Thursdays, 4:00 - 5:30 pm, Elliott N119
Maria Chait, Auditory Cognitive Neuroscience Lab, University College London
"How the brain discovers patterns in sound sequences"
Sensitivity to patterns is fundamental to sensory processing, perhaps particularly so in the auditory system, since most auditory signals only have meaning as successions over time. Indeed, accumulating evidence suggests that the brain is tuned to the statistics of sensory stimulation. However, the process through which these statistical regularities are discovered in the first instance has eluded investigation. In my presentation I will review recent brain imaging and psychophysics findings in my lab that suggest that the auditory brain is a well-tuned 'pattern seeker', continuously scanning the unfolding auditory input for regularities, even when listeners' attention is focused elsewhere. Our data demonstrate that listeners are remarkably sensitive to the emergence of complex patterns within rapidly evolving sound sequences, performing on par with an ideal observer model. Brain responses reveal online processes of evidence accumulation - dynamic changes in tonic activity precisely correlate with the expected precision or predictability of ongoing auditory input. Source analysis demonstrates an interaction between primary auditory cortex, hippocampus, and inferior frontal gyrus in the process of 'discovering' the regularity within the ongoing sound sequence.
Suggested background reading:
Mondays, 12:00 pm, Elliott Hall S204, Lunch will be provided.
October 5 - Replication - Part 1
More Is Different - P.W. Anderson
"The reductionist hypothesis may still be a topic for controversy among philosophers, but among the great majority of active scientists I think it is accepted without question. The workings of our minds and bodies, and of all the animate or inaminate matter of which we have any detailed knowledge, are assumed to be controlled by the same set of fundamental laws, which except under certain extreme conditions we feel we know pretty well.
"It seems inevitable to go on uncritically to what appears at first sight to be an obvious corollary of reductionism: that if everything obeys the same fundamental laws, then the only scientists who are studying anything really fundamental are those who are working on those laws. In practice, that amounts to some astrophysicists, some elementary particle physicists, some logicians and other mathematicians, and few others ..." More ...
The September 22, 2015 issue of PLOS Computational Biology features a paper by CCS members Paul Schrater and Vasileios Christopoulos entitled, "Dynamic Integration of Value Information into a Common Probability Currency as a Theory for Flexible Decision Making".
From their Conclusion:
"In sum, decisions require integrating both good values and action costs, which are often time and state dependent such that simple approaches pre-selection of goals or fixed weighted mixture of policies cannot account for the complexities of natural behavior. By focusing on a fundamental probabilistic computation, we provide a principled way to dynamically integrate these values that can merge work on decision making with motor control."
Their paper may be downloaded in Portable Document Format (pdf, 2.3 mb) at .
(This is an open access article distributed under the terms of the Creative Commons Attribution License.)