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How much about our interactions with and experience of our world can be deduced from basic principles? This talk reviews recent attempts to understand the self-organised behaviour of embodied agents, like ourselves, as satisfying basic imperatives for sustained exchanges with the environment. In brief, one simple driving force appears to explain many aspects of action and perception. This driving force is the minimisation of surprise or prediction error that in the context of perception corresponds to Bayes-optimal predictive coding (that suppresses exteroceptive prediction errors) and in the context of action reduces to classical motor reflexes (that suppress proprioceptive prediction errors). We will look at some of the implications for the anatomy of this active inference, in terms of large-scale anatomical graphs and canonical microcircuits. Specifically, we will look at the functional and anatomical asymmetries in (extrinsic and intrinsic) connections and their implications for spectral responses.Canonical circuits for predictive codingKarl Friston, University College London

Overview

The free-energy principleaction and perceptionpredictive coding with reflexes

The anatomy of inferencegraphical modelscanonical microcircuits

Functional asymmetriesextrinsic connectionsintrinsic connections

Objects are always imagined as being present in the field of vision as would have to be there in order to produce the same impression on the nervous mechanism - von Helmholtz

Thomas BayesGeoffrey HintonRichard FeynmanFrom the Helmholtz machine to the Bayesian brain and self-organizationRichard Gregory

Hermann von Helmholtz Ross Ashby

Minimizing prediction error

Change sensationssensations predictionsPrediction errorChange predictionsActionPerception

Prior distributionPosterior distributionLikelihood distributiontemperature

Prediction errors the Bayesian thermostat

20406080100120

Perception

Action

Overview

The free-energy principleaction and perceptionpredictive coding with reflexes

The anatomy of inferencegraphical modelscanonical microcircuits

Functional asymmetriesextrinsic connectionsintrinsic connections

A simple hierarchyGenerative models

whatwhereSensory fluctuations

Generative modelModel inversion (inference)A simple hierarchyDescendingpredictionsAscending prediction errorsFrom models to perception

Expectations:Predictions:Prediction errors:Predictive coding

Haeusler and Maass: Cereb. Cortex 2006;17:149-162Bastos et al: Neuron 2012; 76:695-711Canonical microcircuits for predictive coding

frontal eye fieldsgeniculatevisual cortexretinal inputponsoculomotor signals

Errors (superficial pyramidal cells)Expectations (deep pyramidal cells)Top-down or backward predictionsBottom-up or forward prediction errorproprioceptive inputreflex arcPerception

David MumfordPredictive coding with reflexesAction

Overview

The free-energy principleaction and perceptionpredictive coding with reflexes

The anatomy of inferencegraphical modelscanonical microcircuits

Functional asymmetriesextrinsic connectionsintrinsic connections

superficialdeep

Errors (superficial pyramidal cells)Expectations (deep pyramidal cells)

02040608010012000.050.10.150.20.250.3020406080100120012frequency (Hz)

02040608010002468101214spectral powerForward transfer function0204060801000123456frequency (Hz)spectral powerBackward transfer function

Andre BastosV4V1

Errors (superficial pyramidal cells)Expectations (deep pyramidal cells)

Linear or driving connectionsNonlinear or modulatory connectionssuperficialdeep

NMDA receptor density

020406080100120012frequency (Hz)

Errors (superficial pyramidal cells)Expectations (deep pyramidal cells)

superficialdeep

Nonlinear (cross frequency) coupling020406080100120012frequency (Hz)

02040608010012000.050.10.150.20.250.3

STNM1STNM1

On dopamineOff dopamine

M1STN

M1STN

Bernadette Van WijkSummary

Hierarchical predictive coding is a neurobiological plausible scheme that the brain might use for (approximate) Bayesian inference about the causes of sensations

Predictive coding requires the dual encoding of expectations and errors, with reciprocal (neuronal) message passing

Much of the known neuroanatomy and neurophysiology of cortical architectures is consistent with the requisite message passing

In particular, the functional asymmetries and laminar specificity of intrinsic and extrinsic connections provide a formal perspective on spectral asymmetries and cross frequency coupling in the brain.Thank you

And thanks to collaborators:

Rick AdamsAndre BastosSven BestmannHarriet BrownCC ChenPascal FriesLee HarrisonStefan KiebelJames KilnerAndre MarreirosJrmie MattoutRosalyn MoranWill PennyKlaas StephanBernadette Van Wijk

And many others