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Deciphering the spike train of a sensory neuron| old_uid | 2636 |
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| title | Deciphering the spike train of a sensory neuron |
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| start_date | 2007/04/13 |
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| schedule | 11h-12h |
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| online | no |
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| summary | Work done with my longterm collaborators Mathew Diamond (SISSA) and Ehsan Arabzadeh (Sidney).
The precise temporal pattern of spikes of sensory neurons conveys substantial sensory information beyond that available in spike count. Many previous studies have focused on the temporal precision of
this code, by studying the precision of the "internal clock" within the spike train, i.e. the timing precision in registering the spikes that is needed to preserve all the information content of the spike
train. However, it is not clear how such a spike timing code could be decoded by a downstream neural system. In particular, it is not known how the amount of information decoded depends on the
precision of the "external clock", i.e., the knowledge of when the spike pattern occurred within the course of a single trial. In fact, spike times are measured with respect to stimulus onset; thus decoding
their information content may require some knowledge of the external clock. For example, decoding response latencies would need a precise "external clock", whereas decoding interspike intervals may
not require such precise external signal. To better understand how information is transmitted across neurons, it is crucial to know to what extent the decodable Information depends on the precision of
these clocks. In this talk I will present a novel informationtheoretic
algorithm that quantifies how spike timing information depends on the precision of both the internal and external clock. To shed
light on how information is transmitted along the ascending somatosensory pathway, we applied the new technique to extracellular recordings from ganglion and cortical somatosensory cells in the rat whisker system. We found that, in both ganglion and cortex, information is transmitted through a very precise internal clock (precision = 4ms). Reading out the ganglion code does not require a precise knowledge of the external clock, whereas reading out the cortical code does require a knowledge of the external clock. Since such external clock information could be available to cortex through an afferent signal from the motor structure initiating whisking, these results suggest that a spike timing code can be effectively transmitted across the somatosensory system. |
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| responsibles | Burle, Blanc, Roll |
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