Feature-positive Discrimination Research Articles

The effects of feature extinction in dual-response feature-positive discriminations.

In a typical feature-positive discrimination, responding is reinforced (+) during the target stimulus (A) on trials with the feature stimulus (X), but not during target-alone trials (A-). When X and A are presented simultaneously, direct control by X is typically observed; however, when the stimuli are presented serially, X sets the occasion for responding to A. In the current dual-response procedures, one response (e.g., left lever press) was reinforced during feature-target trials (XA+) and a different response (e.g., right lever press) was reinforced during target-alone trials (A+). In Experiment 1, rats received either serial (X → A+) or simultaneous (X:A+) presentations of the feature-target compound along with target-alone trials (A+). Contrary to our predictions, the serial group failed to learn the discrimination and the simultaneous group demonstrated occasion setting. In Experiment 2, the salience of the feature was increased, which resulted in direct control by the feature in both groups. In Experiment 3, an additional serial group was included with a longer interval between the feature (X) and target (A). Despite the reduced temporal proximity of X to reinforcement, direct control was again observed in all groups. The current pattern of results in the simultaneous and serial groups is interpreted in relation to the enhanced salience of A relative to X, due to separate pairings of A-alone with reinforcement in the dual-response procedure. Consistent with previous findings, occasion setting was observed when A was most salient relative to X (Experiment 1, simultaneous group), but direct control was found when the salience of X was increased (Experiments 2-3). (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Serial feature positive and feature negative discrimination learning in a taste avoidance preparation: implications for interoceptive control of behavior.

Psychoactive drugs produce interoceptive stimuli that can guide appropriate behaviors by initiating or inhibiting responding. The current study investigated whether an interoceptive morphine state produces similar patterns of serial feature positive (FP) and feature negative (FN) discrimination learning under comparable conditions in a taste avoidance design. Male Sprague-Dawley rats were trained under 10 cycles of FP or FN discrimination. In the FP task, morphine (10 mg/kg, IP) signaled that a saccharin solution was followed by LiCl (1.2 mEq, IP), while the vehicle (saline) signaled that the LiCl was withheld. In the FN task, the contingency was reversed. The FP-trained rats acquired the discrimination after three training cycles, consuming significantly less saccharin on morphine, than on vehicle, sessions (P < 0.05). The FN-trained rats acquired the discrimination after six training cycles, consuming more on morphine than on vehicle sessions (P < 0.05). However, FN-trained rats never recovered saccharin consumption to baseline levels and 40% of the rats continued to avoid saccharin (consuming 0 ml) on morphine sessions. Control rats that never received LiCl consumed high levels of saccharin on morphine and vehicle sessions, indicating that morphine did not produce unconditioned suppression of saccharin consumption. The difficulty to acquire FN discrimination might reflect the limitations of learning about safety contingencies in the taste avoidance design. The rapidity of FP learning when a drug state signals an aversive contingency may have implications for the general role of interoceptive stimuli in the control of behavior.

Supplemental Material for The Effects of Feature Extinction in Dual-Response Feature-Positive Discriminations

Supplemental Material for The Effects of Feature Extinction in Dual-Response Feature-Positive Discriminations

Pavlovian occasion setting in human fear and appetitive conditioning: Effects of trait anxiety and trait depression

Contexts and discrete stimuli often hierarchically influence the association between a stimulus and outcome. This phenomenon, called occasion setting, is central to modulation-based Pavlovian learning. We conducted two experiments with humans in fear and appetitive conditioning paradigms, training stimuli in differential conditioning, feature-positive discriminations, and feature-negative discriminations. We also investigated the effects of trait anxiety and trait depression on these forms of learning. Results from both experiments showed that participants were able to successfully learn which stimuli predicted the electric shock and monetary reward outcomes. Additionally, as hypothesized, the stimuli trained as occasion setters had little-to-no effect on simple reinforced or non-reinforced stimuli, suggesting the former were indeed occasion setters. Lastly, in fear conditioning, trait anxiety was associated with increases in fear of occasion setter/conditional stimulus compounds; in appetitive conditioning, trait depression was associated with lower expectations of monetary reward for the trained negative occasion setting compound and transfer of the negative occasion setter to the simple reinforced stimulus. These results suggest that clinically anxious individuals may have enhanced fear of occasion setting compounds, and clinically depressed individuals may expect less reward with compounds involving the negative occasion setter.

Sex differences in the discriminative stimulus characteristics of a morphine occasion setter in rats

The current study investigated whether the stimulus effects of morphine can function as a positive and negative feature in a Pavlovian occasion setting drug discrimination preparation in male and female rats. Sprague-Dawley rats were assigned to a feature positive (FP) or feature negative (FN) training group and all received intermixed morphine (3.2 mg/kg, IP) or saline injections 15 min before 20-min daily training sessions. For FP rats, on morphine sessions, each of eight 15-s white noise (WN) presentations was followed by 4-s access to sucrose (0.01 ml, 26% w/v); on saline sessions, sucrose was withheld. FN rats learned the reverse contingency. FP discrimination was acquired somewhat sooner than FN discrimination, and females, but not males, became sensitized to the locomotor effects of morphine, which did not influence conditioned responding. Rats then entered dose generalization testing. There was no sex difference in dose generalization for FN groups (ED50 1.26 for males and 1.57 for females). Yet for FP rats, the dose response curve for females was shifted to the right compared to males (ED50 0.54 for males and 1.94 for females). FP females exhibited enhanced responding at a dose higher than that of their original training. These findings reveal the need to reassess our notions of drug stimuli that guide appropriate associative behaviours from the perspective of sex differences.

Blockade of the M1 muscarinic acetylcholine receptors impairs eyeblink serial feature-positive discrimination learning in mice.

The serial feature-positive discrimination task requires the subjects to respond differentially to the identical stimulus depending on the temporal context given by a preceding cue stimulus. In the present study, we examined the involvement of the M1 muscarinic acetylcholine receptors using a selective M1 antagonist VU0255035 in the serial feature-positive discrimination task of eyeblink conditioning in mice. In this task, mice received a 2-s light stimulus as the conditional cue 5 or 6 s before the presentation of a 350-ms tone conditioned stimulus (CS) paired with a 100-ms peri-orbital electrical shock (cued trials), while they did not receive the cue before the presentation of the CS alone (non-cued trials). Each day mice randomly received 30 cued and 30 non-cued trials. We found that VU0255035 impaired acquisition of the conditional discrimination as well as the overall acquisition of the conditioned response (CR) and diminished the difference in onset latency of the CR between the cued and non-cued trials. VU0255035 administration to the control mice after sufficient learning did not impair the pre-acquired conditional discrimination or the CR expression itself. These effects of VU0255035 were almost similar to those with the scopolamine in our previous study, suggesting that among the several types of muscarinic acetylcholine receptors, the M1 receptors may play an important role in the acquisition of the conditional discrimination memory but not in mediating the discrimination itself after the memory had formed in the eyeblink serial feature-positive discrimination learning.

Loss of Hierarchical Control by Occasion Setters Following Lesions of the Prelimbic and Infralimbic Medial Prefrontal Cortex in Rats.

Recent work suggests complementary roles of the prelimbic and infralimbic regions of the rat medial prefrontal cortex in cognitive control processes, with the prelimbic cortex implicated in top-down modulation of associations and the infralimbic cortex playing a role in the inhibition of inappropriate responses. Following selective lesions made to prelimbic or infralimbic regions (or control sham-surgery) rats received simultaneous training on Pavlovian feature negative (A+, XA−) and feature positive (B−, YB+) discriminations designed to lead to hierarchical occasion-setting control by the features (X, Y) over their respective targets (A, B). Evidence for hierarchical control was assessed in a transfer test in which features and targets were swapped (YA, XB). All groups were able to learn the feature negative and feature positive discriminations. Whilst sham-lesioned animals showed no transfer of control by features to novel targets (a hallmark of hierarchical control), rats with lesions of prelimbic or infralimbic regions showed evidence of transfer from the positive feature (Y) to the negative target (A), and from the negative feature (X) to the positive target (B; although this only achieved significance in infralimbic-lesioned animals). These data indicate that damage to either of these regions disrupts hierarchical occasion-setting control, extending our knowledge of their role in cognitive control to encompass flexible behaviours dictated by discrete cues.

Asymmetry between excitatory and inhibitory learning.

Five experiments investigated how learning about the added feature in a feature-positive discrimination or feature-negative discrimination is related to the change in reinforcement rate that the feature signals. Rats were trained in a magazine-approach paradigm with 2 concurrent discriminations between A versus AX and B versus BY. In 2 experiments (1 and 3), X and Y signaled an increase of 0.3 in the probability of reinforcement, from 0.1 to 0.4 (A vs. AX), or from 0.6 to 0.9 (B vs. BY). After extended training, each session included probe test trials in which X and Y were presented alone (Experiment 1) or in compound with another excitatory conditional stimulus (CS), C (Experiment 3). There was no difference in response rate between the 2 types of test trial (X vs. Y; XC vs. YC), consistent with the fact that X and Y signaled the same absolute change in reinforcement. In Experiments 2 and 4, X and Y signaled a decrease of 0.3 in the probability of reinforcement, from 0.4 to 0.1 (A vs. AX) or from 0.9 to 0.6 (B vs. BY). Test trials in which X or Y was presented with C showed that X had greater inhibitory strength than Y, consistent with the fact that X signaled a larger relative change in reinforcement. This was confirmed in Experiment 5, in which X and Y had the same inhibitory strength on test after training in which they signaled the same relative change in reinforcement but different absolute changes (0.3 to 0.1 for A vs. AX; 0.9 to 0.3 for B vs. BY). The results show that excitatory conditioning is linearly related to the increase in reinforcement rate, whereas inhibitory learning is not linearly related to the decrease in reinforcement rate. Implications of this for theories of associative learning are discussed. (PsycINFO Database Record

Role of Muscarinic Acetylcholine Receptors in Serial Feature-Positive Discrimination Task during Eyeblink Conditioning in Mice.

We investigated the role of muscarinic acetylcholine receptors (mAChRs) in eyeblink serial feature-positive discrimination learning in mice using the mAChR antagonist. A 2-s light cue was delivered 5 or 6 s before the presentation of a 350-ms tone paired with a 100-ms periorbital electrical shock (cued trial) but not before the tone-alone presentation (non-cued trial). Mice received 30 cued and 30 non-cued trials each day in a random order. We found that saline-injected control mice were successfully discriminating between cued and non-cued trials within a few days of conditioning. The mice responded more frequently to the tone in cued trials than in non-cued trials. Analysis of conditioned response (CR) dynamics revealed that the CR onset latency was shorter in cued trials than in non-cued trials, despite the CR peak amplitude not differing significantly between the two conditions. In contrast, scopolamine-injected mice developed an equal number of CRs with similar temporal patterns irrespective of the presence of the cue during the 7 days of conditioning, indicating in a failure to acquire conditional discrimination. In addition, the scopolamine administration to the control mice after they had successfully acquired discrimination did not impair the conditional discrimination and expression of pre-acquired CR. These results suggest that mAChRs may play a pivotal role in memory formation in the conditional brain state associated with the feature cue; however they are unlikely to be involved in the development of discrimination after conditional memory had formed in the serial feature-positive discrimination task during eyeblink conditioning.

Hippocampal state-dependent behavioral reflex to an identical sensory input in rats.

We examined the local field potential of the hippocampus to monitor brain states during a conditional discrimination task, in order to elucidate the relationship between ongoing brain states and a conditioned motor reflex. Five 10-week-old Wistar/ST male rats underwent a serial feature positive conditional discrimination task in eyeblink conditioning using a preceding light stimulus as a conditional cue for reinforced trials. In this task, a 2-s light stimulus signaled that the following 350-ms tone (conditioned stimulus) was reinforced with a co-terminating 100-ms periorbital electrical shock. The interval between the end of conditional cue and the onset of the conditioned stimulus was 4±1 s. The conditioned stimulus was not reinforced when the light was not presented. Animals successfully utilized the light stimulus as a conditional cue to drive differential responses to the identical conditioned stimulus. We found that presentation of the conditional cue elicited hippocampal theta oscillations, which persisted during the interval of conditional cue and the conditioned stimulus. Moreover, expression of the conditioned response to the tone (conditioned stimulus) was correlated with the appearance of theta oscillations immediately before the conditioned stimulus. These data support hippocampal involvement in the network underlying a conditional discrimination task in eyeblink conditioning. They also suggest that the preceding hippocampal activity can determine information processing of the tone stimulus in the cerebellum and its associated circuits.

Feature-positive discriminations during a spatial-search task with humans.

During feature-positive operant discriminations, a conditional cue, X, signals whether responses made during a second stimulus, A, are reinforced. Few studies have examined how landmarks, which can be trained to control the spatial distribution of responses during search tasks, might operate under conditional control. We trained college students to search for a target hidden on a computer monitor. Participants learned that responses to a hidden target location signaled by a landmark (e.g., A) would be reinforced only if the landmark was preceded by a colored background display (e.g., X). In Experiment 1, participants received feature-positive training (+←YB/ XA→+/A-/B-) with the hidden target to the right of A and to left of B. Responding during nonreinforced transfer test trials (XB-/YA-) indicated conditional control by the colored background, and spatial accuracy indicated a greater weighting of spatial information provided by the landmark than by the conditional cue. In Experiments 2a and 2b, the location of the target relative to landmark A was conditional on the colored background (+←YA/ XA→+/ ZB→+/ +←C /A-/B-). At test, conditional control and a greater weighting for the landmark's spatial information were again found, but we also report evidence for spatial interference by the conditional stimulus. Overall, we found that hierarchical accounts best explain the observed differences in response magnitude, whereas spatial accuracy was best explained via spatial learning models that emphasize the reliability, stability, and proximity of landmarks to a target.

Narrowing down the conditions for extinction of Pavlovian feature-positive discriminations in humans

The aim of this study was to delineate the minimal conditions for extinction of Pavlovian modulation in humans. Previous experiments at our lab showed that, after X-- A+/A- acquisition training, X- trials did not extinguish differential X-- A+/A- responding, while X-- A- trials did. Additionally, X-- A- extinction training seemed only to extinguish differential X-- A+/A- responding, while leaving differential responding on a concurrently trained Y [Symbol: see text] B+/B- discrimination intact. It thus seemed that the X-- A+/A- discrimination can only be extinguished by X-- A- extinction trials. (Rescorla, Journal of Experimental Psychology: Animal Behavior Processes 12, 16-24, 1986), on the other hand, found that the minimal conditions for extinction were broader in pigeons: Namely, he found that an acquired X-- A+/A- discrimination could be extinguished by presenting the original feature X in combination with a different target (B) that was minimally trained as an exciter. We thus wanted to examine whether this was also the case in humans. We found that nonreinforced X-- B- presentations did not abolish discriminative X-- A/A responding when target B was a nonreinforced stimulus. Nonreinforced X-- B- trials did extinguish the X-- A+/A- discrimination when target B had previously been trained as a target for modulation (X-- B+/B- or Y [Symbol: see text] B+/B- training) or as a reinforced exciter (B+). Our results thusf parallel and extend those in nonhuman animals (Rescorla, Journal of Experimental Psychology: Animal Behavior Processes 12, 16-24, 1986).

An exploration of the feature-positive effect in adult humans

Experiment 1 compared the acquisition of a feature-positive and a feature-negative discrimination in humans. In the former, an outcome was signaled by two stimuli together, but not by one of these stimuli alone. In the latter, the outcome was signaled by one stimulus alone, but not by two stimuli together. Using a within-group design, the experiment revealed that the feature-positive discrimination was acquired more readily than the feature-negative discrimination. Experiment 2 tested an explanation for these results, based on the Rescorla-Wagner theory, by examining how novel discriminations, based on a combination of a feature-positive and a feature-negative discrimination, were solved. The results did not accord with predictions from the theory. Alternative explanations for the results are considered.

Dissociations Between ABA-, ABC-, and AAB-Renewal of Pavlovian Modulation in Human Sequential Feature Positive Discrimination Learning

Using a conditioned suppression preparation, we investigated extinction and aba-, abc-, and aab-renewal of Pavlovian modulation in human sequential Feature Positive (FP) discrimination learning, X → A+/A-. Extinction treatment was administered in the acquisition context a (aaa- and aab-groups) or in a new context b (aba- and abc-groups) and comprised X → A- extinction trials. Discriminative X → A/A responding was lost in all groups when tested in the extinction context. In the aba-group, the discriminative X → A/A responding totally recovered when retested in the acquisition context a. For the aaa-, the aab-, and the abc-group, discriminative X → A/A responding did not reappear when tested for renewal in, respectively, contexts a, b, and c. The demonstration of aba-renewal of extinguished modulation, but not abc- and aab-renewal, suggests that extinction in a context different from the acquisition context and a return to the original acquisition context might both be critical for renewal of Pavlovian modulation in human FP-discrimination learning.

Intertrial interval as a contextual stimulus: further analysis of a novel asymmetry in temporal discrimination learning.

Four experiments investigated discrimination learning when the duration of the intertrial interval (ITI) signaled whether or not the next conditional stimulus (CS) would be paired with food pellets. Rats received presentations of a 10-s CS separated half the time by long ITIs and half the time by short ITIs. When the long ITI signaled that the CS would be reinforced and the short interval signaled that it would not be (Long+/Short-), rats learned the discrimination readily. However, when the short ITI signaled that the CS would be reinforced and the long interval signaled that it would not (Short+/Long-), discrimination learning was much slower. Experiment 1 compared Long+/Short- and Short+/Long- discrimination learning with 16-min/4-min or 4-min/1-min ITI combinations. Experiment 2 found no evidence that Short+/Long- learning is inferior because the temporal cue corresponding to the short interval is ambiguous. Experiment 3 found no evidence that Short+/Long- learning is poor because the end of a long ITI signals a substantial reduction in delay to the next reinforcer. Long+/Short- learning may be faster than Short+/Long-because elapsing time involves exposure to a sequence of hypothetical stimulus elements (e.g., A then B), and feature-positive discriminations (AB+/A-) are learned quicker than feature-negative discriminations (A+/AB-). Consistent with this view, Experiment 4 found a robust feature-positive effect when sequentially presented CSs played the role of elements A and B.

Sign- vs. goal-tracking in a feature positive discrimination task with nicotine: Importance of spatial location of the conditional stimulus

We assessed whether sign-tracking developed along with goal-tracking in a Pavlovian drug discrimination task. Rats had nicotine sessions intermixed with saline sessions. For nicotine sessions, 15-s illumination of a light near (Experiment 1) or far (Experiment 2) from the dipper receptacle was followed by sucrose. Saline sessions were similar to nicotine sessions except sucrose was withheld. Regardless of location, the light evoked goal-tracking only on nicotine sessions. Only rats with the light near the dipper developed sign-tracking.

Hippocampal lesion effects on occasion setting by contextual and discrete stimuli

Three experiments examined the role of the dorsal hippocampus (dHIPP) in occasion setting with diffuse contextual and discrete light stimuli serving as occasion setters in classical fear conditioning with rats. Both sham-operated and dHIPP-lesioned animals readily learned a L→T+, T− serial feature-positive discrimination in which a light (L) “set the occasion” for reinforcement of a tone (T+). dHIPP-lesioned animals were deficient, however, in acquiring a similar discrimination in which different contexts (A and B) served as occasion setters, i.e., A(T+) and B(T−). The lesioned animals also failed to discriminate between a context in which a tone had been partially reinforced and a context in which no conditioning had taken place, whereas sham-operated animals froze more to the tone in the conditioned context than in the novel context. Collectively, the data indicate that the dorsal hippocampus is important in processing information about the signaling value of contextual, but not discrete, stimuli.

Modulación contextual de la tolerancia asociativa al etanol

There is evidence that drug-paired cues not only become associated with the drug effects but also become occasion setters that modulate the association of other cues with the drug effects, contributing to the development of associative tolerance (Ramos, Siegel, & Bueno, 2002). Using a feature-positive discrimination training, we evaluated the contribution of contexts as occasion setters of the ataxic effect of ethanol in rats. The results suggest that the context acquire occasion setter properties of the drug tolerance, and that these properties can be extinguished.

A role for stimulus generalization in conditional discrimination learning.

In each of three experiments on discrimination learning by rats, whether or not a 10-sec target stimulus was followed by food was determined by the nature of a 2-min background stimulus that accompanied it. A conditional discrimination was employed in Experiment 1 such that background A indicated food would follow one target but not the other, whereas this relationship between the targets and food was reversed in the presence of background B. Experiment 2 employed two feature-positive discriminations. Subsequent test trials revealed that the background for one discrimination was able to enhance responding during the target for the other discrimination. Experiment 3 employed a feature-positive and a feature-negative discrimination prior to test trials in which each target was presented separately during a compound of both background stimuli. The compound enhanced responding to the target from the feature-positive discrimination and reduced it to the target from the feature-negative discrimination. We suggest that to accommodate all these findings, the best explanation is provided by a configural model of Pavlovian conditioning.

Estimação de tempo em ratos submetidos a um procedimento de discriminação condicional

Num procedimento de discriminação condicional (DC) de característica positiva, um mesmo estímulo alvo A não é seguido de reforço quando apresentado sozinho, mas é seguido de reforço quando precedido de um estímulo X. Na DC de característica negativa, um mesmo estímulo alvo B é seguido de reforço quando apresentado sozinho, mas nunca quando precedido do estímulo Y. Nesta pesquisa, procurou-se examinar se uma informação amodal relativa a atributos básicos de estímulos, como a duração, tem capacidade de adquirir propriedades condicionais em animais. Ratos foram submetidos a procedimentos de DC positiva e negativa com estímulos X e Y de mesma modalidade física, uma luz, mas com durações diferentes: X= 15-seg e Y= 5-seg; as durações dos estímulos alvo foram A= 5-seg e B= 15-seg. Os resultados mostraram que os animais discriminaram as propriedades condicionais excitatórias (X) e inibitórias (Y) relativas, respectivamente, a duas durações diferentes de um mesmo estímulo, sustentando a hipótese de que a duração, um componente amodal de estímulo, pode ser associada a propriedades condicionais, em ratos.