scholarly journals Learning with reinforcement prediction errors in a model of the Drosophila mushroom body

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
James E. M. Bennett ◽  
Andrew Philippides ◽  
Thomas Nowotny
Keyword(s):  
Mushroom Body ◽  
Dopamine Neurons ◽  
Prediction Errors ◽  
Decision Outcomes ◽  
Effective Decision ◽  
Output Neurons ◽  
Constrained Model ◽  
Effective Decision Making ◽  
Reinforcing Stimuli ◽  
Dependent Learning

AbstractEffective decision making in a changing environment demands that accurate predictions are learned about decision outcomes. In Drosophila, such learning is orchestrated in part by the mushroom body, where dopamine neurons signal reinforcing stimuli to modulate plasticity presynaptic to mushroom body output neurons. Building on previous mushroom body models, in which dopamine neurons signal absolute reinforcement, we propose instead that dopamine neurons signal reinforcement prediction errors by utilising feedback reinforcement predictions from output neurons. We formulate plasticity rules that minimise prediction errors, verify that output neurons learn accurate reinforcement predictions in simulations, and postulate connectivity that explains more physiological observations than an experimentally constrained model. The constrained and augmented models reproduce a broad range of conditioning and blocking experiments, and we demonstrate that the absence of blocking does not imply the absence of prediction error dependent learning. Our results provide five predictions that can be tested using established experimental methods.

scholarly journals Learning with reward prediction errors in a model of the Drosophila mushroom body

2019 ◽  
Author(s):  
James E. M. Bennett ◽  
Andrew Philippides ◽  
Thomas Nowotny
Keyword(s):  
Mushroom Body ◽  
Dopamine Neurons ◽  
Prediction Errors ◽  
Reward Prediction ◽  
Decision Outcomes ◽  
Effective Decision ◽  
Output Neurons ◽  
Constrained Model ◽  
Effective Decision Making ◽  
Reinforcing Stimuli

AbstractEffective decision making in a changing environment demands that accurate predictions are learned about decision outcomes. In Drosophila, such learning is or-chestrated in part by the mushroom body (MB), where dopamine neurons (DANs) signal reinforcing stimuli to modulate plasticity presynaptic to MB output neurons (MBONs). Here, we extend previous MB models, in which DANs signal absolute rewards, proposing instead that DANs signal reward prediction errors (RPEs) by utilising feedback reward predictions from MBONs. We formulate plasticity rules that minimise RPEs, and use simulations to verify that MBONs learn accurate reward predictions. We postulate as yet unobserved connectivity, which not only overcomes limitations in the experimentally constrained model, but also explains additional experimental observations that connect MB physiology to learning. The original, experimentally constrained model and the augmented model capture a broad range of established fly behaviours, and together make five predictions that can be tested using established experimental methods.

scholarly journals Shared mushroom body circuits underlie visual and olfactory memories in Drosophila

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Katrin Vogt ◽  
Christopher Schnaitmann ◽  
Kristina V Dylla ◽  
Stephan Knapek ◽  
Yoshinori Aso ◽  
...  
Keyword(s):  
Mushroom Body ◽  
Visual Learning ◽  
Dopamine Neurons ◽  
Brain Functions ◽  
Economical Design ◽  
Sensory Modalities ◽  
Brain Center ◽  
Reinforcing Stimuli ◽  
The Brain ◽  
Intrinsic Neurons

In nature, animals form memories associating reward or punishment with stimuli from different sensory modalities, such as smells and colors. It is unclear, however, how distinct sensory memories are processed in the brain. We established appetitive and aversive visual learning assays for Drosophila that are comparable to the widely used olfactory learning assays. These assays share critical features, such as reinforcing stimuli (sugar reward and electric shock punishment), and allow direct comparison of the cellular requirements for visual and olfactory memories. We found that the same subsets of dopamine neurons drive formation of both sensory memories. Furthermore, distinct yet partially overlapping subsets of mushroom body intrinsic neurons are required for visual and olfactory memories. Thus, our results suggest that distinct sensory memories are processed in a common brain center. Such centralization of related brain functions is an economical design that avoids the repetition of similar circuit motifs.

A pair of dopamine neurons mediate chronic stress signals to induce learning deficit in Drosophila melanogaster

2021 ◽  
Vol 118 (42) ◽  
pp. e2023674118
Author(s):  
Jia Jia ◽  
Lei He ◽  
Junfei Yang ◽  
Yichun Shuai ◽  
Jingjing Yang ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Chronic Stress ◽  
Dopaminergic Neurons ◽  
Mushroom Body ◽  
Dopamine Neurons ◽  
Learning Deficit ◽  
Dopaminergic Activity ◽  
Output Neurons ◽  
Stress Signals ◽  
Underlying Mechanisms

Chronic stress could induce severe cognitive impairments. Despite extensive investigations in mammalian models, the underlying mechanisms remain obscure. Here, we show that chronic stress could induce dramatic learning and memory deficits in Drosophila melanogaster. The chronic stress–induced learning deficit (CSLD) is long lasting and associated with other depression-like behaviors. We demonstrated that excessive dopaminergic activity provokes susceptibility to CSLD. Remarkably, a pair of PPL1-γ1pedc dopaminergic neurons that project to the mushroom body (MB) γ1pedc compartment play a key role in regulating susceptibility to CSLD so that stress-induced PPL1-γ1pedc hyperactivity facilitates the development of CSLD. Consistently, the mushroom body output neurons (MBON) of the γ1pedc compartment, MBON-γ1pedc>α/β neurons, are important for modulating susceptibility to CSLD. Imaging studies showed that dopaminergic activity is necessary to provoke the development of chronic stress–induced maladaptations in the MB network. Together, our data support that PPL1-γ1pedc mediates chronic stress signals to drive allostatic maladaptations in the MB network that lead to CSLD.

scholarly journals Circuits that encode and predict alcohol associated preference

2019 ◽  
Author(s):  
Kristin M. Scaplen ◽  
Mustafa Talay ◽  
Sarah Salamon ◽  
Kavin M. Nuñez ◽  
Amanda G. Waterman ◽  
...  
Keyword(s):  
Memory Consolidation ◽  
Mushroom Body ◽  
Neural Circuits ◽  
Population Level ◽  
Dopamine Neurons ◽  
Behavioral Choice ◽  
Neuron Activation ◽  
Reward Delivery ◽  
Output Neurons ◽  
Insight Into

AbstractSubstance use disorders are chronic relapsing disorders often impelled by enduring memories and persistent cravings. Alcohol, as well as other addictive substances, remolds neural circuits important for memory to establish obstinate preference despite aversive consequences. How pertinent circuits are selected and shaped to result in these unchanging, inflexible memories is unclear. Using neurogenetic tools available inDrosophila melanogasterwe define how circuits required for alcohol associated preference shift from population level dopaminergic activation to select dopamine neurons that predict behavioral choice. During memory expression, these dopamine neurons directly, and indirectly via the mushroom body (MB), modulate the activity of interconnected glutamatergic and cholinergic output neurons. Transsynaptic tracing of these output neurons revealed at least two regions of convergence: 1) a center of memory consolidation within the MB implicated in arousal, and 2) a structure outside the MB implicated in integration of naïve and learned responses. These findings provide a circuit framework through which dopamine neuron activation shifts from reward delivery to cue onset, and provides insight into the inflexible, maladaptive nature of alcohol associated memories.

scholarly journals Dopamine neurons promotes wakefulness via the DopR receptor in the Drosophila mushroom body

2020 ◽  
Author(s):  
Margaret Driscoll ◽  
Steven Buchert ◽  
Victoria Coleman ◽  
Morgan McLaughlin ◽  
Amanda Nguyen ◽  
...  
Keyword(s):  
Mushroom Body ◽  
Critical Role ◽  
Fruit Fly ◽  
Dopamine Neurons ◽  
Central Complex ◽  
Behavioral Arousal ◽  
Sleep Homeostasis ◽  
Output Neurons ◽  
Gaba Transmission

AbstractNeural circuits involved in regulation of sleep play a critical role in sleep-wake transition and ability of an organism to engage in other behaviors critical for survival. The fruit fly, Drosophila melanogaster is a powerful system for the study of sleep and circuit mechanisms underlying sleep and co-regulation of sleep with other behaviors. In Drosophila, two neuropils in the central brain, mushroom body (MB) and central complex (CX) have been shown to influence sleep homeostasis and receive neuromodulator input critical to sleep-wake switch.Dopamine neurons (DANs) are the primary neuromodulator inputs to the MB but the mechanisms by which they regulate sleep- and wake-promoting neurons within MB are unknown. Here we investigate the role of subsets of DANs that signal wakefulness and project to wake-promoting compartments of the MB. We find that inhibition of specific subsets of PAM and PPL1 DANs projecting to the MB increase sleep in the presence of strong wake-inducing stimuli that reduces GABA transmission, although activity of these neurons is not directly modulated by GABA signaling. Of these subsets we find that DANs innervating the γ5 and β’2 MB compartments require both DopR1 and DopR2 receptors located in downstream Kenyon cells and mushroom body output neurons (MBONs). Further, we report that unlike the activity of wake-promoting MBONs and KCs, whose activity is modulated by sleep-need and PAM-DAN activity is independent of sleep-need. We have characterized a dopamine mediated sleep-circuit providing an inroad into understanding how common circuits within MB regulate sleep, wakefulness and behavioral arousal.

scholarly journals Circuits that encode and guide alcohol-associated preference

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Kristin M Scaplen ◽  
Mustafa Talay ◽  
Kavin M Nunez ◽  
Sarah Salamon ◽  
Amanda G Waterman ◽  
...  
Keyword(s):  
Memory Consolidation ◽  
Mushroom Body ◽  
Neural Circuits ◽  
Population Level ◽  
Dopamine Neurons ◽  
Adaptive Memory ◽  
Behavioral Choice ◽  
Reward Delivery ◽  
Output Neurons ◽  
Insight Into

A powerful feature of adaptive memory is its inherent flexibility. Alcohol and other addictive substances can remold neural circuits important for memory to reduce this flexibility. However, the mechanism through which pertinent circuits are selected and shaped remains unclear. We show that circuits required for alcohol-associated preference shift from population level dopaminergic activation to select dopamine neurons that predict behavioral choice in Drosophila melanogaster. During memory expression, subsets of dopamine neurons directly and indirectly modulate the activity of interconnected glutamatergic and cholinergic mushroom body output neurons (MBON). Transsynaptic tracing of neurons important for memory expression revealed a convergent center of memory consolidation within the mushroom body (MB) implicated in arousal, and a structure outside the MB implicated in integration of naïve and learned responses. These findings provide a circuit framework through which dopamine neuronal activation shifts from reward delivery to cue onset, and provide insight into the maladaptive nature of memory.

Parliamentarism and the Legislative Branch

2017 ◽  
Author(s):  
András Sajó ◽  
Renáta Uitz
Keyword(s):  
Decision Making ◽  
Political Parties ◽  
Legislative Branch ◽  
Effective Decision ◽  
The Law ◽  
Internal Operations ◽  
Effective Decision Making ◽  
The Relationship ◽  
Law Making

This chapter examines the relationship between parliamentarism and the legislative branch. It explores the evolution of the legislative branch, leading to disillusionment with the rationalized law-making factory, a venture run by political parties beyond the reach of constitutional rules. The rise of democratically bred party rule is positioned between the forces favouring free debate versus effective decision-making in the legislature. The chapter analyses the institutional make-up and internal operations of the legislature, the role of the opposition in the legislative assembly, and explores the benefits of bicameralism for boosting the powers of the legislative branch. Finally, it looks at the law-making process and its outsourcing via delegating legislative powers to the executive.

scholarly journals Corporate Social Responsibility (CSR): motivations and challenges of a Multinational Enterprise (MNE) subsidiary’s engagement with host communities in Ghana

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Lyon Salia Awuah ◽  
Kwame Oduro Amoako ◽  
Stephen Yeboah ◽  
Emmanuel Opoku Marfo ◽  
Peter Ansu-Mensah
Keyword(s):  
Stakeholder Engagement ◽  
Multinational Enterprise ◽  
Cost Savings ◽  
Community Members ◽  
Mining Sector ◽  
High Expectations ◽  
Effective Decision ◽  
Effective Decision Making ◽  
Internal Stakeholders ◽  
Corporate Social

AbstractThis paper aims to explore the motivations and challenges of engaging host communities in CSR practices within the context of Newmont Ahafo Mines (NAM), a subsidiary of a Multinational Mining Enterprise (MNE) operating in Ghana’s mining sector. This paper draws insights from stakeholder theory and interviews conducted with internal stakeholders (management and employees) and stakeholders in host communities (traditional rulers and community members). The findings indicate that effective decision-making, gaining legitimacy, cost savings, management of risks, and accountability are some of the perceived motivations of NAM’s stakeholder engagement in CSR. Nonetheless, the most critical challenges to NAM in improving stakeholder engagement in CSR practices are the lack of community members’ support in CSR projects, communities’ high expectations of NAM on development projects and over-dependency on NAM on the part of host communities. Therefore, it is reasonable for MNEs in emerging economies to attune engagement practices to the host community’s context. This will enable CSR practices and policies to fully exploit the latent benefits of CSR in the mining sector.

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