Organization of Spectrotemporal Preferences in the Inferior Colliculus and its Role for Encoding Natural Sounds

2012 2012

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Abstract (summary)

A central hypothesis in sensory coding suggests that auditory neurons are optimized to represent sounds experienced by an organism in natural environments. In order to characterize the relationship between physical characteristics of natural sounds and their neural representation, we first quantified spectral and temporal modulations of a large ensemble of natural sounds that included animal vocalizations, human speech and environmental background sounds. We examined the neural responses to these sound cues in the central nucleus of the inferior colliculus (CNIC). We will demonstrate that neural filtering properties in the CNIC are optimized for encoding natural sounds in a manner that maximize power transfer across the ensemble of neurons.

We next tested whether spectre-temporal sound preferences are hierarchically organized within the CNIC neural ensemble. A distinct laminar organization for sound frequency (tonotopy; Merzenich and Reid 1974; Semple and Aitkins 1979) and temporal modulation preferences (Schreiner and Langner 1988) has been previously demonstrated within the CNIC lamina; yet it is not clear whether higher-level spectral and temporal sound cues are systematically represented within the three-dimensional volume of the CNIC. To test this hypothesis, we recorded neural responses to dynamic moving ripple sounds (Escabi and Schreiner 2002) with a 16 channel acute recording probe placed orthogonal to the isofrequency lamina of the CMG: The probe spatial position was referenced to a three-dimensional coordinate system using a stereotaxic frame assembly. Each penetration was separated by 300µm along the laminar plane.

This procedure allowed us to fully sample the three-dimensional volume of the CNIC. Spectrotemporal receptive fields (STRF) were computed from the neural responses using reverse correlation procedures. We will show that the reconstruction of the spectro-temporal preferences along and across the isofrequency lamina exhibits a systematic organization for important acoustic parameters. Such a distributed organization has implications for how spectral and temporal features in natural sounds are encoded in the CNIC.

In summary, these results provide evidence for an orderly neural representation of spectral and temporal sound cues that is consistent with efficiency coding principles.

Indexing (details)

Biomedical engineering
0300: Audiology
0317: Neurosciences
0541: Biomedical engineering
Identifier / keyword
Biological sciences; Applied sciences; Health and environmental sciences; Auditory neurons; Inferior colliculus; Natural sounds; Sensory coding
Organization of Spectrotemporal Preferences in the Inferior Colliculus and its Role for Encoding Natural Sounds
Rodriguez Campos, Francisco Antonio
Number of pages
Publication year
Degree date
School code
DAI-B 73/08(E), Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Escabi, Monty A.
University of Connecticut
University location
United States -- Connecticut
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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