First Day Of Testing Research Articles

Relative preference for starch and sugar in rats

When given a choice between fluids containing equal amounts of corn starch or glucose, Fischer rats preferred the fluid containing starch when the fluids contained 0.5%, 1%, 5%, or 20% carbohydrate, but not when the fluids contained 10% carbohydrate. Fischer rats preferred 0.5% sucrose over 0.5% starch on the first day of testing, but then switched to preferring starch. Rats of the CD strain also preferred 0.5% starch over 0.5% sucrose or 0.5% glucose, but showed no reliable preference when offered a choice of 5% starch vs. 5% sucrose or 5% glucose. Most experiments used corn starch, but rats prefer 1% rice, wheat, and tapioca starch over 1% glucose. Rats given only one substance to drink, drank more fluid if the fluid contained 1% starch than if it contained 1% glucose. Preexposing rats to either glucose or starch for 3 days did not influence subsequent preference for starch over glucose. Since the starch and glucose mixtures used in the present work had the same number of calories, preference for starch over glucose must be attributed to the hedonic effects of starch flavor rather than to the postingestive effects of starch.

Basal forebrain control of cortical cerebral blood flow is independent of local cortical neurons

To determine whether intrinsic cortical neurons participate in mediating increases in cortical cerebral blood flow (CBF) in response to electrical stimulation of the basal forebrain (BF), cortical CBF was assessed by laser-DOppler flowmetry in rats before and after unilaterally removing local cortical neurons with the excitotoxin ibotenic acid (IBO). On the first day of testing, CBF responses to right and left BF stimulation were nearly identical in right and left frontal cortices, corresponding to the frequency of stimulation, up to a maximum at 25 Hz (+180%). Subsequently, animals received a unilateral microinjection of IBO and a contralateral microinjection of phosphate-buffered saline (PBS) into the responsive cortical sites. After five days, responses in lesioned cortices were remarkably intact both in comparison to the contralateral PBS-injected site and to the same site tested prior to lesioning on day 1. IBO lesions of the response sites were histologically confirmed to extend through the entire depth of the frontal cortex and to encompass a large surface area ( 7.7 ± 0.5mm 2 ). These results indicate that local cortical neurons are not critical to the mediation of increases in cortical CBF as elicited by BF stimulation. This study further supports the role of the BF as a distinct intracerebral neurogenic regulator of cortical CBF.

Effects of long-term administration of anxiolytics on reticular-elicited hippocampal rhythmical slow activity

Buspirone is effective in treating clinical anxiety but, unlike classical anxiolytics, does not have anti-convulsant, sedative or muscle relaxant side-effects and does not interact with GABA. Buspirone may also differ from classical anxiolytics in requiring a period of 2 weeks or more to achieve its full therapeutic action. It has previously been shown that all anxiolytic drugs, including buspirone, reduce the frequency of reticular-elicited hippocampal rhythmical slow activity (RSA). The present experiments tested whether the time course of the effect of buspirone on rhythmical slow activity differed from that of the anxiolytic benzodiazepine chlordiazepoxide. Rats, implanted with reticular stimulation electrodes and subicular recording electrodes, received three intraperitoneal injections per day of buspirone (2.5 mg/kg), chlor-diazepoxide (5 mg/kg) or saline for 45 days. Both buspirone and chlordiazepoxide reduced the frequency of rhythmical slow activity on the first day of testing and Ro15-1788 (10 mg/kg) blocked the effects of chlordiazepoxide but not buspirone. There was no increase in the effect of buspirone with time. These results showed that, if the effect of anxiolytic drugs on rhythmical slow activity provides any basis for their clinical action, then some additional factors are required to explain both the delayed action of buspirone and the immediate action of classical anxiolytic drugs.

Serum time curve characteristics of a fixed dose of beta-carotene in young and old men.

The present study was designed to evaluate age-related differences in serum beta-carotene time curve response characteristics when a beta-carotene dose was given in conjunction with 1500 kcal over the course of a day. On two consecutive days, seven old (73 +/- 4 years) and six young (24 +/- 1 years) men were each fed three 500-kcal meals of an isotonic liquid formula diet containing only trace amounts of beta-carotene. On the first day of testing, no supplemental beta-carotene was given (baseline day). A 15 mg dose of beta-carotene was fed with the morning meal on the second day (test dose day). Fasting blood and hourly blood samples were obtained for 8 consecutive hours on both days. Additional blood was drawn 24 and 48 hours after the test beta-carotene dose. There were no statistical differences in baseline beta-carotene concentrations between the two age groups tested, but, because of high individual variability, serum time curve characteristics were adjusted for fasting beta-carotene levels. After adjustment, the postdose serum beta-carotene response was two to three times greater (p less than or equal to 0.04) in young subjects, as evaluated by peak concentration, area under the curve, or ascending slope of the serum response curve. Examination of factors besides age group that may have accounted for these results suggests that the serum response of the elderly may be more a function of body composition and/or serum lipid patterns than of age per se. However, in the present US population, it may not be valid to control for these factors, which are both closely related to aging.

MK801, an NMDA antagonist, blocks acquisition of a spatial task but does not block maternal experience effects

Two studies were conducted to determine the effect on learning and memory of MK801, an N-methyl-D-aspartate (NMDA) antagonist that acts through noncompetitive blockade of the ion channel associated with the NMDA receptor. In the first study we found a dose-dependent impairment in the acquisition of a modified radial-arm maze task, resulting from injections (IP) of MK801 10 minutes prior to training. The retention of that learning, as measured by the amount of training required for reacquisition on the following day, was unaffected by the drug. In contrast, in the second study, MK801 did not block the experience-based facilitation of maternal responding seen 8 days after one hour of exposure to pups: experienced dams showed facilitated onset of maternal behavior, relative to inexperienced dams, regardless of the drug they received. However, injections of MK-801, either just before or just after the maternal experience, did lead to some deficits in maternal responding on the first day of testing. We have previously shown that these maternal experience effects are blocked by injections (ICV, SC) of cycloheximide, a protein synthesis inhibitor. These results suggest that the NMDA system does not mediate all, if any, of cycloheximide's effects on maternal experience and, furthermore, that the NMDA system may mediate some but not all forms of learning.

Age-related changes in the motor response to environmental novelty in the rat

To examine age-related changes in responsiveness to environmental novelty, 3-, 12-, and 24-month-old male Fischer 344 rats were maintained on a restricted diet and exposed to a modified open field for 10 min on each of 10 consecutive days. On the first day of testing, animals of all groups showed equal amounts of rearing. While the 3-month animals continued to show approximately the same levels of rearing until the 8th day, by day 5, the older groups (12- and 24-month) had significantly reduced their rearing. Conversely, grooming was initially highest among the 24-month-old animals. While 3- and 12-month rats showed habituation of grooming, the oldest animals failed to habituate their grooming response by day 5. By day 10, there were no significant differences among the groups in either rearing or grooming. Although food was available in the center of the modified open field, there was little eating and there were no differences among groups. However, all animals did eat quickly when food was made available in their home cages. Thus, all animals displayed a profile of stress-related responses to open field exposure. Plasma corticosterone levels likewise were elevated in the modified open field. Some, but not all, components of this response profile habituated over teh 10 dyas of exposure Three-month-old animals responded to the novelty predominantly by rearing and 24-month animals predominately by grooming. This suggests that with aging, locomotor responses to stress are replaced by a more self-directed form of displacement activity.

Stress Reduction and Mood Enhancement in Four Exercise Modes: Swimming, Body Conditioning, Hatha Yoga, and Fencing

Abstract The influence of exercise mode and practice qualities on the stress reduction benefits of exercise was examined. College students in swimming, body conditioning, hatha yoga, fencing, exercise, and lecture-control classes completed the Profile of Mood States and the State Anxiety Inventory before and after class on three occasions. Swimmers had unusually positive initial moods and reported less tension and confusion after swimming only on the first day of testing. Participants in yoga, an anaerobic activity that satisfied three of the four mode requirements, were significantly less anxious, tense, depressed, angry, fatigued, and confused after class than before on all three occasions. Supporting the importance of the four mode characteristics, participants in the exercise control activity of fencing reported improvements only in vigor. A possible influence of practice conditions was observed when members of the body conditioning class reported significant increases in fatigue, but no other mood changes. Results of this study supported the possibility that exercise mode and practice requirements in the proposed taxonomy moderate the stress reduction benefits.

A laboratory study of temperament and arousal: A test of Gale's hypothesis

Four groups of 16 people selected for their relatively extreme scores (greater than or equal to 1 standard deviation from the mean) on both the extraversion-introversion and neuroticism-stability scales of the Eysenck Personality Inventory visited the psychophysiological laboratory for four separate but identical testing sessions. Each subject completed self-report inventories on present mood states. Heart rate, basal skin conductance level, spontaneous skin conductance responses, and absolute auditory threshold were recorded. Evidence of an overall decrease in arousal across testing sessions was found for the physiological data and the self-report data. These results support Gale's hypothesis that there are arousal properties associated with the psychophysiological laboratory per se that diminish with familiarity. In support of Eysenckian theory, temperament × stimulation level interactions were found. Extraverts displayed a decrease in physiologically measured arousal across days while introverts displayed no appreciable change. These results support Gale's hypothesis that arousal differences between introverts and extraverts will only emerge under conditions of moderate stimulation. Only on the first day of testing were there significant differences between neurotics and stable individuals on measured tension/anxiety, a result which could confound performance or behavioral measures used in one-session experiments. The results of this study support the use of measures of temperament in psychological research. Levels of stimulation interact with differences in temperament, and level of stimulation is evidently highest on an individual's first visit to the laboratory.

Effects of naloxone and pimozide on initiation and maintenance measures of free feeding

Latency to initiate and duration of eating of 18 daily 5-pellet meal segments was measured in 22-h food-deprived rats under conditions of pimozide (1 mg/kg, i.p.) and naloxone (2.5, 5.0 and 10.0 mg/kg, i.p.) pretreatment. Neither drug increased latency on the first or second day of testing; pimozide increased mean latency slightly on the third test. Both drugs slowed duration scores dramatically; the slowing was progressive both within and across test sessions in the case of pimozide; it was dose-dependent and progressive within (but not across) sessions in the case of naloxone. In each case, shifts in mean duration scores. In each case, shifts in mean duration score reflected an increase in score variance caused by an increase in the number and extremity of long duration scores. In each case best scores under the drug condition were equal to best scores under control conditions; indeed, very fast latency scores were slightly more frequent under each drug on the first day of testing. Thus each drug decreased the probability of moderate scores but neither drug caused a simple change in the ability to make occasional fast responses. While the effects of the two drugs were similar in some ways, naloxone, unlike pimozide, did not completely suppress feeding.

Influence of neonatal handling on blood pressure, locomotor activity, and preweanling heart rate in spontaneously hypertensive and Wistar Kyoto rats.

This experiment tested the hypothesis that increased stimulation early in development would (a) alter developmental changes in heart rate and behavioral reactivity and (b) affect the level at which blood pressure was regulated in adulthood. For this purpose, the effects of daily handling and maternal separation (3 min per day) on both behavioral and cardiovascular measures were examined in spontaneously hypertensive (SHR) and normotensive control Wistar Kyoto (WKY) rats. Prior to weaning, elevated heart rates in pups handled during the first postnatal week were most pronounced among 4-week-old prehypertensive SHR pups. Early handling affected behavior observed during open-field testing similarly in young adult rats of the SHR and WKY strains (e.g., increased locomotor activity on the first day of testing). In female rats of the WKY strain, early handling resulted in a lower baseline blood pressure; the blood pressure of SHR rats was not affected by increased stimulation in infancy. Examination of longitudinal data yielded no support for a direct association between behavioral reactivity or preweanling heart rate and high blood pressure. These findings demonstrate the influence of both early environmental conditions and genetic factors on maturation within the cardiovascular system and suggest that genetic models of pathological conditions may provide a productive means of examining environmentally shaped aspects of individual differences in physiological regulation.

Maternal discrimination of pup sex in rats.

In recent studies (Moore, 1981, 1982; Moore & Morelli, 1979), it has been found that maternal female rats spend more time licking the anogenital region of male than female offspring. This discrimination of pup sex has important implications for the development of a number of sex differences in behavior later in life, and the present study was designed to re-examine Moore's observations while allowing each pup to be individually identified. Litters of Sprague-Dawley rats were delivered by Caesarean section, and the footpads of each animal were tattooed with India ink to permit identification throughout testing. Each litter was then fostered to a maternal female and remained with her except when observations of maternal licking were made--on the fourth, seventh, and tenth days after delivery. On each of these days, the foster mother was placed in a test chamber for 30 min, and each pup was then presented individually for a 10-min session. During this time the number and duration of anogenital licking episodes were recorded. We found, as did Moore, that adult females do distinguish between their male and female pups, spending significantly more time licking the anogenital region of the males in their litters on all but the first day of testing. The possibility that the attentional bias toward male young has important consequences for behavior later in life and contributes to behavioral differences between the sexes (Beach, 1979; Moore, 1982) makes the identification of individual animals throughout development important in the analysis of these effects.

Pharmacologic modulation of the whealing response to histamine in human skin: Identification of doxepin as a potent in vivo inhibitor

Tricyclic antidepressants are known to exert potent in vitro H 1 antihistaminic effects. Doxepin, a heterocyclic variant of amitriptyline, is a particularly effective H 1 -antihistamine in vitro. In this study we examined the ability of doxepin to inhibit histamine-induced whealing reactions in human skin. Percutaneous introduction of histamine into skin on the volar surface of the forearm provoked a whealing response that was linearly related to the concentration of histamine from 0.0002M to 1.0M histamine. An average increase in wheal diameter of 2.39 mm (95% confidence interval of 2.19 to 2.60) was observed for each 10-fold increase in the histamine concentration above threshold. Day-to-day shifts in slopes of dose-response curves in 41 subjects were minimal. Day-to-day changes in the concentrations of histamine required to provoke whealing responses equivalent to responses on the first day of testing averaged 1.8-fold (±0.6 SE). Single doses of 5, 10, or 25 mg of doxepin increased the concentrations of histamine required to provoke responses equivalent to control reactions 5.2 (±0.9 SE), 18.4 (±3.3 SE) and 82.2-fold (±37.7 SE), respectively, when reactions were measured 4 hr after drug administration. A randomized double-blind, placebo-controlled study of the effects of five doses of 5 mg of doxepin administered at 12-hr intervals confirmed the effectiveness of doxepin. The blinded study also demonstrated that the amount of histamine required to provoke a response equivalent to the control response increased from 2.5-fold (±0.8 SE) after one dose to 17.2-fold (±4.7 SE) after three doses and to 22.2-fold (±5.9 SE) after five doses. These experiments demonstrate that doxepin is a potent antihistamine in man and suggest that this agent, related antidepressants, or compounds derived from tricyclic antidepressant structures may be useful in the clinical regulation of histamine-mediated reactions.

The interactive effect of personality, time of day, and caffeine: A test of the arousal model.

The personality dimension of introversion/extraversion is one of the few personality dimensions that can be reliably identified from study to study and investigator to investigator. The importance of this demension within personality theory is due both to the stability of the trait and the influential theory of H. J. Eysenck. The basic assumption in Eysenck's theory of introversion/extraversion is that the personality differences between introverts and extraverts reflect some basic difference in the resting level of cortical arousal or activation. Assuming that there is a curvilinear relationship (an inverted U) between levels of stress and performance leads to a test of this arousal theory. That is, moderate increases in stress should hinder the performance of introverts who are presumably already highly aroused. However, the same moderate increase in stress might help the performance of the presumably underaroused extraverts. Revelle, Amaral, and Turriff reported that the administration of moderate doses of caffeine hindered the performance of introverts and helped the performance of extraverts on a cognitive task similar to the verbal test of the Graduate Record Examination. Assuming that caffeine increases arousal, this interaction between introversion/extraversion and drug condition supports Eysenck's theory. This interaction was explored in a series of experiments designed to replicate, extend, and test the generality of the original finding. The interaction between personality and drug condition was replicated and extended to additional cognitive performance tasks. However, these interactions were affected by time of day and stage of practice, and the subscales of introversion/extraversion, impulsivity, and sociability, were differentially affected. In the morning of the first day, low impulsives were hindered and high impulsives helped by caffeine. This pattern reversed in the evening of the first day, and it reversed again in the evening of Day 2. We concluded that the results from the first day of testing require a revision of Eysenck's theory. Instead of a stable difference in arousal between low and high impulsives, it appeared that these groups differed in the phase of their diurnal arousal rhythms. The result is that low impulsives are more aroused in the morning and less aroused in the evening than are the high impulsives. A variety of peripheral or strategic explanations (differences in caffeine consumption, guessing strategies, distraction, etc.) for the observed performance increments and decrements were proposed and tentatively rejected. It seems probable that some fundamental change in the efficiency with which information is processes is responsible for these performance changes.

The effect of acute and chronic naloxone administration on motor activation in the rat

The acute and chronic effects of naloxone on motor activity was studied in rats. No difference in motor activity was noted between naloxone-treated (2.5, 5.0, 10.0 mg/kg) and saline-treated rats on the first day of testing. By contrast, naloxone, in all three doses tested, blocked the increase in motor activation noted in saline-treated animals upon repeated testing. These data may suggest that endogenous opioid systems may play a role in behavioral activation and adaptation and provide further support to the proposed involvement of endogenous ligands for the opiate receptor in emotional reactivity.

Cardiac and electromyographic indices of attention: Suggested situational adaptation effects

Neck muscle action potentials and heart rate variability were recorded on 30 male hospital patients prior to and during performing on a short-lasting test of detecting auditory lateral shifts. A positive correlation ( r = 0.49) was found during the second day but not during the first day of testing. The correlation is compatible with Obrist's somatic coupling hypothesis. Its absence during the first day suggests that subjects must adapt to the test situation before any reliable relations between physiological measures can be observed.

Short-term changes in responsiveness to models inBetta splendens

In an experiment attempting a detailed analysis of the habituation of aggression in blue male Siamese fighting fish, the fish viewed their mirror images for varying lengths of time, and then the duration of gill-cover erection was measured during a 60-sec presentation of a simplified model. Tests were separated by 24 h. Responsiveness was lower on the first day of testing than on any subsequent day. There was a peak of responsiveness to a blue model following 5-sec mirror exposure, with a decline in responsiveness after longer mirror exposures. Mirror exposure did not affect responsiveness to a green model. These results suggest that there are incremental and decremental effects of responding in this situation, both of which are stimulus-specific.

THE EFFECT OF LITHIUM CHLORIDE ON ONE‐TRIAL PASSIVE AVOIDANCE LEARNING IN RATS

1 Expression of a one-trial passive avoidance learning response in rats was examined following injections of lithium chloride or sodium chloride before and after initial training and before the first day of testing. Five tests were given at daily intervals, 24 h after training being the time of the first test. 2. Lithium given before the first day of testing impaired response expression on the first and all subsequent days of testing; the rate of extinction was unaffected. 3. Given both before and immediately after initial training, lithium impaired response expression on the first day of testing but slowed down the subsequent rate of extinction, leading eventually to improved performance on the fifth day, as compared with placebo-treated control subjects. 4. The results are interpreted in the light of the hypothesis that lithium impaired the central processing of sensory information.

A COMPARISON OF SCHOOL MEAN ACHIEVEMENT SCORES WITH TWO ESTIMATES OF THE SAME SCORES OBTAINED BY THE ITEM‐SAMPLING TECHNIQUE1

ABSTRACTThe study examined the accuracy of estimating test means for groups of twelfth‐grade students by the item‐sampling technique. The subjects used in the study were from 35 twelfth‐grade schools participating in the National Longitudinal Study of Mathematical Abilities. Half of the students in each school were assigned to a treatment condition where they took a complete 24‐item mathematics test on the first day of testing and took item‐sampled versions of the same test on the second day of testing. A second random group of students within each of the schools took the item‐sampled version of the mathematics test on day 2 but did not take the complete version of the mathematics test on day 1. There was no evidence to indicate that the taking of the complete 24‐item mathematics test influenced the performance on the item‐sampled version on the second day of testing. Reasonably close estimates of mean performance were obtained from the item‐sampling situation as compared to the means estimated from the conventional type of testing. The differences between the means estimated from conventional type testing and from item‐sampling testing were found to diminish as a function of the number of students tested in the school (square root transformation).

Mice Reared with Rats: Effects of Mother on Adult Behavior Patterns

Litters of four male and two female mice were fostered, at four days of age, to lactating rat mothers whose own litters (two to six days of age) were removed at the time of fostering. Control mouse litters (four males, two females) remained with their natural mothers. Rat-reared mice had a higher mortality rate between birth and weaning but the survivors weighed more at weaning than did mouse-reared mice. Rat-reared mice were less active in an open field on the first day of testing and were less aggressive than mice reared by mouse mothers. The data definitely implicate the mother as a critical determiner of adult behavioral patterns.

Effect of a Secondary Reinforcement Stimulus on the Auditory Startle Response

Two experiments were carried out in which food-deprived rats received food pellets in the presence of an intermittent light-sound stimulus. The animals were then tested in a stabilimeter device for magnitude of startle reaction to a loud, percussive sound in the presence and absence of the light-sound (secondary reinforcement) stimulus. Exp. I showed a non-significant tendency for the startle amplitude to be less in the presence of the secondary reinforcement stimulus. Exp. II was carried out for 2 test days rather than 1. Results similar to those of Exp. I were found for the first day of testing, the startle being less (non-significantly) in the presence of the secondary reinforcement stimulus. For the second test day, however, this tendency proved to be highly significant ( p < .005). Several interpretations of these findings were discussed.