The Dyadic EEG study, a collaboration with the Swartz Center for Computational Neuroscience, is the first investigation of EEG and motion dynamics of toddler-parent dyads during ‘free’ social interactions. We are collecting high-density EEG on toddlers and parents as they play turn-taking, attention-sharing, or language games on a touch-screen table. This allows us to assess fast-changing rhythmic patterns generated by each partner’s brain while they act and when they react to their partner’s action. Why are we doing this?
Toddlers are undergoing profound changes in their thinking and social behaviors, as well as their brain organization. Little is known about how these factors are related. By relating toddlers’ brain activity to their precise behaviors and to the behaviors of their partner during a social interaction, we can learn much more about how the developing brain supports social development.
We found that 3-year-old children show a socially-relevant EEG phenomenon, called mu-suppression, when playing a turn-taking game with their moms. Mu-suppression is a reduction in power, at the scalp, of oscillating voltage in the frequency range 6-9 Hz, called the ‘mu band’ (because the waves sort of look like the Greek letter μ). In adults, mu-suppression is generated by sources around central sulcus, between primary motor and somatosensory cortices. These sources respond to either: (1) producing a deliberate action, or (2) watching someone else produce an action. So mu suppression reflects our ability to relate our own actions to other peoples’ similar actions. This might be an important sign that young children are making sense of other people’s behaviors. In our lab, Liao, Acer, Makeig, and Deák (2012) found that 3-year-olds show significant mu-suppression not only while taking their turns in a game, but also while watching their parent take turns. Moreover, we showed (1) all properties of mu-suppression documented in adults; (2) the most likely source locations of mu suppression were between somatosensory and motor cortex – where you would expect them in adults – but using a model of 3-year-olds’ brains. We are continuing this challenging line of research!