02409nas a2200217   4500008004100000022001400041245012900055210006900184260000800253300001300261490000700274520171000281100002701991700002502018700002402043700002002067700001902087700001802106700001902124856004802143       2016                        eng d  a1932-620300aSpatio-Temporal Progression of Cortical Activity Related to Continuous Overt and Covert Speech Production in a Reading Task.0 aSpatioTemporal Progression of Cortical Activity Related to Conti  cNov  ae01668720 v113 aHow the human brain plans, executes, and monitors continuous and fluent speech has remained largely elusive. For example, previous research has defined the cortical locations most important for different aspects of speech function, but has not yet yielded a definition of the temporal progression of involvement of those locations as speech progresses either overtly or covertly. In this paper, we uncovered the spatio-temporal evolution of neuronal population-level activity related to continuous overt speech, and identified those locations that shared activity characteristics across overt and covert speech. Specifically, we asked subjects to repeat continuous sentences aloud or silently while we recorded electrical signals directly from the surface of the brain (electrocorticography (ECoG)). We then determined the relationship between cortical activity and speech output across different areas of cortex and at sub-second timescales. The results highlight a spatio-temporal progression of cortical involvement in the continuous speech process that initiates utterances in frontal-motor areas and ends with the monitoring of auditory feedback in superior temporal gyrus. Direct comparison of cortical activity related to overt versus covert conditions revealed a common network of brain regions involved in speech that may implement orthographic and phonological processing. Our results provide one of the first characterizations of the spatiotemporal electrophysiological representations of the continuous speech process, and also highlight the common neural substrate of overt and covert speech. These results thereby contribute to a refined understanding of speech functions in the human brain.1 aBrumberg, Jonathan, S.1 aKrusienski, Dean, J.1 aChakrabarti, Shreya1 aGunduz, Aysegul1 aBrunner, Peter1 aRitaccio, A L1 aSchalk, Gerwin  uhttp://www.ncbi.nlm.nih.gov/pubmed/27875590