Recognizing sequences of sequences

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Stefan J. Kiebel - , University College London, Max Planck Institute for Human Cognitive and Brain Sciences (Author)
  • Katharina Von Kriegstein - , University College London, Max Planck Institute for Human Cognitive and Brain Sciences (Author)
  • Jean Daunizeau - , University College London (Author)
  • Karl J. Friston - , University College London (Author)

Abstract

The brain's decoding of fast sensory streams is currently impossible to emulate, even approximately, with artificial agents. For example, robust speech recognition is relatively easy for humans but exceptionally difficult for artificial speech recognition systems. In this paper, we propose that recognition can be simplified with an internal model of how sensory input is generated, when formulated in a Bayesian framework. We show that a plausible candidate for an internal or generative model is a hierarchy of 'stable heteroclinic channels'. This model describes continuous dynamics in the environment as a hierarchy of sequences, where slower sequences cause faster sequences. Under this model, online recognition corresponds to the dynamic decoding of causal sequences, giving a representation of the environment with predictive power on several timescales. We illustrate the ensuing decoding or recognition scheme using synthetic sequences of syllables, where syllables are sequences of phonemes and phonemes are sequences of sound-wave modulations. By presenting anomalous stimuli, we find that the resulting recognition dynamics disclose inference at multiple time scales and are reminiscent of neuronal dynamics seen in the real brain.

Details

Original languageEnglish
Article numbere1000464
JournalPLOS computational biology
Volume5
Issue number8
Publication statusPublished - Aug 2009
Peer-reviewedYes
Externally publishedYes

External IDs

PubMed 19680429
ORCID /0000-0001-7989-5860/work/142244400