Matchin, Hammerly and Lau in Cortex
Poke into Cortex for "The role of the IFG and pSTS in syntactic prediction," from postdoc William Matchin, Baggett Christopher Hammerly, and their mentor Ellen Lau. The paper raises questions about several neuroimaging experiments that have interpreted activation in the left inferior frontal gyrus (IFG) and posterior superior temporal sulcus (pSTS) as expressive of basic syntactic combination in comprehension. Based on a new fMRI experiment, it provides support for an alternative hypothesis: these regions instead underlie top-down syntactic predictions that facilitate sentence processing but are not necessary for building syntactic structure. The experiment reveals increased activity for both natural and jabberwocky sentences in the left IFG (pars triangularis and pars orbitalis) and pSTS relative to unstructured word lists and two-word phrases, but does not show any such effects for two-word phrases relative to unstructured word lists in these areas. This is most consistent, the authors argue, with the hypothesis that increased activity in IFG and pSTS for basic contrasts of structure reflects syntactic prediction, rather than construction.