Modeling the meaning of words: neural correlates of abstract and concrete noun processing.

We present a model relating analysis of abstract and concrete word meaning in terms of semantic features and contextual frames within a general framework of neurocognitive information processing. The approach taken here assumes concrete noun meanings to be intimately related to sensory feature constellations. These features are processed by posterior sensory regions of the brain, e.g. the occipital lobe, which handles visual information. The interpretation of abstract nouns, however, is likely to be more dependent on semantic frames and linguistic context. A greater involvement of more anteriorly located, perisylvian brain areas has previously been found for the processing of abstract words. In the present study, a word association test was carried out in order to compare semantic processing in healthy subjects (n=12) with subjects with aphasia due to perisylvian lesions (n=3) and occipital lesions (n=1). The word associations were coded into different categories depending on their semantic content. A double dissociation was found, where, compared to the controls, the perisylvian aphasic subjects had problems associating to abstract nouns and produced fewer semantic framebased associations, whereas the occipital aphasic subject showed disturbances in concrete noun processing and made fewer semantic feature based associations.