Age and interstimulus interval in forward and backward long-trace taste-aversion conditioning.

Rats, 70-79 days old and 477-557 days old, experienced either a forward or backward taste-aversion conditioning trial with a 15-min. or 45-min. interstimulus interval.

Effects of september 11th terrorism stress on estimated duration.

Previous research has suggested that the duration of stressful video material is estimated to be longer than one containing less stressful material. The current study sought to examine what effects viewing news coverage of the September 11th 2001 terrorist attacks might have on estimated duration of exposure. 16 participants were recruited from Saint Joseph's College of Maine psychology courses and viewed two 3-min.

The effects of chronic water deprivation on metabolic rate and long-trace taste-aversion conditioning in rats.

The effect of chronic water deprivation on metabolic rate and long-trace taste-aversion conditioning was examined in Wistar-derived rats. Subjects were either maintained on a water deprivation regimen or allowed free access to water for a seven-week period prior to conditioning. At conditioning, rats were presented a saccharin CS followed 0-, 45-, 90-, or 180-min later by an i.

A time contraction effect of acute tail-pinch stress on the associative learning of rats.

The effect of tail-pinch stress interpolated between the saccharin conditioned stimulus (CS) and the illness-inducing unconditioned stimulus (US) during long-trace taste-aversion conditioning was examined in young- and old adult rats with a two-cylinder (saccharin versus water) test. A 2 x 2 x 4 factorial ANOVA was performed on percent-preference-for-saccharin data, with age (young, old), stress condition (stressed, non-stressed), and CS-US interval (22.5-, 45-, 90-, and 180-min) being the factors under consideration.

Effect of low body temperature on associative interference in conditioned taste aversion.

When two novel conditioned stimuli precede an unconditioned stimulus (US), the interval between the two conditioned stimuli (CS1 and CS2) influences the magnitude of the CS-US associability of each CS. As the interval between CS1 and CS2 increases, the associability of CS1 with the US decreases due to interference by CS2 and the associability of CS2 increases, given its temporal proximity to the US. Because hypothermia has been reported to increase the interval at which conditioned taste aversions can be formed, its influence was examined on the above relationship, i.

Hypothermia modifies the effective CS-US interval in conditioned taste aversion in rats.

Conditioned taste aversion can be acquired when rats experience an unconditioned stimulus (US) while anesthetized. In contrast to anesthetics, a hypothermia-induced comatose state immediately after presentation of a taste conditioned stimulus (CS) prevented a taste-illness association at relatively short CS-US intervals and potentiated the aversion at longer intervals. Results at shorter CS-US intervals were explained on the basis of hypothermia's temporally graded amnesitc properties.

Ketaset-Rompun extends the effective interstimulus interval in long-trace taste-aversion conditioning in rats.

The effect of anesthesia (Ketaset-Rompun) interpolated between the conditioned stimulus (CS) and unconditioned stimulus (US) during long-trace taste-aversion conditioning in rats was examined in three experiments. In Experiment 1, rats that were anesthetized immediately after experiencing a saccharin solution formed a taste aversion at a 3-h interval that typically does not support conditioning, a prolongation effect. Prior experience with the anesthetic eliminated the associability of the aversive consequences of the anesthetic but did not eliminate the anesthetic's prolongation effect.

Extended lowered body temperature increases the effective CS-US interval in conditioned taste aversion for adult rats.

Assuming body temperature correlates with metabolic activities, rate of body temperature recovery was manipulated to assess effects on long-trace conditioning in a conditioned taste-aversion paradigm. Following 10 min. access to a .

Low body temperature, time dilation, and long-trace conditioned flavor aversion in rats.

Conditioned flavor aversion was examined in Wistar-derived albino rats that were immersed in cold water for 0, 2.5, 5, or 10 min immediately following 10-min exposure to a.1% saccharin solution and given an intraperitoneal (i.

Aging facilitates long-trace taste-aversion conditioning in rats.

In order to examine age-related changes in long-trace conditioning, five age groups (0.25, 1, 1.5, 2, and 2.

The interaction of age and unconditioned stimulus intensity on long-trace conditioned flavor aversion in rats.

To see if the neural representation of the conditioned stimulus (CS) is available to old-age rats beyond the time it is available to young adults, the intensity of the unconditioned stimulus (US) and the length of the CS-US interval were systematically varied in a trace conditioning experiment. Results indicated that increasing US intensity extends the interval over which trace conditioning is evident in old-age rats but not in young adults, suggesting that trace decay occurs more rapidly in young rats. Results were interpreted in terms of age differences in the workings of hypothesized biochemical timing mechanisms that may directly influence the ability to associate stimuli over trace intervals in conditioned taste-aversion procedures.

Multiple remote-US preexposures and the blocking effect produced by a proximal-US.

Weanling, young-adult, and old-age Wistar albino rats were used to determine whether number of unconditioned stimulus (US) presentations, given 24 h or more (remote preexposure) prior to conditioning, alters the blocking effect of a single-US preexposure given 2 h before (proximal) taste aversion conditioning. As the number of remote-US preexposures increased from 0 to 6, the ability of the proximal-US preexposure to block conditioning initially increased then decreased for all age groups. Of the models put forth to explain US preexposure effects on conditioned taste aversion (CTA), only Wagner's information processing model adequately explained the reduction of the blocking effect of the proximal-US preexposure produced as a result of increasing remote-US preexposures.

Low body temperature affects associative processes in long-trace conditioned flavor aversion.

A series of experiments examined the effect of low body temperature on the associative process in long-trace conditioned flavor aversion. Experiment 1 demonstrated that maintaining a low body temperature between conditioned stimulus (CS) and unconditioned stimulus (US) administration facilitates the associative process and allows a flavor aversion to be conditioned in young rats over an interval that would normally not support conditioning. Experiments 2 and 3 demonstrated that this was due neither to lingering systemic saccharin serving as a CS nor to a cold induced enhancement of US intensity.

Remote and proximal US preexposure and aging effects in taste aversion learning in rats.

Age as a factor in the effect of proximal and remote unconditioned stimulus (US) preexposure on conditioned taste aversion in weanling, young adult, and old rats was studied in 2 experiments. In Experiment 1, 6 daily US preconditioning exposures attenuated conditioning in weanlings and young adults, but not in old rats. In Experiment 2, exposure to a single US 1 h before the conditioning trial curtailed conditioning at all age levels.

Lack of age differences in context-illness associations in the long-delay taste-aversion conditioning of rats.

To evaluate whether previously observed age differences in long-delay taste aversion were due to age-related differences in the shared association of contextual cues and CS with the US, weanling, young-adult, and old-adult rats were given a NaCl or LiCl US immediately after or a LiCl US 3 hr. after a saccharin CS presentation in a black or white context. They were then given a context-preference test in a chamber which was half black and half white.

Age differences and the interstimulus interval context in long-delay taste-aversion conditioning of rats.

Young-adult and old-adult rats were allowed to remain in the conditioning context or were returned to their home cages during a 3-hr. interval to assess whether previously observed age differences in long-delay taste-aversion conditioning may be due to age differences in the use of home-cage cues to mediate the CS-US association over a long delay. The old adults but not the young adults showed an aversion irrespective of the context in which they were detained during the interstimulus interval.

Efficacy of lithium chloride in the taste-aversion conditioning of young-adult and old-age rats.

An absolute amount of a LiCl US was administered to 24 young-adult and 24 old-age rats during taste-aversion conditioning to determine whether the superior performance of old-age rats, when a 1% body-weight injection of a LiCl US is administered 3 hr. after a saccharin CS, is due to age-related differences in US intensity or the efficacy of LiCl. The aversion conditioned in old-age rats with a 3-hr.

Context familiarity and delayed conditioned taste aversion in young-adult and old-age rats.

Familiarity with a conditioning context different from the home-cage environment was examined in immediate and delayed (3-hr.) conditioned taste aversion (CTA) learning for young-adult (90-120 days) and old-age (680-750 days) female Wistar albino rats. Context familiarity increased CTA for young adults at the 3-hr.

Element preexposure, neophobia, and conditioned aversion to a compound flavor stimulus.

Preexposure to one or two elements of a compound flavor stimulus greatly reduced a neophobic reaction to the compound but did not attenuate conditioned flavor aversion in rats. Results indicated that (1) a preexposure effect on conditioned aversion to a flavor compound is not likely to be obtained if subjects initially show a strong neophobic reaction to the elements and (2) the level of neophobia at the time of conditioning has little influence on conditioned flavor aversion.

Preventing and alleviating hypothermia-induced amnesia in weanling and young adult rats.

Reminder (Experiment 1) and familiarization (Experiment 2) treatments were found to have similar effects on the 24-hr retention performance of 24- to 26- and 90- to 100-day-old rats that either did or did not undergo an amnesic treatment (hypothermia) immediately after training. Similar degrees of retrograde amnesia and normal forgetting were evident in both trained age groups that were not subjected to familiarization or reminder treatments. These results suggest that memory processes in weanling and adult rats are similar in susceptibility to disruption by an established amnesic treatment (hypothermia) and in the ease of prevention of and recovery from amnesia by recognized preventive (familiarization) and alleviation (reminder) measures.

Role of the CS-US interval in the US preexposure effect.

Theory and research suggest that long delay taste-aversion conditioning should be less affected by proximal US preexposure than short-delay conditioning. The present research tested this hypothesis by administering illness-inducing LiCl shortly before a saccharin-LiCl pairing in which the postsaccharin LiCl was administered either immediately or 20 min. after access to saccharin.

The role of homecage environmental stimuli in the facilitation of shock-motivated spatial discrimination learning in rat pups.

In three experiments we examined the role of homecage environmental stimuli on learning an aversively motivated spatial discrimination task in 11-day-old rats. Varying the presence and absence of nest shavings in the correct and incorrect arms of a T-maze in Experiment 1 revealed that nest shavings had both nondirective facilitation and approach-eliciting properties. Training the 11-day-old rats in the presence or absence of shavings over three daily sessions and comparing their performance on the third day of training with that of a maturation control in Experiment 2 indicated that there is a residual training effect of the approach-eliciting property of nest shavings on shock-escape behavior.

Weanling and senescent rats process simultaneously presented odor and taste differently than young adults.

Weanling, young-adult, and senescent Wistar albino rats had a novel odor/taste stimulus or a single taste stimulus either paired or explicitly unpaired with the unconditioned stimulus, lithium chloride. Animals were then given a saccharin vs water preference test. Standard preference scores indicated that the odor competed with taste for association with the US in young-adult rats but potentiated the conditioned aversion to taste in weanling and senescent rats.

The effect of home cage stimuli on acquisition and retention of an active avoidance response in previsual rats.

The effect of home cage environmental stimuli on learning and the effects on retention of the presence or absence of these familiar contextual training stimuli during the retention test (Experiment 1) or during the retention interval (Experiment 2) were examined using 10-day-old rats, a multidirectional active avoidance task, and a 30-min retention interval. Home cage environmental stimuli were found to improve learning. A change in stimuli immediately after training, during the 30-min retention interval, was found to have a greater impact on retention performance than stimulus change introduced at the time of the retention test.

Acquisition and retention of active avoidance behavior in previsual rats.

The ability of previsual rats to acquire and retain an active avoidance response at intervals ranging from 0 min to 48 hr was examined in five experiments. Experiments 1 and 2 demonstrated that improvement in avoidance responding over trials was a training effect. Experiments 3 and 4 demonstrated that there was no evidence of retention of the avoidance response over retention intervals ranging from 15 min to 48 hr.