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ANC Workshop Talk: Athina Spiliopoulou and Michael Hull, Chair: Colin Mclean

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What
  • ANC Workshop Talk
When Mar 20, 2012
from 11:00 AM to 12:00 PM
Where IF 4.31/4.33
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Athina Spiliopoulou

A topic model for melodic sequences

In this talk I will introduce the Variable-gram Topic Model for the problem of melody modelling. Learning a probabilistic model for melody directly from musical sequences is a challenging task as one needs to tackle not only the complex statistical dependencies that characterize a music genre, but also the element of novelty, as each music piece is a unique realization of a musical form. The Variable-gram Topic Model couples the latent topic formalism with a systematic model for contextual information, thus allowing us to better model the complexity of melodic sequences. I will show evaluation results using a next-step prediction task. Additionally, I will present a novel way of model evaluation, where we directly compare model samples with data sequences using the Maximum Mean Discrepancy (MMD) of string kernels, to assess how close is the model distribution to the data distribution.

 

Michael Hull

Simple Decision Making: The role of electrical coupling between neurons in the initiation of tadpole swimming

I will talk about my Ph.D project; investigating the initiation of fictive swimming in hatchling Xenopus laevis tapoles.  Experiments have shown that this behaviour can be generated by a central pattern generating (CPG) network of approximately 2000 neurons in the caudal hindbrain and the rostral spinal cord.  These neurons can be subdivided into classes based on morphology and electrical firing characteristics and are found grouped into columns along the rostrocaudal axis.  During swimming, a particular group of neurons with descending axons, (dINs) are the first neurons to fire on each side and act as 'trigger' neurons; synchronizing firing on each side of the CPG. These neurons are tightly electrically coupled via gap junctions on their axons; this coupling is crucial to the generation of reliable swimming rhythm.  Unfortunately, experimental limitations mean that it is very difficult to investigate these neurons experimentally; modelling offers a way to investigate the role of electrical coupling in the decision to initiate swimming.