title: Divergent Human Cortical Regions for Processing Distinct Acoustic-Semantic Categories of Natural Sounds: Animal Action Sounds vs. Vocalizations.
abstract: A major gap in our understanding of natural sound processing is knowledge of where or how in a cortical hierarchy differential processing leads to categorical perception at a semantic level. Here, using functional magnetic resonance imaging (fMRI) we sought to determine if and where cortical pathways in humans might diverge for processing action sounds vs. vocalizations as distinct acoustic-semantic categories of real-world sound when matched for duration and intensity. This was tested by using relatively less semantically complex natural sounds produced by non-conspecific animals rather than humans. Our results revealed a striking double-dissociation of activated networks bilaterally. This included a previously well described pathway preferential for processing vocalization signals directed laterally from functionally defined primary auditory cortices to the anterior superior temporal gyri, and a less well-described pathway preferential for processing animal action sounds directed medially to the posterior insulae. We additionally found that some of these regions and associated cortical networks showed parametric sensitivity to high-order quantifiable acoustic signal attributes and/or to perceptual features of the natural stimuli, such as the degree of perceived recognition or intentional understanding. Overall, these results supported a neurobiological theoretical framework for how the mammalian brain may be fundamentally organized to process acoustically and acoustic-semantically distinct categories of ethologically valid, real-world sounds.
authors.affiliation: Blanchette Rockefellar Neurosciences Institute, Department of Neurobiology & Anatomy, West Virginia University Morgantown, WV, USA.
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Webster
authors.affiliation: Blanchette Rockefellar Neurosciences Institute, Department of Neurobiology & Anatomy, West Virginia UniversityMorgantown, WV, USA; Department of Neurology, Georgetown University Medical CampusWashington, DC, USA.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Skipper-Kallal
authors.affiliation: Department of Physiology and Pharmacology, West Virginia University Morgantown, WV, USA.
authors.forename: Chris A
authors.initials: CA
authors.lastname: Frum
authors.affiliation: Blanchette Rockefellar Neurosciences Institute, Department of Neurobiology & Anatomy, West Virginia University Morgantown, WV, USA.
authors.forename: Hayley N
authors.initials: HN
authors.lastname: Still
authors.affiliation: Department of Biophysics, Medical College of Wisconsin Milwaukee, WI, USA.
authors.forename: B Douglas
authors.initials: BD
authors.lastname: Ward
authors.affiliation: Blanchette Rockefellar Neurosciences Institute, Department of Neurobiology & Anatomy, West Virginia University Morgantown, WV, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Lewis
keywords: acoustic communication; auditory system pathways; fMRI; grounded cognition; mirror neuron system