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Michael E Ragozzino - One of the best experts on this subject based on the ideXlab platform.
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differential involvement of m1 type and m4 type muscarinic cholinergic receptors in the dorsomedial striatum in task switching
Neurobiology of Learning and Memory, 2008Co-Authors: Martha F Mccool, Sima Patel, Ravi Talati, Michael E RagozzinoAbstract:Previous Experiments have demonstrated that the rat dorsomedial striatum is one brain area that plays a crucial role in Learning when conditions require a shift in strategies. Further evidence indicates that muscarinic cholinergic receptors in this brain area support adaptations in behavioral responses. Unknown is whether specific muscarinic receptor subtypes in the dorsomedial striatum contribute to a flexible shift in response patterns. The present Experiments investigated whether blockade of M1-type and/or M4-type cholinergic receptors in the dorsomedial striatum underlie place reversal Learning. Experiment 1 investigated the effects of the M1-type muscarinic cholinergic antagonist, muscarinic-toxin 7 (MT-7) infused into the dorsomedial striatum in place acquisition and reversal Learning. Experiment 2 investigated the effects of the M4-type muscarinic cholinergic antagonist, muscarinic-toxin 3 (MT-3) injected into the dorsomedial striatum in place acquisition and reversal Learning. All testing occurred in a modified cross-maze across two consecutive sessions. Bilateral injections of MT-7 into the dorsomedial striatum at 1 or 2 μg, but not 0.05 μg impaired place reversal Learning. Analysis of the errors revealed that MT-7 at 1 and 2 μg significantly increased regressive errors, but not perseverative errors. An injection of MT-7 2 μg into the dorsomedial striatum prior to place acquisition did not affect Learning. Experiment 2 revealed that dorsomedial striatal injections of MT-3 (0.05, 1 or 2 μg) did not affect place acquisition or reversal Learning. The findings suggest that activation of M1-type muscarinic cholinergic receptors in the dorsomedial striatum, but not M4-type muscarinic cholinergic receptors facilitate the flexible shifting of response patterns by maintaining or Learning a new choice pattern once selected.
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differential effects of m1 muscarinic receptor blockade and nicotinic receptor blockade in the dorsomedial striatum on response reversal Learning
Behavioural Brain Research, 2004Co-Authors: Arianna Tzavos, Jane Jih, Michael E RagozzinoAbstract:Abstract The present studies determined whether blockade of M 1 -like muscarinic or nicotinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal Learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to turn to the left or to the right. In the reversal Learning phase, a rat learned to turn in the opposite direction as required during acquisition. Experiment 1 investigated the effects of the M 1 -like muscarinic receptor antagonist, pirenzepine infused into the dorsomedial striatum on acquisition and reversal Learning. Experiment 2 examined the effects of the nicotinic cholinergic antagonist, mecamylamine injected into the dorsomedial striatum on acquisition and reversal Learning. Bilateral injections of pirenzepine at 10 μg, but not 1 μg, selectively impaired reversal Learning. Analysis of the errors indicated that pirenzepine treatment did not impair the initial shift, but increased reversions back to the original response choice following the initial shift. Bilateral injections of mecamylamine, 6 or 18 μg, did not affect acquisition or reversal Learning. The results suggest that activation of M 1 muscarinic cholinergic receptors, but not nicotinic cholinergic receptors, in the dorsomedial striatum is important for facilitating the flexible shifting of response patterns.
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involvement of the dorsomedial striatum in behavioral flexibility role of muscarinic cholinergic receptors
Brain Research, 2002Co-Authors: Michael E Ragozzino, Jane Jih, Arianna TzavosAbstract:The present Experiments determined whether temporary inactivation or blockade of muscarinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal Learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to make a turn to the left or to the right for 10 consecutive correct choices. In the reversal Learning phase, a rat learned to turn in the opposite direction as required during acquisition for 10 consecutive correct choices. Experiment 1 investigated the effects of the local anesthetic, 2% bupivacaine, infused into the dorsomedial striatum on acquisition and reversal Learning. Experiment 2 examined the effects of the muscarinic cholinergic antagonist, scopolamine injected into the dorsomedial striatum on acquisition and reversal Learning. Bupivacaine infusions did not impair acquisition, but did impair reversal Learning of the response discrimination. Analysis of the errors indicated that the deficit was not due to perseveration of the previously learned strategy, but to an inability to learn the new strategy. Bilateral injections of scopolamine, 1 or 8 microg/side, did not affect acquisition. Infusions of scopolamine at 8 microg, but not 1 microg, produced a reversal Learning deficit. The scopolamine-induced deficit resulted from an inability to learn the new strategy. The results suggest that the dorsomedial striatum is important for behavioral flexibility and that activation of muscarinic cholinergic receptors in this region may facilitate the Learning of situationally adaptive response patterns.
Arianna Tzavos - One of the best experts on this subject based on the ideXlab platform.
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differential effects of m1 muscarinic receptor blockade and nicotinic receptor blockade in the dorsomedial striatum on response reversal Learning
Behavioural Brain Research, 2004Co-Authors: Arianna Tzavos, Jane Jih, Michael E RagozzinoAbstract:Abstract The present studies determined whether blockade of M 1 -like muscarinic or nicotinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal Learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to turn to the left or to the right. In the reversal Learning phase, a rat learned to turn in the opposite direction as required during acquisition. Experiment 1 investigated the effects of the M 1 -like muscarinic receptor antagonist, pirenzepine infused into the dorsomedial striatum on acquisition and reversal Learning. Experiment 2 examined the effects of the nicotinic cholinergic antagonist, mecamylamine injected into the dorsomedial striatum on acquisition and reversal Learning. Bilateral injections of pirenzepine at 10 μg, but not 1 μg, selectively impaired reversal Learning. Analysis of the errors indicated that pirenzepine treatment did not impair the initial shift, but increased reversions back to the original response choice following the initial shift. Bilateral injections of mecamylamine, 6 or 18 μg, did not affect acquisition or reversal Learning. The results suggest that activation of M 1 muscarinic cholinergic receptors, but not nicotinic cholinergic receptors, in the dorsomedial striatum is important for facilitating the flexible shifting of response patterns.
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involvement of the dorsomedial striatum in behavioral flexibility role of muscarinic cholinergic receptors
Brain Research, 2002Co-Authors: Michael E Ragozzino, Jane Jih, Arianna TzavosAbstract:The present Experiments determined whether temporary inactivation or blockade of muscarinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal Learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to make a turn to the left or to the right for 10 consecutive correct choices. In the reversal Learning phase, a rat learned to turn in the opposite direction as required during acquisition for 10 consecutive correct choices. Experiment 1 investigated the effects of the local anesthetic, 2% bupivacaine, infused into the dorsomedial striatum on acquisition and reversal Learning. Experiment 2 examined the effects of the muscarinic cholinergic antagonist, scopolamine injected into the dorsomedial striatum on acquisition and reversal Learning. Bupivacaine infusions did not impair acquisition, but did impair reversal Learning of the response discrimination. Analysis of the errors indicated that the deficit was not due to perseveration of the previously learned strategy, but to an inability to learn the new strategy. Bilateral injections of scopolamine, 1 or 8 microg/side, did not affect acquisition. Infusions of scopolamine at 8 microg, but not 1 microg, produced a reversal Learning deficit. The scopolamine-induced deficit resulted from an inability to learn the new strategy. The results suggest that the dorsomedial striatum is important for behavioral flexibility and that activation of muscarinic cholinergic receptors in this region may facilitate the Learning of situationally adaptive response patterns.
Stefan Schaal - One of the best experts on this subject based on the ideXlab platform.
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reinforcement Learning of motor skills in high dimensions a path integral approach
International Conference on Robotics and Automation, 2010Co-Authors: Evangelos A. Theodorou, Jonas Buchli, Stefan SchaalAbstract:Reinforcement Learning (RL) is one of the most general approaches to Learning control. Its applicability to complex motor systems, however, has been largely impossible so far due to the computational difficulties that reinforcement Learning encounters in high dimensional continuous state-action spaces. In this paper, we derive a novel approach to RL for parameterized control policies based on the framework of stochastic optimal control with path integrals. While solidly grounded in optimal control theory and estimation theory, the update equations for Learning are surprisingly simple and have no danger of numerical instabilities as neither matrix inversions nor gradient Learning rates are required. Empirical evaluations demonstrate significant performance improvements over gradient-based policy Learning and scalability to high-dimensional control problems. Finally, a Learning Experiment on a robot dog illustrates the functionality of our algorithm in a real-world scenario. We believe that our new algorithm, Policy Improvement with Path Integrals (PI2), offers currently one of the most efficient, numerically robust, and easy to implement algorithms for RL in robotics.
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A generalized path integral control approach to reinforcement Learning
The Journal of Machine Learning Research, 2010Co-Authors: Evangelos A. Theodorou, Evangelos Theodorou, Jonas Buchli, Stefan SchaalAbstract:With the goal to generate more scalable algorithms with higher efficiency and fewer open parameters, reinforcement Learning (RL) has recently moved towards combining classical techniques from optimal control and dynamic programming with modern Learning techniques from statistical estimation theory. In this vein, this paper suggests to use the framework of stochastic optimal control with path integrals to derive a novel approach to RL with parameterized policies. While solidly grounded in value function estimation and optimal control based on the stochastic Hamilton-Jacobi-Bellman (HJB) equations, policy improvements can be transformed into an approximation problem of a path integral which has no open algorithmic parameters other than the exploration noise. The resulting algorithm can be conceived of as model-based, semi-model-based, or even model free, depending on how the Learning problem is structured. The update equations have no danger of numerical instabilities as neither matrix inversions nor gradient Learning rates are required. Our new algorithm demonstrates interesting similarities with previous RL research in the framework of probability matching and provides intuition why the slightly heuristically motivated probability matching approach can actually perform well. Empirical evaluations demonstrate significant performance improvements over gradient-based policy Learning and scalability to high-dimensional control problems. Finally, a Learning Experiment on a simulated 12 degree-of-freedom robot dog illustrates the functionality of our algorithm in a complex robot Learning scenario. We believe that Policy Improvement with Path Integrals (PI2) offers currently one of the most efficient, numerically robust, and easy to implement algorithms for RL based on trajectory roll-outs.
Jane Jih - One of the best experts on this subject based on the ideXlab platform.
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differential effects of m1 muscarinic receptor blockade and nicotinic receptor blockade in the dorsomedial striatum on response reversal Learning
Behavioural Brain Research, 2004Co-Authors: Arianna Tzavos, Jane Jih, Michael E RagozzinoAbstract:Abstract The present studies determined whether blockade of M 1 -like muscarinic or nicotinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal Learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to turn to the left or to the right. In the reversal Learning phase, a rat learned to turn in the opposite direction as required during acquisition. Experiment 1 investigated the effects of the M 1 -like muscarinic receptor antagonist, pirenzepine infused into the dorsomedial striatum on acquisition and reversal Learning. Experiment 2 examined the effects of the nicotinic cholinergic antagonist, mecamylamine injected into the dorsomedial striatum on acquisition and reversal Learning. Bilateral injections of pirenzepine at 10 μg, but not 1 μg, selectively impaired reversal Learning. Analysis of the errors indicated that pirenzepine treatment did not impair the initial shift, but increased reversions back to the original response choice following the initial shift. Bilateral injections of mecamylamine, 6 or 18 μg, did not affect acquisition or reversal Learning. The results suggest that activation of M 1 muscarinic cholinergic receptors, but not nicotinic cholinergic receptors, in the dorsomedial striatum is important for facilitating the flexible shifting of response patterns.
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involvement of the dorsomedial striatum in behavioral flexibility role of muscarinic cholinergic receptors
Brain Research, 2002Co-Authors: Michael E Ragozzino, Jane Jih, Arianna TzavosAbstract:The present Experiments determined whether temporary inactivation or blockade of muscarinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal Learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to make a turn to the left or to the right for 10 consecutive correct choices. In the reversal Learning phase, a rat learned to turn in the opposite direction as required during acquisition for 10 consecutive correct choices. Experiment 1 investigated the effects of the local anesthetic, 2% bupivacaine, infused into the dorsomedial striatum on acquisition and reversal Learning. Experiment 2 examined the effects of the muscarinic cholinergic antagonist, scopolamine injected into the dorsomedial striatum on acquisition and reversal Learning. Bupivacaine infusions did not impair acquisition, but did impair reversal Learning of the response discrimination. Analysis of the errors indicated that the deficit was not due to perseveration of the previously learned strategy, but to an inability to learn the new strategy. Bilateral injections of scopolamine, 1 or 8 microg/side, did not affect acquisition. Infusions of scopolamine at 8 microg, but not 1 microg, produced a reversal Learning deficit. The scopolamine-induced deficit resulted from an inability to learn the new strategy. The results suggest that the dorsomedial striatum is important for behavioral flexibility and that activation of muscarinic cholinergic receptors in this region may facilitate the Learning of situationally adaptive response patterns.
Jennifer Culbertson - One of the best experts on this subject based on the ideXlab platform.
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the cultural evolution of complex linguistic constructions in artificial sign languages
Cognitive Science, 2017Co-Authors: Yasamin Motamedi, Marieke Schouwstra, Jennifer Culbertson, Kenny Smith, Simon KirbyAbstract:Though most documented sign languages make use of space to denote relationships between predicate arguments, studies of emerging sign languages suggest that spatial reference does not emerge fully-formed but takes time to develop. We present an artificial sign language Learning Experiment that expands the cultural evolutionary framework to investigate complex linguistic constructions. Our results demonstrate the gradual emergence of consistent devices to distinguish between sentence arguments, some of which rely on iconic spatial contrasts. These findings mirror data from emerging sign languages and point to the cultural mechanisms that facilitate the evolution of complex linguistic structures.
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a bayesian model of biases in artificial language Learning the case of a word order universal
Cognitive Science, 2012Co-Authors: Jennifer Culbertson, Paul SmolenskyAbstract:In this article, we develop a hierarchical Bayesian model of Learning in a general type of artificial language-Learning Experiment in which learners are exposed to a mixture of grammars representing the variation present in real learners’ input, particularly at times of language change. The modeling goal is to formalize and quantify hypothesized Learning biases. The test case is an Experiment (Culbertson, Smolensky, & Legendre, 2012) targeting the Learning of word-order patterns in the nominal domain. The model identifies internal biases of the Experimental participants, providing evidence that learners impose (possibly arbitrary) properties on the grammars they learn, potentially resulting in the cross-linguistic regularities known as typological universals. Learners exposed to mixtures of artificial grammars tended to shift those mixtures in certain ways rather than others; the model reveals how learners’ inferences are systematically affected by specific prior biases. These biases are in line with a typological generalization—Greenberg's Universal 18—which bans a particular word-order pattern relating nouns, adjectives, and numerals.