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C F Flaherty

Publications and source records attributed to C F Flaherty.

At least 37 records · Page 2Linked to original sources
PubMed1989

Effects of intrahippocampal administration of colchicine on incentive contrast and on radial maze performance.

The behavior of rats given intradentate injections of the neurotoxin colchicine was examined in three experimental settings. In Experiment 1, colchicine-treated, artificial cerebrospinal fluid (CSF)-treated, and untreated animals did not differ in the intake of 32% and 4% sucrose solutions, nor did they differ in degree of successive negative contrast when the 32% solution was changed to 4% sucrose. In Experiment 2, the colchicine-treated and CSF-treated animals did not differ in degree of suppression in the intake of a 0.15% saccharin solution when it preceded 32% sucrose in once-daily pairings (anticipatory contrast), nor did they differ in reversal performance when saccharin-sucrose and saccharin-saccharin pairings were reversed. In Experiment 3, the colchicine-treated animals were substantially impaired in radial-arm maze performance compared with CSF-treated controls. These results suggest that a completely functioning hippocampus is not necessary for the memory of reward quality, the comparison of rewards, the suppression of behavior when reward is decreased, the formation of associations between two levels of reward, and the reversal of this association, as long as these processes are reflected in consummatory behavior. The data are interpreted in terms of differences between instrumental behavior and sensory memory and/or consummatory behavior--an interpretation that is not incompatible with a deficiency in working memory in the animals with lesions.

Animals↗
PubMed1989

Negative contrast in the consumption of sucrose and quinine adulterated sucrose solutions.

Rats shifted from a 40% sucrose solution to a quinine-adulterated (30 mg/100 ml) 40% sucrose solution showed a reduction in consumption to a level considerably below that of animals exposed to only the quinine-adulterated solution. The animals tended to recover from this negative contrast effect over a 5-day postshift period and, in general, the degree of contrast was about equivalent to that of animals shifted from a 32% to a 4% sucrose solution. There were no sex differences in the rats shifted from 32% to 4% sucrose, but female rats shifted to the quinine-adulterated sucrose showed larger contrast effects than male rats exposed to the same shift.

Animals↗
PubMed1988

Effect of varied taste experience on negative contrast in consummatory behavior.

Rats shifted from 32% to 4% sucrose consume less 4% sucrose than animals that experience only the 4% solution. Previous experiments have suggested that a stress/emotional factor may be causally related to this negative contrast effect on the second postshift day, but not on the first postshift day. The present experiment was concerned with the possibility that contrast on the first postshift day is related to a neophobic response to the postshift solution. Results showed that giving animals experience with variously flavored (seven different flavors) 32% sucrose during the preshift period reduced degree of contrast when the animals were shifted to 4% sucrose. These data are considered in terms of solution novelty, specific loss of "sweetness", and caloric loss as contributors to negative contrast.

Animals↗
PubMed1988

From contrast to reinforcement: role of response contingency in anticipatory contrast.

Intake of a 0.15% saccharin solution is suppressed if access to the saccharin is followed by access to 32% sucrose in brief daily pairings. The present series of four experiments was concerned with factors that lead to this anticipatory contrast effect (suppressed saccharin intake) rather than a reinforcement effect. In Experiment 1, anticipatory contrast was obtained with an autoshaping procedure (no lick requirement on the initial tube), and degree of contrast did not vary as a function of intersolution interval in the range of 0-15 s. Experiments 2 and 3 showed that requirements of 10, 100, 200, or 400 licks on the first tube available led to a reinforcement effect in latency, but a requirement of 0 licks (autoshaping procedure) led to a contrast effect in licks and latency. In Experiment 4, a group with a 200-contingent-lick requirement showed a reinforcement effect in latency, but a group yoked to this contingent group showed a contrast effect in both latency and licks. Overall, the results suggest that anticipatory contrast occurs under conditions of a "relaxed" instrumental contingency. The data are discussed in terms of control of behavior by stimulus-stimulus, response-stimulus, and stimulus-response associations, and the results are related to behavioral contrast, to flavor-outcome associations, and to "misbehavior" produced by Pavlovian-instrumental interactions.

Animals↗
PubMed1987

The effects of morphine in the consummatory contrast paradigm.

Rats shifted from 32% to 4% sucrose show a negative contrast effect, licking significantly less than animals that receive only 4% sucrose. The effects of morphine sulfate (0.5, 1.0, 2.0, 4.0, 8.0, and 16.0 mg/kg) on negative contrast were investigated in four experiments. Contrast was reduced on both the 1st and 2nd postshift day by the 4.0 and 8.0 mg/kg doses, but the effects were less robust than those seen with the benzodiazepines. The effects of morphine on contrast were dissociable from simple increases in sucrose consumption. Naloxone (0.25, 0.5, and 1.0 mg/kg) had no effect on contrast or sucrose intake. However, the contrast-reducing effect of morphine (4.0 mg/kg) was blocked by pretreatment with naloxone (0.50 mg/kg). The results are discussed in terms of other anxiolytic screening paradigms that have obtained "partial anxiolytic effects" using morphine.

Animals↗
PubMed1987

Effect of clonidine on consummatory negative contrast and on novelty-induced stress.

In Experiments 1 and 1a rats were shifted from 32% to 4% sucrose solutions. The resultant negative contrast effect in consummatory behavior was not alleviated by clonidine (3.12, 6.25, 12.5, 25.0 and 50.0 micrograms/kg). The lower dose of the drug had no effect on behavior, the higher doses reduced consumption in shifted and unshifted rats in a dose dependent fashion. In Experiment 2 clonidine (6.25, 12.5 micrograms/kg) raised plasma glucose levels in a dose dependent fashion when the animals were exposed to a novel environment. These results are at variance with those obtained with chlordiazepoxide (and other anxiolytics in the case of contrast effects) and suggest limits on the degree to which clonidine can be considered to function as an anxiolytic.

Animals↗
PubMed1987

Relative novelty of conditioning context influences directionality of glycemic conditioning.

Previous experiments in which insulin was administered in a Pavlovian conditioning procedure obtained both hyperglycemic and hypoglycemic conditioned responses (CRs). In the present experiment the relationship of the conditioning context and the housing environment was varied. Two environments, wastebasket (WB) and metal cage (MC), were varied factorially as housing and conditioning contexts. Subgroups were injected with either insulin or saline for 6 days and then, on a test day for conditioning, all animals were administered saline. The results suggested that a hyperglycemic CR could be expected when the conditioning context is different from the housing context, but a hypoglycemic CR could be expected when the conditioning context and housing context are similar. The magnitude and reliability of conditioning were greater when it was conducted in the WB context than when conditioning was conducted in the MC context. These results are discussed in terms of stress arising from relative novelty of the conditioning environment and in terms of the salience of the conditioned stimulus (CS) used in glycemic conditioning studies.

Animals↗
PubMed1986

Corticosterone, novelty-induced hyperglycemia, and chlordiazepoxide.

Rats moved to novel environments for a 20 minute period showed increased plasma corticosterone levels--the greater the difference between the housing context and the novel environment, the greater the increase in corticosterone. Plasma glucose levels (PGL) also increased with increasing environmental novelty and these PGL changes were moderated by pretreatment with chlordiazepoxide (10 mg/kg). The increases in corticosterone and PGL were greater in a context previously shown to lead to hyperglycemic conditioning following insulin administration than in a context previously shown to lead to hypoglycemic conditioning. These results imply that the directionality of glycemic conditioning may be related to the initial stressfulness of the conditioning environment.

Animals↗
PubMed1986

Successive, simultaneous, and anticipatory contrast in the consumption of saccharin solutions.

Contrast effects were obtained in rats in the consumption of saccharin solutions in three different paradigms. Degree of negative contrast varied as a function of concentration disparity, but not equally in the three procedures. Successive negative contrast occurred following shifts from 0.15% to either 0.075% or 0.05% saccharin but did not occur following shifts to 0.10% or 0.125% saccharin. Some degree of simultaneous contrast was obtained with all four concentration disparities. Anticipatory contrast, where the intake of the first substance is suppressed by a more preferred second substance, occurred only in the case of the 0.05%-0.15% difference in concentrations. It was suggested that the several contrast paradigms engage somewhat different psychological processes differentially involving emotional, sensory, and associative mechanisms, but all lead to behavior based on relative value. A modification of Toates's (1981) incentive model of ingestive behavior was suggested to incorporate relativity effects based on both associative and nonassociative factors in the consumption of both nutritive and nonnutritive substances.

Animals↗
PubMed1984

Medial and lateral amygdalectomy differentially influences consummatory negative contrast.

Rats shifted from a 32% to 4% sucrose solution consume substantially less 4% sucrose than unshifted animals that experience only the 4% solution. This negative contrast effect was found to be attenuated by lesions of the lateral aspects of the amygdala (basolateral, lateral, and basomedial nuclei) and eliminated by lesions of the medial aspects of the amygdala (corticomedial and central nuclei). The results are discussed in terms of the possible role the amygdala may play in some of the proposed determining factors mediating consummatory negative contrast (e.g., emotionality, neophobia, memory).

Amygdala↗
PubMed1984

Influence of conditioned stimulus context on hyperglycemic conditioned responses.

Glycemic conditioning was investigated in four experiments in which insulin was administered to animals in particular stimulus contexts. Both hyperglycemic and hypoglycemic conditioned responses were obtained, with the directionality of the CR dependent upon which environmental complex was used as the CS. These bidirectional glycemic CRs were obtained in both within-Subject and between-Subject conditioning procedures. Additional experiments indicated that the hyperglycemic CR was probably not related to illumination differences between the two conditioning contexts, nor to a differential opportunity for activity in the two conditioning contexts. Several possible reasons for the occurrence of bidirectional glycemic CRs were considered.

Animals↗
PubMed1984

Effects of chlordiazepoxide on novelty-induced hyperglycemia and on conditioned hyperglycemia.

Moving rats from their home cages to a different environment for a twenty minute period tended to raise plasma glucose levels (PGLs). In general, the more different the novel environment was from the housing condition, the greater the rise in PGL. Stimulus contexts that have led to conditioned hyperglycemia in previous experiments caused a larger rise in PGLs than stimulus contexts that led to conditioned hypoglycemia in previous experiments. These glycemic effects of environmental novelty did not habituate across seven exposure periods. Experiment 2 showed that chlordiazepoxide (CDP) reduced PGLs in animals transported to novel environments. Experiment 2 also showed that conditioned hyperglycemia occurred when insulin was administered in the environment that led to the highest PGLs in Experiment 1, and that conditioned hypoglycemia occurred in this same environment when the animals were regularly pretreated with CDP. Administering insulin in an environment that did not initially elicit a large rise in PGL resulted in a tendency towards conditioned hypoglycemia that was not influenced by CDP.

Animals↗
PubMed1983

Chlordiazepoxide and ethanol additively reduce gustatory negative contrast.

Negative contrast that occurs when rats are shifted from 32% to 4% sucrose has been shown to be reduced by chlordiazepoxide (CDP) and ethanol (ETOH). In a previous experiment, doses of 0.75 and 1.0 g/kg ETOH substantially reduced contrast while doses of 0.25 and 0.5 g/kg ETOH were much less effective. In this study, doses of 6 and 8 mg/kg CDP were shown to attenuate the negative contrast effect while smaller doses (2 and 4 mg/kg) influenced contrast to a lesser degree. Evidence for an additive effect of CDP and ETOH on contrast reduction was obtained when 4 mg/kg CDP and 0.5 g/kg ETOH were administered together.

Animals↗
PubMed1983

Incentive relativity effects reduced by exogenous insulin.

In two experiments rats shifted from 32% to 4% sucrose consumed less of the 4% than rats maintained on the 4% solution. This negative contrast effect was eliminated if the rats were injected with insulin (5.4 U/kg) on the shift day. This insulin dose reduced blood glucose levels to less than 50% of control levels, but the brief access period to 4% sucrose just before blood sampling reliably increased blood glucose levels. The results were discussed in terms of the effects of deprivation conditions on incentive relativity.

Animals↗
PubMed1982

Influence of ethanol on contrast in consummatory behavior.

Negative contrast that occurs when rats are shifted from 32% to 4% sucrose was reduced by IP injections of ethanol (1.0 g/kg) on postshift day 2, but not on postshift day 1. Smaller doses (0.25 and 0.5 g/kg) were ineffective, while larger doses (1.5 and 2 g/kg) produced sedation. A dose of 0.75 g/kg had effects similar to the 1.0 g/kg dose when administered on post-shift day 2. These results parallel those obtained with chlordiazepoxide and differ somewhat from amobarbital treatment.

Animals↗
PubMed1980

Amobarbital sodium reduces successive gustatory contrast.

Amobarbital sodium (17.5 mg/kg) produced equivalent reductions in negative contrast when injected for the first time on either day 1 or 2 following a shift from 32% to 4% sucrose. These results differed from those obtained in earlier studies with chlordiazepoxide.

Amobarbital↗
PubMed1980

Conditions under which chlordiazepoxide influences gustatory contrast.

Rats shifted from 32% sucrose to 4% sucrose consumed less 4% than animals without prior experience with 32% sucrose. The influence of chlordiazepoxide (CDP) on this successive negative contrast obtained in sucrose ingestion was investigated in four experiments. The results indicated that (1) rats injected with CDP during both preshift experience with 32% sucrose and post-shift experience with 4% sucrose showed an essentially unchanged contrast effect compared with saline-injected rats, (2) CDP injection for the first time on post-shift day 2 eliminated contrast but post-shift day 1 injections had little effect, (3) animals injected with CDP throughout preshift and switched to saline coincident with the sucrose shift showed a contrast effect at least as great as control animals, and (4) injections of CDP tended to elevate lick rate regardless of other conditions. These results indicate a disinhibitory effect of CDP and possible neophobia operating on the first post-shift day.

Animals↗