Autism spectrum disorder is a developmental disorder characterized by social, behavioral, and communicative deficits. Although there is no known cure for autism, there are many research-based interventions that aid in strengthening such deficits, especially those associated with failures of stimulus control One way to address such failures is to provide additional stimuli that enhance or override information provided by naturally occurring stimuli. Contingency maps are one such example. This study uses an observing response (i.e., hand-raising) to allow the subjects to request contingency maps. The purpose of this study is to identify if contingency maps function as reinforcers and if requests for information can be acquired using an observing-response paradigm. Major findings of the present study indicate that requests for information can be acquired and maintained by access to CMs.

This study examined the use of shaping with a percentile schedule to increase the duration of the interaction following a bid for joint attention in children with autism. Specifically, the therapist initiated a bid for joint attention and reinforced longer successive approximations in seconds of sustained interaction with the therapist and activity. A percentile schedule ranked the most recent 10 observations and reinforcement was provided if the current observation equaled the sixth ranking. Most-to-least prompting was used if the child failed to meet the calculated criterion. Shaping with a percentile schedule of reinforcement was effective at increasing the duration of sustained interaction following a bid for joint attention, for all participants from an average baseline duration of 13 s to an average intervention duration of 215 s.

Rationale: Amphetamine abuse by adolescents predicts long-term drug dependence. Heightened vulnerability to drug abuse could be due to higher sensitivity to drug’s reinforcing effects. Rodents are used to study age-related sensitivities to drugs. Objective: We compared intravenous amphetamine self-administration between adolescent and adult male rats on an operant schedule of reinforcement measuring the reinforcing efficacy of a drug. Methods: After surgery, adolescent and adult rats acquired lever-pressing behavior reinforced by amphetamine infusions. Results: Both age groups exhibited more infusions per session as dose increased. However, neither the number of infusions per session nor total amphetamine intake differed across age groups. Conclusion: Although rapid transition is reliable to test reinforcing properties of stimulants, results suggest that amphetamine is an equally efficacious reinforcer among both age groups. In regards to humans, these results suggest that other factors, like social influences, explain higher rates of drug intake by adolescent compared with adult humans.

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Made available in DSpace on 2016-04-29T13:18:05Z (GMT). No. of bitstreams: 1 ana carmen.pdf: 438103 bytes, checksum: 918d056717333d77fc09477efa760621 (MD5) Previous issue date: 2004-04-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Chronic Mild Stress-induced anhedonia is an animal experimental model that exposes rats to a mild stressors regime for a long period of time. This model was proposed in 1987 Willner, Towell, Sampson, Sophokleus e Muscat. The purpose of the present study was to verify whether the exposure of rats to an operate procedure when a concurrent schedule with equal FR component, each one producing a different reinforcer (water or sucrose) would alter: a) the body weight; b) the water and sucrose intake, measured on weekly consumption and preference tests; c) the number of lever pressing responses on operant sessions, before, during and after the stress regime. The experimental design had three experimental conditions: total fluid intake and preference of sucrose over water tests, operant sessions of concurrent and the chronic mild stress regime. The subjects were differently exposed to these conditions. Group 1 subjects were exposed to six weeks of stress regime. Group 2 subjects were first submitted to the concurrent sessions (FR water FR sucrose), then they were exposed to the stress regime for six weeks and finally were put back in the concurrent schedule sessions. Group 3 subjects were submitted to concurrent sessions during the stress regime. All subjects of the three groups were submitted weekly to fluid intake and sucrose preference tests before, during and after the stress regime. A control subject was submitted to the consumption and preference tests without exposure either to stress regime or the operant sessions. Results showed five major points: 1) a change of body weight for all subjects exposed to the stress regime; 2) reduction in sucrose intake and in the preference for sucrose over water during the stress regime, measured by consumption and preference tests; 3) subjects submitted to the concurrent sessions before the stress regime recovered sucrose intake and preference for sucrose in the consumption and preference tests after the stress regime; 4) subjects submitted to the operant sessions presented more responses in the sucrose correspondent lever than in the water correspondent lever before and after the stress regime; 5) subjects submitted to operant sessions during the stress regime decreased response in sucrose correspondent lever during the stress regime, however two out of these three subjects recovered to the level of responding prior to stress regime before the stress regime was terminated / Chronic Mild Stress é um modelo animal experimental de anedonia induzida através da exposição de ratos a estressores moderados por um longo período de tempo. Este modelo foi proposto, em 1987, Willner, Towell, Sampson, Sophokleus e Muscat . O objetivo do presente estudo foi verificar se a exposição de ratos a sessões operantes de esquema concorrente FR água FR sacarose, de mesmo valor, durante este regime crônico de estressores moderados iria produzir alterações: a) no peso corporal dos sujeitos; b) no consumo de água e de sacarose, medido em testes semanais de consumo e de preferência de líquidos c) no número de respostas de pressão à barra emitidas nas sessões operantes comparado-se o número de respostas emitidas antes, durante e depois do regime de estressores. O delineamento foi composto de três condições experimentais: teste de consumo e de preferência de líquidos, sessões operantes de esquema concorrente e regime crônico de estressores moderados. Essas condições ocorreram de três diferentes maneiras para três grupos. Os sujeitos do grupo 1 foram expostos a seis semanas de regime de estressores. Os sujeitos do grupo 2 foram, primeiramente, expostos a sessões operantes de esquema concorrente FR água FR sacarose e, logo em seguida, passaram pelo regime de estressores e depois, novamente, pelas sessões de esquema concorrente. No grupo 3, as sessões de esquema concorrente FR água FR sacarose continuaram a acontecer uma vez por semana, durante o regime de estressores. Todos os sujeitos dos três grupos foram submetidos aos testes semanais de consumo e de preferência de líquidos antes, durante e depois do regime de estressores. Um sujeito controle foi submetido apenas aos testes de consumo e de preferência de líquidos, não houve exposição aos estressores nem foi submetido à sessões operantes. Cinco pontos principais foram observados nos resultados: 1) uma alteração do peso corporal presente em todos os sujeitos que foram exposto ao regime de estressores.; 2) uma redução na ingestão de sacarose e na preferência pela sacarose sobre a água ocorridas durante a exposição ao regime de estressores, medido através do teste de consumo e de preferência de líquidos; 3) os sujeitos que haviam sido submetidos às sessões operantes antes do regime de estressores voltaram a apresentar, nos teste de consumo e de preferência de líquidos, a mesma ingestão anterior à exposição aos estressores, ao contrário daqueles que não haviam sido submetidos às sessões operantes; 4) todos os sujeitos submetidos às sessões operantes responderam com maior freqüência na barra correspondente à liberação de sacarose do que na barra correspondente à água, tanto nas sessões realizadas antes do início, quanto nas realizadas após o término da exposição ao regime de estressores e 5) todos sujeitos submetidos a sessões operantes durante o regime de estressores reduziram o número de respostas na barra correspondente à sacarose durante da exposição aos estressores. Entretanto, dois destes três sujeitos retornaram aos valores anteriores antes do término da exposição aos estressores

本研究利用兩種時間關聯之操作式制約行為作業探討韁核的行為功能，一為區辨性增強低頻反應作業（簡稱DRL作業），另一為固定時距作業（簡稱FI作業）。本研究以神經毒素鵝膏蕈酸（ibotenic acid）破壞韁核的方式來測試大白鼠受試在上述行為作業之不同歷程的影響效果，包含習得歷程、行為表現階段以及已習得後轉換得酬賞之反應標準等三個階段。實驗一的結果顯示破壞韁核對於DRL作業的習得歷程具有明顯的影響，其影響效果在DRL短時距作業中造成無法以有效率的壓桿反應模式獲得酬賞；反之，破壞操弄的效果並不影響FI長與短時距作業的習得歷程。實驗二的結果顯示破壞韁核並不影響已習得的DRL作業與FI作業的行為表現，兩項作業的實驗組受試皆能維持穩定的行為反應模式且與控制組無明顯差異。實驗三對已習得的DRL行為進行時距參數的轉換（含調高及降低兩部份），結果顯示破壞韁核之操弄並未明顯的影響這項轉換新的時距之作業要求，但實驗組受試的確比控制組較遲緩達到新的時距要求。綜合而言，本研究以專屬性較高的神經毒素破壞韁核，用較多元指標的行為分析方式探討韁核的行為功能；其結果發現韁核參與DRL行為內含的區辨學習與對於錯誤偵測的負向迴饋，這些功能是需要透過韁核與其他中腦及邊緣系統的組織互動。 / This study examined the function of habenula (Hb) by two kinds of operant conditioned behavior tasks based on temporal contingency, including the differential reinforcement of low-rate responding (DRL) task and fixed-interval (FI) task. The effects of Hb lesion induced by neurotoxin ibotenic acid were examined at the different stages of operant conditioned behavior, including acquisition, performance, and transition stages. The results showed that bilateral lesions of Hb did not affect the locomotor activity and the basic lever-pressing. In Experiment 1, Hb lesion group had less reinforced responses and lower peak time indicating the deficits of acquisition of the DRL task. In contrast, the same lesion manipulation on the FI task did not produce any difference between the lesion group and the control group. The data of Experiment 2 showed that Hb lesion did not significantly affect the learned behavior maintained on DRL-10s or FI-30s schedule. In Experiment 3, Hb lesion produced a subtle, but not significant, impairment on behavioral transition from a learned interval to a newly-set interval (upward or downward). The lesioned subjects made a slower transition than the controls. In conclusion, these data suggest that the function of habenula is involved in discrimination learning and error detection for acquiring DRL behavior. However, it is likely that these Hb functions have to rely upon dynamic relationship between Hb and other midbrain limbic systems.