 0.2 M NaCl flavor followed by 4 g/kg ethanol (B6 mice) or 2 g/kg ethanol (D2 mice) on trials 1-4. Ethanol-naive mice of each strain developed similar levels of conditioned taste aversion. Ethanol preexposure produced greater retardation of conditioned aversion in B6 mice than in D2 mice. These results demonstrate genetic differences in the ability of ethanol preexposure to reduce the development of ethanol-induced conditioned taste aversion.

Animals↗
PubMedDate not supplied

Autoshaped discrimination learning in chicks incubated under normobaric hyperoxia.

White Leghorn chicken eggs were exposed to either 60% O2 or room air (21% O2) for the first 19 days of incubation. Chicks that hatched from these eggs were then tested in discrimination learning tasks in which keypecking was autoshaped to colored lights that were paired with either access to food (Experiment 1) or heat (Experiment 2). Chronic prenatal exposure to 60% O2 reduced hatchability but did not affect mean hatching time. Although previous research has shown that hyperoxic treatment accelerates growth in chick embryos until the 18th day of incubation, experimental chicks weighed either the same (Experiment 1) or less (Experiment 2) than controls at hatching. Prenatal exposure to hyperoxia depressed rate of acquisition, but not final performance level in both discrimination tasks. The initial performance deficit appeared to reflect a temporary depression of activity or arousal, possibly due to a relatively greater hypothermia in experimental chicks. This general pattern of results was attributed to premature depletion of essential nutrients within the egg as a result of oxygen-induced growth acceleration.

Animals↗