Memory consolidation in Drosophila operant visual learning.
(9/1603)
A new conditioning procedure, developed for the operant learning paradigm at the flight simulator, leads to stronger learning scores in wild-type flies. This procedure produces mean learning indices up to LI = 0.52. The heat-avoidance behavior acquired during training is very difficult to extinguish during extinction. Memory decays quickly during the first 3 hr after training and still is measurable 48 hr later. Disruption experiments demonstrate that memory can be disrupted by cold anesthesia within the first approximately 20 min after training, whereas KCl- and CXM-feeding regimens abolish memory soon after training and 3 hr later, respectively. These results initially suggest at least three distinct memory phases involved in memory consolidation in Drosophila after operant conditioning. (+info)
Extinction of behavior in infant rats: development of functional coupling between septal, hippocampal, and ventral tegmental regions.
(10/1603)
Learning of a behavior at a particular age during the postnatal period presumably occurs when the functional brain circuit mediating the behavior matures. The inability to express a learned behavior, such as inhibition, may be accounted for by the functional dissociation of brain regions comprising the circuit. In this study we tested this hypothesis by measuring brain metabolic activity, as revealed by fluorodeoxyglucose (FDG) autoradiography, during behavioral extinction in 12- and 17-d-old rat pups. Subjects were first trained on a straight alley runway task known as patterned single alternation (PSA), wherein reward and nonreward trials alternate successively. They were then injected with FDG and given 50 trials of continuous nonreward (i.e., extinction). Pups at postnatal day 12 (P12) demonstrated significantly slower extinction rates compared to their P17 counterparts, despite the fact that both reliably demonstrated the PSA effect, i.e., both age groups distinguished between reward and nonreward trials during acquisition. Covariance analysis revealed that the dentate gyrus, hippocampal fields CA1-3, subiculum, and lateral septal area were significantly correlated in P17 but not P12 pups. Significant correlations were also found between the lateral septal area, ventral tegmental area, and the medial septal nucleus in P17 pups. Similar correlative patterns were not found in P12 and P17 handled control animals. Taken together, these results suggest that septal, hippocampal, and mesencephalic regions may be functionally dissociated at P12, and the subsequent maturation of functional connectivity between these regions allows for the more rapid expression of behavioral inhibition during extinction at P17. (+info)
Neurotoxic basolateral amygdala lesions impair learning and memory but not the performance of conditional fear in rats.
(11/1603)
We examined the influence of extensive overtraining (75 trials) on the impact of neurotoxic basolateral amygdala (BLA) lesions on Pavlovian fear conditioning in rats. As we have shown previously, pretraining BLA lesions yielded severe deficits in the acquisition of conditional freezing in rats trained with either 1 or 25 conditioning trials. However, extensive overtraining (50 or 75 trials) mitigated deficits in conditional freezing. Under these conditions the rats with BLA lesions expressed normal and robust freezing behavior, although they required at least 10 times as much training as control rats to reach this level of performance. The ability of rats with BLA lesions to acquire and express conditional freezing after extensive overtraining was modality-specific; conditional freezing in individual rats was acquired to contextual, but not acoustic, conditional stimuli. These results suggest that neural circuitry outside of the amygdala can mediate contextual fear conditioning under some conditions. In contrast to pretraining lesions, post-training BLA lesions eradicated the memory for Pavlovian fear in rats trained with either 1 or 75 trials; this deficit was not modality-specific. Together, these results reveal that impairments in the acquisition and expression of conditional fear in rats with BLA lesions are not attributable to deficits in the performance of the freezing response but are attributable to disruptions in the learning and memory of Pavlovian fear conditioning. (+info)
Further analysis of problem behavior in response class hierarchies.
(12/1603)
A functional analysis identified the reinforcers for 3 participants' problem behavior, but only relatively mild problem behaviors (e.g., screaming, disruption) were observed when all topographies produced tested consequences. We then conducted an extinction analysis in which specific topographies produced a reinforcer while all other topographies were on extinction. The extinction analysis confirmed that the same reinforcer identified in the initial functional analysis maintained more severe topographies of problem behavior (e.g., aggression). In addition, results of the extinction analysis indicated that 2 of the participants displayed patterns of responding consistent with a response class hierarchy hypothesis, in which less severe problem behavior frequently occurred prior to more severe topographies. The 3rd participant displayed a response pattern indicative of differential reinforcement effects. (+info)
Competition between positive and negative reinforcement in the treatment of escape behavior.
(13/1603)
We compared the effects of reinforcing compliance with either positive reinforcement (edible items) or negative reinforcement (a break) on 5 participants' escape-maintained problem behavior. Both procedures were assessed with or without extinction. Results showed that compliance was higher and problem behavior was lower for all participants when compliance produced an edible item rather than a break. Treatment gains were achieved without the use of extinction. Results are discussed regarding the use of positive reinforcement to treat escape behavior. (+info)
Reducing wandering by persons with dementia using differential reinforcement.
(14/1603)
Wandering behavior of 4 geriatric patients with dementia residing in a long-term care facility was assessed using direct behavioral observations. The consequences identified during the observations as maintaining wandering for each patient were then applied for the absence of wandering using differential reinforcement of other behavior (DRO). The effectiveness of the DRO procedure was evaluated using an ABAB design. Results indicated significant reductions in wandering during treatment. (+info)
Plasticity in the mediodorsal thalamo-prefrontal cortical transmission in behaving mice.
(15/1603)
We studied changes in thalamo-prefrontal cortical transmission in behaving mice following both low-frequency stimulation of the mediodorsal thalamus (MD) and during extinction of a conditioned fear response. Electrical stimulation of the MD induces a field potential in the medial prefrontal cortex (mPFC) characterized by two initial negative-positive complexes (N1-P1 and N2-P2) followed by two positive-negative complexes (P2-N3 and P3-N4). The N1-P1 and N2-P2 complexes were identified as resulting from orthodromic and antidromic prefrontal activation, respectively. Because the two complexes were not often easily dissociated, plasticity in the prefrontal synaptic transmission was considered to result from changes in N1-P2 amplitude. Low-frequency thalamic stimulation (1, 200 pulses at 2 Hz) produced either long-term (at least 32 min) depression or potentiation of the N1-P2 amplitude. Mice submitted to fear conditioning (tone-shock association), displayed on the first day of extinction (tone-alone presentations) a strong freezing behavior, which decreased progressively, but was still high the following day. Extinction of conditioned fear was accompanied the first day by a depression of prefrontal transmission, which was converted into potentiation the following day. Potentiation of prefrontal transmission lasted at least 24 h following the second day of the fear extinction procedure. In conclusion, low-frequency thalamic stimulation can produce, in behaving mice, either depression or potentiation of prefrontal synaptic transmission. Decrease in prefrontal synaptic transmission observed during the first day of extinction may reflect processing of the high degree of predictiveness of danger (unconditioned stimulus: US) by the aversive conditioned stimulus (CS). However, the subsequent potentiation of transmission in the mPFC may be related to processing of cognitive information such as the CS will no longer be followed by the US, even if emotional response (freezing) to the CS is still high. (+info)
Empirically supported treatments in pediatric psychology: bedtime refusal and night wakings in young children.
(16/1603)
OBJECTIVE: To review the literature for empirically supported treatments for bedtime refusal and night wakings in young children. METHODS: An extensive review of the literature resulted in the inclusion of 41 studies that were evaluated according to the criteria established by the Task Force on Promotion and Dissemination of Psychological Procedures (1995). RESULTS: Evidence exists indicating that extinction and parent education on the prevention of sleep problems can be considered well-established treatments. Furthermore, graduated extinction and scheduled awakenings are probably efficacious treatments, with positive routines a promising intervention. CONCLUSIONS: A discussion of effectiveness, treatment feasibility, cost-effectiveness, and methodological limitations of the studies is provided. Recommendations for future directions for research in the treatment of these two common sleep disorders are presented. (+info)