Fig. 4

Cortical pathways for speech motor control and proposed dorsal stream pathway involved in beat-based processing. A Hickok et al. s dual speech coordination system model [85] (cf. Fig. 3) with the proposed dorsal stream pathway involved in beat processing superimposed [71]. This pathway is schematically shown as two lines connecting to inferior parietal cortex in the vicinity of angular gyrus (AG). The red line connects auditory regions in poterior superior temporal gyrus to this inferior parietal region, and the orange line connects this inferior parietal region to dorsal premotor regions. Area Spt (Sylvian parietal-temporal cortex), a sensorimotor region involved in both speech and music, is indicated by a small green circle for reference. (Locations of AG and Spt in this figure are approximate and were kindly provided by Greg Hickok, who notes that Spt is mostly located within the Sylvian fissure at its posterior-most extent and is difficult to see in a lateral reconstruction.) The red and orange lines in A are suggested to be part of known brain pathways shown in (B), based on a review of the neuroanatomy of language by Edward Chang and colleagues [109]. Specifically, the solid red line in (A) is proposed to be part of the temporo-parietal branch of the superior longitudinal fasciculus (SLF-tp, red lines in B), and the solid orange line in (A) is proposed to be part of the second branch of the superior longitudinal fasciculus (SLF-II, orange lines in B)