Аннотация:Meaning of action words is presumably acquired in the course of co-activation of cortical areas related to speech processing and motor control. We hypothesized that as a result of Hebbian coincidence learning, an attractor neural network may form, that could involve both forward and backward connections and thus induce activation of speech-related cortical areas during planning and initiation of the associated motor action.
On order to test this prediction, we recorded MEG in 28 adult subjects who were involved in a novel auditory-motor learning procedure. The participants were required to discover meaning of novel pseudowords by way of “trial-and-error” learning during one experimental session. Cortical sources of response-locked magnetic field were reconstructed using MNE software.
We found that in the course of such speech-motor learning, strong activation emerged in perisylvian areas, including STG/STS/MTG, posterior insula, and an area at the temporoparietal boundary. The effect was time-locked to the movement onset and lasted from -500 to -150 ms relative to the movement onset.
Our results demonstrate for the first time that experiential association between acoustically presented pseudowords and actions involves activation of speech-related cortical areas during action planning and initiation. Presumable, newly formed auditory-motor attractor neural networks induce recurrent reactivation of phonological and lexical circuits during planning and initiation of associated motor actions, thus likely promoting further increase in the strength and specificity of the association between newly learned pseudowords and corresponding actions.