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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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Sensory attenuation in schizophrenia: Left panel results of the force-matching simulation repeated under different levels of self-generated force. For normal levels of sensory attenuation (blue circles), internally produced force is higher than externally generated force at all levels of force, consistent with published data. Force-matching typical of schizophrenia (red circles) was simulated by reducing sensory attenuation and increasing the precision of prediction errors at higher levels of the hierarchy. This resulted in a more veridical perception of internally generated force (small circles). Right panel empirical results using the same format adapted (with permission) from (Shergill et al. 2003, 2005)
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Fig7: Sensory attenuation in schizophrenia: Left panel results of the force-matching simulation repeated under different levels of self-generated force. For normal levels of sensory attenuation (blue circles), internally produced force is higher than externally generated force at all levels of force, consistent with published data. Force-matching typical of schizophrenia (red circles) was simulated by reducing sensory attenuation and increasing the precision of prediction errors at higher levels of the hierarchy. This resulted in a more veridical perception of internally generated force (small circles). Right panel empirical results using the same format adapted (with permission) from (Shergill et al. 2003, 2005)

Mentions: To simulate the force-matching paradigm, we repeated these simulations under different levels of self-generated forces by modulating the prior beliefs about the internal hidden cause (from a half to twice the normal amplitude). The results are shown in Fig. 7 (blue line) by plotting the self-generated force against the yoked or matched external force with a corresponding 90 % confidence interval. These results are remarkably similar to those obtained empirically (Shergill et al. 2003, 2005) and reveal sensory attenuation through an illusory increase in the self-generated force, relative to matched forces over a wide range of forces. In the final simulations, we ask what would happen if subjects compensated for a failure in sensory attenuation by increasing the precision of their prior beliefs.Fig. 7


Active inference, sensory attenuation and illusions.

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

Sensory attenuation in schizophrenia: Left panel results of the force-matching simulation repeated under different levels of self-generated force. For normal levels of sensory attenuation (blue circles), internally produced force is higher than externally generated force at all levels of force, consistent with published data. Force-matching typical of schizophrenia (red circles) was simulated by reducing sensory attenuation and increasing the precision of prediction errors at higher levels of the hierarchy. This resulted in a more veridical perception of internally generated force (small circles). Right panel empirical results using the same format adapted (with permission) from (Shergill et al. 2003, 2005)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig7: Sensory attenuation in schizophrenia: Left panel results of the force-matching simulation repeated under different levels of self-generated force. For normal levels of sensory attenuation (blue circles), internally produced force is higher than externally generated force at all levels of force, consistent with published data. Force-matching typical of schizophrenia (red circles) was simulated by reducing sensory attenuation and increasing the precision of prediction errors at higher levels of the hierarchy. This resulted in a more veridical perception of internally generated force (small circles). Right panel empirical results using the same format adapted (with permission) from (Shergill et al. 2003, 2005)
Mentions: To simulate the force-matching paradigm, we repeated these simulations under different levels of self-generated forces by modulating the prior beliefs about the internal hidden cause (from a half to twice the normal amplitude). The results are shown in Fig. 7 (blue line) by plotting the self-generated force against the yoked or matched external force with a corresponding 90 % confidence interval. These results are remarkably similar to those obtained empirically (Shergill et al. 2003, 2005) and reveal sensory attenuation through an illusory increase in the self-generated force, relative to matched forces over a wide range of forces. In the final simulations, we ask what would happen if subjects compensated for a failure in sensory attenuation by increasing the precision of their prior beliefs.Fig. 7

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