Biomedical subjects

K L Krauss

Publications and source records attributed to K L Krauss.

3 recordsLinked to original sources

PubMed1994

Relative hedonic value modulates anticipatory contrast.

Intake of an initial substance (e.g., 0.15% saccharin) is suppressed when the presentation of this substance precedes the availability of a preferred solution (e.g., 32% sucrose) in brief daily pairings. The present experiments show that degree of this anticipatory contrast effect is related to the relative hedonic value of the substances paired each day. When the initial substance has low hedonic value relative to the second substance (e.g., water or empty tube paired with 32% sucrose), then a facilitation effect rather than contrast occurs. As the hedonic value of the initial substance increases (0.0015% saccharin, 0.5% sucrose, 0.015% saccharin, 1% sucrose, 2% sucrose, 0.15% saccharin), facilitation is replaced by contrast, which develops sooner and becomes larger the greater the hedonic value of the initial substance. The serotonin antagonist cyproheptadine increased absolute lick frequencies, but did not alter contrast. The serotonin1A agonist buspirone tended to decrease absolute lick frequencies, but did not alter contrast. The occurrence of contrast is discussed in terms of response competition, inhibition, and devaluation of the initial substance.

Animals↗

PubMed1994

Selective breeding for negative contrast in consummatory behavior.

Rats showing either large or small reductions in licking following a shift from 32% to 4% sucrose were selectively bred for 7 generations. Rats from the 2 resulting lines reliably differed in successive negative contrast and in activity (radial-arm maze and open field). Differences in activity and contrast were not correlated. Heritability (h2) of the reaction to sucrose shift was reliable in the last 6 filial generations and equaled 0.64 in the F7 generation. The 2 lines did not differ (a) in response to the absolute rewarding value of sucrose or cocaine; (b) in open-field defecations or thigmotaxis; (c) in anticipatory contrast; or (d) in responsivity to midazolam. Responsivity to reward reduction may involve a relatively delimited psychological process that is amenable to selection.

Animals↗

PubMed1990

Effect of serotonergic drugs on negative contrast in consummatory behavior.

The effect of acute and chronic administration of the 5-HT1A agonist buspirone on successive negative contrast was investigated in Experiments 1-6. Contrast in consummatory behavior was induced by shifting rats from a 32% to a 4% sucrose solution. Experiments 1-5 showed that buspirone (0.125, 0.25, 0.5, 1.0, 2.0, 15.0 mg/kg) was ineffective in alleviating contrast or in facilitating recovery from contrast. The 15 mg/kg dose substantially decreased consummatory responding. Experiment 6 showed that the chronic (24 days) administration of buspirone (0.5, 2.0 mg/kg) also did not alleviate contrast. The chronic, but not the acute administration of the 2.0 mg/kg dose decreased consummatory behavior. In Experiment 7 the 5-HT1A agonist gepirone (2.5, 5.0 and 10.0 mg/kg) was also found to be ineffective in reducing contrast but, at the higher doses, decreased overall sucrose intake. Experiments 8 and 9 found that the 5-HT2 antagonists ketanserin (2.0 and 8.0 mg/kg) and ritanserin (0.63 and 2.5 mg/kg) also did not alleviate contrast. Midazolam (1.0 mg/kg), included as a positive control, eliminated contrast. These data suggest that serotonergic mechanisms are not involved in negative contrast.

Animals↗