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Abstract:
The way groups of auditory neurons interact to code acoustic
information is investigated using an information theoretic
approach. We develop measures of redundancy among groups of
neurons, and apply them to the study of collaborative coding
efficiency in two processing stations in the auditory pathway:
the inferior colliculus (IC) and the primary auditory cortex
(AI). Under two schemes for the coding of the acoustic content,
acoustic segments coding and stimulus identity coding, we show
differences both in information content and group redundancies
between IC and AI neurons. These results provide for the first
time a direct evidence for redundancy reduction along the
ascending auditory pathway, as has been hypothesized for
theoretical considerations [Barlow 1959, 2001]. The redundancy
effects under the single-spikes coding scheme are significant
only for groups larger than ten cells, and cannot be revealed
with the redundancy measures that use only pairs of cells. The
results suggest that the auditory system transforms low level
representations that contain redundancies due to the statistical
structure of natural stimuli, into a representation in which
cortical neurons extract rare and independent component of
complex acoustic signals, that are useful for auditory scene
analysis.
References
H. B. Barlow. Sensory mechanisms, the reduction of redundancy,
and intelligence. In
Mechanisation of thought processes
, pages 535-539. Her Majesty's stationary office, London,
1959.
H. B. Barlow. Redundancy reduction revisited.
Network: Computation in Neural Systems
, 12:241-253, 2001.
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