Tokiko Harada

Neural basis of extraordinary empathy and altruistic motivation.

A central evolutionary challenge for social groups is uniting a heterogeneous set of individuals towards common goals. One means by which social groups form and endure is by endowing group members with extraordinary prosocial proclivities, such as ingroup love, towards other group members. Here we examined the neural basis of extraordinary empathy and altruistic motivation in African-American and Caucasian-American individuals using functional magnetic resonance imaging. Our results indicate that empathy for ingroup members is neurally distinct from empathy for humankind, more generally. People showed greater response within anterior cingulate cortex and bilateral insula when observing the suffering of others, but African-American individuals additionally recruit medial prefrontal cortex when observing the suffering of members of their own social group. Moreover, neural activity within medial prefrontal cortex in response to pain expressed by ingroup relative to outgroup members predicted greater empathy and altruistic motivation for ones ingroup, suggesting that neurocognitive processes associated with self identity underlie extraordinary empathy and altruistic motivation for members of ones own social group. Taken together, our findings reveal distinct neural mechanisms of empathy and altruistic motivation in an intergroup context and may serve as a foundation for future research investigating the neural bases of intergroup prosociality, more broadly construed.

Neural basis of individualistic and collectivistic views of self

Individualism and collectivism refer to cultural values that influence how people construe themselves and their relation to the world. Individualists perceive themselves as stable entities, autonomous from other people and their environment, while collectivists view themselves as dynamic entities, continually defined by their social context and relationships. Despite rich understanding of how individualism and collectivism influence social cognition at a behavioral level, little is known about how these cultural values modulate neural representations underlying social cognition. Using cross‐cultural functional magnetic resonance imaging (fMRI), we examined whether the cultural values of individualism and collectivism modulate neural activity within medial prefrontal cortex (MPFC) during processing of general and contextual self judgments. Here, we show that neural activity within the anterior rostral portion of the MPFC during processing of general and contextual self judgments positively predicts how individualistic or collectivistic a person is across cultures. These results reveal two kinds of neural representations of self (eg, a general self and a contextual self) within MPFC and demonstrate how cultural values of individualism and collectivism shape these neural representations. Hum Brain Mapp, 2009.

Dynamic cultural influences on neural representations of the self

People living in multicultural environments often encounter situations which require them to acquire different cultural schemas and to switch between these cultural schemas depending on their immediate sociocultural context. Prior behavioral studies show that priming cultural schemas reliably impacts mental processes and behavior underlying self-concept. However, less well understood is whether or not cultural priming affects neurobiological mechanisms underlying the self. Here we examined whether priming cultural values of individualism and collectivism in bicultural individuals affects neural activity in cortical midline structures underlying self-relevant processes using functional magnetic resonance imaging. Biculturals primed with individualistic values showed increased activation within medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC) during general relative to contextual self-judgments, whereas biculturals primed with collectivistic values showed increased response within MPFC and PCC during contextual relative to general self-judgments. Moreover, degree of cultural priming was positively correlated with degree of MPFC and PCC activity during culturally congruent self-judgments. These findings illustrate the dynamic influence of culture on neural representations underlying the self and, more broadly, suggest a neurobiological basis by which people acculturate to novel environments.

Cultural influences on neural basis of intergroup empathy

Cultures vary in the extent to which people prefer social hierarchical or egalitarian relations between individuals and groups. Here we examined the effect of cultural variation in preference for social hierarchy on the neural basis of intergroup empathy. Using cross-cultural neuroimaging, we measured neural responses while Korean and American participants observed scenes of racial ingroup and outgroup members in emotional pain. Compared to Caucasian-American participants, Korean participants reported experiencing greater empathy and elicited stronger activity in the left temporo-parietal junction (L-TPJ), a region previously associated with mental state inference, for ingroup compared to outgroup members. Furthermore, preferential reactivity within this region to the pain of ingroup relative to outgroup members was associated with greater preference for social hierarchy and ingroup biases in empathy. Together, these results suggest that cultural variation in preference for social hierarchy leads to cultural variation in ingroup-preferences in empathy, due to increased engagement of brain regions associated with representing and inferring the mental states of others.

Neural representations of social status hierarchy in human inferior parietal cortex.

Mental representations of social status hierarchy share properties with that of numbers. Previous neuroimaging studies have shown that the neural representation of numerical magnitude lies within a network of regions within inferior parietal cortex. However the neural basis of social status hierarchy remains unknown. Using fMRI, we studied subjects while they compared social status magnitude of people, objects and symbols, as well as numerical magnitude. Both social status and number comparisons recruited bilateral intraparietal sulci. We also observed a semantic distance effect whereby neural activity within bilateral intraparietal sulci increased for semantically close relative to far numerical and social status comparisons. These results demonstrate that social status and number comparisons recruit distinct and overlapping neuronal representations within human inferior parietal cortex.

Asymmetrical Neural Substrates of Tactile Discrimination in Humans: A Functional Magnetic Resonance Imaging Study

The left-hand advantage seen during tactile discrimination tasks suggests hemispheric-processing asymmetry, although its neural substrates are not well known. We used functional magnetic resonance imaging to evaluate the laterality of the neural substrates involved in tactile discrimination in 19 normal volunteers. Passive tactile discrimination tasks, along with appropriate control tasks, were performed with both the right and left hands to evaluate the effects of the hand used and hemispheric effects (i.e., laterality of the activation pattern). Regardless of the hand used, the right dorsolateral prefrontal cortex, posterior parietal cortex, pre-supplementary motor area, and rostral portion of the dorsal premotor cortex (PMdr) were activated asymmetrically during tactile discrimination. This confirms the previous finding of a right-sided asymmetry for tactile shape discrimination. Hand effects were found in the left caudal portion of PMd (PMdc) adjacent to the central sulcus, which showed prominent activation during right-handed but not left-handed discrimination tasks. This asymmetric activation in the left PMdc might be related to the asymmetric interhemispheric interaction during right-handed tactile discrimination.

Neural Basis of Preference for Human Social Hierarchy versus Egalitarianism

A fundamental way that individuals differ is in the degree to which they prefer social dominance hierarchy over egalitarianism as a guiding principle of societal structure, a phenomenon known as social dominance orientation. Here we show that preference for hierarchical rather than egalitarian social relations varies as a function of neural responses within left anterior insula and anterior cingulate cortices. Our findings provide novel evidence that preference for social dominance hierarchy is associated with neural functioning within brain regions that are associated with the ability to share and feel concern for the pain of others; this suggests a neurobiological basis for social and political attitudes. Implications of these findings for research on the social neuroscience of fairness, justice, and intergroup relations are discussed.

Theory and methods in cultural neuroscience

Cultural neuroscience is an emerging research discipline that investigates cultural variation in psychological, neural and genomic processes as a means of articulating the bidirectional relationship of these processes and their emergent properties. Research in cultural neuroscience integrates theory and methods from anthropology, cultural psychology, neuroscience and neurogenetics. Here, we review a set of core theoretical and methodological challenges facing researchers when planning and conducting cultural neuroscience studies, and provide suggestions for overcoming these challenges. In particular, we focus on the problems of defining culture and culturally appropriate experimental tasks, comparing neuroimaging data acquired from different populations and scanner sites and identifying functional genetic polymorphisms relevant to culture. Implications of cultural neuroscience research for addressing current issues in population health disparities are discussed.

Differential dorsal and ventral medial prefrontal representations of the implicit self modulated by individualism and collectivism: An fMRI study

Individualism and collectivism, or self-construal style, refer to cultural values that influence how people think about themselves and their relation to the social and physical environment. Recent neuroimaging evidence suggests that cultural values of individualism and collectivism dynamically modulate neural response within cortical midline structures, such as the medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC), during explicit self-evaluation. However, it remains unknown whether cultural priming modulates neural response during self-evaluation due to explicit task demands. Here we investigated how cultural priming of self-construal style affects neural activity within cortical midline structures during implicit self-evaluation in bicultural individuals. Results indicate that ventral MPFC showed relatively less deactivation during implicit evaluation of both self- and father-relevant information as compared to control condition (e.g., information of an unfamiliar person), irrespective of cultural priming. By contrast, dorsal MPFC showed relatively less deactivation during implicit evaluation of father-relevant information, but not self-relevant information, as compared to control condition, only when they were primed with individualism. Furthermore, dorsal MPFC showed relatively less deactivation during implicit evaluation of father-relevant information as compared to self-relevant condition only when they were primed with individualism. Hence, our results indicate that cultural priming modulates neural response within dorsal, but not ventral, portions of MPFC in a stimulus-driven rather than task-driven manner. More broadly, these findings suggest that cultural values dynamically shape neural representations during the evaluation, rather than the detection, of self-relevant information.

Distinction between the literal and intended meanings of sentences: A functional magnetic resonance imaging study of metaphor and sarcasm

To comprehend figurative utterances such as metaphor or sarcasm, a listener must both judge the literal meaning of the statement and infer the speakers intended meaning (mentalizing; Amodio and Frith, 2006). To delineate the neural substrates of pragmatic comprehension, we conducted functional magnetic resonance imaging (fMRI) with 20 normal adult volunteers. Participants read short stories followed by a target sentence. Depending on the context provided by the preceding stories, the target sentences were classified as follows: (1) metaphor versus literally coherent; (2) metaphor versus literally incoherent; (3) sarcasm versus literally coherent; and (4) sarcasm versus literally incoherent. For each task pair, we directly compared the activations evoked by the same target sentences in the different contexts. The contrast images were incorporated into a 2 (metaphor and sarcasm)×2 (literal coherency and incoherency) design. Metaphor-specific activation was found in the head of the caudate, which might be involved in associating statements with potential meanings, and restricting sentence meanings within a set of possible candidates for what the speaker intended. Sarcasm-specific activation was found in the left amygdala, which is an important component of the neural substrates of social behavior. Conjunction analysis revealed that both metaphor and sarcasm activated the anterior rostral medial frontal cortex (arMFC), which is a key node of mentalizing. A distinct literal coherency effect was found in the orbital MFC, which is thought to be involved in monitoring. These mesial frontal areas are jointly involved in monitoring literal coherency and mentalizing within social contexts in order to comprehend the pragmatic meanings of utterances.