Straight Alley Research Articles

Dissociation of autonomic and behavioral components of conditioned fear during development in the rat.

Classical conditioning of heart rate (HR) was examined in unrestrained preweanling and weanling (16-, 19-, 21-, 25-, and 28-day-old) rats, with tone and light as the conditioned stimuli (CS) and electric shock as the unconditioned stimulus. The conditioned cardiac response was a sustained deceleration in HR which did not emerge until Day 21 for the tone CS and until Day 28 for the light CS. In contrast, when suppression of a behavioral response (running in a straight alley for dry suckling as reward) was used as the index of conditioning, the suppressive effects of the CS were evident around Day 16 for the tone and around Day 19 for the light. These findings indicate that during ontogenesis (a) the behavioral and autonomic responses to the same conditioned stimulus do not develop at the same pace, (b) the emergence of conditioned responses to tone and light stimuli parallel the sequential order in which the relevant sensory modalities achieve maturity (first audition, next vision), and (c) there is no clear-cut interdependence between development of the HR orienting response and conditionability of HR because unconditioned cardiac deceleration to both auditory and visual stimuli first appears about Day 16 in the developing rat, well before conditioned HR responses can be established to either stimulus.

Enhanced frustrative nonreward effect following 6-hydroxydopamine lesions of the lateral septum in the rat.

The effect of local injections of 6-hydroxydopamine (6-OHDA) into the lateral septum was tested in a paradigm known to lead to an energizing behavior, through a possible frustrative effect, induced by partial or total omission of reward in hungry rats. Biochemical assays in the septum showed that 6-OHDA reduced endogenous dopamine and, to a lesser extent, noradrenaline concentrations and left intact noncatecholaminergic neurons such as serotoninergic terminals. The first behavioral experiment was conducted in a double straight alley. The animals were submitted to three phases of testing with differing degrees of reinforcement: (a) an acquisition phase, in which the reinforcement was continuously delivered in the goal box of the two alleys, (b) a partial reinforced phase, in which animals received 50% partial reinforcement in the first alley and continuous reinforcement in the second alley, and (c) an extinction phase performed in one alley without any reinforcement. Animals with lesions ran faster for food than controls in the partial reinforcement or extinction situation, although there was no difference between the two groups in the acquisition phase of the continuous schedule of reinforcement or in the 50% reinforced trials of the partial reinforcement phase. The two groups also behaved similarly after the first six trials of the extinction phase. In a second experiment, the animals were tested in a lever-press conditioning task. Animals with lesions and control animals learned this task equally well, both with respect to the number of lever presses and the time to obtain a fixed number of food pellets.(ABSTRACT TRUNCATED AT 250 WORDS)

Dissociation of autonomic and behavioral components of conditioned fear during development in the rat.

Classical conditioning of heart rate (HR) was examined in unrestrained preweanling and weanling (16-, 19-, 21-, 25-, and 28-day-old) rats, with tone and light as the conditioned stimuli (CS) and electric shock as the unconditioned stimulus. The conditioned cardiac response was a sustained deceleration in HR which did not emerge until Day 21 for the tone CS and until Day 28 for the light CS. In contrast, when suppression of a behavioral response (running in a straight alley for dry suckling as reward) was used as the index of conditioning, the suppressive effects of the CS were evident around Day 16 for the tone and around Day 19 for the light. These findings indicate that during ontogenesis (a) the behavioral and autonomic responses to the same conditioned stimulus do not develop at the same pace, (b) the emergence of conditioned responses to tone and light stimuli parallel the sequential order in which the relevant sensory modalities achieve maturity (first audition, next vision), and (c) there is no clear-cut interdependence between development of the HR orienting response and conditionability of HR because unconditioned cardiac deceleration to both auditory and visual stimuli first appears about Day 16 in the developing rat, well before conditioned HR responses can be established to either stimulus.

Long-term partial reinforcement extinction effect and long-term partial punishment effect in a one-trial-a-day paradigm

Two experiments were run to demonstrate the presence of a partial reinforcement extinction effect (PREE) and a partial punishment effect (PPE) 4 weeks after training in a 1-trial/day procedure. In the PREE paradigm, two groups of animals were trained to run a straight alley for food reward; one group was rewarded on every trial (CRF), whereas the other was rewarded on only 50% of the trials (PRF). In the test phase, extinction, no reward was present on any trial. Four weeks after the end of acquisition, and subsequent to 7 days of CRF retraining, PRF animals showed greater resistance to extinction than did their CRF controls. The PPE paradigm resembled the PREE paradigm in all aspects, except that mild electric foot shock, together with the food reward, was used instead of nonreward on 50% of the acquisition trials. In the test phase, all animals were shocked and given a food reward on every trial. Four weeks after the end of acquisition and retraining, the animals with previous experience of shock in acquisition showed greater resistance to punishment than did their controls.

Erratum to: Acquisition of running in the straight alley following experience with responseindependent food

Erratum to: Acquisition of running in the straight alley following experience with responseindependent food

Acquisition of running in the straight alley following experience with response-independent food

During Phase 1, rats received contingent reinforcement (food), noncontingent reward, or no treatment in an operant chamber. The results, which did not support a “leamed-helplessness” interpretation, showed response-independent food to facilitate rather than inhibit the acquisition of a running response in the straight alley during Phase 2.

Long term effects of chronic chlordiazepoxide (CDP) administration.

Three experiments were carried out to test the long-term behavioral effects of 12 days administration of CDP (5 mg/kg/day) in rats. In the first two experiments, 4 weeks after the end of drug administration (CDP or placebo), and after 2 weeks of training to run a straight alley for food reward, animals were tested in extinction, i.e., following omission of reward (Expt. 1) or with punishment, i.e., 0.3 mA electric shock in addition to the food reward (Expt. 2). Drug-treated animals showed significantly increased resistance to extinction and to punishment compared with controls. In the third experiment, 10 weeks after drug administration, animals were exposed to 60 s of intense noise to induce audiogenic seizures. The convulsant metrazol was injected 5 min prior to successive sessions (10 min apart) with doses starting at 10 mg/kg an increased by 10 mg/kg each session up to 40 mg/kg. Drug-treated animals were significantly less susceptible to seizures than their placebo controls. These results suggest that chronic benzodiazepine treatment causes long-term neurochemical changes which are responsible for the observed behavioral effects.

Effects of acute trimethyltin exposure on appetitive acquisition and extinction performance in the adult rat.

Adult male rats were given one intragastric infusion of either 7 mg/kg trimethyltin chloride (dose calculated as the base of trimethyltin [TMT]) or physiological saline. Twenty-one days after dosing, subjects from each condition were divided into two equal-sized groups and trained with either partial (PRF) or continuous (CRF) reinforcement in a straight alley maze. The acquisition phase of training, lasting 40 trials (4 trials/day), was followed by 20 trials of extinction training (4 trials/day). Analyses performed on total speed revealed that TMT-treated subjects performed at lower levels during acquisition than controls regardless of schedule condition. Also, the rate of resistance to extinction was significantly reduced for treated subjects compared with that of controls regardless of the training schedules used during acquisition. A partial reinforcement extinction effect was observed for both control and TMT-treated subjects, that is, independent of dose regimen; PRF training occasioned greater persistence during extinction than did CRF training. These findings are discussed in terms of their implications for contemporary empirical and theoretical issues relating to TMT-induced hippocampal lesions.

The representation of items in serial position

Four experiments with rats tested their ability to anticipate serial patterns made from elements of reward magnitudes (14, 7, 3, 1, or 0 food pellets). Anticipation was measured by the running time in a straight alley. Elements arranged in a monotonically descending pattern were more easily anticipated than were the same elements arranged in a nonmonotonic pattern. Better anticipation was also observed when training utilized four trials per day with short interrun intervals (10–15 sec), spent in the startbox of the runway, than when training utilized one trial per day with long interrun intervals (4–5 min), spent in the rat’s home cage. Anticipation of the monotonie sequence was also superior when training consisted of one trial per day with a short interrun interval relative to that observed with four trials per day and a long interrun interval. Following acquisition of anticipation of the monotonie sequence with a short interrun interval, transfer to the same sequence with a long interrun interval resulted in disruption of anticipation. Finally, anticipation of a well-learned monotonie sequence was not disrupted by replacement of individual rewarded elements in the sequence with a 0-pellet element. These experiments indicate that the duration between runs of a trial, but not that between trials or the number of trials per day, is important in the formation of serial expectancies. They also suggest that the rats come to represent the sequence as items in serial position.

Social reinstatement and open-field testing in chickens

Based on a model which holds that open-field behavior represents a combination of predator evasion tactics and attempts to reinstate contact with conspecifics, five experiments were conducted with chickens to assess the effects on them of social separation in response to being placed in a novel enclosure. As a means of independently demonstrating reinstatement tendencies, it was shown that birds would run faster down a straight alley if the goalbox contained one or more conspecifics than if it was empty or contained a guinea pig. For birds tested in pairs, the effects were different, depending on whether they had been reared in pairs or in larger groups. On the other hand, although chicks froze and remained silent longer in pairs, they seemed to be relatively insensitive to whether the pair member was a cagemate or a stranger. Finally, as predicted, reinstatement tendencies diminished and predator evasion tactics predominated with increasing age.

Lesions of the dorsal noradrenergic bundle and rewarded running: The role of pretraining

Local injection of 6-hydroxydopamine was used to selectively destroy the dorsal ascending noradrenergic bundle (DB), producing 75% loss of hippocampal noradrenaline. Lesioned and control rats were trained to run in a straight alley for food reward with or without pretraining (handling and habituation to the apparatus). Lesioned rats ran more slowly than controls only if they had not been pretrained. This result may explain previous discrepancies in the literature; it is discussed in relation to existing hypotheses of DB function.

Acquisition and extinction of continuously and partially reinforced running in rats with lesions of the dorsal noradrenergic bundle

Local injection of 6-hydroxydopamine was used to selectively destroy the dorsal ascending noradrenergic bundle (DB) in rats. Two lesion procedures were used, differing in the extent of depletion of forebrain noradrenaline they produced (>90% or 77%). In Experiments 1–3 the rats were run in a straight alley for food reward on continuous (CR) or partial (PR) reinforcement schedules. The smaller lesion reduced and the larger lesion eliminated the partial reinforcement acquisition effect (i.e. the faster start and run speeds produced by PR during training) and the partial reinforcement extinction effect (PREE, i.e. the greater resistance to extinction produced by PR training); these changes were due to altered performance only in the PR condition. Abolition of the PREE by the larger DB lesion occurred with 50 acquisition trials, but with 100 trials the lesion had no effect. In Experiment 4 rats were run in a double runway with food reward on CR in the second goal box, and on CR, PR or without reinforcement in the first. The larger lesion again eliminated the PREE in the first runway, but did not block the frustration effect in the second runway (i.e. the faster speeds observed in the PR condition after non-reward than after reward in the first goal box). These results are consistent with the hypothesis that DB lesions alter behavioural responses to signals of non-reward, but not to non-reward itself. They cannot be predicted from two other hypotheses: that the DB mediates responses to reward or that it subserves selective attention. Since septal and hippocampal, but not amygdalar, lesions have been reported to produce similar behavioural changes, it is proposed that the critical DB projection for the effects observed in these experiments is to the septo-hippocampal system.

Resistance to Extinction After Gradually Increased or Decreased Ratio of Partial Reward Schedule

Resistance to extinction of the gradually increased (gI) or decreased (gD) ratio of partial reinforcement has been investigated in order to assess effectively partial-reinforcement theories. COGAN et al. (1975) reported greater resistance in gD than in gI employing an extensive acquisition training and the sucrose solution as a reinforcer, and interpreted the results as supporting AMSEL'S frustration hypothesis. ISHIDA (1978), however, found the opposite result with food reward after a moderate number of acquisition trials. Thus, the present study was desingned to determine the resistance to extinction after gI and gD schedules under appropriately arranged experimental conditions, and to assess partial-reinfocement hypotheses.Three groups of 9 rats each were trained with extensive acquisition trials (12 trials a day for 9 days) and then extinguished (12 trials a day for 6 days) in a straight alley. Groups gI and gD received the reward sequences as shown in Table 1. Group RA, which was added as a control, received random sequence. All three groups were rewarded at 53% with food pellets.There was not a significant difference among groups during acquisition, although performance of gI was below those of the other two groups in early trials (Fig. 1). During extinction three groups differed significantly, i. e., group gI was most resistant to extinction, RA was less, and gD was least (Fig. 2).The extinction results did not support the AMSEL'S view that the later occuring nonreinforcements (the group of gD) should produce greater frustration and greatest resistance to extinction. The present findings are interpreted both by reinforcement-level view (CAPALDI, 1978) and attention theory (SUTHERLAND and MACKINTOSH, 1971). However, it is suggested that CAPALDI'S thesis is more appropriate one, considering the predictability of the results, especially the difference between RA and each of gI and gD.

Appetitive Performance Following Exposure to Inescapable Shocks of Short or Long Duration

Four groups of rats received either no shock or shock of short (3 sec) or long (15 sec) duration prior to appetitive acquisition and extinction in a straight alley. During pretreatment,, group 60-3 sec was administered 60 shocks of 3 sec duration on each of 4 days; group 300-3 sec, 300 shocks of 3 sec duration; group 60-15 sec, 60 shocks of 15 sec duration; and group NS no pretreatment shock. All subjects subsequently experienced 40 appetitive acquisition trials followed by 28 extinction trials. The results showed that exposure to short shocks (regardless of number) had the effect of increasing resistance to extinction. Conversely, exposure to long shocks slowed acquisition and hastened extinction in the appetitive test situation. The theoretical implications of these findings were discussed in terms of viable accounts of interference phenomena associated with exposure to uncontrollable responseoutcome events. The literature on the effects of inescapable shock exposure on subsequent instrumental responding reveals divergent, often contradictory findings. This is, perhaps, most clearly evident in cases where noncontingent aversive stimulation is experienced prior to instrumental training. For instance, numerous reports relevant to the learned helplessness phenomenon (cf. Maier & Seligman, 1976) show that forced exposure to inescapable shock has the effects of retarding the acquisition of a novel instrumental test behavior and of hastening the extinction of previously learned responses. Discordant results have been obtained by Chen and Amsel (1977): it was found that experience with inescapable shock had the consequences of facilitating appetitive acquisition performances in a runway and prolonging extinction.

Stimulus control in a simple instrumental task: The role of internal and external stimuli

Two experiments using rats in a straight alley runway task tested the hypothesis that standard stimuli such as tones and lights (“external” stimuli) and schedule-generated aftereffect stimuli (“internal” stimuli) operate similarly and are similarly subject to the compounding rules specified by R. A. Rescorla and A. R. Wagner (In A. Black & W. Prokasy (Eds.), Classical conditioning II: Current theory and research. New York: Appleton-Century-Crofts, 1972) . The experimental task was an instrumental analog of the classic blocking experiment (L. J. Kamin, In M. R. Jones (Ed.), Miami symposium on the prediction of behavior: Aversive stimulation. Miami: Univ. of Miami Press, 1968) . In Experiment 1, blocking of an external discriminative stimulus by a different asymptotic discrimination was accomplished. In Experiment 2, blocking of an internal stimulus discrimination by an asymptotic external stimulus discrimination was obtained. The present results support the view that internal and external stimuli are indeed similar and function in the same manner with regard to blocking of stimulus control.

Changes in neuronal transmission in the rat hippocampus during behavior

Rats with implanted stimulating and recording microelectrodes were trained in a straight alley to repeatedly press a bar placed at one end of the alley and to run for water reward available at the other end. Stimulating the commissural input evoked field EPSP and population spike in the CA1 region while no population spike was observed in the dentate area. The amplitude of the CA1 population spike was maximum during running and smallest during drinking. Field potentials in the dentate gyrus changed in an opposite manner (drink greater than groom greater than press greater than run). Perforant path evoked cell discharges in the dentate gyrus which were maximal during drinking and smallest during running. The behavior dependent changes of the evoked potentials covaried with the frequency and power of the simultaneously recorded theta activity. Perforant path stimulation during the negative-going phase of the dentate theta cycle evoked significantly greater granule cell responses than stimuli during the positive-going phase. These observations suggest that the medical septum exerts a potent biasing effect on the efficacy of other afferent to the hippocampus.

Auditory imprinting in domestic chicks during tonic immobility.

In present study we attempted to determine whether the characteristic unresponsiveness of animals during tonic immobility is due to sensory or motor inhibition. Specifically, we exposed domestic chicks to an auditory imprinting stimulus during tonic immobility. Seventy-five White Leghorn chicks were tested in 1 of 5 conditions: (1) immobilized and imprinted; (2) restrained but not immobilized, and imprinted; (3) imprinted only; (4) immobilized but not imprinted; and (5) neither immobilized nor imprinted. Chicks in the 1st 3 groups all imprinted to the same degree in that they did not differ in median run times in a straight alley with the imprinting stimulus. These results demonstrate that chicks do process auditory stimuli during tonic immobility and the reduced responsiveness observed during tonic immobility is due mainly to motor inhibition.

The partial reinforcement extinction effect: influence of chlordiazepoxide in septal lesioned rats.

Rats sustained electrolytic lesions either in the medial septal (MS) or lateral septal (LS) area or they were sham-operated. They were tested in the straight alley with food reward on either continuous (CRF) or partial (PRF) reinforcement at one trial a day and were injected with either 5 mg/kg chlordiazepoxide HCl (CDP) or with saline before the daily trial throughout the acquisition and extinction. The effects of the drug on resistance to extinction interacted with those of the LS lesion in ways which were consistent with the hypothesis that CDP acts via the lateral septal area if it is injected during acquisition on a PRF schedule. MS lesions produced only small changes in the effects of CDP. In general, CDP acted to reverse the effects produced by each lesion: Under those conditions in which MS lesions produced faster running speeds, CDP caused the lesioned animals to run slower; and under those conditions in which LS lesions produced slower running speeds, CDP caused the lesioned animals to run faster.

Resistance to satiation: Reinforcing effects of food and eating under satiation

It has been shown previously that rats which have learned a response when hungry will continue to make that response when tested satiated, a phenomenon labeled resistance to satiation. Here we showed that rats which were previously trained hungry will learn a new response for the opportunity to consume pellets in a new situation when tested satiated. In four experiments various groups received each of the components of the training given when rats learn an instrumental response when hungry. Rats were placed in the goalbox of a straight alley and given food pellets when hungry or were hungry only in their home cages prior to running a straight alley in the satiated test in Experiment 1. In Experiments 2, 3, and 4 learning of a differential conditioning problem for pellets in S+ (nonreward in S−) was measured in the satiated test. Groups given pellets in their home cages when hungry with or without alley exposure learned to run more rapidly in S+ than in S− in the satiated test phase. The tendency to eat pellets in the apparatus and the reinforcing effect of eating the pellets was larger for rats which ate the pellets when hungry in their home cage than for rats which ate the pellets when satiated in their home cage. Being hungry in the home cage with no pellets was not sufficient to produce eating or running for pellets in the satiated test, indicating that any inherent reinforcing effect of the pellets is not sufficient to produce eating or running, and that incomplete satiation cannot account for the learning. These data indicate that a reinforcing effect of eating pellets under satiation is an important determiner of resistance to satiation.

Caudate nucleus lesions impair the ability of rats to learn a simple straight-alley task.

Learning to run down a straight alley for a food reward was investigated in rats with lesions of the telencephalon. Over 84 trials the running latencies of rats with lesions of the caudate nucleus were significantly greater than those of subjects with lesions of the frontal cortex or sham-lesioned rats. The running latencies of the cortical- and the sham-lesioned groups were not significantly different. It was suggested that the performance of the caudotomized rats reflected a learning deficit.