Distinct processing of function verb categories in the human brain

A subset of German function verbs can be used either in a full, concrete, 'heavy' ("take a computer") or in a more metaphorical, abstract or 'light' meaning ("take a shower", no actual 'taking' involved). The present magnetoencephalographic (MEG) study explored whether this subset of 'light' verbs is represented in distinct cortical processes. A random sequence of German 'heavy', 'light', and pseudo verbs was visually presented in three runs to 22 native German speakers, who performed lexical decision task on real versus pseudo verbs. Across runs, verbs were presented (a) in isolation, (b) in minimal context of a personal pronoun, and (c) 'light' verbs only in a disambiguating context sentence. Central posterior activity 95-135 ms after stimulus onset was more pronounced for 'heavy' than for 'light' uses, whether presented in isolation or in minimal context. Minimal context produced a similar heavy>light differentiation in the left visual word form area at 160-200 ms. 'Light' verbs presented in sentence context allowing only for a 'heavy reading' evoked larger left-temporal activation around 270-340 ms than the corresponding 'light reading'. Across runs, real verbs provoked more pronounced activation than pseudo verbs in left-occipital regions at 110-150 ms. Thus, 'heavy' versus 'light readings' of verbs already modulate early posterior visual evoked response even when verbs are presented in isolation. This response becomes clearer in the disambiguating contextual condition. This type of study shows for the first time that language processing is sensitive to representational differences between two readings of one and the same verb stem.