title: Emergent categorical representation of natural, complex sounds resulting from the early post-natal sound environment.
abstract: Cortical sensory representations can be reorganized by sensory exposure in an epoch of early development. The adaptive role of this type of plasticity for natural sounds in sensory development is, however, unclear. We have reared rats in a naturalistic, complex acoustic environment and examined their auditory representations. We found that cortical neurons became more selective to spectrotemporal features in the experienced sounds. At the neuronal population level, more neurons were involved in representing the whole set of complex sounds, but fewer neurons actually responded to each individual sound, but with greater magnitudes. A comparison of population-temporal responses to the experienced complex sounds revealed that cortical responses to different renderings of the same song motif were more similar, indicating that the cortical neurons became less sensitive to natural acoustic variations associated with stimulus context and sound renderings. By contrast, cortical responses to sounds of different motifs became more distinctive, suggesting that cortical neurons were tuned to the defining features of the experienced sounds. These effects lead to emergent "categorical" representations of the experienced sounds, which presumably facilitate their recognition.
authors.affiliation: Keck Center for Integrative Neuroscience, University of California, San Francisco, CA 94143, USA. Electronic address: sbao@berkeley.edu.
authors.forename: S
authors.initials: S
authors.lastname: Bao
authors.affiliation: Keck Center for Integrative Neuroscience, University of California, San Francisco, CA 94143, USA.
authors.forename: E F
authors.initials: EF
authors.lastname: Chang
authors.affiliation: Keck Center for Integrative Neuroscience, University of California, San Francisco, CA 94143, USA.
authors.forename: C-L
authors.initials: CL
authors.lastname: Teng
authors.affiliation: Keck Center for Integrative Neuroscience, University of California, San Francisco, CA 94143, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Heiser
authors.affiliation: Keck Center for Integrative Neuroscience, University of California, San Francisco, CA 94143, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Merzenich
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D004777:Environment; D009474:Neurons / Q000502:physiology*; D051381:Rats; D013997:Time Factors; D014828:Vocalization, Animal
keywords: natural sound; neurogram; sparse coding; spectrotemporal receptive field; unsupervised learning