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Karl J Friston - One of the best experts on this subject based on the ideXlab platform.

  • is the free Energy Principle a formal theory of semantics from variational density dynamics to neural and phenotypic representations
    Entropy, 2020
    Co-Authors: Maxwell J D Ramstead, Karl J Friston, Inês Hipólito
    Abstract:

    The aim of this paper is twofold: (1) to assess whether the construct of neural representations plays an explanatory role under the variational free-Energy Principle and its corollary process theory, active inference; and (2) if so, to assess which philosophical stance—in relation to the ontological and epistemological status of representations—is most appropriate. We focus on non-realist (deflationary and fictionalist-instrumentalist) approaches. We consider a deflationary account of mental representation, according to which the explanatorily relevant contents of neural representations are mathematical, rather than cognitive, and a fictionalist or instrumentalist account, according to which representations are scientifically useful fictions that serve explanatory (and other) aims. After reviewing the free-Energy Principle and active inference, we argue that the model of adaptive phenotypes under the free-Energy Principle can be used to furnish a formal semantics, enabling us to assign semantic content to specific phenotypic states (the internal states of a Markovian system that exists far from equilibrium). We propose a modified fictionalist account—an organism-centered fictionalism or instrumentalism. We argue that, under the free-Energy Principle, pursuing even a deflationary account of the content of neural representations licenses the appeal to the kind of semantic content involved in the ‘aboutness’ or intentionality of cognitive systems; our position is thus coherent with, but rests on distinct assumptions from, the realist position. We argue that the free-Energy Principle thereby explains the aboutness or intentionality in living systems and hence their capacity to parse their sensory stream using an ontology or set of semantic factors.

  • Some interesting observations on the free Energy Principle
    arXiv: Neurons and Cognition, 2020
    Co-Authors: Karl J Friston, Lancelot Da Costa, Thomas Parr
    Abstract:

    Biehl et al (2020) present some interesting observations on an early formulation of the free Energy Principle in (Friston, 2013). We use these observations to scaffold a discussion of the technical arguments that underwrite the free Energy Principle. This discussion focuses on solenoidal coupling between various (subsets of) states in sparsely coupled systems that possess a Markov blanket - and the distinction between exact and approximate Bayesian inference, implied by the ensuing Bayesian mechanics.

  • A free Energy Principle for a particular physics
    arXiv: Neurons and Cognition, 2019
    Co-Authors: Karl J Friston
    Abstract:

    This monograph attempts a theory of every 'thing' that can be distinguished from other things in a statistical sense. The ensuing statistical independencies, mediated by Markov blankets, speak to a recursive composition of ensembles (of things) at increasingly higher spatiotemporal scales. This decomposition provides a description of small things; e.g., quantum mechanics - via the Schrodinger equation, ensembles of small things - via statistical mechanics and related fluctuation theorems, through to big things - via classical mechanics. These descriptions are complemented with a Bayesian mechanics for autonomous or active things. Although this work provides a formulation of every thing, its main contribution is to examine the implications of Markov blankets for self-organisation to nonequilibrium steady-state. In brief, we recover an information geometry and accompanying free Energy Principle that allows one to interpret the internal states of something as representing or making inferences about its external states. The ensuing Bayesian mechanics is compatible with quantum, statistical and classical mechanics and may offer a formal description of lifelike particles.

  • The free-Energy Principle: a unified brain theory?
    Nature Reviews Neuroscience, 2010
    Co-Authors: Karl J Friston
    Abstract:

    Adaptive agents must occupy a limited repertoire of states and therefore minimize the long-term average of surprise associated with sensory exchanges with the world. Minimizing surprise enables them to resist a natural tendency to disorder. Surprise rests on predictions about sensations, which depend on an internal generative model of the world. Although surprise cannot be measured directly, a free-Energy bound on surprise can be, suggesting that agents minimize free Energy by changing their predictions (perception) or by changing the predicted sensory inputs (action). Perception optimizes predictions by minimizing free Energy with respect to synaptic activity (perceptual inference), efficacy (learning and memory) and gain (attention and salience). This furnishes Bayes-optimal (probabilistic) representations of what caused sensations (providing a link to the Bayesian brain hypothesis). Bayes-optimal perception is mathematically equivalent to predictive coding and maximizing the mutual information between sensations and the representations of their causes. This is a probabilistic generalization of the Principle of efficient coding (the infomax Principle) or the minimum-redundancy Principle. Learning under the free-Energy Principle can be formulated in terms of optimizing the connection strengths in hierarchical models of the sensorium. This rests on associative plasticity to encode causal regularities and appeals to the same synaptic mechanisms as those underlying cell assembly formation. Action under the free-Energy Principle reduces to suppressing sensory prediction errors that depend on predicted (expected or desired) movement trajectories. This provides a simple account of motor control, in which action is enslaved by perceptual (proprioceptive) predictions. Perceptual predictions rest on prior expectations about the trajectory or movement through the agent's state space. These priors can be acquired (as empirical priors during hierarchical inference) or they can be innate (epigenetic) and therefore subject to selective pressure. Predicted motion or state transitions realized by action correspond to policies in optimal control theory and reinforcement learning. In this context, value is inversely proportional to surprise (and implicitly free Energy), and rewards correspond to innate priors that constrain policies. A free-Energy Principle has been proposed recently that accounts for action, perception and learning. This Review looks at some key brain theories in the biological (for example, neural Darwinism) and physical (for example, information theory and optimal control theory) sciences from the free-Energy perspective. Crucially, one key theme runs through each of these theories — optimization. Furthermore, if we look closely at what is optimized, the same quantity keeps emerging, namely value (expected reward, expected utility) or its complement, surprise (prediction error, expected cost). This is the quantity that is optimized under the free-Energy Principle, which suggests that several global brain theories might be unified within a free-Energy framework. Karl Friston shows that different global brain theories all describe Principles by which the brain optimizes value and surprise. He discusses how these brain theories fit into the free-Energy framework, suggesting that this framework might provide a unified account of brain function.

  • The free-Energy Principle: A unified brain theory?
    Nature Reviews Neuroscience, 2010
    Co-Authors: Karl J Friston
    Abstract:

    A free-Energy Principle has been proposed recently that accounts for action, perception and learning. This Review looks at some key brain theories in the biological (for example, neural Darwinism) and physical (for example, information theory and optimal control theory) sciences from the free-Energy perspective. Crucially, one key theme runs through each of these theories - optimization. Furthermore, if we look closely at what is optimized, the same quantity keeps emerging, namely value (expected reward, expected utility) or its complement, surprise (prediction error, expected cost). This is the quantity that is optimized under the free-Energy Principle, which suggests that several global brain theories might be unified within a free-Energy framework.

Ryan A. Loomis - One of the best experts on this subject based on the ideXlab platform.

  • investigating the minimum Energy Principle in searches for new molecular species the case of h2c3o isomers
    The Astrophysical Journal, 2015
    Co-Authors: Ryan A. Loomis, Brett A. Mcguire, Christopher N. Shingledecker, Chelen H. Johnson, Samantha Blair, A. N. Robertson, Anthony J. Remijan
    Abstract:

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum Energy Principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this Principle, we have fully characterized the spectra of the three isomers of C_3H_2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C_3H_2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point Energy isomer, propadienone (CH_2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum Energy Principle.

  • Investigating the Minimum Energy Principle in Searches for New Molecular Species?The Case of H2C3O Isomers
    The Astrophysical Journal, 2015
    Co-Authors: Ryan A. Loomis, Brett A. Mcguire, Christopher N. Shingledecker, Chelen H. Johnson, Samantha Blair, A. N. Robertson, Anthony J. Remijan
    Abstract:

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum Energy Principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this Principle, we have fully characterized the spectra of the three isomers of C_3H_2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C_3H_2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point Energy isomer, propadienone (CH_2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum Energy Principle.

Anthony J. Remijan - One of the best experts on this subject based on the ideXlab platform.

  • investigating the minimum Energy Principle in searches for new molecular species the case of h2c3o isomers
    The Astrophysical Journal, 2015
    Co-Authors: Ryan A. Loomis, Brett A. Mcguire, Christopher N. Shingledecker, Chelen H. Johnson, Samantha Blair, A. N. Robertson, Anthony J. Remijan
    Abstract:

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum Energy Principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this Principle, we have fully characterized the spectra of the three isomers of C_3H_2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C_3H_2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point Energy isomer, propadienone (CH_2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum Energy Principle.

  • Investigating the Minimum Energy Principle in Searches for New Molecular Species?The Case of H2C3O Isomers
    The Astrophysical Journal, 2015
    Co-Authors: Ryan A. Loomis, Brett A. Mcguire, Christopher N. Shingledecker, Chelen H. Johnson, Samantha Blair, A. N. Robertson, Anthony J. Remijan
    Abstract:

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum Energy Principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this Principle, we have fully characterized the spectra of the three isomers of C_3H_2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C_3H_2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point Energy isomer, propadienone (CH_2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum Energy Principle.

Brett A. Mcguire - One of the best experts on this subject based on the ideXlab platform.

  • investigating the minimum Energy Principle in searches for new molecular species the case of h2c3o isomers
    The Astrophysical Journal, 2015
    Co-Authors: Ryan A. Loomis, Brett A. Mcguire, Christopher N. Shingledecker, Chelen H. Johnson, Samantha Blair, A. N. Robertson, Anthony J. Remijan
    Abstract:

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum Energy Principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this Principle, we have fully characterized the spectra of the three isomers of C_3H_2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C_3H_2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point Energy isomer, propadienone (CH_2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum Energy Principle.

  • Investigating the Minimum Energy Principle in Searches for New Molecular Species?The Case of H2C3O Isomers
    The Astrophysical Journal, 2015
    Co-Authors: Ryan A. Loomis, Brett A. Mcguire, Christopher N. Shingledecker, Chelen H. Johnson, Samantha Blair, A. N. Robertson, Anthony J. Remijan
    Abstract:

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum Energy Principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this Principle, we have fully characterized the spectra of the three isomers of C_3H_2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C_3H_2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point Energy isomer, propadienone (CH_2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum Energy Principle.

A. N. Robertson - One of the best experts on this subject based on the ideXlab platform.

  • investigating the minimum Energy Principle in searches for new molecular species the case of h2c3o isomers
    The Astrophysical Journal, 2015
    Co-Authors: Ryan A. Loomis, Brett A. Mcguire, Christopher N. Shingledecker, Chelen H. Johnson, Samantha Blair, A. N. Robertson, Anthony J. Remijan
    Abstract:

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum Energy Principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this Principle, we have fully characterized the spectra of the three isomers of C_3H_2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C_3H_2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point Energy isomer, propadienone (CH_2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum Energy Principle.

  • Investigating the Minimum Energy Principle in Searches for New Molecular Species?The Case of H2C3O Isomers
    The Astrophysical Journal, 2015
    Co-Authors: Ryan A. Loomis, Brett A. Mcguire, Christopher N. Shingledecker, Chelen H. Johnson, Samantha Blair, A. N. Robertson, Anthony J. Remijan
    Abstract:

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum Energy Principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this Principle, we have fully characterized the spectra of the three isomers of C_3H_2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C_3H_2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point Energy isomer, propadienone (CH_2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum Energy Principle.