Neural dynamics of grip and goal integration during the processing of others' actions with objects: An ERP study

Abstract

Recent behavioural evidence suggests that when processing others' actions, motor acts and goal-related information both contribute to action recognition. Yet the neuronal mechanisms underlying the dynamic integration of the two action dimensions remain unclear. This study aims to elucidate the ERP components underlying the processing and integration of grip and goal-related information. The electrophysiological activity of 28 adults was recorded during the processing of object-directed action photographs (e.g., writing with pencil) containing either grip violations (e.g. upright pencil grasped with atypical-grip), goal violations (e.g., upside-down pencil grasped with typical-grip), both grip and goal violations (e.g., upside-down pencil grasped with atypical-grip), or no violations. Participants judged whether actions were overall typical or not according to object typical use. Brain activity was sensitive to the congruency between grip and goal information on the N400, reflecting the semantic integration between the two dimensions. On earlier components, brain activity was affected by grip and goal typicality independently. Critically, goal typicality but not grip typicality affected brain activity on the N300, supporting an earlier role of goal-related representations in action recognition. Findings provide new insights on the neural temporal dynamics of the integration of motor acts and goal-related information during the processing of others' actions.

Figure 1

(A) ERP as a function of Grip typicality and Goal-typicality at the posterior site. Ribbons represent standard errors. (B) Mean estimates of the main effect of grip-typicality (yellow bar), main effect of goal-typicality (blue bar) and Grip x Goal interaction (green bar), for the P100, N170 and P300 components. Error bars represent standard errors. *p < 0.05; ***p < 0.001.

Figure 2

(A) ERP as a function of Grip typicality and Goal-typicality at the anterior site. The green font represents the time-window of the N300 component. The orange font represents the time-window of the N400 component. Ribbons represent standard errors. (B) Mean estimates of the main effect of grip-typicality (yellow bar), main effect of goal-typicality (blue bar) and Grip x Goal interaction (green bar), for the N300 and N400 components. Error bars represent standard errors. *p < 0.05; **p < 0.01; ***p < 0.001.

Figure 3

Design and procedure of the experiment. (A) Stimuli were divided in four experimental conditions by manipulating the typicality of the grip and the goal of the action. A fifth neutral condition was added as a control of object information. (B) Procedure on a given trial. Responses were prompted for only 12% of the trials.

Figure 4

(A) Scalp map distribution corresponding to the two identified time-regions. Bold circles indicate the electrodes that have been averaged to obtain the mean amplitude of the P100, N170 and P300 respectively. (B) Grand average ERP at the posterior site.

Figure 5

(A) Scalp map distribution corresponding to the two identified time-regions. Bold circles indicate the electrodes that have been averaged to obtain the mean amplitude of the N300 and N400 respectively. (B) Grand average ERP at the anterior site.