Semantic priming increases left hemisphere theta power and intertrial phase synchrony

Information is stored in distributed cortical networks, but it is unclear how distributed stores are synthesized into a unified percept. Activation of local circuits in the gamma range (30 < < 80 Hz), and distributed stores in the low theta range (3-5 Hz) may underlie perceptual binding. Words have a crucial role in semantic memory. Within memory, the activation of distributed semantic stores is facilitated by conceptually related previous items, termed semantic priming. We sought to detect event-related brain oscillations (EROs) sensitive to semantic activation and priming. Here, we show that low theta evoked power and intertrial phase locking (4-5 Hz) from 250-350 msec over left hemisphere language areas was greater to related than to unrelated words. Theta band event-related oscillations over left hemisphere language areas may provide a brain signature for semantic activation across distributed stores being facilitated by semantic priming.