How learning to abstract shapes neural sound representations.

Anke Ley,Elia Formisano,Jean Vroomen

doi:10.3389/fnins.2014.00132

Anke Ley, Elia Formisano + Show 1 more

Open Access

https://doi.org/10.3389/fnins.2014.00132

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Abstract

The transformation of acoustic signals into abstract perceptual representations is the essence of the efficient and goal-directed neural processing of sounds in complex natural environments. While the human and animal auditory system is perfectly equipped to process the spectrotemporal sound features, adequate sound identification and categorization require neural sound representations that are invariant to irrelevant stimulus parameters. Crucially, what is relevant and irrelevant is not necessarily intrinsic to the physical stimulus structure but needs to be learned over time, often through integration of information from other senses. This review discusses the main principles underlying categorical sound perception with a special focus on the role of learning and neural plasticity. We examine the role of different neural structures along the auditory processing pathway in the formation of abstract sound representations with respect to hierarchical as well as dynamic and distributed processing models. Whereas most fMRI studies on categorical sound processing employed speech sounds, the emphasis of the current review lies on the contribution of empirical studies using natural or artificial sounds that enable separating acoustic and perceptual processing levels and avoid interference with existing category representations. Finally, we discuss the opportunities of modern analyses techniques such as multivariate pattern analysis (MVPA) in studying categorical sound representations. With their increased sensitivity to distributed activation changes—even in absence of changes in overall signal level—these analyses techniques provide a promising tool to reveal the neural underpinnings of perceptually invariant sound representations.

Highlights

How learning to abstract shapes neural sound representationsDespite the ease with which humans generally accomplish this task, the detection of relevant and invariant information in the complexity of the sensory input is not straightforward
SOUND PERCEPTION—MORE THAN TIME-FREQUENCY ANALYSIS Despite major advances in the past years to unravel the functional organization principles of the auditory system, the neural processes underlying sound perception are still far from being understood
In recent years, the phenomenon of perceptual categorization has stimulated a tremendous amount of research on the neural representation of perceptual sound categories in animals and humans

Summary

How learning to abstract shapes neural sound representations

Despite the ease with which humans generally accomplish this task, the detection of relevant and invariant information in the complexity of the sensory input is not straightforward This is reflected in the performance of artificial voice and speech recognition systems for human-computer interaction, that is far below that of humans, which is mainly due to the difficulty of dealing with the naturally occurring variability in speech signals (Benzeguiba et al, 2007). The need for perceptual abstraction in everyday functioning manifests itself in pathological conditions such as the autism spectrum disorder (ASD) To their susceptibility to more general cognitive deficits in abstract reasoning and concept formation (Minshew et al, 2002), individuals with ASD tend to show enhanced processing of detailed acoustic information while processing of more complex and socially relevant sounds such as speech may be diminished (reviewed in Ouimet et al, 2012). There is not a clear boundary between two phoneme categories such as www.frontiersin.org

Experience shapes neural sound representations

CONCLUSION