The neural correlates of 'vitality form' recognition: an fMRI study: this work is dedicated to Daniel Stern, whose immeasurable contribution to science has inspired our research

Abstract

The observation of goal-directed actions performed by another individual allows one to understand what that individual is doing and why he/she is doing it. Important information about others' behaviour is also carried out by the dynamics of the observed action. Action dynamics characterize the 'vitality form' of an action describing the cognitive and affective relation between the performing agent and the action recipient. Here, using the fMRI technique, we assessed the neural correlates of vitality form recognition presenting participants with videos showing two actors executing actions with different vitality forms: energetic and gentle. The participants viewed the actions in two tasks. In one task (what), they had to focus on the goal of the presented action; in the other task (how), they had to focus on the vitality form. For both tasks, activations were found in the action observation/execution circuit. Most interestingly, the contrast how vs what revealed activation in right dorso-central insula, highlighting the involvement, in the recognition of vitality form, of an anatomical region connecting somatosensory areas with the medial temporal region and, in particular, with the hippocampus. This somatosensory-insular-limbic circuit could underlie the observers' capacity to understand the vitality forms conveyed by the observed action.

Keywords: action observation; fMRI; insula; social cognition; vitality form.

Fig. 1

Example of video-clips as viewed by the participants of this study. (A1) Frame representing an action without object in the start position; (A2) frame representing the actress executing a stop gesture; (B1) frame representing an action with object in the start position; (B2) frame representing the actor executing an action with object in the end position (passing a bottle).

Fig. 2

Kinematic and dynamic profiles associated with one of the actions (passing a bottle) performed by the female actress with the two vitality forms (gentle; energetic). (A) Velocity profiles (y-axes) and duration (x-axes). (B) Trajectories (gentle, green line; energetic, red line). (C) Potential energy (blue line), that is the energy that the actress gave to the object during the lifting phase of the action; kinetic energy (red line), that is the energy that the actress gave to the object to move it with a specific velocity from the start to the end point. (D) Power required to perform the action on the object in an energetic (blue solid line) and gentle (blue dashed line) vitalities. As it can be observed in the graphs, the vitality forms gentle and energetic generally differ from each other on each of the tested parameters.

Fig. 3

Signal change during (A) the task what and (B) the task how vs implicit baseline (fixation cross). Signal change during (C) the task what and (D) the task how vs explicit baseline (static controls). The activations (P_FWE < 0.05 at vxl level) are rendered into a standard MNI brain template.

Fig. 4

Brain activations resulting from the direct contrast between (A) what vs how task and (B) how vs what task. These activations (P_FWE < 0.05 at cluster level) are rendered into a standard MNI brain template. (C) Activation profile within right dorso-central insula (maxima: 34 12 12) in the direct contrast how vs what task. (D) Activation profile in dorso-central insula (maxima: 34 12 12) as a function of vitality form (energetic, gentle) during how task (E) Activation profile in dorso-central insula (maxima: 34 12 12) as a function of action-type (with object, without object) during how task. (F) Percent correct responses (hits) during discrimination of what (is it the same or a different type of action?) and how (is it the same or a different form of vitality?) within each respective task, showing no differences in performance difficulty between tasks (P > 0.05).