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PubMed1993

Effects of mazindol on behavior maintained or occasioned by cocaine.

The effects of mazindol, cocaine and D-amphetamine were studied in rhesus monkeys trained to self-administer cocaine, and in rats and squirrel monkeys trained to discriminate cocaine from saline. Non-contingent intravenous drug injections were administered to monkeys responding under a session consisting of a 5-min period during which lever-pressing produced food reinforcement and a 60-min session in which responding produced i.v. cocaine infusions (10 or 33 micrograms/kg per infusion). Acute i.v. injections of cocaine (0.1-1.7 mg/kg), D-amphetamine (0.1-1 mg/kg) and the dopamine re-uptake inhibitor mazindol (0.03-0.56 mg/kg) given 5 min before the session decreased self-administration of cocaine, but also decreased rates of behavior maintained by the presentation of food. In both rats and squirrel monkeys trained to discriminate cocaine from saline in a two-lever, food-maintained procedure, mazindol, cocaine and D-amphetamine substituted for cocaine in a dose-related manner. Despite a lack of selectivity to decrease cocaine self-administration as compared to behavior maintained by food, the present data provide some rationale for further consideration of mazindol as a potential pharmacotherapy for stimulant abuse, due to its relatively low abuse liability and cocaine-like discriminative stimulus effects.

Animals↗
PubMed1991

Control over response number by a targeted percentile schedule: reinforcement loss and the acute effects of d-amphetamine.

Two fixed-consecutive-number-like procedures were used to examine effects of acute d-amphetamine administration on control over response number. In both procedures, rats were required to press the left lever at least once and then press the right lever to complete a trial. The consecutive left-lever presses on each trial comprised a "run." Under the targeted percentile schedule, reinforcement was provided if the current run length was closer to the target length (16) than half of the most recent 24 runs. This differentially reinforced run length while holding reinforcement probability constant at .5. A second group acquired the differentiation under the targeted percentile schedule, but were then shifted to a procedure that yoked reinforcement probability by subject and run length to that obtained under the targeted percentile schedule. The two procedures generated practically identical control run lengths, response rates, reinforcement probabilities, and reinforcement rates. Administration of d-amphetamine disrupted percentile responding to a greater degree than yoked control responding. This disruption decreased reinforcement frequency less in the former than the latter procedure. The similar baseline responding under these two procedures suggests that this difference in sensitivity was due to behavioral adjustments to drug prompted by reduction of reinforcement density in the yoked control but not the percentile schedule. These adjustments attenuate the drug's effects under the former, but not the latter, procedure.

Animals↗
PubMed1991

The interaction between stimulus and reinforcer control on remembering.

In a symbolic matching-to-sample task, 6 pigeons obtained food by pecking a red side key when the brighter of two white lights had been presented on the center key and by pecking a green side key when the dimmer of two white lights had been presented on the center key. Across Part 1 and Parts 6 to 10, the delay between sample-stimulus presentation and the availability of the choice keys was varied between 0 s and 25 s. Across Parts 1 to 5, the delay between the emission of a correct choice and the delivery of a reinforcer was varied between 0 s and 30 s. Although increasing both types of delay decreased stimulus discriminability, lengthening the stimulus-choice delay produced a greater decrement in choice accuracy than did lengthening the choice-reinforcer delay. Additionally, the relative reinforcer rate for correct choice was varied across both types of delay. The sensitivity of behavior to the distribution of reinforcers decreased as discriminability decreased under both procedures. These data are consistent with the view, based on the generalized matching law, that sample stimuli and reinforcers interact in their control over remembering.

Animals↗
PubMed1997

Memory of radial maze behavior in pigeons after ablations of the presumed equivalent of mammalian prefrontal cortex.

Pigeons were trained and postoperatively tested in an 8-arm radial maze in which 1 arm was always used for start, 3 were never baited, and 4 were always baited. Of 2 groups of pigeons, 1 (n = 6) received ablations of the postero-dorso-lateral neostriatum (PDLNS) as well as the corticoid, and the other (n = 8) was sham operated. After the surgery, in the PDLNS group the number of reference memory errors (entering the never-baited arms) was significantly increased, but the number of working memory errors (entering previously visited baited arms) was not. Two of 6 pigeons with PDLNS ablations did not show any impairment, 3 were impaired in the reference memory, and 1 was impaired in working memory. This outcome resembles behavioral effects obtained in rats with prefrontal lesions. In pigeons and rats, the lesion seems to "release" the normal "win-shift" tendency and/or impair the ability to choose correctly in simultaneous multiple-choice situations.

Animals↗
PubMed2004

Involvement of the sigma1 receptor in the appetitive effects of cocaine.

Cocaine induces in the brain a drastic plasticity affecting numerous neurotransmission systems. In turn, the drug provokes a complex pattern of behavioral responses, including locomotor hyperactivity, stereotyped behaviors, sensitization, and appetitive and reinforcing properties that rapidly generate the addictive process. The involvement of sigma (1) receptors in cocaine effects has been suggested initially through the observation that sigma (1) antagonists could attenuate several acute effects induced by the drug, such as hyperlocomotion, stereotypies, convulsions and lethality. We will describe thereafter the recent results showing that activation of the sigma (1) receptor is also involved in the appetitive properties of cocaine, as measured using place preference conditioning in mice. Using selective sigma (1) antagonists or an in vivo antisense strategy, the role of the sigma (1) receptor in acquisition, expression and reactivation of conditioned place preference was demonstrated. The observation that repeated administration of cocaine rapidly provokes overexpression of the sigma (1) receptor outlines its major role in these first psychological steps of addictive processes. The physiological interaction between cocaine and sigma (1) receptors is detailed and the possibility that effective therapeutical strategies could target the sigma (1) receptor is considered.

Animals↗
PubMed1994

Hemispheric lateralization in rhesus monkeys can be task-dependent.

Two rhesus monkeys with transection of the forebrain commissures were trained on two grating orientation-discrimination tasks. In one task, the simultaneous orientation identification task, monkeys had to decide which of two simultaneously presented gratings was horizontal. In the other task, the temporal same-different task, the monkey had to decide whether or not two successively presented gratings differed in orientation. Both monkeys showed a statistically significant individual asymmetry in the performance on the same-different task with the left hemisphere supporting superior performance compared with the right hemisphere. No such consistent lateralization was found for the identification task. These results show that the demonstration of a behavioral asymmetry depends on the type of discrimination task performed and suggest that the asymmetry is related to interhemispheric differences in higher order stimulus (cognitive) processing and not to a lateralization of early visual processes.

Animals↗
PubMed1990

Delay-dependent impairment of reversal learning in rats treated with trimethyltin.

Recent theories of hippocampal function focus on its role in the formation of associations in the temporal domain. A reversal learning paradigm based on leverpress automaintenance was developed to vary the CS-US relationship along two independent dimensions, one temporal and one not: CS(+)-US delay and the probability of reinforcement [P(RFT)] following the CS+. Eight male hooded Long-Evans rats were trained to reverse these automaintained discriminations repeatedly, until stable performance was achieved. The neurotoxicant trimethyltin (TMT) was used to induce lesions in the CNS, including the CA3-4 region of Ammon's Horn in dorsal hippocampus. Following iv injection of 7 mg/kg TMT to half the rats, reversal learning was assessed under varying conditions of delay and P(RFT). After recovery from the acute effects of TMT (1-2 weeks), treated rats reversed normally when no delay separated the CS+ and US; with delays of 2 to 4 s, they reversed less completely within a session than did controls. Changing P(RFT) did not affect reversal learning in either group, but reduced response rates similarly in both groups. Morphological damage was quantified by measuring the length of the remaining pyramidal cell line in sections of dorsal hippocampus. The degree of behavioral impairment correlated significantly with hippocampal damage only at nonzero CS(+)-US delays. These results indicate that TMT impaired ability of rats to integrate temporal relationships between stimulus events, and are consistent with theories of hippocampal mediation of temporal associations.

Animals↗
PubMed2004

Food-carrying behavior increased under risk-approaching signal in rats (Rattus norvegicus).

Food-carrying behavior in foraging rats has been assumed to have an advantage to avoid risks by shortening time spent outside their nests. However, there is no experimental evidence for this. In the present study, food-carrying behavior for four sizes of food pellets (45, 100, 200, and 1000 mg) was measured under the presentation of risk-approaching signal (shock-conditioned tone) to verify whether food-carrying behavior is related to risk avoidance or not. The results supported the hypothesis as a whole that food-carrying behavior has close relation to risk avoidance. Food-carrying behavior was increased by the signal for all food sizes, especially statistically significant in the 200 mg condition, while it decreased to the baseline at early stage of the test. These findings are discussed in relation to predatory risk.

Animals↗
PubMed1994

Periodic behavior in a random environment.

Animals' tendency to search periodically in temporally random environments was studied by presenting rats with random-interval (RI) 60-s and 120-s schedules. Power spectra revealed a periodicity of responding of 20-50 s for all animals regardless of condition. A second periodicity of 5-10-s was strongest under the RI 60-s schedule. Optimality theory suggests that periodic responding is better than random responding in obtaining food sooner on average, but the theory does not account for multiple periodicities. These multiple periodicities also cannot be explained by a single-oscillator, information-processing version of scalar expectancy theory (J. Gibbon & R. M. Church, 1992) or by the behavioral theory of timing (P.R. Killeen & J. G. Fetterman, 1988). The periodicities are consistent with a connectionist version of scalar expectancy theory that has nonscalar emergent properties, including multiple periodicities that are not proportional to the rate of random events.

Animals↗
PubMed1992

The effects of early social isolation on the motivation for social play in juvenile rats.

Fifteen-day-old rats were subjected to one of three housing conditions: mother-and-peer (family), peer, and isolation conditions. At 24 days of age, all subjects were rehoused individually. In Experiment 1, play behaviors were monitored in like-raised pairs. Despite their gross lack of social experience, isolation-reared subjects did not exhibit a deficit in frequencies of rough-and-tumble play. It is concluded that the fundamental motivation for rough-and-tumble play is relatively independent of prior learning in rats. Indeed, their elevated dorsal contacts suggested that isolation-raised subjects may have higher appetitive motivation for play. In Experiment 2, the levels of social motivation were compared between family- and isolation-raised animals, using a T-maze. The isolation-raised animals made reliably more choices for social interaction reward over food reward than family-raised animals. Although inconclusive, the results from the two experiments suggest that prolonged social isolation increases the appetitive motivation for social play.

Animals↗
PubMedDate not supplied

Studies of complex forms of behavior in various vertebrates.

In the evolutionary series of vertebrates, a correlation was established between degrees of structural and functional organization of the brain and features of the formation of complex behavioral acts. Gradual evolution of a complex sequence of motor, food-obtaining, conditioned reflexes, and a capacity for visual discrimination in the phylogenetic line of vertebrates (cartilaginous and marine bony fishes, reptiles, and mammals--insectivores, rodents, and primates) was disclosed.

Animals↗
PubMed1989

Allocentric spatial and tactile memory impairments in rats with dorsal caudate lesions are affected by preoperative behavioral training.

Rats with caudate lesions and pretrained for 36 trials demonstrated impaired performance on the "reference memory" or invariant aspect of a 12-arm radial maze and normal performance on the "working memory" or variable aspect of the maze. Rats with caudate lesions and no pretraining were also impaired on an invariant tactile discrimination in a T maze, but they were not impaired on the variable goal-arm choice of the T maze. More extensive preoperative training ameliorated behavioral deficits of rats with caudate lesions in the T maze and radial arm maze. Results showed that behavioral impairment after damage to the caudate is not restricted to egocentric tasks as previously suggested, but the caudate seems to be involved in the initial acquisition of information that is invariant over many trials.

Animals↗
PubMed2001

Explaining avoidance: two factors are still better than one.

Two-factor theory remains a viable account of avoidance behavior. By emphasizing the interplay of respondent and operant contingencies, two-factor theory encourages the analysis of stimuli that mediate molar consequences and incorporates control by local events as well as events that are temporally remote, improbable, or cumulative.

Animals↗
PubMed1977

Offspring survival, development, and operant performance following maternal ethanol consumption.

Gravid Sprague-Dawley-derived rats received 35-40% of their total calories in alcohol during pregnancy or pregnancy and the 23-day nursing period. Ethanol was administered both as the sole fluid source in a .1% saccharin solution and by twice daily subcutaneous injections. Two gravid control groups were matched for caloric and fluid intake to the experimental groups and received injections of the saline vehicle. The offspring were monitored from birth to adulthood on a variety of vital, developmental, and operant measures. Littermates of the behavioral offspring were sacrificed and necropsied at 1 and 12 months of age and the major organs examined for pathology. Differences between alcohol and control groups were found for maternal weight gain, length of gestation, number of neonatal deaths, growth retardation of offspring to postnatal Day 72, date of eye opening, distance traversed on Day 15, contingent performance in the 1st week on continuous reinforcement, fixed ratio, and timing appetitive schedules, and on number of shock initiations and ability to discriminate contingencies on punishment schedules. No gross abnormalities were observed in the major organs at necropsy.

Alcohol Drinking↗
PubMed2002

Response rate viewed as engagement bouts: resistance to extinction.

Rats obtained food pellets by nose poking a lighted key, the illumination of which alternated every 50 s during a session between blinking and steady, signaling either a relatively rich (60 per hour) or relatively lean (15 per hour) rate of reinforcement. During one training condition, all the reinforcers in the presence of the rich-reinforcement signal were response dependent (i.e., a variable-interval schedule); during another condition only 25% were response dependent (i.e., a variable-time schedule operated concurrently with a variable-interval schedule). An extinction session followed each training block. For both kinds of training schedule, and consistent with prior results, response rate was more resistant to extinction in the presence of the rich-reinforcement signal than in the presence of the lean-reinforcement signal. Analysis of interresponse-time distributions from baseline showed that differential resistance to extinction was not related to baseline differences in the rate of initiating response bouts or in the length of bouts. Also, bout-initiation rate (like response rate) was most resistant to extinction in the presence of the rich-reinforcement signal. These results support the proposal of behavioral momentum theory (e.g., Nevin & Grace, 2000) that resistance to extinction in the presence of a discriminative stimulus is determined more by the stimulus-reinforcer (Pavlovian) than by the stimulus-response-reinforcer (operant) contingency.

Animals↗
PubMed2006

The effects of different predator species on antipredator behavior in the Trinidadian guppy, Poecilia reticulata.

Different types of predators often elicit different antipredator responses in a common type of prey. Alternatively, some prey species may adopt a general response, which provides limited protection from many different types of predator. The Trinidadian guppy, Poecilia reticulata, is faced with a wide range of different predators throughout its range and is known to display varying levels of antipredator behavior depending on the predator assemblage. Pike cichlids, Crenicichla frenata, are regarded as the primary aquatic guppy predator in streams in the northern mountain range in Trinidad. As such, they are seen to be responsible for many of the differences in morphology, life history traits, and behavior between guppy populations from areas with few predators and those from areas with many pike cichlids. In this study we investigated how guppies responded when faced with different predator species using three common aquatic predators. We exposed shoals of ten guppies to one out of four treatments: no predator (control), pike cichlid, acara cichlid (Aequidens pulcher), and wolf fish (Hoplias malabaricus); and we made behavioral observations on both focal individuals and the shoal as a whole. Guppies showed significantly greater levels of predator inspection and shoaling behavior, foraged less, spent more time in the surface water, and stayed in significantly larger shoals when faced with pike cichlids than in other treatments. We discuss these results in the context of multiple predator effects.

Animals↗
PubMed1991

An assessment of handedness in mice.

Mice from a pool of inbred strains (384 males and 329 females) were tested for handedness according to Collins' protocol in order to assess the reliability of this measurement. As previously reported by Collins these data revealed that a) approximately half of the mice were right-handed and half left-handed, b) most of the mice were strongly lateralized and c) females were more lateralized than males. The study of the psychometric characteristics of the test suggested that this measurement of behavioral asymmetry is both stable and observer independent. The test of paw preference also appeared to measure preexisting lateralization and was not a function of training during the test.

Animals↗
PubMed1992

A behavioral study of the contributions of cells and fibers of passage in the red nucleus of the rat to postural righting, skilled movements, and learning.

Although the red nucleus consists of cells of origin for the rubro-spinal and rubro-olivary tracts, fibers of passage, including those of the superior cerebellar peduncle, which project from the cerebellum to the ventrolateral thalamus, pass through it. This study examined the relative effect of cell vs. fiber damage in the red nucleus on a number of behaviors thought to involve the red nucleus, including a skilled movement of reaching for food with a forelimb, postural righting on a surface and in the air, and learning a place response in a swimming pool test. Rats received unilateral or bilateral red nucleus lesions, using either the relatively cell-specific neurotoxins, ibotenic and quinolinic acid, or non-specific electrolytic anodal lesions. Both neurotoxic lesions effectively eliminated all red nucleus cell bodies, and in some animals they produced small cavities in the red nucleus and/or loss of cells in adjacent structures. Electrolytic lesions destroyed both cells and fibers, leaving a large cavity. The severity of the behavioral deficits were not related to the loss of red nucleus cells and there was a close relation between fiber damage and behavioral impairments on all of the tasks. The results suggest that for a number of behaviors, which have been thought to involve the red nucleus, impairments are more closely associated with fiber damage or damage to structures outside the red nucleus than they are to damage to cells of the red nucleus.

Animals↗