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Embodied Inference: or “I think therefore I am, if I am what I think”
"... This chapter considers situated and embodied cognition in terms of the free-energy principle. The free-energy formulation starts with the premise that biological agents must actively resist a natural tendency to disorder. It appeals to the idea that agents are essentially inference machines that ..."
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This chapter considers situated and embodied cognition in terms of the free-energy principle. The free-energy formulation starts with the premise that biological agents must actively resist a natural tendency to disorder. It appeals to the idea that agents are essentially inference machines that
The computational anatomy of psychosis
"... This paper considers psychotic symptoms in terms of false inferences or beliefs. It is based on the notion that the brain is an inference machine that actively constructs hypotheses to explain or predict its sensations. This perspective provides a normative (Bayes-optimal) account of action and perc ..."
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This paper considers psychotic symptoms in terms of false inferences or beliefs. It is based on the notion that the brain is an inference machine that actively constructs hypotheses to explain or predict its sensations. This perspective provides a normative (Bayes-optimal) account of action and perception that emphasizes probabilistic representations; in partic-ular, the confidence or precision of beliefs about the world. We will consider hallucinosis, abnormal eye movements, sensory attenuation deficits, catatonia, and delusions as vari-ous expressions of the same core pathology: namely, an aberrant encoding of precision. From a cognitive perspective, this represents a pernicious failure of metacognition (beliefs about beliefs) that can confound perceptual inference. In the embodied setting of active (Bayesian) inference, it can lead to behaviors that are paradoxically more accurate than Bayes-optimal behavior. Crucially, this normative account is accompanied by a neuronally plausible process theory based upon hierarchical predictive coding. In predictive coding, precision is thought to be encoded by the post-synaptic gain of neurons reporting prediction error.This suggests that both pervasive trait abnormalities and florid failures of inference in the psychotic state can be linked to factors controlling post-synaptic gain – such as NMDA
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, 2010
"... We suggested recently that attention can be understood as inferring the level of uncertainty or precision during hierarchical perception. In this paper, we try to substantiate this claim using neuronal simulations of directed spatial attention and biased competition. These simulations assume that ne ..."
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We suggested recently that attention can be understood as inferring the level of uncertainty or precision during hierarchical perception. In this paper, we try to substantiate this claim using neuronal simulations of directed spatial attention and biased competition. These simulations assume that neuronal activity encodes a probabilistic representation of the world that optimizes free-energy in a Bayesian fashion. Because free-energy bounds surprise or the (negative) log-evidence for internal models of the world, this optimization can be regarded as evidence accumulation or (generalized) predictive coding. Crucially, both predictions about the state of the world generating sensory data and the precision of those data have to be optimized. Here, we show that if the precision depends on the states, one can explain many aspects of attention. We illustrate this in the context of the Posner paradigm, using the simulations to generate both psychophysical and electrophysiological responses. These simulated responses are consistent with attentional bias or gating, competition for attentional resources, attentional capture and associated speed-accuracy trade-offs. Furthermore, if we present both attended and nonattended stimuli simultaneously, biased competition for neuronal representation emerges as a principled and straightforward property of Bayes-optimal perception.
Modelling object perception in cortex: hierarchical Bayesian
"... networks and belief propagation ..."
unknown title
"... re ic osi reas (pre and visual studies of deviance detection suggesting that the memory representations inferred from these studies meet the criteria set for perceptual object representations. Based on this evidence we then argue Helmholtz's (1860/1962) notion of uncon out the relatively short ..."
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re ic osi reas (pre and visual studies of deviance detection suggesting that the memory representations inferred from these studies meet the criteria set for perceptual object representations. Based on this evidence we then argue Helmholtz's (1860/1962) notion of uncon out the relatively short history of psychology, the empiricist tradition. mathematical descriptions, see Baldeweg, 2007; Hohwy et al.,
Advance Access publication October 18, 2010 Neural Correlates of Developing and Adapting Behavioral Biases in Speeded Choice Reactions—An fMRI Study on Predictive Motor Coding
"... In reaction-time (RT) tasks with unequally probable stimuli, people respond faster and more accurately in high-probability trials than in low-probability trials. We used functional magnetic resonance imaging to investigate brain activity during the acquisition and adaptation of such biases. Particip ..."
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In reaction-time (RT) tasks with unequally probable stimuli, people respond faster and more accurately in high-probability trials than in low-probability trials. We used functional magnetic resonance imaging to investigate brain activity during the acquisition and adaptation of such biases. Participants responded to arrows pointing to either side with different and previously unknown probabilities across blocks, which were covertly reversed in the middle of some blocks. Changes in response bias were modeled using the development of the selective RT bias at the beginning of a block and after the reversal as parametric regressors. Both fresh development and reversal of an existing response bias were associated with bilateral activations in inferior parietal lobule, intraparietal sulcus, and supplementary motor cortex. Further activations were observed in right temporoparietal junction, dorsolateral prefrontal cortex, and dorsal premotor cortex. Only during initial development of biases at the beginning of a block, we observed additional activity in ventral premotor cortex and anterior insula, whereas the basal ganglia (bilaterally) were recruited when the bias was adapted to reversed probabilities. Taken together, these areas constitute a network that updates and applies implicit predictions to create an attention and motor bias according to environmental probabilities that transform into specific facilitation.
Cerebral Cortex doi:10.1093/cercor/bhq188 Neural Correlates of Developing and Adapting Behavioral Biases in Speeded Choice Reactions—An fMRI Study on Predictive Motor Coding
"... In reaction-time (RT) tasks with unequally probable stimuli, people respond faster and more accurately in high-probability trials than in low-probability trials. We used functional magnetic resonance imaging to investigate brain activity during the acquisition and adaptation of such biases. Particip ..."
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In reaction-time (RT) tasks with unequally probable stimuli, people respond faster and more accurately in high-probability trials than in low-probability trials. We used functional magnetic resonance imaging to investigate brain activity during the acquisition and adaptation of such biases. Participants responded to arrows pointing to either side with different and previously unknown probabilities across blocks, which were covertly reversed in the middle of some blocks. Changes in response bias were modeled using the development of the selective RT bias at the beginning of a block and after the reversal as parametric regressors. Both fresh development and reversal of an existing response bias were associated with bilateral activations in inferior parietal lobule, intraparietal sulcus, and supplementary motor cortex. Further activations were observed in right temporoparietal junction, dorsolateral prefrontal cortex, and dorsal premotor cortex. Only during initial development of biases at the beginning of a block, we observed additional activity in ventral premotor cortex and anterior insula, whereas the basal ganglia (bilaterally) were recruited when the bias was adapted to reversed probabilities. Taken together, these areas constitute a network that updates and applies implicit predictions to create an attention and motor bias according to environmental probabilities that transform into specific facilitation.
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, 2013
"... I would like to take this opportunity to thank many people who helped and supported my journey to purse a PhD degree. I thank my advisor, Dr. Jose C. Principe, for giving me the opportunity and means to pursue this work; without his constant support and guidance this work would not have been possibl ..."
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I would like to take this opportunity to thank many people who helped and supported my journey to purse a PhD degree. I thank my advisor, Dr. Jose C. Principe, for giving me the opportunity and means to pursue this work; without his constant support and guidance this work would not have been possible. I am very indebted to Dr. Yunmei Chen for many patient and insightful discussions that helped shape this work significantly and Dr. Anand Rangarajan for stimulating my intellectual curiosity through his course work. I would also like to thank Dr. Sean Meyn and Dr. John Harris for serving on my committee and for many constructive comments. I feel fortunate to be in company of some amazing people, who made this last five
