Archivio per 29 novembre 2011

29
Nov
11

PLoS Biology: An Information Theoretic Characterisation of Auditory Encoding

Via Scoop.itBounded Rationality and Beyond

Understanding how the brain makes sense of our acoustic environment remains a major challenge. One way to describe the complexity of our acoustic environment is in terms of information entropy: acoustic signals with high entropy convey large amounts of information, whereas low entropy signifies redundancy. To investigate how the brain processes this information, we controlled the amount of entropy in the signal by using pitch sequences. Participants listened to pitch sequences with varying amounts of entropy while we measured their brain activity using functional magnetic resonance imaging (fMRI). We show that the planum temporale (PT), a region of auditory association cortex, is sensitive to the entropy in pitch sequences. In two convergent fMRI studies, activity in PT increases as the entropy in the pitch sequence increases. The results establish PT as an important “computational hub” that requires less resource to encode redundant signals than it does to encode signals with high information content.
Via www.plosbiology.org

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29
Nov
11

PLoS Biology: Converging Intracranial Markers of Conscious Access

Via Scoop.itBounded Rationality and Beyond

We compared conscious and nonconscious processing of briefly flashed words using a visual masking procedure while recording intracranial electroencephalogram (iEEG) in ten patients. Nonconscious processing of masked words was observed in multiple cortical areas, mostly within an early time window (<300 ms), accompanied by induced gamma-band activity, but without coherent long-distance neural activity, suggesting a quickly dissipating feedforward wave. In contrast, conscious processing of unmasked words was characterized by the convergence of four distinct neurophysiological markers: sustained voltage changes, particularly in prefrontal cortex, large increases in spectral power in the gamma band, increases in long-distance phase synchrony in the beta range, and increases in long-range Granger causality. We argue that all of those measures provide distinct windows into the same distributed state of conscious processing. These results have a direct impact on current theoretical discussions concerning the neural correlates of conscious access.
Via www.plosbiology.org

29
Nov
11

The End of Rational Economics? | Paul Krugman | Big Think

Via Scoop.itBounded Rationality and Beyond

The Nobel Prize winner says economics should move beyond the limits of ‘rational self-interest.’..Paul Krugman: I think the biggest challenge is that the method that has worked so well for economics is probably close to its limits. Economics has gotten a tremendous amount of mileage about . . . by saying what would a rational, self-interested person do? That has been the core. And for very many things, that has been a very productive way. You learn an enormous amount, and it serves as the basis not just for abstract theories, but for actual empirical analysis of behavior and of policy. But in a way we’ve sort of done what you can do with that, and more and more the key issues in economics are . . . involve the limits of rationality; involve the places where people don’t have the ability to assess all of the data they have where people are . . . don’t make rational choices.
Via bigthink.com




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