A Temporal Hierarchy for Conspecific Vocalization Discrimination in Humans

Abstract

The ability to discriminate conspecific vocalizations is observed across species and early during development. However, its neurophysiologic mechanism remains controversial, particularly regarding whether it involves specialized processes with dedicated neural machinery. We identified spatiotemporal brain mechanisms for conspecific vocalization discrimination in humans by applying electrical neuroimaging analyses to auditory evoked potentials (AEPs) in response to acoustically and psychophysically controlled nonverbal human and animal vocalizations as well as sounds of man-made objects. AEP strength modulations in the absence of topographic modulations are suggestive of statistically indistinguishable brain networks. First, responses were significantly stronger, but topographically indistinguishable to human versus animal vocalizations starting at 169 -219 ms after stimulus onset and within regions of the right superior temporal sulcus and superior temporal gyrus. This effect correlated with another AEP strength modulation occurring at 291-357 ms that was localized within the left inferior prefrontal and precentral gyri. Temporally segregated and spatially distributed stages of vocalization discrimination are thus functionally coupled and demonstrate how conventional views of functional specialization must incorporate network dynamics. Second, vocalization discrimination is not subject to facilitated processing in time, but instead lags more general categorization by ϳ100 ms, indicative of hierarchical processing during object discrimination. Third, although differences between human and animal vocalizations persisted when analyses were performed at a single-object level or extended to include additional (man-made) sound categories, at no latency were responses to human vocalizations stronger than those to all other categories. Vocalization discrimination transpires at times synchronous with that of face discrimination but is not functionally specialized.

The animal nature of spontaneous human laughter

“…No previous research to our knowledge has examined judgments of whether stimuli were produced by human or nonhuman animals, but neuroimaging work has examined cerebral responses to nonhuman animal vocalizations relative to a variety of other stimuli including human voices (e.g., Lewis, Brefczynski, Phinney, Janik, & DeYoe, 2005;Altmann, Doehrmann, & Kaiser, 2007;Belin et al, 2008). De Lucia, Clarke, andMurray (2010) found that human and nonhuman animal vocalizations elicited early responses in statistically indistinguishable brain networks.…”

Balanced bilinguals favor lexical processing in their opaque language and conversion system in their shallow language

“…The solution space included 3005 nodes, selected from a 6 Â 6 Â 6 mm grid equally distributed within the gray matter of the averaged brain of the Montreal Neurological Institute (MNI; courtesy of Grave de Peralta Menendez and Gonzalez Andino, University Hospital of Geneva, Geneva, Switzerland). In order to control for multiple comparisons, only solutions with a minimal cluster size of 15 consecutive points (k E ) were retained (see also De Lucia, Clarke, & Murray, 2010;Knebel & Murray, 2012).…”

Looming Signals Reveal Synergistic Principles of Multisensory Integration

“…The optimal number of temporally stable ERP clusters (i.e., the minimal number of maps that accounts for the greatest variance of the dataset) was determined using a modified Krzanowski-Lai criterion (Murray et al, 2008). The clustering makes no assumption on the orthogonality of the derived template maps (Pourtois et al, 2008;De Lucia et al, 2010). Template maps identified in the group-average ERP were then submitted to a fitting procedure wherein each time point of each single-subject ERP is labeled according to the template map with which it best correlated spatially (Murray et al, 2008) so as to statistically test the presence of each map in the moment-by-moment scalp topography of the ERP and the differences in such across conditions.…”