Is the homunculus `aware' of sensory adaptation?

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• Peggy Seriès (The University of Edinburgh)
• Tuesday 09 June 2009, 16:00-17:00
• Cambridge University Engineering Department, CBL Rm #438 (http://blg.eng.cam.ac.uk/t/bin/view/Public/Directions).

If you have a question about this talk, please contact Dr Jean-Pascal Pfister.

The properties of sensory neurons are not fixed. They change dynamically according to the spatial and temporal context and the task being performed. Adaptation, for example, is known to result in a decrease in response amplitude, while attention enhances responses. How does the rest of the brain interpret these changes? Does the read-out adapt at the same time as the sensory neurons ?

We explore this question in the context of sensory adaptation, focusing on the examples of motion direction adaptation and contrast adaptation. In our framework, perception is modeled as resulting from an encoder-decoder cascade. The encoder corresponds to the response properties of a population of cortical neurons and changes during adaptation. Different types of decoders are considered, which are either fixed and ‘unaware’ of the adaptation state, or which change dynamically at the same time as the encoder, being thus always optimal and ‘aware’ of the adaptation state. Their predictions are compared with the psychophysical data for estimation and discrimination tasks.

We find that simple models of neural adaptation coupled with ‘unaware’ read-outs can account for the main features of the psychophysical results. We discuss the significance of having ‘unaware’ read-outs, and their relevance in other phenomena, such as contextual interactions, attention and perceptual learning.

Work in collaboration with E. P. Simoncelli and A. Stocker (NYU).

This talk is part of the Computational Neuroscience series.

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