Delay activity in avian prefrontal cortex--sample code or reward code?

In the current study, we examined whether delay activity in the avian equivalent of the prefrontal cortex (PFC) represents a neural correlate of a to-be-remembered sample stimulus or an upcoming reward. Birds were trained on a directed forgetting paradigm in which sample stimuli (red and white) were either followed by a cue to remember (high-frequency tone) or a cue to forget (low-frequency tone). The task also incorporated a differential outcomes procedure in which a correct response on the memory test following a red (remember) sample was rewarded with food, but correct responses on the memory test following the white (remember) sample were not. If delay activity represents a sample code, then it should be seen on both red-remember and white-remember trials. On the other hand, if delay activity represents a reward code, then delay activity should be seen only on red-remember trials, but not white-remember trials. Our findings suggest that activity in the avian PFC represents the outcome associated with each sample (reward or no reward) rather than memory for the sample itself.

Lipopolysaccharide-induced immune activation impairs attention but has little effect on short-term working memory.

Cytokine-induced CNS inflammation has been theorized to contribute to cognitive dysfunction in sickness and neurodegenerative disease. We investigated the effects of systemic endotoxin-induced acute immune activation and inflammation on working memory and attention functions in pigeons assessed through two variations of an operant symbolic matching-to-sample (SMTS) task, employing doses of lipopolysaccharide (LPS) sufficient to induce fever. LPS produced moderate impairments in comparison to saline on the SMTS task designed to measure visual vigilance and attention, but the impairments were not as marked as those produced by chlordiazepoxide (CDP) which is known to disrupt attention. In contrast, LPS had no significant effect on short-term working memory performance compared to saline, while scopolamine, a cholinergic antagonist known to disrupt working memory, did impair performance. The results have implications for the cognitive impairments seen in illnesses characterized by chronic cytokine activation (e.g., Alzheimer's disease) as well as illnesses treated with cytokines (e.g., multiple sclerosis) suggesting that some cognitive failures attributed to working memory impairments per se may better be attributed to prior attention impairments.

Sensitization and conditioning as contributors to gastrointestinal vulnerability.

Electric shocks are stressful and if signalled can result in Pavlovian conditioning of the stress response. Stress arising from such shocks or conditioned psychological "threat" influences vulnerability to gastrointestinal disorders. Reviewed are our studies with rats showing that unconditioned stress experiences sensitize the glandular portion of the stomach to later restraint-in-water induced erosions, as an animal model of ulcer disease. These stress effects are not attributable to corticoids but may be opioid/endorphin dependent. The unconditioned stress-induced sensitization is reduced by allowing the rat either control over or prediction of the shocks even though the direct experience with shocks is identical. Elicitation of the conditioned stress response by a signal during the ulcer induction or even shortly afterwards increases gastric vulnerability to erosions. We are now finding parallel unconditioned stress effects on colonic erosions and increases in intestinal permeability induced by dextran sulphate sodium, as an animal model of inflammatory bowel disease. We conclude that psychological context of past trauma and/or current threat increases vulnerability to gastrointestinal disorders.

Trauma and resulting sensitization effects are modulated by psychological factors.

Traumas have both immediate consequences and proactive consequences. Examples include learned helplessness, HPA-axis responsivity, gastrointestinal vulnerability to ulcer, and other correlates of anxiety disorders. Both immediate and proactive consequences may be modulated by behavioral and cognitive evolutionary evolved adaption processes, among which are forms of learning that enable 'coping'. Examples of associative and non-associative forms of coping and effects on learned helplessness, HPA-axis responsivity, and gastrointestinal vulnerability are presented. The importance of attention to behavioral contingencies in situations in which potentially traumatic events occur is emphasized as critical to understanding that it is not the physical event(s) per se that determine the immediate and long term consequences.

The role of Pavlovian cues in alcohol seeking in dependent and nondependent rats.

OBJECTIVE: Recent treatment approaches to substance use disorders have focused on reducing drug use by modifying drug-seeking behaviors in response to drug-associated cues. Understanding the effect of alcohol-related stimuli on alcohol-seeking responses is therefore of interest in the study of alcoholism. The present study examined the impact of ethanol- (ETOH) associated cues on selective ETOH-seeking behavior, using a Pavlovian-instrumental transfer design in groups of alcohol-dependent and nondependent rats. METHOD: Rats (N = 24) received Pavlovian conditioning in which each of two stimuli, a tone and white noise, was paired alternately with a 10% sweetened ETOH solution and a polycose-quinine solution. The rats were trained to perform two instrumental actions, with one action earning access to the sweetened ETOH and the other to the polycose-quinine. After training, half of the animals were made ETOH-dependent by intragastric administration of 36 g/kg of ETOH over 4 days, whereas the remainder received intragastric administration of an isocaloric polycose solution. On the following day, subjects were given a choice extinction test in which they were free to choose between both actions with no outcomes being delivered. During this test, the ETOH- and polycose-associated Pavlovian cues were presented to assess performance of the two instrumental actions both in the presence and absence of these stimuli. RESULTS: Pavlovian cues associated with both the ETOH or the polycose exerted a nonspecific excitatory influence on reward-seeking behavior in both nondependent and alcohol-dependent rats. CONCLUSIONS: Responses through which rats gain access to ETOH appear to be subject to the general excitatory influence of the general motivational arousal induced by reward-related cues. It appears the rats' performance did not depend on encoding the specific consequences of their actions and thus was not affected by the selective retrieval or priming of those consequences in memory.

An acute stressor enhances sensitivity to a chemical irritant and increases 51CrEDTA permeability of the colon in adult rats.

We investigated the effect of prior acute stress on colonic permeability induced by a chemical irritant known to induce symptoms similar to inflammatory bowel disease in rodents. Adult male rats (n = 12) were stressed by a single session of ten unpredictable, uncontrollable foot shocks, and half were home cage controls (n = 12). Twenty-nine days later, half of each treatment group was exposed to 4% DSS (dextran sulphate sodium) solution in their drinking water for 48 hours while half received pure water over two periods separated by 17 days. After food deprivation overnight and light isoflurane anaesthesia the following morning, the animals were given a colonic infusion of 2000 nCi (nanocurie) 51CrEDTA (51Cr-labelled ethylenediaminetetraacetic acid) and then placed individually in metabolic cages for a six hours continuous urine collection. Radioactivity in urine was measured by a gamma counter and percentage recovery of 51CrEDTA calculated as an indicator of colonic mucosal permeability. Results concluded that pre-shocked animals exposed to DSS showed significantly higher mucosal permeability than the pre-shocked animals given water, and the non-shocked animals given either DSS or water. Pre-shock in combination with two exposures to a chemical irritant separated by 17 days had a pronounced effect on colonic permeability, indicating that stress should be considered a possible initiating or contributory factor to increased intestinal permeability related to a mucosal challenge.

Differential outcomes effect in children and adults with down syndrome.

In previous studies, researchers have demonstrated that learning of symbolic relations is facilitated when a particular outcome is associated with each relation to be learned. In the present study, we extend this differential outcomes procedure to children and adults with Down syndrome who had to learn a symbolic conditional discrimination task. Participants showed a better terminal accuracy and a faster learning of the task when the alternative correct responses were each followed by unique different outcomes than when nondifferential outcomes were arranged. These findings confirm that the differential outcomes procedure can be a useful tool to ameliorate discriminative learning deficits and demonstrate the benefits of this procedure for people with Down syndrome.

On learned helplessness.

"Learned helplessness" and its Pavlovian analog, learned irrelevance, are phenomena thought integral to understanding depression, PTSD, psychosomatic vulnerability, and a variety of diseases and immune disorders. The origin and development of research on learned helplessness is briefly overviewed with attention to the reasons for the controversy that surrounds the study of learned helplessness and derived physiological, psychological, and behavioral phenomena. The need to remedy past focus on American research and English language journals in this area is noted. The heuristic value as well as the wide ranging empirical value of the research domain is lauded. The meretricious emerging social and legal barriers to this research are noted to be unrealistic and unfortunate.

Effects of lipopolysaccharide on consolidation of partial learning in the Y-maze.

Research on consolidation of long-term memory suggests that acute immune system activation induced by endotoxin lipopolysaccharide (LPS) may disrupt consolidation of newly acquired learning. Adult male Sprague-Dawley rats were trained to perform a simple Y-maze task and were immediately afterwards administered LPS (15 microg/kg) or saline. After a seven-day interval, subjects were returned to the Y-maze and were retrained to criterion. It was found that subjects treated with saline required significantly fewer trials to relearn the task relative to the LPS group and a no-partial-learning control group, which themselves did not differ. These results are most readily explained in terms of a disruptive effect of acute immune system activation on consolidation of newly induced acquired memories.

Not so bird-brained: Pigeons show what-where-when memory both as time of day and how long ago.

In an ever-changing world, the ability to track what significant events occur and where and when is beneficial to a variety of animal species. The purpose of the present studies was to assess the presence of this ability to track what-where-when memory in pigeons based both on when during the day the events occurred and how long ago events occurred. In these studies, pigeons were trained to discriminate between two foods that differed in quality (what), making one more "attractive" than the other. The birds were required to alter their choice of keylights (where) to get these differential foods based on the time of day (Experiments 1-2) or how long ago (Experiments 3-5) they were in a session (when). Pigeons were able to correctly choose the key that yielded the "attractive" food using both time of day and how long ago, indicating a what-where-when memory. However, the pigeons failed to transfer this knowledge to a novel situation, showing limited flexibility in use of the learned what-where-when information. These findings suggest that pigeons have abilities to track what-where-when events as do caching birds and other animal species, but perhaps represented in a more rigid manner.

Restoring psychology's role in peptic ulcer.

This paper reviews the history of the transition from the belief that gastrointestinal ulcers are caused primarily by psychological factors to the current state of belief that they are caused primarily by infection and argues that neither is fully accurate. We argue that psychological factors play a significant role as predisposing to vulnerability, modulating of precipitation, and sustaining of gastric ulceration. We review data that challenge the assumption of a simple infectious disease model and adduce recent preclinical data that confirm the predisposing, modulatory, and sustaining roles for psychological factors. We note that others, too, are now challenging the adequacy of the contemporary simple bacterial infection model. We hope to replace the competition between psychology and medicine with cooperation in understanding and treating patients suffering gastric ulceration and ulcer.

James J. Jenkins (1923-2012).

Presents an obituary for James J. Jenkins. Jim Jenkins, fondly known as "J-cubed," was born on July 29, 1923, in St. Louis, Missouri. He attended William Jewell College but enlisted in the Army in 1942. He received a bachelor's degree in physics from the University of Chicago in 1944 as part of his training as a meteorologist. After serving in the South Pacific, he returned to William Jewell College, obtaining a bachelor's degree in psychology in 1947. Jenkins received a master's degree (1948) and a doctorate (1950) from the University of Minnesota under a giant in industrial psychology, Donald G. Paterson. He joined the Minnesota Psychology Department faculty upon graduation (turning down an offer from General Motors at triple the salary). Jenkins helped lead psychology's "cognitive revolution" from the second half of the 20th century into the present one. His work advanced multiple research areas: learning and memory, sentence processing, aphasia, speech perception, and perceptual organization. His remarkable combination of abilities led to nearly 200 scholarly publications and 500 conference and meeting presentations; multiple leadership positions, teaching awards, and professional accolades; and intense devotion from generations of students.

The Differential Outcomes Effect Using Sensory Outcomes in a Many-to-One Matching-to-Sample Task / Consequências Diferenciais Sensoriais em uma Tarefa de Pareamento ao Modelo "Muitos para Um"

Abstract The present study was designed to evaluate the use of sensory outcomes (visual vs. auditory) using a differential outcomes procedure to facilitate learning in a many-to-one matching-to-sample task. For one group of participants (differential outcomes) each correct stimulus-choice sequence was always followed by a different outcome; whereas for the rest of participants (non-differential outcomes) each correct sequence was followed by the same outcome. Participants trained with differential outcomes showed a faster acquisition and higher overall accuracy than participants trained with non-differential outcomes. The results provide a new extension the differential outcomes effect by using sensory outcomes and many-to-one matching to-sample task; applications of the differential outcomes procedure are discussed.

Resumo O presente estudo foi delineado para avaliar o uso de consequências sensoriais utilizando um procedimento de consequências diferenciais em uma tarefa de pareamento ao modelo "muitos para um". Para um grupo de participantes, cada sequência correta de escolha de estímulos era sempre seguida por uma consequência diferente; enquanto para os outros participantes, cada sequência correta era seguida pela mesma consequência. Participantes treinados com consequências diferenciais apresentaram aquisição mais rápida e, em geral, maior acurácia do que participantes treinados com consequências não diferenciais. Esses resultados demonstram uma nova extensão do efeito de consequências diferenciais por meio do uso de consequências sensoriais e de uma tarefa de pareamento ao modelo "muitos para um". Aplicações do procedimento de consequências diferenciais são discutidas.

Neural correlates of cue-unique outcome expectations under differential outcomes training: an fMRI study.

In conditional discriminative choice learning, one learns the relations between discriminative/cue stimuli, associated choices, and their outcomes. When each correct cue-choice occurrence is followed by a cue-unique trial outcome (differential outcomes, DO, procedure), learning is faster and more accurate than when all correct cue-choice occurrences are followed by a common outcome (CO procedure)--differential outcomes effect (DOE). Superior DO performance is theorized to be mediated by the additional learning of cue-unique outcome expectations that "enrich" the prospective code available over the delay between cue and choice. We anticipated that such learned expectations comprise representations of expected outcomes. Here, we conducted an event-related functional MR imaging (fMRI) analysis of healthy adults who trained concurrently in two difficult but similar perceptual discrimination tasks under DO and CO procedures, respectively, and displayed the DOE. Control participants performed related tasks that differentially biased them towards delay-period retrospection versus prospection. Indeed, when differential outcomes were sensory-perceptual events (visual vs. auditory), delay-period expectations were experienced as sensory-specific imagery of the respectively expected outcome content, generated by sensory-specific cortices. Visual-specific imagery additionally activated stimulus-specific representations in prefrontal, lateral and medial frontal, fusiform and cerebellar regions, whereas auditory-specific imagery recruited claustrum/insula. Posterior parietal cortex (PPC), BA 39, was non-modality specific in mediating delay-period cue-unique outcome expectations. Greater hippocampal involvement in retrospection than prospection contrasted against the PPC's role in prospection. Time course analyses of hippocampal versus PPC responses suggest the DOE derives from an earlier transition from retrospection to prospection, which taps into long-term associative memory--more enduring.

Improving conditional discrimination learning and memory in five-year-old children: differential outcomes effect using different types of reinforcement.

Previous studies have demonstrated that discriminative learning is facilitated when a particular outcome is associated with each relation to be learned. When this training procedure is applied (the differential outcomes procedure; DOP), learning is faster and better than when the typical common outcomes procedure or nondifferential outcomes (NDO) is used. Our primary purpose in the two experiments reported here was to assess the potential advantage of DOP in 5-year-old children using three different strategies of reinforcement in which (a) children received a reinforcer following a correct choice (" + "), (b) children lost a reinforcer following an incorrect choice (" - "), or (c) children received a reinforcer following a correct choice and lost one following an incorrect choice (" + / - "). In Experiment 1, we evaluated the effects of the presence of DOP and different types of reinforcement on learning and memory of a symbolic delayed matching-to-sample task using secondary and primary reinforcers. Experiment 2 was similar to the previous one except that only primary reinforcers were used. The results from these experiments indicated that, in general, children learned the task faster and showed higher performance and persistence of learning whenever differential outcomes were arranged independent of whether it was differential gain, loss, or combinations. A novel finding was that they performed the task better when they lost a reinforcer following an incorrect choice (type of training " - ") in both experiments. A further novel finding was that the advantage of the DOP over the nondifferential outcomes training increased in a retention test.

Enhancing challenged students' recognition of mathematical relations through differential outcomes training.

Previous studies have reported that the differential outcomes procedure enhances learning and memory in special populations with cognitive deficits (see Goeters, Blakely, & Poling, 1992, for a review). In the present study we extend these findings to healthy adults who were asked to discriminate between the symbols " > " and " < " in mathematical statements. In Experiment 1, the performance of participants who showed difficulties in discriminating between these symbols was better (shorter response times) for the differential outcomes condition than for the nondifferential outcomes condition. In Experiment 2, the difficulty of the task was increased by using signed decimal numbers. Similar to Experiment 1, participants who initially had difficulties in discriminating between the symbols showed better performance (higher accuracy) for the differential outcomes condition than for the nondifferential outcomes condition, but only when both numbers were negative. These findings suggest that the differential outcomes procedure can be used to improve performance of challenged healthy adults on discrimination tasks with mathematical symbols and relations.

Associatively activated representations of food events resemble food outcome expectancies more closely than they resemble food-based memories.

When Pavlovian stimuli activate representations of food, do these representations resemble memories of food consumed in the recent past or expectancies of food that is imminent? In Experiments 1A and 1B, this question was addressed by training pigeons on a symbolic matching-to-sample task involving different grains as memory cues or as expectancy cues for correct choices. Autoshaping trials involving these same grains were interspersed among matching-to-sample trials, as were test trials involving the substitution of autoshaping stimuli for cues in the matching-to-sample task. Control over choices transferred to autoshaping stimuli in both experiments, suggesting that associatively activated representations of food resemble both memories and expectancies. In Experiment 2, pigeons were trained on a symbolic matching-to-sample task in which food and no-food memory cues (i.e., the samples) were juxtaposed with no-food and food expectancy cues. Subsequently, autoshaping stimuli, which activated representations of food and no food, were substituted for the samples. Choices by the pigeons indicated that associatively activated representations of food-related events resemble expectancies more closely than they do memories.

Recommended housing conditions and test procedures can interact to obscure a significant experimental effect.

Routine animal husbandry variables, such as group housing of mice and the order of testing of cage-mates, are currently viewed to be essentially neutral with respect to the outcome of most, if not all, animal-based experiments, including those that utilize behavioral measurements. During the course of experiments that have utilized the elevated plus-maze to examine the ability of a bacterial challenge of mice to induce anxiety-like behavior, due to the activation of various cytokine pathways, we followed the recommendation of laboratory animal care staff to house the mice in pairs. Whenwe testedthe members of the pairs successively, it was found, for the first experimental set, that the behavior that reflects anxiety (time in closed arms) of the first-tested animal differed from that of the second-tested animal for both the experimental and the control animals and, critically, that these changes were in the opposite directions for the controls and the experimental animals, thus obscuring the effect of the experimental manipulation. A second, independent experimental set also obtained a significant effect for the order of testing effect in the bacterial-challenged group, but not in the saline control group, although a similar trend was evident in this group as well. These results indicate that special care should to be taken in implementing housing recommendations and that preliminary tests may be necessary to ensure that housing conditions do not interact with tests of the phenomenon under experimental investigation.

A comparison of spaced retrieval to other schedules of practice for people with dementia.

Spaced retrieval training uses a schedule of practice trials distributed according to a learner's performance. The authors compared spaced retrieval to four alternative schedules of practice to determine whether it is more effective than other schedules for people with dementia. Participants practiced (a) pill names or (b) nonverbal sequences. Spaced retrieval did not produce long-term retention more often than other schedules of practice on either task. Participants with higher scores on one portion of the Hopkins Verbal Learning Test-Revised were more likely to show long-term retention of pill names regardless of schedule of practice (Experiment 1).

Sensitization, conditioning, and learning: can they help us understand somatization and disability?

This paper reviews those features of non-associative and associative forms of learning, as elaborated in the experimental literature, that might contribute to experienced and reported discomfort in the workplace. Emphasis is given to sensitization, while noting that some models of habituation (e.g. the opponent process model) also produce sensitization-like effects as a by-product that could contribute to persistent complaints. Also noted are ways in which these non-associative processes may enhance associative learning of workplace-avoidance behaviors that are exceptionally persistent - even in the absence of further somatic discomfort.