Hierarchical and asymmetric temporal sensitivity in human auditory cortices

Abstract

Lateralization of function in auditory cortex has remained a persistent puzzle. Previous studies using signals with differing spectrotemporal characteristics support a model in which the left hemisphere is more sensitive to temporal and the right more sensitive to spectral stimulus attributes. Here we use single-trial sparse-acquisition fMRI and a stimulus with parametrically varying segmental structure affecting primarily temporal properties. We show that both left and right auditory cortices are remarkably sensitive to temporal structure. Crucially, beyond bilateral sensitivity to timing information, we uncover two functionally significant interactions. First, local spectrotemporal signal structure is differentially processed in the superior temporal gyrus. Second, lateralized responses emerge in the higher-order superior temporal sulcus, where more slowly modulated signals preferentially drive the right hemisphere. The data support a model in which sounds are analyzed on two distinct timescales, 25-50 ms and 200-300 ms.

Speech perception at the interface of neurobiology and linguistics

“…The evidence for a rightward asymmetry of slow integration is growing and the evidence for a leftward asymmetry of rapid integration is unsettled. Minimally, both hemispheres are equipped to deal with subtle temporal variation (Boemio et al 2005). (b) Functional lateralization as a consequence of temporal integration.…”

“…If distinct auditory cortical fields are found to be differentially sensitive to temporal information, such data would support the model that different time scales are processed in parallel. In a recent fMRI study, Boemio et al (2005) tested this hypothesis using non-speech signals that were constructed to closely match certain properties of speech signals. They observed that STG, bilaterally, is exquisitely sensitive to rapid temporal signals; however, right STS was preferentially driven by longer-duration signals, supporting the hypothesis that signals are not only processed on multiple time scales but also that the processing is partially lateralized, with slower signals differentially associated with right hemisphere mechanisms in higher-order auditory (and the canonical multisensory) area, STS.…”

“…20 Hz) temporal analyses. Naturally, multiresolution processing is but one of many relevant implementational issues, but it has received recent empirical support in both human and animal studies (Boemio et al 2005;Narayan et al 2006) and has interesting consequences for the architecture of the system; consequently we focus on that issue here. Multiresolution processing is widely observed in other systems (e.g.…”

Minding time in an amodal representational space

“…The aforementioned results challenge this notion and recent models have indeed made use of specifically sized temporal windows of integration for the analysis of speech signals (Poeppel 2003;Poeppel et al 2008), models that heavily rely on neuroimaging evidence (e.g. Boemio et al 2005). In this example, it is clearly the content of a temporal window that matters, not the temporal window itself, i.e.…”

Fragile Spectral and Temporal Auditory Processing in Adolescents with Autism Spectrum Disorder and Early Language Delay

“…In the general population, speech and language processing are largely lateralized to the left hemisphere, a specialization which is already apparent in infancy (e.g., Dehaene-Lambertz et al 2002). Several studies have linked hemispheric specialization for speech to an asymmetry in cortical auditory tuning and revealed that the auditory cortices are differentially sensitive to particular spectrotemporal features: slow acoustic amplitude modulations (3-7 Hz AM) and spectral aspects, like pitch, are preferentially processed in the right auditory cortex, whereas temporal aspects, like duration, rhythm and faster modulations (12-50 Hz AM), are more left lateralized (e.g., Boemio et al 2005;Jamison et al 2006;Poeppel 2003;Rosen et al 2011;Schönwiesner et al 2005;Zatorre and Belin 2001;Zatorre and Gandour 2008). Given that speech perception requires an accurate tracking of fast temporal cues, e.g., formant transitions (Schwartz and Tallal 1980), it seems natural that speech perception, and by extension linguistic processing, is lateralized to the left hemisphere (Telkemeyer et al 2009; but see Abrams et al 2008).…”