1,068 research outputs found

    Exploring adult hippocampal neurogenesis using optogenetics

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    In the 1980s, it was widely accepted that new neurons are continuously generated in the dentate gyrus of the mammalian hippocampus. Since its acceptance, researchers have employed various techniques and behavioral paradigms to study the proliferation, differentiation, and functional role of adult-born neurons. This literature thesis aims to discuss how optogenetics is able to overcome the limitations of past techniques and provide the field with new insights into the functional role of neurogenesis. We will review the current knowledge on both adult hippocampal neurogenesis and optogenetics, present representative studies using optogenetics to investigate neurogenesis and discuss potential limitations and concerns involved in using optogenetics

    The Explanatory Indispensability of Memory Traces

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    During the first half of the twentieth century, many philosophers of memory opposed the postulation of memory traces based on the claim that a satisfactory account of remembering need not include references to causal processes involved in recollection. However, in 1966, an influential paper by Martin and Deutscher showed that causal claims are indeed necessary for a proper account of remembering. This, however, did not settle the issue, as in 1977 Malcolm argued that even if one were to buy Martin and Deutscher’s argument for causal claims, we still don’t need to postulate the existence of memory traces. This paper reconstructs the dialectic between realists and anti-realists about memory traces, suggesting that ultimately realists’ arguments amount to inferences to the best explanation. I then argue that Malcolm’s anti-realist strategy consists in the suggestion that causal explanations that do not invoke memory traces are at least as good as those that do. But then, Malcolm, I argue that there are a large number of memory phenomena for which explanations that do not postulate the existence of memory traces are definitively worse than explanations that do postulate them. Next, I offer a causal model based on an interventionist framework to illustrate when memory traces can help to explain memory phenomena and proceed to substantiate the model with details coming from extant findings in the neuroscience of memory

    Memory Engram Cells Have Come of Age

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    The idea that memory is stored in the brain as physical alterations goes back at least as far as Plato, but further conceptualization of this idea had to wait until the 20th century when two guiding theories were presented: the “engram theory” of Richard Semon and Donald Hebb’s “synaptic plasticity theory.” While a large number of studies have been conducted since, each supporting some aspect of each of these theories, until recently integrative evidence for the existence of engram cells and circuits as defined by the theories was lacking. In the past few years, the combination of transgenics, optogenetics, and other technologies has allowed neuroscientists to begin identifying memory engram cells by detecting specific populations of cells activated during specific learning epochs and by engineering them not only to evoke recall of the original memory, but also to alter the content of the memory.RIKEN Brain Science InstituteHoward Hughes Medical InstituteJPB Foundatio

    Optogenetics, Pluralism and Progress

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    Optogenetic techniques are described as “revolutionary” for the unprecedented causal control they allow neuroscientists to exert over neural activity in awake behaving animals. In this paper, I demonstrate by means of a case study that optogenetic techniques will only illuminate causal links between the brain and behavior to the extent that their error characteristics are known and, further, that determining these error characteristics requires (1) comparison of optogenetic techniques with techniques having well known error characteristics (methodological pluralism) and (2) consideration of the broader neural and behavioral context in which the targets of optogenetic interventions are situated (perspectival pluralism)

    Optogenetics, Pluralism and Progress

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    Optogenetic techniques are described as “revolutionary” for the unprecedented causal control they allow neuroscientists to exert over neural activity in awake behaving animals. In this paper, I demonstrate by means of a case study that optogenetic techniques will only illuminate causal links between the brain and behavior to the extent that their error characteristics are known and, further, that determining these error characteristics requires (1) comparison of optogenetic techniques with techniques having well known error characteristics (methodological pluralism) and (2) consideration of the broader neural and behavioral context in which the targets of optogenetic interventions are situated (perspectival pluralism)

    Psychoneural reduction: a perspective from neural circuits

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    Abstract: Psychoneural reduction has been debated extensively in the philosophy of neuroscience. In this article I will evaluate metascientific approaches that claim direct molecular and cellular explanations of cognitive functions. I will initially consider the issues involved in linking cellular properties to behaviour from the general perspective of neural circuits. These circuits that integrate the molecular and cellular components underlying cognition and behaviour, making consideration of circuit properties relevant to reductionist debates. I will then apply this general perspective to specific systems where psychoneural reduction has been claimed, namely hippocampal long-term potentiation and the Aplysia gill-withdrawal reflex

    The ethics of memory modification : personal narratives, relational selves and autonomy

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    For nearly two decades, ethicists have expressed concerns that the further development and use of memory modification technologies (MMTs) - techniques allowing to intentionally and selectively alter memories - may threaten the very foundations of who we are, our personal identity, and thus pose a threat to our well-being, or even undermine our "humaneness". This paper examines the potential ramifications of memory-modifying interventions such as changing the valence of targeted memories and selective deactivation of a particular memory as these interventions appear to be at the same time potentially both most promising clinically as well as menacing to identity. However, unlike previous works discussing the potential consequences of MMTs, this article analyzes them in the context of the narrative relational approach to personal identity and potential issues related to autonomy. I argue that such a perspective brings to light the ethical aspects and moral issues arising from the use of MMTs that have been hidden from previously adopted approaches. In particular, this perspective demonstrates how important the social context in which an individual lives is for the ethical evaluation of a given memory-modifying intervention. I conclude by suggesting that undertaking memory modifications without taking into account the social dimension of a person’s life creates the risk that she will not be able to meet one of the basic human needs - the autonomous construction and maintenance of personal identity. Based on this conclusion, I offer some reflections on the permissibility and advisability of MMTs and what these considerations suggest for the future

    An optogenetic headstage for optical stimulation and neural recording in life science applications

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    L'optogénétique est une nouvelle méthode de contrôle de l’activité neuronale dans laquelle la lumière est employée pour activer ou arrêter certains neurones. Dans le cadre de ce travail, un dispositif permettant l’acquisition de signaux neuronaux et conduisant à une stimulation optogénétique de façon multicanale et temps-réel a été conçu. Cet outil est muni de deux canaux de stimulation optogénétique et de deux canaux de lecture des signaux neuronaux. La source de lumière est une DEL qui peut consommer jusqu’à 150 milliampères. Les signaux neuronaux acquis sont transmis à un ordinateur par une radio. Les dimensions sont d’environ 20×20×15 mm3 et le poids est de moins de 7 grammes, rendant l’appareil utile pour les expériences sur les petits animaux libres. Selon nos connaissances actuelles, le résultat de ce projet constitue le premier appareil de recherche optogénétique sans-fil, compact offrant la capture de signaux cérébraux et la stimulation optique simultanée.Optogenetics is a new method for controlling the neural activity where light is used to activate or silence, with high spatial and temporal resolution, genetically light-sensitized neurons. In optogenetics, a light source such as a LED, targets light-sensitized neurons. In this work, a light-weight wireless animal optogenetic headstage has been designed that allows multi-channel simultaneous real-time optical stimulation and neural recording. This system has two optogenetic stimulation channels and two electrophysiological reading channels. The optogenetic stimulation channels benefit from high-power LEDs (sinking 150 milliamps) with flexible stimulation patterns and the recorded neural data is wirelessly sent to a computer. The dimensions of the headstage are almost 20×20×15 mm3 and it weighs less than 7 grams. This headstage is suitable for tests on small freely-moving rodents. To the best of our knowledge, this is the first reported fully wireless headstage to offer simultaneous multichannel optical stimulation along with multichannel neural recording capability

    Experience without Memory: Optogenetics, the Self, and the Ethics of Forgetting

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    The horizon of clinical memory modification, long the domain of science fiction, is rapidly approaching; it is therefore imperative that we understand the ethical implications of such neuromodificatory technologies. We might begin such inquiry with the public’s worries about these technologies, namely that modifying memory will concomitantly modify the self. Yet, before discerning the reasonableness of this worry, we must understand the meaning of “the self” in relation to memory. Distilling this conception of the self is the principal aim of this thesis. I argue that many popular self-conceptions cannot capture our worries about neuromodification. Hence, I distill a novel such conception, which I call the Proustian Self—marshaling, to that end, not only neuroscientific evidence and metaphysical arguments but also literary-phenomenological analysis. I ultimately argue that this conception should be the target of further neuroethical inquiry regarding the prospect memory modification and its effects on putative patients

    Kuhnian revolutions in neuroscience: the role of tool development.

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    The terms "paradigm" and "paradigm shift" originated in "The Structure of Scientific Revolutions" by Thomas Kuhn. A paradigm can be defined as the generally accepted concepts and practices of a field, and a paradigm shift its replacement in a scientific revolution. A paradigm shift results from a crisis caused by anomalies in a paradigm that reduce its usefulness to a field. Claims of paradigm shifts and revolutions are made frequently in the neurosciences. In this article I will consider neuroscience paradigms, and the claim that new tools and techniques rather than crises have driven paradigm shifts. I will argue that tool development has played a minor role in neuroscience revolutions.The work received no fundin
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