Neural correlates of naming actions and of naming spatial relations

In a [O-15] water PET experiment, 10 normal subjects retrieved words denoti ng actions (performed with or without an implement), and another 10 normal subjects retrieved words denoting the spatial relations between objects, Ou r objective was to test the following hypothesis: that the salient neural a ctivity associated with naming actions and spatial, relations occurs in lef t frontal operculum and left parietal association cortices, but not in the left inferotemporal cortices (IT) or in the right parietal association cort ices. There were two control tasks, one requiring a decision on the orienta tion of unknown faces (a standard control task in our laboratory) and anoth er requiring the retrieval of words denoting the concrete entities used in the action and spatial relations tasks. In accordance with the hypothesis, both naming actions and spatial relations (using the face orientation task as control activated the left frontal operculum; naming actions also activa ted the left parietal lobe, However, sectors of the left posterior IT were also engaged in both naming actions and spatial relations, When the naming of concrete entities was subtracted from the naming of actions performed wi th such entities, area MT in the posterior temporo-occipital region was act ivated bilaterally, On the other hand, when naming of the concrete entities was subtracted from the naming of spatial relations, left parietal activat ion was found, and when two tasks of naming spatial relations were contrast ed to each other bilateral parietal activation was seen, right when abstrac t stimuli were used and left when concrete objects were used. The activity in posterior IT is thought to be related to object processing and possibly name retrieval at a subconscious level, (C) 2001 Academic Press.