Neural mechanisms of empathy in humans: a relay from neural systems for imitation to limbic areas

Abstract

How do we empathize with others? A mechanism according to which action representation modulates emotional activity may provide an essential functional architecture for empathy. The superior temporal and inferior frontal cortices are critical areas for action representation and are connected to the limbic system via the insula. Thus, the insula may be a critical relay from action representation to emotion. We used functional MRI while subjects were either imitating or simply observing emotional facial expressions. Imitation and observation of emotions activated a largely similar network of brain areas. Within this network, there was greater activity during imitation, compared with observation of emotions, in premotor areas including the inferior frontal cortex, as well as in the superior temporal cortex, insula, and amygdala. We understand what others feel by a mechanism of action representation that allows empathy and modulates our emotional content. The insula plays a fundamental role in this mechanism.

Figure 1

Peaks of activations in the right central (labeled M1) and precentral (labeled PMC) sulcus. The peak labeled M1 (x = 44, y = −10, z = 36) corresponds entirely (considering spatial resolution and variability factors) with meta-analytic PET data (x = 48 ± 5.2, y = −9 ± 5.6, z = 35 ± 5.5) for the mouth region of human primary motor cortex. The peak labeled PMC (x = 48, y = 8, z = 28) corresponds well with previously reported premotor mouth (x = 48, y = 0, z = 32) peaks.

Figure 2

Time-series of peaks of activity in right central (M1) and precentral (PMC) sulcus shown in Fig. 1. Task-related activity is observable not only during imitation but also during observation of emotional facial expressions, especially in PMC.

Figure 3

Activations in the right insula (green) and right (blue) and left (red) inferior frontal cortex. Relative time-series are coded with the corresponding colors. The time-series have been normalized to the overall activity of each region. The activity profile of these three regions is extremely similar throughout the whole series of tasks.

Figure 4

Significantly increased activity in the right amygdala during imitation of emotional facial expressions compared with simple observation.