Resistance to extinction of a learned taste aversion varies with time of conditioning

Abstract

Sixteen rats were maintained out of doors in cages with natural light, temperature, and social stimulation for 3 months. Subsequently, by pairing the taste of sucrose with IP injections of LiCI, the rats were conditioned to avoid sucrose. Each of four groups of rats received the CS-US pairing at a different time of day. Times of conditioning were 6 a.m., 12 a.m., 6 p.m. and 12 p.m. EST. A twobottle preference test between 4% sucrose solution and tap water was initiated 24-h after conditioning. Daily measurements of preference were continued for 16 consecutive days. Results indicated that, although all groups initially exhibited equivalent sucrose aversions, the groups conditioned at 12 a.m. and 6 p.m. extinguished within 12 days while the 6 a.m. and 12 p.m. groups continued to manifest profound aversions for sucrose throughout the 16 test days.Several factors affect the response strength of conditioned taste aversions. Prior exposure to either the CS (Ahlers & Best, 1971; Oomjan, 1972; Revusky & Bedarf, 1968;Vogel & Clody, 1972) or the US (Berman & Cannon, 1974; Brookshire & Brackbill, 1972;Elkins, 1974) is known to impair and in some instances completely block conditioning. Parameters such as the paradigm (US preceding CS or CS preceding US), the interstimulus interval (Barker & Smith, 1974;Barker, Suarez, & Gray, 1974), and the amount of CS consumed (Barker, 1976; Bond & Oi Giusto, 1975;Bond & Harland, 1975) have differential effects on the strength of a flavor aversion.US intensity also affects response strength. Garcia, Kimeldorf, and Koelling (1955) reported that the strength of a conditioned taste aversion, measured by both the degree of ~he initial aversion as well as resistance to extinction, was dose dependent when radiation was employed as the US. Smith and Morris (Note 1) found that while the rate of irradiation did not affect the degree of initial aversion, its strength was directly related to the total cumulative dose. Nachman and Ashe (1973) found a monotonic relationship between the dose of lithium chloride (LiCI) injected on a single trial and the strength of the learned taste aversion. The concentration, volume, and route of administration did not significantly affect the degree of conditioning. Garcia, Ervin, and Koelling (1967) varied dose magnitudes of cyclophosphamide and reported an orderly relationship between aversion acquisition and dose parameters. Elkins (1973) also used cyclophosphamide as an US and found long-lasting saccharin aversions which were dose-dependent relative to both

Temporal and Qualitative Dynamics of Conditioned Taste Aversion Processing: Combined Generalization Testing and Licking Microstructure Analysis.

“…Extinction rates reported in the literature vary considerably as a result of the extent of food or water deprivation, time of testing, and method of CS delivery (e.g., Abelson, Pierrel-Sorrentino, & Blough, 1977;Fouquet, Oberling, & Sandner, 2001;Nolan et al, 1997;Ternes, 1976;J. Yamamoto, Fresquet, & Sandner, 2002).…”

Vertebrate Behavioral Rhythms

“…In one study, performance efficiency, but not acquisition, was affected by time of day of testing (Ghiselli and Patton, 1976); in another, initial performance was equivalent among groups, but resistance to extinction varied dramatically with time of training (Ternes, 1976). Electroconvulsive shock (ECS) given to mice immediately after training disrupted memory equally well at two times of day, but ECS given 3 min after training disrupted memory only in mice tested during the D phase and not in those tested in L (Stephens, McGaugh, and Alpern, 1967).…”

“…The performance of laboratory animals on a learning task varies with the phase of an LD cycle at which they are tested; such variations have been reported for conditioned suppression (Stroebel, 1967;Evans and Patton, 1970); avoidance learning (Davies, Navaratnam, and Redfern, 1973;Ghiselli and Patton, 1976;Gordon and Scheving, 1968); maze learning (Hostetter, 1966;Stavnes, 1972); and taste-aversion learning (Rusak and Zucker, 1974;Ternes, 1976). Daily rhythms might influence learning and performance in several ways; (1) variations in arousal, motivation (e.g., hunger), or sensory thresholds during acquisition and/or testing could modify the salience of discriminative cues as well as the value of rewards or punishments; (2) the ability to consolidate and store acquired information might vary with time of training; and (3) the ability to retain and recall stored information might vary with time of testing.…”

Measuring circadian cycles: A simple temperature recording preparation

“…Circadian rhythms, the fluctuations of several biological functions over a 24-h period, have been found to correlate with a variety of behavioral measures. Research with infrahumans has revealed a number of significant relationships between circadian rhythms and processes such as learning, memory, and motivation (e.g., Stephens & McGaugh, 1968;Stroebel, 1967;Ternes, 1976). Of particular interest are recent studies which suggest that both adult and child psychotics exhibit abnormal circadian rhythm functions (Hill, Wagner, Shedlarski, & Sears, in press;Morgan & Cheadle, 1976).…”