The social brain: neural basis of social knowledge

Abstract

Social cognition in humans is distinguished by psychological processes that allow us to make inferences about what is going on inside other people-their intentions, feelings, and thoughts. Some of these processes likely account for aspects of human social behavior that are unique, such as our culture and civilization. Most schemes divide social information processing into those processes that are relatively automatic and driven by the stimuli, versus those that are more deliberative and controlled, and sensitive to context and strategy. These distinctions are reflected in the neural structures that underlie social cognition, where there is a recent wealth of data primarily from functional neuroimaging. Here I provide a broad survey of the key abilities, processes, and ways in which to relate these to data from cognitive neuroscience.

Figure 1

Is social cognition special? Debates about the modularity of social information processing often revolve around the two dimensions shown in this schematic: Is the specialization at the level of processing algorithms (functional specialization) or at the level of the type of information being processed (stimulus selectivity)? A mechanism might be functionally monolithic and apply to a restricted set of stimuli (region 1) or applicable to a large domain of different kinds of stimuli (region 2). Alternatively, a mechanism might contribute to several distinct processes, but in the service of processing either a restricted stimulus class (region 3) or many (region 4). (Modified from Atkinson et al. 2008, Wheeler & Atkinson 2001.)

Figure 2

Figure 2a: Processes and brain structures involved in social cognition. Brain structures involved. This is, of course, an incomplete list and emphasizes those structures discussed in the review and outlined in Figure 2b (see color insert). (Top left) A right lateral view of a brain that shows somatosensory cortices and superior temporal gyrus regions; roughly between them and posterior would be the temporoparietal junction, which is not shaded to preserve clarity of the figure. (Top right) Left prefrontal regions are also involved in making personality attributions to others, and indicated again here is the superior temporal gyrus, involved in processes such as biological motion. Below these images are a picture of the insula, revealed when the frontal operculum is removed, and below that, a ventral view of the brain showing medial prefrontal cortex (in this ventral view, medial orbitofrontal cortex) and, more posteriorly, the fusiform gyrus, involved in face processing. Below that, a medial view of the right hemisphere shows the anterior cingulate and again the medial prefrontal cortex. If one takes a coronal section along the line indicated, this cut reveals the amygdala in the medial temporal lobe (very bottom image). Figure 2b: The schematic outlines a set of processes related more to emotion and empathic simulation (yellow and red boxes, left), and a set of processes related to detailed perception of faces, biological motion, and theory of mind (blue boxes, right). Although there are many examples of processes from the list on the left being distinct from, or in opposition to, processes from the list on the right, the two often complement one another and come into play concurrently. All boxes can be modulated by controlled processing and context, although the extent of this is greatest for the more central processes (different shading of arrows, right). This schematic omits the substantial cross-talk between all of the boxes shown as well as the important role of feedback from “higher” to “lower” structures, part of which is encompassed by the self-regulation and reappraisal modulations (black arrows). (Modified from Adolphs 2003, Adolphs & Spezio 2008.)

Figure 2

Figure 2a: Processes and brain structures involved in social cognition. Brain structures involved. This is, of course, an incomplete list and emphasizes those structures discussed in the review and outlined in Figure 2b (see color insert). (Top left) A right lateral view of a brain that shows somatosensory cortices and superior temporal gyrus regions; roughly between them and posterior would be the temporoparietal junction, which is not shaded to preserve clarity of the figure. (Top right) Left prefrontal regions are also involved in making personality attributions to others, and indicated again here is the superior temporal gyrus, involved in processes such as biological motion. Below these images are a picture of the insula, revealed when the frontal operculum is removed, and below that, a ventral view of the brain showing medial prefrontal cortex (in this ventral view, medial orbitofrontal cortex) and, more posteriorly, the fusiform gyrus, involved in face processing. Below that, a medial view of the right hemisphere shows the anterior cingulate and again the medial prefrontal cortex. If one takes a coronal section along the line indicated, this cut reveals the amygdala in the medial temporal lobe (very bottom image). Figure 2b: The schematic outlines a set of processes related more to emotion and empathic simulation (yellow and red boxes, left), and a set of processes related to detailed perception of faces, biological motion, and theory of mind (blue boxes, right). Although there are many examples of processes from the list on the left being distinct from, or in opposition to, processes from the list on the right, the two often complement one another and come into play concurrently. All boxes can be modulated by controlled processing and context, although the extent of this is greatest for the more central processes (different shading of arrows, right). This schematic omits the substantial cross-talk between all of the boxes shown as well as the important role of feedback from “higher” to “lower” structures, part of which is encompassed by the self-regulation and reappraisal modulations (black arrows). (Modified from Adolphs 2003, Adolphs & Spezio 2008.)

Figure 3

Abstract functions of the amygdala contribute to social perception. Bilateral amygdala lesions impair the use of the eyes and gaze to the eyes during emotion judgment. (a) A patient with bilateral damage to the amygdala made significantly less use of information from the eye region of faces when judging emotion. (b) While looking at whole faces, the patient (right column of images) exhibited abnormal face gaze, making far fewer fixations to the eyes than did controls (left column of images). This was observed across emotions (free viewing, emotion judgment, gender discrimination). (c) Magnetic resonance imaging scan of the patient's brain, whose lesion was relatively restricted to the entire amygdala, a very rare lesion in humans. The two round black regions near the top middle of the image are the lesioned amygdalae. (d) When the subject was instructed to look at the eyes (“SM eyes”) in a whole face, she could do this, resulting in a remarkable recovery in ability to recognize the facial expression of fear. The findings show that an apparent role for the amygdala in processing fearful facial expressions is in fact more abstract and involves the detection of, and attentional direction onto, features that are socially informative. (Modified from Adolphs et al. 2005).