Early influences of word length and frequency: a group study using MEG.

In what way are linguistic word properties reflected in the neurophysiological brain response? During a memory task we presented written words orthogonally varied in length (long, short) and frequency (high, low). Brain responses of 15 subjects were recorded using a 148-channel magnetoencephalogram. Very early after stimulus onset (60 ms), long words led to significantly stronger activation than short words, as revealed by the global field power (GFP). Later on, low frequency words led to stronger brain responses than high frequency words. This effect depended on word length: it was seen 120-170 ms after stimulus onset, for short words only, but at 225-250 ms exclusively for long words. Source localisation revealed that effects due to word length were pronounced over occipital areas whereas frequency effected more widespread cortical areas with a strong focus over left occipitotemporal areas (visual word form areas).