Thursday, March 22, 2012

Beyond mirror neurons - the neuroscience of real social encounters

A recent draft manuscript by Schilbach et al (PDF) has a nice summary of what a second-person neuroscience would be like, moving beyond spectator theories of knowledge:
Two neuroanatomically distinct large-scale networks have gained center stage as the neural substrates of social cognition: the so-called “mirror neuron system” and the “mentalizing network” . both of these paradigms are investigating actual, but limited domains of social cognition. Both are, in effect, committed to spectator theories of knowledge. They have focused on the use of isolation paradigms in which participants are required to merely observe others or think about their mental states rather than participate in social interaction with them. Consequently, it has remained unclear whether and how activity in the large-scale neural networks described above is modulated by the degree to which a person does or does not feel actively involved in an ongoing interaction and whether the networks might subserve complementary or mutually exclusive roles in this case
The article outlines work from his and other laboratories on brain imaging done during real time human interactions, noting in particular a ground-breaking study by Saito et al., who have devised a setup in which they not only use hyper-scanning, but also allow participants to interact in real-time by exchanging gaze behavior. Two MRI scanners were equipped with infrared eyetracking systems and video cameras. A live video image of the respective interaction partner’s face could be broadcast into the respective other scanner to generate a mediated face-to-face situation.

Here is the summary from Saito et al.:
Eye contact provides a communicative link between humans, prompting joint attention. As spontaneous brain activity might have an important role in the coordination of neuronal processing within the brain, their inter-subject synchronization might occur during eye contact. To test this, we conducted simultaneous functional MRI in pairs of adults. Eye contact was maintained at baseline while the subjects engaged in real-time gaze exchange in a joint attention task. Averted gaze activated the bilateral occipital pole extending to the right posterior superior temporal sulcus, the dorso-medial prefrontal cortex, and the bilateral inferior frontal gyrus. Following a partner’s gaze toward an object activated the left intraparietal sulcus. After all the task-related effects were modeled out, inter-individual correlation analysis of residual time-courses was performed. Paired subjects showed more prominent correlations than non-paired subjects in the right inferior frontal gyrus, suggesting that this region is involved in sharing intention during eye contact that provides the context for joint attention.

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