The role of the left posterior temporal cortex in speech monitoring

Speech monitoring abilities vary among individuals with stroke-induced aphasia, with brain lesion location as a potential factor. Left posterior temporal cortex (pLTC) regions are thought to be central to lexical access. We tested whether pLTC lesions affect the medial frontal action monitoring system, as indexed by the Error-Related Negativity (ERN), which has been implicated in inner speech monitoring. Electroencephalography was recorded during picture naming in 11 individuals with pLTC lesions (4 from each of two institutions included in EEG analyses), 7 with lesions sparing the pLTC (6 included), and 20 matched controls (14 included). Individuals with pLTC lesions were slower and less accurate than other groups. Individuals with lesions sparing the pLTC showed the expected ERN; individuals with pLTC lesions did not. Therefore, the medial frontal monitoring mechanism may be compromised when regions central to lexical access are damaged, indicating that pLTC-medial frontal interactions may support inner speech monitoring.