- The effect of high-fat diet consumption on appetitive instrumental behavior in rats. [Journal Article]
- AAppetite 2016 Oct 3; 108:203-211
- Evidence now indicates that the chronic consumption of high-calorie foods, such as a high-fat diet (HFD), is associated with impaired control over food-seeking, yet the extent of this alteration is n...
Evidence now indicates that the chronic consumption of high-calorie foods, such as a high-fat diet (HFD), is associated with impaired control over food-seeking, yet the extent of this alteration is not fully understood. Using different reinforcement schedules, we evaluated whether HFD intake from weaning to adulthood modifies instrumental responding and induces a shift from goal-directed actions to habitual responding. We first observed reduced instrumental performance and motivation for a food reward in HFD-fed rats trained under schedules of reinforcement that facilitate habitual responding [Random Interval (RI)]. However, this deficit was alleviated if rats trained under RI were subsequently trained with reinforcement schedules that promote goal-directed strategies [Random Ratio (RR)]. Using an outcome devaluation procedure, we then demonstrated that consumption of a HFD promoted habitual behavior in rats trained under RI but not RR schedules. Finally, extended HFD exposure did not interfere with the ability of RR training to overcome impaired RI instrumental performance and to favor goal-directed behavior. These results indicate that chronic consumption of a HFD changes the co-ordination of goal-directed actions and habits and that alteration of food-seeking may be reversed under particular behavioral conditions.
- Extending the duration of long-term memories: Interactions between environmental darkness and retinoid signaling. [Journal Article]
- NLNeurobiol Learn Mem 2016 Sep 16; 136:34-46
- Retinoid signaling plays an important role in hippocampal-dependent vertebrate memories. However, we have previously demonstrated that retinoids are also involved in the formation of long-term implic...
Retinoid signaling plays an important role in hippocampal-dependent vertebrate memories. However, we have previously demonstrated that retinoids are also involved in the formation of long-term implicit memory following operant conditioning of the invertebrate mollusc Lymnaea stagnalis. Furthermore, we have discovered an interaction between environmental light/dark conditions and retinoid signaling and the ability of both to convert intermediate-term memory into long-term memory. In this study, we extend these findings to show that retinoid receptor agonists and environmental darkness can both also extend the duration of long-term memory. Interestingly, exposure to constant environmental darkness significantly increased the expression of retinoid receptors in the adult central nervous system, as well as induced specific changes in a key neuron mediating the conditioned behaviour. These studies not only shed more light on how retinoids influence memory formation, but also further link environmental light conditions to the retinoid signaling pathway.
- The neurobiology of social play and its rewarding value in rats. [Review]
- NBNeurosci Biobehav Rev 2016; 70:86-105
- In the young of many mammalian species, including humans, a vigorous and highly rewarding social activity is abundantly expressed, known as social play behaviour. Social play is thought to be importa...
In the young of many mammalian species, including humans, a vigorous and highly rewarding social activity is abundantly expressed, known as social play behaviour. Social play is thought to be important for the development of social, cognitive and emotional processes and their neural underpinnings, and it is disrupted in pediatric psychiatric disorders. Here, we summarize recent progress in our understanding of the brain mechanisms of social play behaviour, with a focus on its rewarding properties. Opioid, endocannabinoid, dopamine and noradrenaline systems play a prominent role in the modulation of social play. Of these, dopamine is particularly important for the motivational properties of social play. The nucleus accumbens has been identified as a key site for opioid and dopamine modulation of social play. Endocannabinoid influences on social play rely on the basolateral amygdala, whereas noradrenaline modulates social play through the basolateral amygdala, habenula and prefrontal cortex. In sum, social play behaviour is the result of coordinated activity in a network of corticolimbic structures, and its monoamine, opioid and endocannabinoid innervation.
- Carolyn Rovee-Collier's legacy to applied psychology, intervention, and public policy. [Review]
- DPDev Psychobiol 2016; 58(7):918-922
- In this article, we reflect upon Carolyn Rovee-Collier's pioneering research on learning and memory in infants, especially that using the mobile conjugate reinforcement task, for our understanding of...
In this article, we reflect upon Carolyn Rovee-Collier's pioneering research on learning and memory in infants, especially that using the mobile conjugate reinforcement task, for our understanding of (a) cognitive development in infants born prematurely and those with Down's syndrome and (b) her prediction that infants' performance in the mobile conjugate reinforcement and similar operant tasks would predict later intellectual functioning. We then examine the implications of her research on time windows (the integration of new information into a memory) and memory reactivation (the retrieval of a forgotten memory as a result of the re-exposure to a component of the original learning experience) for early intervention programs and clinicians treating victims of early trauma. We conclude with a discussion of the value of Rovee-Collier's work for the growing field of infant/toddler science and how this science has informed public policy and program development.
- Early age noise exposure increases loudness perception - A novel animal model of hyperacusis. [Journal Article]
- HRHear Res 2016 Oct 13
- The neural mechanisms that give rise to hyperacusis, a reduction in loudness tolerance, are largely unknown. Some reports suggest that hyperacusis is linked to childhood hearing loss. However, the ev...
The neural mechanisms that give rise to hyperacusis, a reduction in loudness tolerance, are largely unknown. Some reports suggest that hyperacusis is linked to childhood hearing loss. However, the evidence for this is largely circumstantial. In order to rigorously test this hypothesis, we studied loudness changes in rats caused by intense noise exposure (12 kHz narrow band noise, 115 dB SPL, 4 h) at postnatal 16 days. Rats without noise exposure were used as controls. The exposed noise group (n = 7) showed a mean 40-50 dB hearing loss compared to the control group (n = 8) at high frequencies (>= 8 kHz) and less hearing loss at lower frequencies. Loudness was evaluated using sound reaction time and loudness response functions in an operant conditioning-based behavioral task using narrow-band noise (40-110 dB SPL, centered at 2, 4 and 12 kHz). Interestingly, the sound reaction time of the noise group was significantly shorter than the control group at supra-threshold levels. The average reaction time was less than 100 ms in the noise group at 100 dB SPL, which was three times shorter than the control group. Our results indicate that early noise-induced hearing loss leads to a significant increase of loudness, a behavior indicative of hyperacusis. Our results are consistent with clinical reports suggesting that hearing loss at an early age is a significant risk factor for hyperacusis.
- Occasion setting, inhibition, and the contextual control of extinction in Pavlovian and instrumental (operant) learning. [Review]
- BPBehav Processes 2016 Oct 6
- An occasion setter is a stimulus that modulates the ability of another stimulus to control behavior. A rich history of experimental investigation has identified several important properties that defi...
An occasion setter is a stimulus that modulates the ability of another stimulus to control behavior. A rich history of experimental investigation has identified several important properties that define occasion setters and the conditions that give rise to occasion setting. In this paper, we first consider the basic hallmarks of occasion setting in Pavlovian conditioning. We then review research that has examined the mechanisms underlying the crucial role of context in Pavlovian and instrumental extinction. In Pavlovian extinction, evidence suggests that the extinction context can function as a negative occasion setter whose role is to disambiguate the current meaning of the conditioned stimulus; the conditioning context can also function as a positive occasion setter. In operant extinction, in contrast, the extinction context may directly inhibit the response, and the conditioning context can directly excite it. We outline and discuss the key results supporting these distinctions.
- Psychologic theories in functional neurologic disorders. [Journal Article]
- HCHandb Clin Neurol 2017; 139:105-120
- In this chapter we review key psychologic theories that have been mooted as possible explanations for the etiology of functional neurologic symptoms, conversion disorder, and hysteria. We cover Freud...
In this chapter we review key psychologic theories that have been mooted as possible explanations for the etiology of functional neurologic symptoms, conversion disorder, and hysteria. We cover Freudian psychoanalysis and later object relations and attachment theories, social theories, illness behavior, classic and operant conditioning, social learning theory, self-regulation theory, cognitive-behavioral theories, and mindfulness. Dissociation and modern cognitive neuroscience theories are covered in other chapters in this series and, although of central importance, are omitted from this chapter. Our aim is an overview with the emphasis on breadth of coverage rather than depth.
- Generalizing prosodic patterns by a non-vocal learning mammal. [Journal Article]
- ACAnim Cogn 2016 Sep 22
- Prosody, a salient aspect of speech that includes rhythm and intonation, has been shown to help infants acquire some aspects of syntax. Recent studies have shown that birds of two vocal learning spec...
Prosody, a salient aspect of speech that includes rhythm and intonation, has been shown to help infants acquire some aspects of syntax. Recent studies have shown that birds of two vocal learning species are able to categorize human speech stimuli based on prosody. In the current study, we found that the non-vocal learning rat could also discriminate human speech stimuli based on prosody. Not only that, but rats were able to generalize to novel stimuli they had not been trained with, which suggests that they had not simply memorized the properties of individual stimuli, but learned a prosodic rule. When tested with stimuli with either one or three out of the four prosodic cues removed, the rats did poorly, suggesting that all cues were necessary for the rats to solve the task. This result is in contrast to results with humans and budgerigars, both of which had previously been studied using the same paradigm. Humans and budgerigars both learned the task and generalized to novel items, but were also able to solve the task with some of the cues removed. In conclusion, rats appear to have some of the perceptual abilities necessary to generalize prosodic patterns, in a similar though not identical way to the vocal learning species that have been studied.
- Sleep restriction in rats leads to changes in operant behaviour indicative of reduced prefrontal cortex function. [Journal Article]
- JSJ Sleep Res 2016 Sep 16
- Sleep deprivation has profound effects on cognitive performance, and some of these effects may be mediated by impaired prefrontal cortex function. In search of an animal model to investigate this rel...
Sleep deprivation has profound effects on cognitive performance, and some of these effects may be mediated by impaired prefrontal cortex function. In search of an animal model to investigate this relationship we studied the influence of restricted sleep on operant conditioning in rats, particularly the performance in a differential reinforcement of low rate responding (DRL) task, which is highly dependent upon an intact prefrontal cortex. Animals were trained to withhold a lever press until an imposed delay of 30 s after the last press had passed in order to achieve a food reward. Once the animals had mastered the task, they were sleep-restricted for 7 days with 20 h of sleep deprivation per day. At the end of each daily sleep deprivation session, performance on the DRL task was assessed. The results show that sleep-restricted animals were less able to time their responses correctly, started pressing the lever more randomly and showed signs of behavioural disinhibition, the latter possibly reflecting enhanced impulsivity. Our data support the hypothesis that a sleep debt has disruptive consequences for the functioning of the prefrontal cortex. This model offers possibilities for future studies investigating the underlying biochemical and molecular mechanisms of this relationship.
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- Operant Conditioning in Honey Bees (Apis mellifera L.): The Cap Pushing Response. [Journal Article]
- PlosPLoS One 2016; 11(9):e0162347
- The honey bee has been an important model organism for studying learning and memory. More recently, the honey bee has become a valuable model to understand perception and cognition. However, the tech...
The honey bee has been an important model organism for studying learning and memory. More recently, the honey bee has become a valuable model to understand perception and cognition. However, the techniques used to explore psychological phenomena in honey bees have been limited to only a few primary methodologies such as the proboscis extension reflex, sting extension reflex, and free flying target discrimination-tasks. Methods to explore operant conditioning in bees and other invertebrates are not as varied as with vertebrates. This may be due to the availability of a suitable response requirement. In this manuscript we offer a new method to explore operant conditioning in honey bees: the cap pushing response (CPR). We used the CPR to test for difference in learning curves between novel auto-shaping and more traditional explicit-shaping. The CPR protocol requires bees to exhibit a novel behavior by pushing a cap to uncover a food source. Using the CPR protocol we tested the effects of both explicit-shaping and auto-shaping techniques on operant conditioning. The goodness of fit and lack of fit of these data to the Rescorla-Wagner learning-curve model, widely used in classical conditioning studies, was tested. The model fit well to both control and explicit-shaping results, but only for a limited number of trials. Learning ceased rather than continuing to asymptotically approach the physiological most accurate possible. Rate of learning differed between shaped and control bee treatments. Learning rate was about 3 times faster for shaped bees, but for all measures of proficiency control and shaped bees reached the same level. Auto-shaped bees showed one-trial learning rather than the asymptotic approach to a maximal efficiency. However, in terms of return-time, the auto-shaped bees' learning did not carry over to the covered-well test treatments.