This study investigated cognitive and neural processes involved
in gap filling during on-line sentence comprehension.
Electroencephalogram (EEG) coherences were used to demonstrate
that increases in the synchronization of neural activity in
different cortical regions occur during gap filling when load
in semantic working memory is high due to semantically unrelated
words in the filler-gap interval. Sentences could either require
gap filling at a verb or not, and the nouns preceding the verb
could be either semantically related or unrelated. In the unrelated
but not related condition, coherences in the beta band were
larger during verb processing for sentences requiring gap filling
compared to sentences not requiring gap filling. The coherence
changes involved linkages between frontal and posterior
temporal-parietal sites in both hemispheres. These results further
indicate that semantic working memory is involved in the process
of gap filling.