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At least 811 records · Page 45Linked to original sources
PubMed2004

D-Amphetamine reinstates behavior previously maintained by food: importance of context.

The drug self-administration reinstatement procedure provides an important animal model of relapse. While the procedure is widely used, there has been little investigation of the basic processes involved. This experiment determined the specificity of reinstatement by examining reinstatement of food seeking by D-amphetamine. During training, 24 rats pressed levers for food. Eight rats received 3.0 mg/kg D-amphetamine before and saline after sessions. Eight rats received saline before and after sessions. The final eight rats received saline before and 3.0 mg/kg D-amphetamine after sessions. All rats then experienced saline injections and extinction. During a reinstatement test, all rats received 3.0 mg/kg D-amphetamine. D-Amphetamine significantly increased lever pressing for rats with prior exposure to amphetamine as a predictive cue for food (pre-session) and for rats with no prior exposure to amphetamine. The effect was larger for rats with pre-session exposure to amphetamine than for rats with no previous exposure. Rats with exposure to amphetamine but not as a predictive cue for food (after sessions) did not show significant reinstatement of lever pressing. Therefore, the reinstating effects of amphetamine are not restricted to behavior previously maintained by amphetamine self-administration. In animal models of relapse, reinstatement of drug seeking could be due, in part, to discriminative and direct effects of self-administered drug.

Animals↗
PubMed1993

"Transitive inference" in multiple conditional discriminations.

We used multiple conditional discriminations to study the inferential abilities of pigeons. Using a five-term stimulus series, pigeons were trained to respond differentially to four overlapping pairs of concurrently presented stimuli: A+ B-, B+ C-, C+ D-, and D+ E-, where plus and minus indicate the stimulus associated with reinforcement and extinction, respectively. Transitive inference in such situations has been defined as a preference for Stimulus B over Stimulus D in a transfer test. We measured this and other untrained preferences (A vs. C, A vs. D, B vs. E, etc.) during nonreinforced test trials. In three experiments using a novel, rapid training procedure (termed autorun), we attempted to identify the necessary and sufficient conditions for transitive inference. We used two versions of autorun: response-based, in which the subject was repeatedly presented with the least well-discriminated stimulus pair; and time-based, in which the subject was repeatedly presented with the least-experienced stimulus pair. In Experiment 1, using response-based autorun, we showed that subjects learned the four stimulus pairs faster than, but at a level comparable to, a previous study on transitive inference in pigeons (Fersen, Wynne, Delius, & Staddon, 1991), but our animals failed to show transitive inference. Experiments 2 and 3 compared time- and response-based autorun. Discrimination performance was maintained, but transitive inference was observed only on the second exposure to the response-based procedure. These results show that inferential behavior in pigeons is not a reliable concomitant of good performance on a series of overlapping discriminations. The necessary and sufficient conditions for transitive inference in pigeons remain to be fully defined.

Animals↗
PubMed1993

Effects of haloperidol on a run-climb-run behavioral task: distance climbed does not alter within-session decrements.

Effects of haloperidol (0.04-0.32 mg/kg) were assessed in 10 hungry rats trained in a 10-trials-per-day format to run down an alleyway, climb a vertical rope, and run across a horizontal board to obtain sweetened milk. Rope lengths of 0.59 m and 1.32 m defined low- and high-effort requirements, respectively. Haloperidol produced substantial within-session decrements on Trials 2-10, but the drug did not affect rope-climbing speed more than horizontal running speed. Drug-induced within-session decrements were similar for both low- and high-effort requirements. After treatment with the 0.16-mg/kg dose, force-time waveforms of the climbing behavior documented instances of arrest of movement on the rope, but no bradykinesia of individual locomotor acts was discerned. Results suggest that haloperidol may produce associative deficits as well as disruptions of motor processes.

Animals↗
PubMed1997

Stimulus contingencies that permit classical conditioning of opioid activity in the rat fetus.

In a prenatal model of classical conditioning, rat fetuses received presentations of an artificial nipple (conditioned stimulus; CS) paired with milk (unconditioned stimulus). Infusion of milk promotes activity in the kappa opioid system of the fetus, but after 2, 3, or 6 pairings with the artificial nipple, milk evoked both kappa and mu opioid activity. The nipple CS has no effect on opioid activity, but after pairing with milk evoked a mu opioid response. Conditioned mu opioid activity was evident in 60% of subjects tested after 1 paired conditioning trial. Significantly more fetal subjects (90%) exhibited conditioned opioid activity if preexposed to the nipple twice before conditioning. CS preexposure altered behavior during the conditioning trial, with preexposed fetuses showing more pronounced responses to milk infusion. Exposure to familiar stimuli facilitates classical conditioning of physiological responses, including opioid activity, during the first suckling episode.

Animals↗
PubMed1997

Frontal-subcortical circuits: the anatomic basis of executive, social and motivated behaviors.

A series of discrete, parallel frontal-subcortical circuits have been demonstrated to link specific areas of the frontal lobe to areas within the basal ganglia and thalamus. A variety of circuit-specific behaviors can be described involving the dorsolateral prefrontal, orbitofrontal and anterior cingulate circuits. Interruptions or imbalance occurring at various levels within these closed looped circuits is felt to underlie the characteristic behavioral patterns seen. The intricate neurochemical arrangement of the striatum and the complex neurotransmitter interactions that occur within these key subcortical structures from the basis for modulatory influences that can affect these circuits.

Animals↗
PubMed2000

Sleep after immobilization stress and sleep deprivation: common features and theoretical integration.

The goal of the present paper is to elucidate and to resolve contradictions in the relationships among different forms of stress, sleep deprivation, and paradoxical sleep (PS) functions. Acute immobilization stress and the stress of learned helplessness are accompanied by an increase of PS, whereas the stress of defense behavior and the stress of self-stimulation cause PS reduction. Recovery sleep after total sleep deprivation performed on the rotating platform is marked by a dramatic rebound of PS although NREM (non-rapid eye movement) sleep deprivation is more prominent than PS deprivation. This PS rebound leads to a quick reversal of the pathology caused by prolonged sleep deprivation. The search activity (SA) concept presents an explanation for these contradictions. SA increases body resistance to stress and diseases, whereas renunciation of search (giving up, helplessness) decreases body resistance. PS and dreams contain covert SA, which compensates for the lack of the overt SA in the preceding period of wakefulness. The requirement for PS increases after giving up and decreases after active defense behavior and self-stimulation. Immobilization stress prevents SA in waking behavior and increases the need in PS. Sleep deprivation on the rotating platform, like immobilization stress, prevents SA, produces conditions for learned helplessness and, suppresses PS. Such a combination increases PS pressure and decreases body resistance.

Animals↗
PubMed1978

Instinctive predatory behavior of the ferret (Putorius putorius furo L.) modified by chlordiazepoxide hydrochloride (Librium).

The predatory behavior of ferrets (Putorius putorius furo L.) consists mainly of instinctive behavioral patterns that are elicited by simple external stimuli. For the ferret, the time needed to catch and kill rats depends on the size of the rats in relation to that of the ferret. Killing success decreases with a relative increase in prey size. Chlordiazepoxide hydrochloride injections (1 mg/kg, i.m.) modified this behavior. Drugged ferrets needed less time and less bites to kill relatively large rats; killing success was also increased. Chlordiazepoxide seemed to disinhibit the ferrets when they were presented with large rats, which they normally attack more cautiously.

Animals↗
PubMed2001

The molarity of molecular theory and the molecularity of molar theory.

Dinsmoor (2001) rejects shock-frequency reduction as a reinforcer for avoidance behavior, and considers this to be an invalidation of so-called molar avoidance theory. This is a narrow view of operant avoidance theory, for which shock-frequency reduction is by no means the only reinforcer.

Animals↗
PubMed2003

Convergent mechanisms mediate preparatory states and repetition priming in the feeding network of Aplysia.

Improvement of behavioral responses to expected stimuli has been attributed to a change in the preparatory state. In this study, we take advantage of the accessibility of the nervous system of Aplysia and develop an in vitro analog of the preparatory state for feeding behaviors. We provide evidence that the change in the preparatory state may be elicited initially by activity of identified serotonergic metacerebral cells (MCCs). We demonstrate, however, that the preparatory state is maintained through MCC-independent repetition priming that is embedded in the properties of the behavior-generating network. Both MCC-dependent and MCC-independent processes converge on the same site in the behavior-generating network to mediate the change in the preparatory state. Thus, we propose a model of how multiple neuronal structures interact to elicit and maintain changes in the preparatory states in the CNS.

Animals↗
PubMed1987

Dopamine and preparatory behavior: I. Effects of pimozide.

The involvement of dopaminergic systems in appetitive and ingestive feeding behaviors was investigated in two experiments. Conditioned preparatory responses to a conditional stimulus (CS+) signaling delivery of a meal were attenuated in rats by doses of 0.4 and 0.6 mg/kg of the dopamine receptor antagonist pimozide. In contrast, animals responded in a normal fashion following the delivery of food. Similarly, in a separate study, the 20-min free-feeding intake of liquid diet by rats that had been deprived of food for 23 hr was unaffected by doses of pimozide as high as 0.6 mg/kg. These findings are consistent with the involvement of dopamine in the production of preparatory behaviors elicited by incentive stimuli.

Animals↗
PubMed1986

Spontaneous mouse killing rats: gentling and food deprivation result in killing behavior almost identical to that of rats with medial hypothalamic lesions.

Rats that were found to kill a mouse spontaneously were divided into two groups. One group was left untreated and allowed free access to food while the other was gentled for 15 min/day and given only 15 g of food/day. Nonkilling rats were induced to kill mice by lesions of the medial hypothalamus. Seven to ten days after being divided into groups or subjected to brain lesions, each rat's behavior toward a series of stimuli was observed. The stimuli were a live mouse, a second live mouse, a freshly killed mouse, and a cotton wad. Food-deprived/gentled spontaneous killers and rats induced to kill by medial hypothalamic lesions each tended to attack with higher intensities and lower latencies than control spontaneous killers. The food-deprived/gentled spontaneous killers and lesion-induced killers (but not the control spontaneous killers) also attacked a dead prey moved vertically and then held onto the prey with sufficient intensity that their feet would leave the floor of the cage before they would release their grip on the prey. It is argued that the behavior of food-deprived spontaneous killers may constitute a more valid model of spontaneous mouse killing than that of sated spontaneous killers. The close correspondence between behavior toward a prey by lesion-induced killers and food-deprived spontaneous killers suggests that the lesion-induced killers fit this model of mouse killing remarkably well.

Aggression↗
PubMed1987

Food arousal in the pond snail, Lymnaea stagnalis.

Factors affecting food arousal were examined in a behavioral study of the freshwater, browsing pulmonate, Lymnaea stagnalis. Presentation of a food stimulus (sucrose) leads to a progressive decrease in interbite interval over the first four subsequent bites. This is thought to represent an increase in food-induced arousal. The latency to first bite is correlated with total number of bites in the first 5 min following application of food. Latency to bite is significantly reduced for up to 15 min following a brief food stimulus. Previous levels of food consumption do not significantly affect latency to bite (i.e., food responsiveness). However, hunger does lead to an increase in spontaneous biting activity in the absence of food (i.e., food search activity). Latency to bite is negatively correlated with a more general measure of behavioral arousal, the Behavioral State Score. These results are discussed in relation to previous work on other gastropod species. It is concluded that mechanisms of food arousal are adapted to the animal's habitat and life-style.

Animals↗
PubMed2002

Nucleus accumbens dopamine and work requirements on interval schedules.

Considerable evidence indicates that nucleus accumbens dopamine (DA) is involved in the regulation of instrumental response output, and that interference with DA transmission disrupts the ability of rats to overcome work-related response costs. The present experiments were conducted to assess the effects of accumbens DA depletions on the performance of variable interval schedules, to determine if the intermittence of a schedule, in itself, is an important determinant of sensitivity to accumbens DA depletions. For this purpose, two variable interval 30 s lever pressing schedules were used, each with different response requirements added to the interval requirement. For one of the schedules, the animals were reinforced for the first response after the interval elapsed (tandem variable interval/fixed ratio 1: VI/FR1). On the other schedule an additional work requirement was attached by requiring the rats to make five responses after the interval in order to receive reinforcement (tandem variable interval/fixed ratio 5: VI/FR5). Attachment of the additional work requirement led to greater response rates during baseline training. After training, rats were injected with either ascorbate vehicle or 6-hydroxydopamine (6-OHDA) into the nucleus accumbens. The effects of DA depletion on responding were highly schedule-dependent. DA depletions had no significant effect on lever pressing under the condition with low response requirement (VI/FR1), but these depletions substantially disrupted responding on the schedule with the higher response requirement (VI/FR5). The disruption of responding on the schedule with the high response requirement showed recovery over the 4 weeks of post-surgical testing. In a second experiment, the effect of 6-OHDA on spontaneous locomotion in an open field was assessed. The DA-depleted animals had impairments in locomotion and rearing compared with the vehicle treated rats when tested 8 days after surgery, but not when tested 29 days after surgery, which demonstrates recovery of locomotor function after the accumbens DA depletions. The results of these experiments support the hypothesis that nucleus accumbens DA is involved in regulating behavioral activation. The lever pressing experiment indicates that depletions of DA in the accumbens interfere with the processes that enable rats to overcome behavioral constraints such as work-related response costs, and suggest that the intermittence of reinforcement per se is not the most critical factor in determining sensitivity to accumbens DA depletions.

Animals↗
PubMed2001

Cognitive task performance after lidocaine-induced inactivation of different sites within the basolateral amygdala and dorsal striatum.

To determine whether discrete components of amygdaloid and striatal memory systems could interact to guide behavior in a radial arm maze, conditioned cue preference (CCP) and win-stay accuracy were examined after lidocaine inactivation of either the rostral (rBLA) or caudal (cBLA) basolateral amygdala, the lateral (lDST) or medial (mDST) dorsal striatum, or a control site in rats. CCP expression was blocked only after rBLA or cBLA inactivation. lDST inactivation prevented attainment of criteria win-stay performance, whereas rBLA and mDST inactivation delayed it. Control site inactivation did not influence performance in either task. These findings suggest that the amygdala works independently of other memory systems to regulate learned responses in the CCP task, the rBLA may work cooperatively with the lDST to guide behavior in the win-stay task, and the mDST is less critical than the lDST for attaining criteria performance in the win-stay task.

Amygdala↗
PubMed1995

Dominance fades with distance: an experiment on food competition in long-tailed macaques (Macaca fascicularis).

Dominant animals often can suppress the competitive behavior of subordinates by overt aggression or by their mere presence. This experiment on pairs of long-tailed macaque females explored whether this effect of dominant animals is influenced by interindividual distance. A dominant and a subordinate, but stronger, animal could compete for food by a tug-of-war on a bar. The animals were separated by 2 grids, spaced at either 30 or 100 cm. At 30 cm, 7 of 8 subordinate subjects either did not pull the bar or did not obtain a major share of the available food. In contrast, at 100 cm, all subordinate subjects obtained more food than the dominant. Thus, the dominant animals could suppress the competitive behavior of the subordinate only at the short interindividual distance, despite the fact that the dominant could not approach or attack even at the short distance and could be fully seen by the subordinate even at the large distance.

Animals↗
PubMed1997

Response-reinforcement learning is dependent on N-methyl-D-aspartate receptor activation in the nucleus accumbens core.

The nucleus accumbens, a site within the ventral striatum, is best known for its prominent role in mediating the reinforcing effects of drugs of abuse such as cocaine, alcohol, and nicotine. Indeed, it is generally believed that this structure subserves motivated behaviors, such as feeding, drinking, sexual behavior, and exploratory locomotion, which are elicited by natural rewards or incentive stimuli. A basic rule of positive reinforcement is that motor responses will increase in magnitude and vigor if followed by a rewarding event. It is likely, therefore, that the nucleus accumbens may serve as a substrate for reinforcement learning. However, there is surprisingly little information concerning the neural mechanisms by which appetitive responses are learned. In the present study, we report that treatment of the nucleus accumbens core with the selective competitive N-methyl-D-aspartate (NMDA) antagonist 2-amino-5-phosphonopentanoic acid (AP-5; 5 nmol/0.5 microl bilaterally) impairs response-reinforcement learning in the acquisition of a simple lever-press task to obtain food. Once the rats learned the task, AP-5 had no effect, demonstrating the requirement of NMDA receptor-dependent plasticity in the early stages of learning. Infusion of AP-5 into the accumbens shell produced a much smaller impairment of learning. Additional experiments showed that AP-5 core-treated rats had normal feeding and locomotor responses and were capable of acquiring stimulus-reward associations. We hypothesize that stimulation of NMDA receptors within the accumbens core is a key process through which motor responses become established in response to reinforcing stimuli. Further, this mechanism, may also play a critical role in the motivational and addictive properties of drugs of abuse.

2-Amino-5-phosphonovalerate↗
PubMed2005

Whistles of small groups of Sotalia fluviatilis during foraging behavior in southeastern Brazil.

Whistle emissions were recorded from small groups of marine tucuxi dolphins (Sotalia fluviatilis) in two beaches located in an important biological reserve in the Cananéia estuary (25 degrees 03'S, 47 degrees 58'W), southeastern Brazil. A total of 17 h of acoustic data was collected when dolphins were engaged in a specific feeding foraging activity. The amount of 3235 whistles was recorded and 40% (n=1294) were analyzed. Seven acoustic whistle parameters were determined: duration (ms), number of inflection points, start and end frequency (kHz), minimum and maximum frequency (kHz), and frequency range (kHz). Whistles with up to four inflection points were found. Whistles with no inflection points and rising frequency corresponded to 85% (n=1104) of all analyzed whistles. Whistle duration varied from 38 to 627 ms (mean=229.6+/-109.9 ms), with the start frequency varying between 1 and 16 kHz (mean=8.16+/-3.0 kHz) and the end frequency between 2 and 18 kHz (mean=14.35+/-3.0 kHz). The importance of this study requires an accurate measurement of the whistles' emissions in an unusual foraging feeding behavior situation on two beaches where several tucuxis, mostly mother-calf pairs, are frequently present. These two beaches are located in a federal and state environment Environmental Protected Area threatened by the progressive increase of tourism.

Animals↗
PubMed1994

Comparison of neurokinin substance P with morphine in effects on food-reinforced operant behavior and feeding.

In the present study, substance P (SP) was injected intraperitoneally (IP), and its effects on operant behavior were assessed in rats, which had been trained to bar press for food reward on a fixed-ratio (FR) 20 schedule. These effects were compared with IP injection of morphine sulfate, which had previously been shown to strongly suppress operant responding on FR schedules. The IP injection of SP resulted in a dose-related decrement in response rates. SP in a dose range of 250-500 micrograms/kg decreased operant responding, whereas SP in a dose range of 5-50 micrograms/kg did not influence response rates. The IP injection of morphine (10 mg/kg) markedly suppressed operant responding. However, in contrast to the rate-decreasing effects of SP, this suppression was not selective for the reinforced lever as responding on the nonreinforced lever, used as a control, was also decreased. Furthermore, both injection of 10 mg/kg morphine and SP in a dose range of 250-500 micrograms/kg was found to reduce food intake when the animals had free access to food subsequent to the operant conditioning session. The present results provide the first evidence that systemically administered neurokinin SP can affect operant responding for food reward. The suppressive effects on operant behavior and feeding obtained with systemic SP or morphine are discussed with respect to recent findings showing that both drugs can modulate mesolimbic dopamine activity after systemic drug injection.

Animals↗