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PubMed1992

Analysis of the ongoing behavior of rats in non-matching-to-sample: improved acquisition and performance is related to facilitation of investigation.

In a non-matching-to-sample task, rats were trained according to the conventional procedure in which the displacement of the sample object resulted in food reinforcement and termination of the sample period. Compared to these animals, rats given a longer duration sample period, and rats not reinforced with food for displacing the object in the sample period, improved their rate of acquisition and their accuracy of performance. Detailed behavioral observations indicated that improved discrimination was related to increased investigation of the objects in the sample period, reduced side preferences, and an inclination to examine both objects in the test period. The results suggest that more accurate performance was related to the generalization of sampling habits from the sample period to the test period.

Animals↗
PubMed2002

The development of emergent differential sample behavior in pigeons.

Three experiments attempted to replicate Manabe, Kawashima, and Staddon's (1995) finding of emergent differential sample behavior in budgerigars that has been interpreted as evidence of functional equivalence class formation. In Experiments 1 and 2, pigeons initially learned two-sample/ two-alternative matching to sample in which comparison presentation was contingent on pecking one sample on a differential-reinforcement-of-low-rate (DRL) schedule and the other on a fixed-ratio (FR) schedule. Later, two new samples were added to the task. Comparison presentation on these trials occurred after the first sample peck following a predetermined interval (Experiment 1) or after completion of either the DRL or FR requirement, whichever occurred first (Experiment 2). Experiment 1 found no evidence for emergent spaced versus rapid responding to the new samples as they established conditional control over the familiar choices. By contrast, differential responding did emerge for some pigeons in Experiment 2, with responding to each new sample coinciding with the pattern explicitly conditioned to the original sample occasioning the same comparison choice. This emergent effect, however, disappeared for most pigeons with continued training. Experiment 3 systematically replicated Experiment 2 using differential peck location as the sample behavior. Differential location pecking emerged to the new samples for most pigeons and remained intact throughout training. Our findings demonstrate a viable pigeon analogue to the budgerigar emergent calling paradigm and are discussed in terms of equivalence- and non-equivalence-based processes.

Animals↗
PubMed1995

Measures of cocaine-seeking behavior using a multiple schedule of food and drug self-administration in rats.

Animal models of human drug abuse measuring (i) cocaine-seeking behavior maintained by primary or secondary reinforcers, (ii) the time to extinction of cocaine-seeking behavior, and (iii) following extinction, reinstatement of operant responding resulting in presentation of a cocaine-associated stimulus were developed in rats. Animals were trained to respond on a multiple schedule of food and intravenous cocaine reinforcement during which either food or cocaine paired with auditory or visual stimuli were available during four alternating 30-min schedule components. At the beginning of each experimental session, a 10-min component (stimulus component) was introduced during which the stimuli associated with the primary reinforcers were made available response-contingently. Subsequent non-contingent presentation of food or cocaine at the beginning of the stimulus component produced a significant increase in lever-pressing resulting in presentation of the respective reinforcer-associated stimulus. Removal of cocaine and the associated stimulus during all schedule components led to extinction of drug-seeking behavior within six days. Lever-pressing resulting in presentation of the drug-associated stimulus was subsequently by non-contingent delivery of cocaine, but not by non-contingent presentation of the stimulus alone. These results suggest that different aspects of cocaine-seeking behavior, such as operant responding resulting in presentation of a cocaine-associated external stimulus, time to extinction in the absence of primary reinforcement, and reinstatement of responding following extinction can be measured in the rat. These tests may provide useful tools for the assessment of potential treatment drugs for human cocaine abuse.

Animals↗
PubMed2000

Lesions of the medial shell of the nucleus accumbens impair rats in finding larger rewards, but spare reward-seeking behavior.

The goal of this study was to help better understand the importance of the nucleus accumbens (Nacc) in the processing of position and reward value information for goal-directed orientation behaviors. Sixteen male Long-Evans rats, under partial water deprivation, were trained in a plus-maze to find water rewards in the respective arms which were lit in pseudo-random sequence (training trials). Each day one reward arm was selected to deliver six drops of water (at 1 s intervals) the others provided only one drop per visit. After 32 visits, probe trials were intermittently presented among training trials. Here, all four arms were lit and offered the previously assigned reward. The rats rapidly learned to go to the highly rewarded arm. Six trained rats were given bilateral electrolytic lesions in the Nacc shell, two others had unilateral lesions and eight had sham operations (with approved protocols). Field potentials evoked by fornix stimulation were recorded in lesion electrodes to guide placements. Only the lesioned rats showed significant impairments (P<0.05) in selecting the greater reward on probe trials. However on training trials, lesioned (and sham-operated) rats made only rare errors. While the motivation to drink and the capacity for cue-guided goal-directed orientation behavior was spared, lesioned rats were impaired in learning the location of the larger reward. The accumbens lesions apparently impaired integration of position and reward value information, consistent with anatomical and electrophysiological data showing the convergence of hippocampal, amygdalar, ventral tegmental area (VTA) and prefrontal cortical inputs there.

Amygdala↗
PubMed1994

Individual differences in schedule-induced and conditioned behaviors.

Previous experiments have shown that subjects which exhibit a high locomotor response to novelty (HR) also show a greater locomotor response to psychomotor stimulants than subjects which have a low locomotor response to a novel environment (LR). The current experiments were designed to examine in more detail the behavioral differences between HR and LR rats in non-drug paradigms. In the first experiment HR rats acquired schedule-induced polydipsia (SIP) more readily than LR rats. Panel pressing to gain access to the food pellets, however, was greater in LR rats compared to HR rats, especially after stable levels of SIP had been attained. In the second experiment one group of rats were fed daily after a 30-min period in photocell-cages (food conditioning; FC) while a control group was fed in the home-cage (non-conditioned; NC). FC subjects developed heightened locomotor activity in anticipation of feeding in the initial 30 min in the test-cage compared to NC rats. This anticipatory locomotor activity developed more rapidly and to a greater level in HR rats than in LR rats. The concentrations of dopamine, dihydroxyphenylacetic acid, homovanillic acid, serotonin, 5-hydroxyindoleacetic acid, and norepinephrine were determined at the completion of behavioral testing in both the food conditioned and non-conditioned rats. The food conditioned experiment showed that variations in both the dopaminergic and serotoninergic systems may underlie individual differences in behavioral responsiveness. However, no clear pattern of neurochemical differences emerged. The current set of experiments have demonstrated differences between HR and LR rats in non-drug related paradigms and that HR rats appear to show a greater motivational excitement induced by periodic food delivery than LR rats.

Animals↗
PubMed2006

Momentary maximizing and optimal foraging theories of performance on concurrent VR schedules.

Optimal foraging theory proposes that animals obtain the highest rate of reinforcers for the least effort and momentary maximizing theory proposes that animals make the response that at that instant is most likely to be reinforced. While each theory may account for matching on concurrent schedules, the data supporting each theory are weak. Two experiments assessed these theories by considering concurrent choice as consisting of two pairs of stay and switch schedules. Symmetrical arrangements, which are equivalent to standard concurrent schedules, maintained behavior described by the generalized matching law. Weighted arrangements, in which the programmed rate of earning reinforcers was always greater at one alternative, maintained behavior that was biased towards the weighted alternative, yet the bias was less than that predicted by optimal foraging theory. Asymmetrical arrangements, in which the stay and switch schedules operating at an alternative are the same, maintained behavior that favored one alternative, even though momentary maximizing predicted indifference. The generalized matching law poorly described each rat's pooled data from all conditions but these data were described by an equation based on the stay and switch reinforcers earned per-visit and included elements of optimal foraging and momentary maximizing theories of choice.

Animals↗
PubMed2000

Artificial turf foraging boards as environmental enrichment for pair-housed female squirrel monkeys.

We investigated the use of artificial turf foraging boards to determine if providing captive squirrel monkeys an opportunity for semi-natural foraging behavior would 1) alter the monkeys' time budget to better approximate that seen in wild populations, 2) reduce the stereotypic, self-injurious, and aggressive behavior occasionally seen in captive squirrel monkeys, and 3) provide sustained enrichment. Five groups of pair-housed female squirrel monkeys were videotaped the week prior to, the week following, and for 2 weeks during the enrichment phase, when treat-enhanced boards were provided for 2 h daily. During the first 30 min of daily enrichment, inactivity declined 35.3%, locomotion increased 3.8%, and board-related behaviors occupied 36.3% of the activity budget; these changes were not evident after 1.5 h. Stereotypic behavior (pacing, headswinging, tailchewing) and aggression were not altered by the foraging opportunity. The foraging board retained the interest of the subjects across 2 weeks in the same daily pattern. Use of the foraging board altered the squirrel monkeys' time budget to become more like activity patterns seen in wild populations.

Animal Husbandry↗
PubMed1999

Movement dysfunction following repetitive hand opening and closing: anatomical analysis in Owl monkeys.

Repetitive strain injuries are thought to result from biomechanical stress and tissue microtrauma. The purpose of this study was to investigate the presence of local inflammation, scarring or anatomical variations of the flexor tendons and the median and ulnar nerves in four Owl monkeys behaviorally trained at a repetitive motor or sensory task. Three monkeys were trained to repetitively open and close a handpiece. The two monkeys that used rapid, stereotypical hand squeezing developed a task-specific movement dysfunction (one in 5 weeks and one in 24 weeks). The third monkey used a variable shoulder-pulling strategy and did not develop movement problems. The fourth monkey served as a control subject for the repetitive motor movements, trained on a repetitive sensory task, and did not develop a task-specific movement dysfunction. On dissection and histologic staining, there were no signs of active inflammation in the median nerve, the ulnar nerve, or the flexor tendons in any of the monkeys. However, the monkey that developed movement problems after 5 weeks of repetitive hand squeezing had an anatomical restriction of the flexor profundus tendon on the fourth digit of the trained side and the third digit of the untrained side. Reorganization of the representation of the hand on the contralateral somatosensory cortex (area 3b) was noted in the two monkeys that developed motor control problems and in the monkey performing the repetitive sensory task. These findings suggest that repetitive, stereotypical motor behaviors can lead to motor control problems without local signs of tendon or nerve inflammation. Preexisting anatomical restrictions may modify the time course for the development of movement dysfunction under conditions of stressful repetition. This animal model may simulate clinical focal hand dystonia (or occupational hand cramps) which can develop in human subjects who perform prolonged, repetitive, stereotypical movements.

Animals↗
PubMed2004

Dynamics of neural coding in the accumbens during extinction and reinstatement of rewarded behavior.

Neural correlates of reward-seeking behavior are observed in the nucleus accumbens (NAC). The dependence of these correlates upon the presence of a reward was studied by comparing the behavioral correlates observed when the presence of the reward was manipulated within a single behavioral session. Rats were well-trained on a continuous reinforcement instrumental task reinforced by 0.1 ml drops of 5% sucrose. Extracellular single-unit neural activity was recorded from electrode arrays implanted into the NAC when instrumental behavior was and then was not reinforced with sucrose (within-session extinction). A variable delay between the instrumental response and the sucrose delivery allowed for separation of neural activity related to these task events. A spike activity increase around the time of the instrumental response was the most common behavioral correlate, while a decrease in spike activity upon sucrose delivery was the second most common behavioral correlate. Following removal of the reinforcer, subjects continued to perform the instrumental response, allowing for the examination of response-related spike activity under extinction conditions in which the response was no longer reinforced by sucrose. A majority of the response-related neural activity patterns were lost when sucrose was no longer available. New neural responses also were detected during this period. For some subjects, the reinforcer was again made available during the same session. Encoding of the primary behavioral events during this period of reinstated reinforcer was similar, but not identical, to that observed during the first period of reinforced responding. These findings reveal that instrumental task-associated spike activity within the NAC is partially dependent upon the presence of the reinforcer, and that encoding across the population is distinct under reinforced and extinction conditions.

Animals↗
PubMed1993

The effects of atrial natriuretic peptide on food-reinforced conditioning in rats. Interactions with neurotransmitters.

The effects of two doses of rat atrial natriuretic peptide (TANP-1-28), 200 and 500 ng, on 6-day acquisition and extinction of food-reinforced conditional learning (conditional stimulus: light) were studied in rats following administration into the lateral cerebroventricle. With the higher dose, there was a tendency for facilitated acquisition and significantly delayed extinction of the positively reinforced learning task. In order to clarify whether the effect of the peptide is obtained through the involvement of neurotransmitters, the experimental animals were pretreated with different receptor blockers in selected doses that did not influence the behavioral test. Haloperidol, atropine, phenoxybenzamine, and propranolol blocked the action of ANP on extinction of the food-reinforced conditioning, whereas naloxone, bicuculline, and methysergide were ineffective. The results suggest that ANP might be considered a modulating agent in a positively reinforced conditional learning task, and that its action might involve dopaminergic, cholinergic, and alpha- and beta-adrenergic mechanisms.

Animals↗
PubMed1992

Role of the cerebellum in spatial orientation in the rat.

Adult DA/HAN strain rats were submitted to a spatial orientation task consisting of finding a reward in an open field. They were first submitted to an initial learning session and 10 days later to a retrieval test. The animals were divided into four groups of five rats each: animals that were cerebellectomized before the initial learning session or after the initial learning session, sham-operated rats, and control (intact) animals. Different parameters that characterize the spatiotemporal organization of the rat's exploratory behavior were quantified. From the results, it can be concluded that the cerebellum is not absolutely necessary in the processes that sustain spatial learning but that it is involved in the mechanisms sustaining focused spatial memory and in the cognitive processes of the motor program elaboration and not only in the regulation of the movement being done.

Animals↗
PubMed1990

Linguistic analogies and behavior: the finite-state behavioral grammar of food-hoarding in hamsters.

Rodger and Rosebrugh (1979) developed a method for identifying sets of rules by which discrete responses are combined to form functional sequences of behavior. In the present study, this so-called finite-state behavioral grammar method was used to analyze the food-hoarding behavior of Syrian golden hamsters (Mesocricetus auratus). Specifically, it was used to analyze 127 videotaped food-hoarding sequences that were observed in 14 male, adult hamsters in an apparatus that comprised a home compartment, a foraging area, and a connecting tunnel. An integral part of grammar derivation is the development of hypotheses about the function of the observed response patterns to guide the grammar derivation. Two such hypotheses guided the present analysis: first, we hypothesized that behaviors observed in the foraging area after the hamsters' cheek pouches were filled served an exploratory function; second, we hypothesized that behaviors observed in the home compartment prior to the hamsters emptying their cheeck pouches served to assess potential food deposition sites. In addition to generating these two hypotheses and the grammars for the hoarding sequences, this study demonstrates how the finite-state grammar method can be used as a productive means of gaining insights into the organization of consummatory response sequences.

Animals↗
PubMed2002

Modeling fast dopamine neurotransmission in the nucleus accumbens during behavior.

Recent advances in electrophysiology and voltammetry permit monitoring of dopamine (DA) neuronal activity in real time in the brain of awake animals. Studies using these approaches demonstrate that behaviorally relevant events elicit characteristic patterns of electrical activity in midbrain DA neurons as well as large, transient changes in extracellular DA in the nucleus accumbens (NAc). In addition to providing insight into the role of the DA system in the processing of motor, motivational, and sensory information, the new findings also shed light on fast DA neurotransmission in a behavioral context. This report, (1). summarizes the information obtained by electrophysiological and real-time voltammetric approaches and (2). describes a general model of phasic DA signaling in the NAc that links the observed changes in DA electrical activity and extracellular dynamics. The analysis demonstrates that the behaviorally evoked DA transients are governed by similar mechanisms as those produced by short trains of electrical stimulation. Thus, action potential-dependent release and presynaptic uptake are primary determinants of functional DA levels in the brain during behavior. Interestingly, the model predicts that the same burst of electrical activity generated at DA cell bodies produces markedly different DA dynamics in forebrain projection fields. The distinct changes result from heterogeneous release and uptake rates and may underlie region-specific effects of DA. Auto- and heteroreceptors, as well as other sites of presynaptic control, could further modulate the DA transients.

Animals↗
PubMed1992

Competition between stimulus-reinforcer contingencies and anticipatory contrast.

Procedures used to study anticipatory contrast are conceptually similar to those used to study autoshaping, in that two target stimuli signal either higher or lower rates of reinforcement in the following components of the schedule. Despite this signal contingency, anticipatory contrast entails response rates that are higher to the target stimulus followed by the lower rate of reinforcement. To determine the relation between such effects and autoshaping, different variations of the procedure were used in which the signal contingency was presented in the absence of reinforcement in the target components themselves and in which the reinforcement schedules in the different following components were signaled by the same stimulus. Autoshaping effects of this signal contingency were demonstrated when no reinforcement was available during the target-component signals themselves. Intermediate patterns of behavior occurred when reinforcement was available during the target-component signals and when their different following schedules were correlated with the same stimulus. Attempts to isolate these signal and contrast effects functionally by using the signal-key procedure were unsuccessful. The results demonstrate that Pavlovian stimulus contingencies are in competition with the dynamics of anticipatory contrast, thus reducing its occurrence under some circumstances.

Animals↗
PubMed1976

[Change of a releasing mechanism involved in pre-catching behavior during the development of Salamandra salamandra (L.)].

Preycatching behaviour in salamanders (Salamandra salamandra L.) was studied before (60 larvae) and after metamorphosis (50 juveniles) to find out whether there are differences in releasing mechanisms depending on the developmental stage. Responses to prey dummies of different size, shape and orientation were recorded. With advancing age salamanders respond more selectively, preferring "wormlike" dummies. The releasing mechanism is narrowed down during 10 months after metamorphosis. This is not caused by learning processes.

Animals↗
PubMed2000

Subchronic in vivo effects of a high static magnetic field (9.4 T) in rats.

The potential adverse biologic effects of sub chronic (cumulatively 10 weeks) exposure to a high magnetic field (9.4 T) were evaluated in young adult male and female Fischer rats as well as in their progeny. Biologic end points in adult rats included changes in daily clinical observations; spatial memory tests; weekly heart rates, body weights, food and water consumption, and the feed efficiency ratio; terminal hematologic, blood biochemical and urinary parameter changes; gross pathologic findings; and major organ weights. In offspring, biologic end points included the gestation period, number of live births, number of pups, ratio of male to female pups/litter; postnatal time period of eye opening; birth and weekly body weights, behavioral changes, central nervous system responses, as well as hematologic, blood biochemistry, and urinary parameter changes; and gross pathologic findings. Findings from this study showed that there were no adverse biologic effects in male and female adult rats or their progeny that could be attributed to 10-week exposure to a 9.4-T static magnetic field.

Age Factors↗
PubMed1990

Anticipatory wheel-running in behaviorally anosmic rats.

Rats rendered behaviorally anosmic by the intranasal infusion of zinc sulfate were placed on a single daily meal, 2 hr in duration. Anosmic rats and controls showed a similar degree of wheel-running anticipatory to the meal. It was concluded that the stimulus for entrainment of meal-associated rhythmicity is not olfaction and that other characteristics of food intake need to be systematically investigated.

Animals↗
PubMed1992

Effects of morphine and naloxone on ethanol- and sucrose-reinforced responding in nondeprived rats.

In the following series of experiments, effects of morphine (0.1, 0.3, 1.0, 3.0, and 10.0 mg/kg) and naloxone (0.1, 0.3, and 1.0 mg/kg) were assessed in nondeprived rats trained to leverpress with 10% ethanol, sweetened ethanol, or 5% sucrose and water as the reinforcers. Morphine, at doses of 0.1, 0.3, and 1.0 mg/kg had little effect on responding with ethanol or sweetened ethanol available on a fixed ratio 4 (FR4) schedule of reinforcement, but at the 3.0 mg/kg dose, morphine suppressed responding to near zero. Similar results were obtained when 10% ethanol and water were available on a concurrent FR4 FR4 schedule of reinforcement. When 5% sucrose and water were available concurrently, morphine suppressed responding at 3.0 and 10 mg/kg. Naloxone (0.1, 0.3, and 1.0 mg/kg) decreased responding for ethanol, sweetened ethanol, and sucrose solutions in a dose-dependent manner. Naloxone decreased total number of responses/session by shortening the duration of responding without affecting momentary rate. Overall, the data suggest that the endogenous opioid system plays a role in the ability of ethanol to reinforce operant behavior. However, this role does not appear to be specific to ethanol because similar results were observed with sucrose reinforcement. Failure to find enhanced ethanol intakes following morphine injections in the operant situation suggests that the method used to measure ethanol self-administration makes a difference in assessing the effects of drugs on ethanol intake.

Alcohol Drinking↗