LAUSR

Research on the neural basis of empathy has undergone a significant transformation over the past fifty years. From early studies focusing on basic neuroanatomy, this field has developed into many branches that explore the complex etiology and mechanisms underlying empathy, and its implications for mental health and social behavior. As early as the 1970s, and 80s, researchers began to theorize about the potential neural basis of empathy (Heilman et al., 1975; Brothers, 1989). Early empathy research, throughout the 1990s, focused primarily on brain lesion studies and implicated cerebral and frontal lobe lesions in empathy deficits (e.g. Grattan et al., 1994). The solid foundation of lesion studies laid the groundwork for neuroimaging studies examining the neural underpinning of empathy in healthy populations. With the technological advances of the 21st century, studies began using functional magnetic resonance imaging (fMRI) to research empathy, frequently using empathy for pain as their experimental paradigm. Two seminal studies (Decety and Jackson, 2004; Singer et al., 2004) simultaneously posited that a specific set of regions of the ‘pain matrix’ (specifically the anterior cingulate cortex [ACC] and anterior insula [AI]) are activated both by experiencing pain and by watching others experience pain. A surge of studies of empathy ensued, replicating these findings and showing how empathy related activations are modulated depending on the context (Hein and Singer, 2008, for review; Lamm et al., 2011, for meta-analysis). Based on an increased understanding of the mechanisms underlying empathy, research concerning different subtypes of empathy has emerged. This evolution in defining empathy has led to more nuanced research, as subsequent studies often investigated these subtypes. One model divides empathy into emotional empathy – sharing the emotions of others – and cognitive empathy – understanding the thoughts and motivations of others (Shamay-Tsoory et al., 2009). Another model divides empathy into personal distress (also called empathetic or vicarious distress) – which is self-oriented and focused on alleviating one's own pain – and empathetic concern (also called compassion) – which entails feeling sympathy for another person (Eisenberg and Eggum, 2009; Singer and Klimecki, 2014). Given these advances in understanding empathy, further research has explored the societal issues of empathy. One line of research focuses on empathy biases and group membership. Many fMRI and EEG studies have shown reduced levels of empathy directed towards people of different racial or social groups (Han, 2018, for review). Another line of research focused on the role of empathy in psychopathology, as variety of psychiatric and neurological conditions including autism, schizophrenia, bipolar disorder, borderline personality disorder and psychopathy are associated with deficits (or surpluses) in different subtypes of empathy (Gonzalez-Liencres et al., 2013). Other research has focused on the neurochemical basis of empathy, implicating opioids (Rutgen et al., 2017, in this issue) and neuropeptides, mainly oxytocin, in empathy (e.g. Hurlemann et al., 2010). This line of research has clinical implications for a range of disorders, including autism and schizophrenia. In recent years criticisms of the methodologies commonly used to study the neural basis of social behavior are beginning to emerge (e.g. Schilbach et al., 2013), motivating methodological advances towards increasing the external validity of the findings in social neuroscience. Owing to the increasing importance of understanding social behavior in natural settings the field of empathy recently took a step towards understanding more real-life empathic interactions with either interactive avatars (Jackson et al., 2015) or real face-to-face interactions (Goldstein et al., 2018). Indeed, given that empathy by its nature requires active participation in social exchange with social agents, measuring a response of an isolated passive observer may fail to capture the genuine mechanisms of empathy. Based on the more widespread use of brain stimulation methods as well as of psychopharmacological manipulations, we are also beginning to gain more causal-mechanistic insights into the neural underpinnings of empathy, and how they are related to (pro)social behavior (Lamm et al., 2017, for review). In light of this history and the more recent developments, the present special issue of Neuropsychologia, “The neuroscience of empathy – from past to present and future,” has compiled a broad range of contributions advancing our understanding of the intricacies of empathy, which we would like to summarize and highlight as follows.