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Conditioning Paradigm (conditioning + paradigm)
Selected AbstractsOlfactory association learning and brain-derived neurotrophic factor in an animal model of early deprivationDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2009Betty Zimmerberg Abstract Animal models can serve to explore neural mechanisms underlying the effects of stressful early experiences on behaviors supporting attachment. Neonatal rats primarily use olfaction for attachment, and Brain-Derived Neurotrophic Factor (BDNF) may be a key transcription target in olfactory association learning. In this experiment, neonatal male and female rats were isolated individually for 3 hr daily in the first week of life while their dams were left with partial litters (Early Deprivation, ED) or remained undisturbed (Control). At 1 week of age, subjects were tested using a 2-day classical conditioning paradigm. The conditioned group (O/M) was exposed to a novel odor paired with a milk infusion. Three additional groups included an unpaired odor and milk exposure group (O/M unP), an odor exposure alone group (O/NM), and neither an odor nor a milk group (NO/NM). Learning the odor association, as revealed in a position preference for the novel odor, was accompanied by an increase in hippocampal BDNF in O/M subjects from undisturbed Control litters. BDNF levels were also positively related to degree of preference for the odor in the O/M Control group. ED subjects did not make the classically conditioned odor association and did not show an increase in hippocampal BDNF. ED increased BDNF levels in the olfactory bulb compared to Controls regardless of training group; individual levels were not correlated with performance because samples were pooled. These results suggest that changes in the transcription of BDNF may underlie some of the long-term consequences of the early stress of maternal separation. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 333,344, 2009. [source] Contribution of NMDA receptor NR2B subunit to synaptic plasticity during associative learning in behaving ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2007Mauricio Valenzuela-Harrington Abstract The difference in the amounts of NR2 subunits contained in NMDA receptors of the hippocampus has been related to their different involvement in activity-dependent synaptic plasticity. Here, we show that Ro 25-6981, a high-affinity and selective blocker of NMDA receptors containing NR2B subunits, is able to block the acquisition of a trace conditioning paradigm in adult rats, a task that requires the active participation of hippocampal circuits. Reconditioning with the same trace paradigm was also prevented by Ro 25-6981. In addition, we show that the slope of monosynaptic field excitatory postsynaptic potentials evoked at the dentate gyrus by single pulses presented to the medial perforant pathway increases significantly across conditioning sessions and during reconditioning, in a linear relationship with the increase in the number of classically conditioned eyelid responses. Administration of Ro 25-6981 prevented these learning-related changes in synaptic strength at the perforant pathway,dentate granule cell synapse. The present results suggest the involvement of NR2B-containing NMDA receptors in hippocampal functions related to both associative learning and activity-dependent synaptic plasticity. [source] Neurogenesis may relate to some but not all types of hippocampal-dependent learningHIPPOCAMPUS, Issue 5 2002Tracey J. Shors Abstract The hippocampal formation generates new neurons throughout adulthood. Recent studies indicate that these cells possess the morphology and physiological properties of more established neurons. However, the function of adult generated neurons is still a matter of debate. We previously demonstrated that certain forms of associative learning can enhance the survival of new neurons and a reduction in neurogenesis coincides with impaired learning of the hippocampal-dependent task of trace eyeblink conditioning. Using the toxin methylazoxymethanol acetate (MAM) for proliferating cells, we tested whether reduction of neurogenesis affected learning and performance associated with different hippocampal dependent tasks: spatial navigation learning in a Morris water maze, fear responses to context and an explicit cue after training with a trace fear paradigm. We also examined exploratory behavior in an elevated plus maze. Rats were injected with MAM (7 mg/kg) or saline for 14 days, concurrent with BrdU, to label new neurons on days 10, 12, and 14. After treatment, groups of rats were tested in the various tasks. A significant reduction in new neurons in the adult hippocampus was associated with impaired performance in some tasks, but not with others. Specifically, treatment with the antimitotic agent reduced the amount of fear acquired after exposure to a trace fear conditioning paradigm but did not affect contextual fear conditioning or spatial navigation learning in the Morris water maze. Nor did MAM treatment affect exploration in the elevated plus maze. These results combined with previous ones suggest that neurogenesis may be associated with the formation of some but not all types of hippocampal-dependent memories. Hippocampus 2002;12:578,584. © 2002 Wiley-Liss, Inc. [source] Conditioning of stress in Nile tilapiaJOURNAL OF FISH BIOLOGY, Issue 4 2004P. S. A. Moreira A Pavlovian conditioning paradigm was used to induce a connection between a conditioned stimulus, light (CS), associated with an unconditioned stimulus, confinement (US) in Nile tilapia Oreochromis niloticus, which resulted in a conditioned endocrine response (CR) to the CS alone manifested as an increase in plasma cortisol. Individual isolated Nile tilapia were submitted for 10 days to the conditioning treatment consisting of turning on a light (CS) for 1 min with subsequent 30 min confinement (US). On the 10th day of the experiment, plasma cortisol was not increased when fish were subjected to no handling at all, or only light, or even a daily stressor for the 9 days. On the other hand, at the 10th day cortisol was significantly increased only when light was presented either with or without pairing with the stressor. These results confirmed that the cue, light (CS), was not stressful in itself, but when given as the CS in the absence of the US post conditioning the hypothalamus,pituitary,interrenal axis was activated. Therefore, it was concluded that memory of a previous experience with a stressor can be recalled by a conditioned stimulus and induce stress, which is the first demonstration of a memory-induced stress in fishes. [source] Reduction of Ethanol-Derived Acetaldehyde Induced Motivational Properties by l -CysteineALCOHOLISM, Issue 1 2009Alessandra T. Peana Background:, Experimental evidences suggest that acetaldehyde (ACD) contributes to the positive motivational properties of ethanol (EtOH) as assessed by the place conditioning paradigm; indeed, we found that by reducing ACD production and/or by using ACD-sequestrating agents, EtOH is deprived from its motivational properties. Thiol products, such as the amino acid cysteine, are known to be effective ACD-sequestering agents. Cysteine is able to covalently bind ACD thereby forming a stable, nontoxic 2-methyl-thiazolidine-4-carboxylic acid compound. Thus, we treated rats with l -cysteine before intragastric administration of EtOH or ACD. Methods:, Male Wistar rats were pretreated intraperitoneally with saline or l -cysteine (10, 20, or 30 mg/kg), before intragastric administration of saline, EtOH (1 g/kg), or ACD (20 mg/kg). The specificity of l -cysteine effect was addressed using morphine-induced conditioned place preference (cpp) (2.5 mg/kg, i.p.). Results:,l -cysteine dose-dependently prevented both EtOH and ACD-induced cpp but did not interfere with morphine-induced cpp, suggesting that l -cysteine specifically modulates the motivational properties of EtOH. Conclusion:, The present results further underscore the role of EtOH-derived ACD in EtOH-induced motivational properties. l -cysteine, by binding EtOH-derived ACD, would deprive it of its rewarding properties and reduce its abuse liability. [source] Ethanol as a Reinforcer in the Newborn's First Suckling ExperienceALCOHOLISM, Issue 3 2001Sarah J. Cheslock Background: Recent evidence suggests that human infants prefer alcohol-flavored milk when fed through a bottle. Animal models also indicate a surprising predisposition for neonatal and infant rats to voluntarily and willingly ingest ethanol. These findings suggest high susceptibility to the reinforcing properties of ethanol early in ontogeny. Methods: A surrogate nipple technique,a highly effective tool for investigation of the reinforcing properties of different fluids,was applied in the present study. Tests of ethanol reinforcement were accomplished in terms of two basic paradigms of Pavlovian conditioning. In one paradigm, the conditioned stimulus (CS) was the surrogate nipple, and in the other, the CS was a novel odor. Results: Newborn rats showed sustained attachment to the nipple providing 5% ethanol, and later reproduced this behavioral pattern toward the empty nipple (CS alone). Ingestion of ethanol yielding appetitive reinforcement was accompanied by detectable blood alcohol concentrations, with most in the range of 20,30 mg/dl. The reinforcing efficacy of ethanol was also confirmed in the classical olfactory conditioning paradigm: following pairing with intraoral ethanol infusions, the odor (CS) alone elicited sustained attachment to an empty nipple. Females showed better olfactory conditioning with low concentrations of ethanol, whereas males were effectively more conditioned to high concentrations. Although there were no reinforcing consequences of intraperitoneally injected ethanol [as an unconditioned stimulus (US)] when a neutral odor was the CS, when paired with ingestion of water from a nipple, the injection of ethanol had a reinforcing effect. Conclusions: The present series of experiments revealed ethanol reinforcement in the newborn rat. Two varieties of Pavlovian conditioning established that ethanol can serve as an effective US, and hence reinforcer, in such a way as to increase the approach and responsiveness toward stimuli paired with that US, indicating appetitive reinforcement. [source] Genetic reductions of ,-site amyloid precursor protein-cleaving enzyme 1 and amyloid-, ameliorate impairment of conditioned taste aversion memory in 5XFAD Alzheimer's disease model miceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2010Latha Devi Abstract Although transgenic mouse models of Alzheimer's disease (AD) recapitulate amyloid-, (A,)-related pathologies and cognitive impairments, previous studies have mainly evaluated their hippocampus-dependent memory dysfunctions using behavioral tasks such as the water maze and fear conditioning. However, multiple memory systems become impaired in AD as the disease progresses and it is important to test whether other forms of memory are affected in AD models. This study was designed to use conditioned taste aversion (CTA) and contextual fear conditioning paradigms to compare the phenotypes of hippocampus-independent and -dependent memory functions, respectively, in 5XFAD amyloid precursor protein/presenilin-1 transgenic mice that harbor five familial AD mutations. Although both types of memory were significantly impaired in 5XFAD mice, the onset of CTA memory deficits (,9 months of age) was delayed compared with that of contextual memory deficits (,6 months of age). Furthermore, 5XFAD mice that were genetically engineered to have reduced levels of ,-site amyloid precursor protein-cleaving enzyme 1 (BACE1) (BACE1+/,·5XFAD) exhibited improved CTA memory, which was equivalent to the performance of wild-type controls. Importantly, elevated levels of cerebral ,-secretase-cleaved C-terminal fragment (C99) and A, peptides in 5XFAD mice were significantly reduced in BACE1+/,·5XFAD mice. Furthermore, A, deposition in the insular cortex and basolateral amygdala, two brain regions that are critically involved in CTA performance, was also reduced in BACE1+/,·5XFAD compared with 5XFAD mice. Our findings indicate that the CTA paradigm is useful for evaluating a hippocampus-independent form of memory defect in AD model mice, which is sensitive to rescue by partial reductions of the ,-secretase BACE1 and consequently of cerebral A,. [source] | ||||||||||