Discoveries about the brain mechanisms involved in language processing

Language and memory have traditionally been studied as separate constructs that are supported by distinct networks of brain structures. However, work by researchers in the Language Program and others, suggest that current models of the language network may have to be expanded to include the hippocampus – an integral component of the memory system. Unfortunately, the hippocampus has long been considered inaccessible to non-invasive electrophysiological measurements because of its deep location. Associate Professor Blake Johnson and colleagues ran a set of experimental studies demonstrating that the human hippocampus can be measured non-invasively using magnetoencephalography (Pu, Cornwell, Cheyne, & Johnson, 2017). In these studies, human participants played a video game in which they navigated through a virtual maze, analogous to a spatial memory task that activated the hippocampi of rodents. The first finding was that activation of the hippocampus in humans was strongly correlated with how well participants performed on the maze task. Two subsequent studies applied ‘deep source imaging’ to language processing. Results showed hippocampal activation when participants read semantically incongruent sentences whereas no hippocampal response was seen with syntactically incongruent sentences. Taken together, the findings open a new window for non-invasive studies of the human hippocampus and lay the foundation for future studies which incorporate the hippocampus as a crucial component of the language apparatus.