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Active inference, sensory attenuation and illusions.

Brown H, Adams RA, Parees I, Edwards M, Friston K - Cogn Process (2013)

Bottom Line: Furthermore, it explains the force-matching illusion and reproduces empirical results almost exactly.This is important, given the negative correlation between sensory attenuation and delusional beliefs in normal subjects--and the reduction in the magnitude of the illusion in schizophrenia.It also provides a functional account of deficits in syndromes characterised by false inference and impaired movement--like schizophrenia and Parkinsonism--syndromes that implicate abnormal modulatory neurotransmission.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neurology, The Wellcome Trust Centre for Neuroimaging, UCL, 12 Queen Square, London, WC1N 3BG, UK, harriet.brown.09@ucl.ac.uk.

ABSTRACT
Active inference provides a simple and neurobiologically plausible account of how action and perception are coupled in producing (Bayes) optimal behaviour. This can be seen most easily as minimising prediction error: we can either change our predictions to explain sensory input through perception. Alternatively, we can actively change sensory input to fulfil our predictions. In active inference, this action is mediated by classical reflex arcs that minimise proprioceptive prediction error created by descending proprioceptive predictions. However, this creates a conflict between action and perception; in that, self-generated movements require predictions to override the sensory evidence that one is not actually moving. However, ignoring sensory evidence means that externally generated sensations will not be perceived. Conversely, attending to (proprioceptive and somatosensory) sensations enables the detection of externally generated events but precludes generation of actions. This conflict can be resolved by attenuating the precision of sensory evidence during movement or, equivalently, attending away from the consequences of self-made acts. We propose that this Bayes optimal withdrawal of precise sensory evidence during movement is the cause of psychophysical sensory attenuation. Furthermore, it explains the force-matching illusion and reproduces empirical results almost exactly. Finally, if attenuation is removed, the force-matching illusion disappears and false (delusional) inferences about agency emerge. This is important, given the negative correlation between sensory attenuation and delusional beliefs in normal subjects--and the reduction in the magnitude of the illusion in schizophrenia. Active inference therefore links the neuromodulatory optimisation of precision to sensory attenuation and illusory phenomena during the attribution of agency in normal subjects. It also provides a functional account of deficits in syndromes characterised by false inference and impaired movement--like schizophrenia and Parkinsonism--syndromes that implicate abnormal modulatory neurotransmission.

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Related in: MedlinePlus

A simulation of akinesia: This figure uses the same format as previous figure but reports the results of simulations when sensory attenuation is much lower (γ = 2). In this case, bottom-up prediction errors retain a higher precision than descending predictions during movement. Conditional expectations that are updated by ascending prediction errors (upper right panel) overwhelm prediction errors based upon top-down predictions, and consequently infer that there is no change in the state of the world. This means that proprioceptive prediction errors are not produced (upper left panel) and action is profoundly suppressed (lower right panel)
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Fig4: A simulation of akinesia: This figure uses the same format as previous figure but reports the results of simulations when sensory attenuation is much lower (γ = 2). In this case, bottom-up prediction errors retain a higher precision than descending predictions during movement. Conditional expectations that are updated by ascending prediction errors (upper right panel) overwhelm prediction errors based upon top-down predictions, and consequently infer that there is no change in the state of the world. This means that proprioceptive prediction errors are not produced (upper left panel) and action is profoundly suppressed (lower right panel)

Mentions: Compare these results with the equivalent simulation when sensory attenuation was reduced from six to two (Fig. 4). Here, the sensory attenuation leaves the sensory precision higher than the precision of the prior beliefs about internal hidden causes. This means that bottom-up sensory prediction errors predominate over top-down projections, and the expected internal hidden force is profoundly suppressed—and inferred with a high degree of confidence. Because there are no predictions about proprioceptive changes, there is a consequent hypokinesia and failure of movement.Fig. 4


Active inference, sensory attenuation and illusions.

Brown H, Adams RA, Parees I, Edwards M, Friston K - Cogn Process (2013)

A simulation of akinesia: This figure uses the same format as previous figure but reports the results of simulations when sensory attenuation is much lower (γ = 2). In this case, bottom-up prediction errors retain a higher precision than descending predictions during movement. Conditional expectations that are updated by ascending prediction errors (upper right panel) overwhelm prediction errors based upon top-down predictions, and consequently infer that there is no change in the state of the world. This means that proprioceptive prediction errors are not produced (upper left panel) and action is profoundly suppressed (lower right panel)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3824582&req=5

Fig4: A simulation of akinesia: This figure uses the same format as previous figure but reports the results of simulations when sensory attenuation is much lower (γ = 2). In this case, bottom-up prediction errors retain a higher precision than descending predictions during movement. Conditional expectations that are updated by ascending prediction errors (upper right panel) overwhelm prediction errors based upon top-down predictions, and consequently infer that there is no change in the state of the world. This means that proprioceptive prediction errors are not produced (upper left panel) and action is profoundly suppressed (lower right panel)
Mentions: Compare these results with the equivalent simulation when sensory attenuation was reduced from six to two (Fig. 4). Here, the sensory attenuation leaves the sensory precision higher than the precision of the prior beliefs about internal hidden causes. This means that bottom-up sensory prediction errors predominate over top-down projections, and the expected internal hidden force is profoundly suppressed—and inferred with a high degree of confidence. Because there are no predictions about proprioceptive changes, there is a consequent hypokinesia and failure of movement.Fig. 4

Bottom Line: Furthermore, it explains the force-matching illusion and reproduces empirical results almost exactly.This is important, given the negative correlation between sensory attenuation and delusional beliefs in normal subjects--and the reduction in the magnitude of the illusion in schizophrenia.It also provides a functional account of deficits in syndromes characterised by false inference and impaired movement--like schizophrenia and Parkinsonism--syndromes that implicate abnormal modulatory neurotransmission.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neurology, The Wellcome Trust Centre for Neuroimaging, UCL, 12 Queen Square, London, WC1N 3BG, UK, harriet.brown.09@ucl.ac.uk.

ABSTRACT
Active inference provides a simple and neurobiologically plausible account of how action and perception are coupled in producing (Bayes) optimal behaviour. This can be seen most easily as minimising prediction error: we can either change our predictions to explain sensory input through perception. Alternatively, we can actively change sensory input to fulfil our predictions. In active inference, this action is mediated by classical reflex arcs that minimise proprioceptive prediction error created by descending proprioceptive predictions. However, this creates a conflict between action and perception; in that, self-generated movements require predictions to override the sensory evidence that one is not actually moving. However, ignoring sensory evidence means that externally generated sensations will not be perceived. Conversely, attending to (proprioceptive and somatosensory) sensations enables the detection of externally generated events but precludes generation of actions. This conflict can be resolved by attenuating the precision of sensory evidence during movement or, equivalently, attending away from the consequences of self-made acts. We propose that this Bayes optimal withdrawal of precise sensory evidence during movement is the cause of psychophysical sensory attenuation. Furthermore, it explains the force-matching illusion and reproduces empirical results almost exactly. Finally, if attenuation is removed, the force-matching illusion disappears and false (delusional) inferences about agency emerge. This is important, given the negative correlation between sensory attenuation and delusional beliefs in normal subjects--and the reduction in the magnitude of the illusion in schizophrenia. Active inference therefore links the neuromodulatory optimisation of precision to sensory attenuation and illusory phenomena during the attribution of agency in normal subjects. It also provides a functional account of deficits in syndromes characterised by false inference and impaired movement--like schizophrenia and Parkinsonism--syndromes that implicate abnormal modulatory neurotransmission.

Show MeSH
Related in: MedlinePlus