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Workshop: Mark van Rossum and Andrew Stewart, Chair: Colin Buchanan

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What
  • ANC Workshop Talk
When Mar 05, 2013
from 11:00 AM to 12:00 PM
Where IF 4.31/4.33
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Mark van Rossum

On population coding of multiple stimuli

The coding of sensory stimuli in the neural response is a fundamental property of neural systems that impacts many of its properties.
The coding scheme also determines how many different stimuli a population of neurons can represent. Although the coding of single stimuli has been studied extensively, coding of multiple stimuli has been studied far less. Here we study the representational capacity in the visual system when stimulus pairs are represented simultaneously. We assume that the response to the individual stimuli is given, and that the neurons interacts non-linearly to form the response to the pair. Using a Bayesian read-out we find that using a linear sum leads to a smaller capacity, than a maximum-like interaction. Thus non-linear interaction improve coding capacity. The results provide a novel interpretation for the non-linear interaction observed experimentally.

 

Andrew Stewart

Real-time classification of human vision from EEG

Non-invasive neuroimaging allows data to be gathered from many normal behaving humans. Electroencephalography can record at brain data millisecond precision, perhaps 1000x more than fMRI. Brain-computer interfaces using EEG data give fairly high bitrate, demonstrating that there is information there.

In this project, we apply support vector machines to EEG data from humans in a visual presentation experiment. We find, with use of filtering and ICA, the visual object shown to the subject can be classified in real-time from the EEG signal at well above chance performance.

We suggest this might be used for novel experiments into human visual cognition.