Abstract
The superior temporal sulcus (STS) in the left hemisphere is functionally diverse, with sub-areas implicated in both linguistic and non-linguistic functions. However, the number and boundaries of distinct functional regions remain to be determined. Here, we present new evidence, from meta-analysis of a large number of positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies, of different functional specificity in the left STS supporting a division of its middle to terminal extent into at least three functional areas. The middle portion of the left STS stem (fmSTS) is highly specialized for speech perception and the processing of language material. The posterior portion of the left STS stem (fpSTS) is highly versatile and involved in multiple functions supporting semantic memory and associative thinking. The fpSTS responds to both language and non-language stimuli but the sensitivity to non-language material is greater. The horizontal portion of the left STS stem and terminal ascending branches (ftSTS) display intermediate functional specificity, with the anterior-dorsal ascending branch (fatSTS) supporting executive functions and motor planning and showing greater sensitivity to language material, and the horizontal stem and posterior-ventral ascending branch (fptSTS) supporting primarily semantic processing and displaying greater sensitivity to non-language material. We suggest that the high functional specificity of the left fmSTS for speech is an important means by which the human brain achieves exquisite affinity and efficiency for native speech perception. In contrast, the extreme multi-functionality of the left fpSTS reflects the role of this area as a cortical hub for semantic processing and the extraction of meaning from multiple sources of information. Finally, in the left ftSTS, further functional differentiation between the dorsal and ventral aspect is warranted.
Highlights
The human superior temporal sulci occupy an important fraction of the temporal cortex, strategically located at the junction of major temporal—parietal and—frontal functional pathways
Functional neuroimaging data suggests that the left superior temporal sulcus (STS) can be divided along its anterior-to-posterior axis, with the left middle STS consistently associated with speech perception (Liebenthal et al, 2005; Obleser et al, 2007; Leaver and Rauschecker, 2010; DeWitt and Rauschecker, 2012) and more posterior areas associated with multiple functions including semantic processing (Dronkers et al, 2004), audiovisual integration (Calvert et al, 2001; Beauchamp, 2005), biological motion processing (Puce et al, 1998) and phonological processing (Wise et al, 2001; Buchsbaum et al, 2005; Liebenthal et al, 2010, 2013)
Note that in region of interest (ROI) 1, none of the categories survived the statistical threshold, likely due to a small number of activation peaks falling within this area. Based on these differences in functional specificity, we propose a division of the left STS into middle, posterior and terminal functional areas, labeled respectively f middle STS stem (mSTS), functional area in the left posterior STS (f pSTS), and f tSTS
Summary
The human superior temporal sulci occupy an important fraction of the temporal cortex, strategically located at the junction of major temporal—parietal and—frontal functional pathways. Portions of the superior temporal sulcus (STS) in each hemisphere have been assigned numerous specialized perceptual and cognitive functions (Hein and Knight, 2008). Structural and functional connectivity patterns to the inferior frontal cortex support a division of the superior temporal cortex into at least two, and perhaps three, segments that are part of functionally distinct anterior-ventral and posterior-dorsal streams for language processing (Frey et al, 2008; Saur et al, 2008; Rauschecker and Scott, 2009; Rauschecker, 2011; Turken and Dronkers, 2011), reminiscent of the dual stream model of auditory perception (Rauschecker and Tian, 2000). Previous studies of the STS have compared pairs of similar functions within a cognitive domain, such as for example voice and speech www.frontiersin.org
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
