Figure 1.
Brain maps from a range of studies implicating a dorsal precentral gyrus region in speech processing (red arrows). (A) PET study showing activation associated with repeating words minus saying ‘crime’ after hearing a reversed word.27 (B) Functional MRI study showing activation associated with both auditory (listening to nonsense sentences) and motor (silently rehearsing nonsense sentences) speech.29 (C) Functional MRI study showing activation associated with listening to syllables (heat map) and producing the same syllables (outline).28 (D) Myelin (left) and functional MRI task activation (right) map from the Human Connectome Project database showing area 55b.37 (E) Schematic diagram of the dual stream model of speech processing showing two frontal regions associated motor speech-related processes.35