Towards the neural basis of joint attention

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Attention allows us to select particular aspects of information impinging on our sensory systems, to bring them to consciousness and to choose appropriate behavioural responses. Attention can be attracted by salient sensory features or, conversely, it can be allocated endogenously, guided by prior experience, expectations or conscious decisions. Social signals such as eye or head orientation are a particularly powerful class of sensory cues guiding attention. They allow us to define objects of common interest, objects of joint attention, a key step in developing a theory of (the other ones) mind. Our work on humans and rhesus monkeys in the preceding funding period has allowed us to establish that gaze following activates a distinct cortical region (the gaze following patch) in the posterior superior temporal sulcus in very similar locations in both species. Our comparative psychophysical work on gaze following in monkeys and man has established that in both shifts of attention guided by gaze cues occur very fast and cannot be fully controlled, even though gaze following may be vetoed by the context. Considering the fact that gaze following behaviour is known to emerge early during development in both human and non-human primates, we may conclude that gaze following is a domain-specific faculty. The strong similarities moreover suggest a homologous faculty. The findings obtained in the preceding funding period clearly suggest that the gaze following patch (GFP) plays a central and, moreover, highly specific role in orchestrating gaze following behaviour. Yet, this conclusion is so far solely based on correlational data (fMRI, single unit and local field potential recordings). We therefore plan to carry out experiments using reversible activation/deactivation with microstimulation, muscimol injections and optogenetic silencing in monkeys in order to establish a causal role of the GFP in gaze following and to work out the contribution of the neighbouring middle face patch (mFP).