Neural activation for conceptual identification of correct versus incorrect tool-object pairs.

Appropriate tool-object pairing is a natural part of our lives. When preparing to clean our teeth, we know that a toothbrush is useful, but not a screwdriver. The neural correlates of this pairing process remain unclear. We recorded 64-channel electroencephalography to determine neural correlates of identification of tool-object matches and mismatches. Subjects were shown a target tool (e.g. spoon) later paired with an object that was either a conceptual match (e.g. bowl) or mismatch (e.g. wood). To verify that activity was not related to general concept of match-mismatch, in a second condition subjects saw non-tool environmental items (e.g. bird) later paired with a conceptual match (e.g. nest) or mismatch (e.g. spider web). Analysis was focused on time bins after each picture, using standardized low-resolution brain electromagnetic tomography (sLORETA). Tool-object match versus mismatch revealed significant differences in the posterior cingulate, precuneus, left insula and superior temporal gyrus. These patterns were not present for environmental match versus mismatch. This work suggests a specific network in comprehending tool-based pairings, but not extensive to other pairings. The posterior cingulate, precuneus, insula and superior temporal gyrus preferentially differentiates tool-object matching and mismatching, identifying a potential locus related to impairments in comprehending appropriate and inappropriate tool-object relationships that arise after neural injury.