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CDS Thesis Seminar: Explicit Object Representation By Sparse Neural Codes Stephen Waydo Friday, September 21, 20071:00 PM to 2:00 PM Broad 100 Neurons have been identified in the human medial temporal lobe (MTL) that display a strong selectivity for only a few stimuli (such as familiar individuals or landmark buildings) out of perhaps 100 presented to the test subject. While highly selective for a particular object or category, these cells are remarkably insensitive to different presentations (i.e. different poses and views) of their preferred stimulus. This invariant, sparse, and explicit representation of the world may be crucial to the transformation of complex visual stimuli into more abstract memories. In this talk I will first discuss the issue of how best to quantify sparseness, particularly in very sparse systems where biases are significant, and show the results of this analysis applied to human MTL data. From there I move into the computational realm. Sparse coding as a computational constraint applied to the representation of natural images has been shown to produce receptive fields strikingly similar to those observed in mammalian primary visual cortex. I apply sparse coding as a model for processing further along the visual hierarchy: |
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