Empathy, Neuroaesthetics, &  Multisensory Modalities: Applications of Neural Regions & Mirror Neurons

Abstract

Aesthetics, a topic not uncommon to philosophical critic, has been notorious as an experience of complete subjectivity. In more recent years, however, the field of neuroaesthetics questions that assumption. Empathy, the subjective experience of another individual's experience, has often been used in philosophy to study the aesthetic experience. Similar to the field of neuroaesthetics, the subjective experience of empathy is likewise becoming more grounded in research and biological psychology. This review paper seeks to examine the relationship between neuroaesthetics and empathy, specifically the utilization of mirror neurons and applications of specific neural networks. In regards to applying the relationship between neuroaesthetics and empathy to manifestations of the creative process, this paper will inquire on art and neuroaesthetics across sensory modalities and how mirror neurons and previously mentioned neural networks can be utilized.

 

Empathy and Aesthetics

Towards the end of the 19th century, theories of empathy were entertained by many German philosophical circles. By 1909, psychologist Edward Titchener translated the German word for empathy, Einfühlung, into the English language as “feeling into.” Soon, a philosophical relationship between empathy and aesthetics developed as this definition allowed for an understanding of how one could “feel into” beauty, art, and nature.

This relationship, however, was not brought under thorough scrutiny until the philosophical work of Theodor Lipps. Lipps introduced a definition of empathy that is arguably more precise and direct than that of Titchener’s and proposed an aesthetic component. Within Lipps' philosophy, empathy was understood as the “experience of another human being.” Additionally, aesthetic experience would arise because empathy allows one to see other people, objects or experiences from their perspectives. For example, we see another object as beautiful because empathy allows us to see it in analogy to another human body.

 

Neural Mechanisms of Empathy in the Brain

When attempting to quantify the link between aesthetics and empathy, issues arise regarding the subjective nature of both experiences. Research into neural mechanisms that produce empathy, however, has produced substantial data of this experience. Therefore, in order to further quantify the relationship between aesthetics and empathy already established by Lipps and numerous other philosophers, it is necessary to understand the neural mechanisms which produce these experiences in the brain.

 

Beyond philosophical discussion, the empirical study of empathy is made possible in many regards to the work of Giacomo Rizzolatti and colleagues. Unintentionally, while studying the premotor area F5 of Macaque monkeys, the research team observed neurons that fired not only when the monkey performed an action but also when the monkey observed the action (Pellegrino, Fadiga, Fogassi, Gallese, & Rizzolatti, 1992). These mirror neurons, named appropriately after their mirroring properties, brought into question whether or not humans have similar mechanisms for imitative behavior. Subsequently, human brain regions containing mirror neurons have been observed at the primary motor cortex, supplementary motor area, primary somatosensory cortex, inferior parietal cortex, ventral premortal area, Broca's area, Wernicke's area, fusiform gyrus, and angular gyrus (Acharya & Shukla, 2012).

 

Mirror neurons, therefore, lend themselves well to begin providing a physiological understanding of the aesthetic empathy that Lipps referred to as the ability to “experience another human being.” Specific brain regions containing mirror neurons have been suggested to be especially active during the experience of empathy. The inferior frontal gyrus (IFG), the human homologue of area F5 in monkeys, was first identified to contain mirror neurons in 1996 (Rizzolatti, Fadiga, Gallese, & Fogassi, 1996). More recently in 2009, the IFG was affirmed to be implicated in motor recognition utilizing mirror neurons (Kilner, Neal, Weiskopf, Friston, & Frith, 2009). Additional research has suggested that the IFG may be specifically involved in the experience of empathy. A study conducted by Harada, Hayashi, Sadato, & Iidaka demonstrated the application of the IFG in facial and emotional recognition, essential to development of empathy in humans (Harada, Hayashi, Sadato, & Iidaka, 2016). Furthermore, the IFG has been recognized to be implicated in the experience of empathy and face to face interaction (Schulte-Rüther, Markowitsch, Fink, & Piefke, 2007).

 

The IFG, mirror neurons, or other regions identified as being involved in imitation behavior, are not solely responsible for the experience of empathy. A study by Carr, Iacoboni, Dubeau, Mazziotta, & Lenzi developed a model of empathy that understands the IFG to work in conjunction with emotional processing areas in the limbic system via the insula (Carr, Iacoboni, Dubeau, Mazziotta, & Lenzi, 2003). This model recognizes mirror neurons as the mechanism for recognition and stimulation of facial expressions while emotional processing and evaluation of these expressions to occur in the limbic system, thus producing the experience of that emotion in the observer, i.e. empathy. Further studies have validated the application of the insula in empathetic experience, which, as will be discussed, may be essential to aesthetic processing of empathy (Fan, Duncan, Greck, & Northoff, 2011).

 

This model is further validated in a study researching the link between mirror neuron dysfunction and autism spectrum disorder (ASD), a disorder characterized by social deficits and poor emotional recognition of others. The study demonstrated that children with ASD showed no mirror neuron activity in the IFG. Furthermore, the typically developing children displayed activity in IFG, limbic structures, and insula when observing emotional expressions (Dapretto, et al., 2005).  An additional study examined subjects with lesions to the IFG in comparison with control subjects. Significant deficits were found in emotional empathy in subjects with lesions to the IFG (Shamay-Tsoory, Aharon-Peretz, & Perry, 2009).

 

Neuroaesthetics and Empathy: Applications of mirror neurons and regions associated with empathy

Attempts to quantify the subjective experience of beauty, the basis of the field of neuroaesthetics, are relatively new. The term neuroaesthetics was introduced by vision researcher Semir Zeki of University College London towards the end of the 20th century. Similar to Zeki’s interest in the visual applications of neuroaesthetics, most research conducted in the field of neuroaesthetics is in regards to visual art (Marin, 2015). Recent research in the field, however, seeks to bridge the gap and establish neural underpinnings for aesthetic experience across sensory modalities (Brown, Gao, Tisdelle, Eickhoff, & Liotti, 2011).

 

An area of substantial research in neuroaesthetics, which conveniently applies itself to discussion on aesthetics and empathy, is that of facial expressions, emotional expressions, and facial attractiveness. As mirror neurons fire when individuals both complete a motor action and when observing, the same is true for imitative behavior of facial expressions. Observing facial expressions, specifically, seems to interact with the emotional processing of the empathetic model previously discussed. Indeed, research has validated a correlation between an empathetic trait and emotional face processing (Balconi & Canavesio, 2016). Analysing the empathetic trait with the Balanced Emotional Empathy Scale (BEES), research compared high-BEES with low-BEES subjects in regards to response times and facial activity using an EMG. Response times and facial activity were found to be modulated by BEES, with high-BEES subjects displaying more responsiveness to emotional facial expressions.

 

An additional study that may be more specifically applied to the intersection of neuroaesthetics and empathy, studied neural correlates of sadness when observing traditional Japanese Noh masks (Osaka, Minamoto, Yaoi, & Osaka, 2012). An fMRI scan revealed activation in the amygdala, a region associated with the limbic areas implicated in Carr et al.’s proposed model of empathy, when viewing sad Noh masks. Therefore, representations of life, e.g. masks displaying overt emotion, may be just as useful as face to face interaction in evoking empathy in observers. To expand on this statement and the current study, analysis of additional regions utilized in Carr et al.’s model, such as the IFG and insula, during evaluation of theatrical representations of life would be necessary.

 

Despite these findings, however, studies have demonstrated that other visual art mediums that utilize emotional facial expressions may be more effective in evoking empathy than mere representations. Research conducted by Han, Jiang, Humphreys, Zhou, & Cai, suggests that photography or film, i.e. real representations of humans, may be most useful (Han, Jiang, Humphreys, Zhou, & Cai, 2005). The team used fMRI scans to understand what brain regions become active when viewing movie clips of real humans versus cartoon clips. Unlike the results displayed when viewing cartoon clips, the viewing of movie clips activated the medial prefrontal cortex. Not surprisingly, contained in this region is the IFG, the first area implicated in Carr et al.’s model of empathy.

 

Similar findings were found indirectly in a study examining the neural responses when participants viewed movie clips of either neutral or emotional situations (Jabbi & Keysers, 2008). Using psychophysiological interaction it was observed that motor mirroring functions of the IFG triggered responses in the anterior insula and adjacent frontal operculum (IFO) in response to emotional facial expressions as opposed to neutral facial expressions. Furthermore, this study demonstrated that the the link between IFG and IFO is causal. Using Granger Causality Modeling, a linear autoregressive model of time whereby each data point is a linear combination of k previous data points, it was found that regions involved in higher motor functions, specifically the BA45 of the IFG, directly triggers responses in the IFO.

 

When applying studies on empathy and facial expression recognition to the field of neuroaesthetics, research has demonstrated that the context in which the evaluation takes places may evoke different neural responses. A study by Chatterjee, Thomas, Smith, & Aguirre, used an fMRI scan to compare regions that became active when evaluating a face for attractiveness or for identity (Chatterjee, Thomas, Smith, & Aguirre, 2009). The team found that a network including the ventral occipital, insula, dorsal posterior parietal, and medial prefrontal cortices became active when participants were asked to judge facial beauty. Conversely, when asked to judge facial identity, only the ventral occipital region remained responsive. This demonstrates that the context of facial evaluation affect neural mechanisms, which explains why we may experience more emotional responses when viewing portraiture in museums or as an aesthetic object.

 

A similar context-oriented study by researchers Cupchik, Vartanian, Crawley, & Mikulis looked at fMRI scans of participants briefed to either perceive various paintings under aesthetic or pragmatic conditions (Cupchik, Vartanian, Crawley, & Mikulis, 2009). The results revealed greater activity in the insula when viewing paintings under aesthetic conditions. This study suggests that within the context of beauty or aesthetic evaluation individuals are more likely to have responses in the emotional and empathetic processing of the insula, further demonstrating the value of context on evoking the relationship between aesthetics and empathy.

 

Research conducted by Dio, Macaluso, & Rizzolatti not only further validates the reach of context on our judgement of aesthetic objects, but also proposes a system to explain the sense of beauty that is related to regions implicated in the model of empathy proposed by Carr et al. (Dio, Macaluso, & Rizzolatti, 2007). The team developed two sets of stimuli of images of Classical and Renaissance sculptures, one set with the original images and one set consisting of images with altered proportions. Participants were instructed to judge the sculpture under either an observational condition, i.e. as if they were in a museum, an aesthetic judgement, or a proportional judgement. The results demonstrated that the insula was most active under the observation condition when viewing the original images, as opposed to those with altered proportions. When instructed to view the images under aesthetic conditions, the amygdala was most active. The researchers understood these results to suggest a system of beauty whereas objective beauty is processed via cortical neurons activated by a stimulus and the insula. Conversely, they proposed that subjective beauty is the result of emotional processing in the amygdala. Perhaps this study could substantiate the relationship between empathy and aesthetics in that we first observe a stimulus objectively, activating the insula and completing the second step of Carr et al.’s model of empathy. Then, if viewing under aesthetic conditions and instructed to make aesthetic judgments, the observer experiences subjective beauty, activating the emotional processing of the amygdala in the limbic system. Considering context and condition may be of value when studying the relationship between empathy and aesthetics, and this study suggests that empathetic experiences may be more plausible under certain aesthetic conditions.

 

Although the field of neuroaesthetics has typically been concerned with visual art, it is becoming increasingly interested in studying aesthetics applied to other sensory modalities. When discussing neuroaesthetics and its relationship with empathy, it is interesting to note that mirror neurons are multimodality cells. Sound, specifically, has been observed to cause the same imitative firing effect in mirror neurons as observing motor functions. Gazzola, Aziz-Zadeh, & Keysers demonstrated this phenomenon when they compared action sounds and white noise (Gazzola, Aziz-Zadeh, & Keysers, 2006). Results showed that mirror neurons discharged at the sound of an action, even in the absence of the visual input related to the action.

 

The same study suggested the application of auditory activated mirror neurons to evoke empathy. The researchers additionally administered a perspective taking scale, a measurement of empathy, and found that those participants who had scored higher activated an auditory mirror system, a left lateralized circuit composed of bilateral mid-temporal gyrus, left inferior parietal lobule, and left premotor cortex, more strongly. Additionally, validating auditory stimuli use in activating a mirror neuron and empathetic response, higher motor functions were observed in the IFG, specifically BA44, when participants listened to actions and executed them.

 

Thus far, research suggests that mirror neurons indeed response to modalities other than vision and that there is activity in the IFG. To continue along Carr et al.’s model of empathy, research has additionally demonstrated the participation of the insula in aesthetic appraisal across sensory modalities. In a meta-analysis of 93 neuroimaging studies, analysing negative and positive valenced stimuli aesthetic appraisal across four sensory modalities, demonstrated the anterior insula to be the most consistently activated (Brown, Gao, Tisdelle, Eickhoff, & Liotti, 2011).

 

Although neuroaesthetics has traditionally been concerned with vision and increasingly the aesthetics of hearing, it is not unknown that beauty is accessible through all sensory modalities. Olfactory stimuli as an artistic medium may be a unique area of research in neuroaesthetics and additionally useful in pursuing understanding of a link between neuroaesthetics and empathy. As olfaction is notorious for evoking episodic or autobiographical memories because of its neural pathways that bypass the thalamus, this may lend itself to empathetic responses. (Fernyhough, 2012) Memory has been related to empathy in that memories of past experiences aid individuals in the development of Theory of Mind (Ciaramelli, Bernardi, & Moscovitch, 2013). An additional study demonstrated that after sharing an autobiographical memory, participants displayed an increase in empathy (Bluck, Baron, Ainsworth, Gesselman, & Gold, 2012).

 

Additional support that suggests the ability of olfaction to activate empathetic responses is found in Wicker et al.’s study that analyzed the emotional response to disgust. The researchers compared responses of participants when presented with either a visual stimulus, a film clip of another individual displaying facial reactions of disgust, or an olfactory stimulus, noxious odors distributed into the room. According to the fMRI scans, both stimuli activated the same areas of the anterior insula (Wicker, et al., 2003).

 

Discussion

Inevitably, there are limits to the research considered in the current review. Most noteable is the debate as to whether or not mirror neurons exist. A study by Lingnau, Gesierich, and Caramazza argued that asymmetrical adaption of mirror neurons disproves their existence (Lingnau, Gesierich, & Caramazza, 2009). Using fMRI to observe adaption in mirror neurons, the researchers compared motor acts that were repeatedly observed or executed, first observed and then executed, and first executed and then observed. Mirror neuron theory supposes that adaptation would be observed in all conditions. The researchers thus determined the existence of mirror neurons to be disproven when they observed no adaption of mirror neurons when the motor action was first executed and then observed. Perhaps these findings do not necessarily disprove the existence of neurons but instead question the current theory of mirror neurons.

 

Although the relationship between empathy and aesthetics has thus been philosophical, perhaps a relationship can soon be substantiated through biological psychology and the increasingly relevant field of neuroaesthetics. For one, the studies presented by this review consider neural mechanisms that control the ways in which we experience empathy. Mirror neurons, IFG, and insula, have been suggested to be valuable. Interestingly, the IFG and especially the insula have been demonstrated to be important in several studies on aesthetics. Additionally, this review paper examined neuroaesthetics and empathy across sensory modalities. Thus studied, visual art seems to be most applicable to the relationship of neuroaesthetics and empathy within the realm of facial expressions and emotional expressions. Recent research is expanding the reach of both neuroaesthetics and mirror neurons to be understood as multi sensory modality platforms. Finally, olfactory art and its autobiographical memory eliciting abilities is considered. Altogether, this review paper provides a brief understanding of the biological psychology that facilitates the philosophized and subjective relationship between aesthetics and empathy across a range of experiences.



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