Brain rhythms of language: nouns versus verbs.

Electrocortical activity was recorded from scalps of human subjects reading nouns and verbs. Current source density analysis of EEG signals and calculation of spectral responses revealed differences between word categories in the 30 Hz range. Verbs elicited stronger 30 Hz activity at recording sites over the motor cortices, while nouns elicited stronger responses at sites over visual cortices in the occipital lobes. Behavioural testing indicated that, at the cognitive level, this double dissociation corresponds to motor and visual associations prompted by verbal stimuli. These results suggest that local high-frequency brain responses can be indicators of conscious processing of motor and visual associations of verbal material. Furthermore, the results provide additional evidence that nouns and verbs have distinct neuronal generators in the intact human brain.