The inherent contradictions of an area-focused meta-analysis
Lindquist et al. are rightfully critical of the approach that has been prominent in the majority of brain imaging studies aspiring to localize the neurofunctional basis of each single emotion in a dedicated brain area. For example, the amygdala was the fear area, the insula was the disgust area, and so forth. Meta-analyses inherit the weak points of still less-than-perfect brain imaging techniques and cannot but endorse and amplify them. fMRI studies vary widely in scanner properties, in settings, in designs, and in tasks, including the involvement of attention, awareness, and contrast stimuli or conditions. The meta-analysis exploits the very procedures under attack by using positive activation levels of isolated brain areas themselves obtained in a wide variety of studies. The meta-analytic conclusion that some areas play or do not play their anticipated role, does not invalidate their role, and this role may or may not show up in fMRI analysis. For example, the amygdala was repeatedly shown to play a role in processing of emotional stimuli, and brain imaging studies of autism are consistent with this. However, patients with Urbach-Wiethe syndrome have a major deficit of the basolateral amygdala, yet show no signs of autistic behavior. There are many more examples illustrating that there is no rigid link between a brain area and a functional deficit. But the suggestion of attributing functions to a network rather that to a single area is likely to beg the question. Another approach to emotions is needed. It must be possible to avoid naive naturalism and extreme psychologism.
Emotions are mind organs
Emotions are mind/body adaptations, evolved in natural and social contexts (in a partly species-specific way). As emotions serve different goals, they have evolved next to each other and inhabit brain/body resources in different ways to fit their goals (Panksepp Reference Panksepp1998). Yet in contrast to many approaches, different emotions are interdependent and interrelated. We do not believe that emotions must await neuroanatomical dissection to prove that they operate as cooperating distinct entities, even if functional distinctions can be made and appear in clinical symptoms. We know that this is unrealistic with current functional neuroimaging techniques. For example, different emotions produce different facial expressions in a predictable way, although we can reasonably assume that we are unable at the moment to distinguish between motor activity associated with angry versus fearful expressions. In the very same way, the visceral activation and the associated feeling will be different between disgust and anger, but it is unlikely that these emotional experiences can be disentangled spatially by their cortical somatosensory responses. In our view, emotions entail a distributed neural system, and focusing on its components, whether from a locationist or from a psychological constructionist perspective, is equally and inherently reductionist. First, psychological constructivism reduces emotions to a sum of parts, ignoring that a particular neural component exerts its function in relation to and sometimes driven by the other components of the individual emotion system (e.g., Benuzzi et al. Reference Benuzzi, Lui, Duzzi, Nichelli and Porro2009; Liang et al. Reference Liang, Zebrowitz and Aharon2009). This emotion-specific connectivity pattern is an essential and mandatory characteristic of emotions. Second, by attributing a specific psychological operation to a gross anatomical component, the degrees of freedom of the functional contribution of this component to a particular emotional state are reduced. For example, the amygdala may signal motivational salience in some instances but may critically contribute to the fear response in others. Patients with epilepsy caused by sclerosis of the amygdala, for example, may experience intense fear during their seizures, in the absence of any relevant object (Van Paesschen et al. Reference Van Paesschen, King, Duncan and Connelly2001). Third, emotion-specific activation at the cellular level in monkey studies (Kuraoka & Nakamura Reference Kuraoka and Nakamura2007) somewhat contradicts the postulation of generic regional operations that is made by psychological constructivism.
Just as organs have different functions in the body, emotions serve different functions in the mind. The traditional terminology of basic emotions as states is indeed inappropriate to catch these functions. They encompass not just a network of brain areas, as these activation peaks are the tip of the iceberg. Beneath the neurofunctional facts revealed by brain imaging studies of neurotypical subjects, are structural facts, inhibitory and excitatory modulations in dynamic networks, endocrinological signatures, behavioral engrams laid down by phylogenetic and ontogenetic experience, and so on. Most importantly in this context, the function of an organ, in this case the minds' emotions, needs to be understood in relation to the others and of the whole. Just as the body cannot be reduced to a collection of independent organs, the emotions operate in concert, and whether in health or in sickness, they need to be considered together. Balanced or unbalanced, the interaction between the emotion organs makes and breaks the self. One may still call this “psychologism,” but then any view on emotions is “psychologism.”
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Lindquist et al. challenge the view that the most familiar emotion words and the linguistically expressed emotion experiences are ultimately the natural kinds found in the brain/mind, referred to as “naturalism” for short. Naturalism traditionally refers to the view that some of the entities the mind reasons with and decides about exist outside of and independent from these mental operations. Let us label this physicalist naturalism. However, when naturalism is used to refer to putative entities in the mind/brain, the situation is much more complex. Mentalistic naturalism as opposed to physicalist naturalism, seems to postulate that there are entities in the mind that are not mind-made. As Lindquist et al. present it, for naturalism basic emotions are such mind-independent entities. Emotions, in the naturalistic view the authors challenge, stand for mind-independent or for biological categories, which are essentially present in the mind-brain. Psychologism, by contrast, does not build on anything given other than its own operations, which are the same whatever the subject matter.
Interestingly, the description of the alternative view Lindquist et al. endorse, psychological constructivism, consists of entirely content-general mental operations that operate over inputs that are not necessarily emotional. So, other aspects aside, the contrast the authors set up is between emotional determinism and emotional indeterminism of the mind's building blocks.
The inherent contradictions of an area-focused meta-analysis
Lindquist et al. are rightfully critical of the approach that has been prominent in the majority of brain imaging studies aspiring to localize the neurofunctional basis of each single emotion in a dedicated brain area. For example, the amygdala was the fear area, the insula was the disgust area, and so forth. Meta-analyses inherit the weak points of still less-than-perfect brain imaging techniques and cannot but endorse and amplify them. fMRI studies vary widely in scanner properties, in settings, in designs, and in tasks, including the involvement of attention, awareness, and contrast stimuli or conditions. The meta-analysis exploits the very procedures under attack by using positive activation levels of isolated brain areas themselves obtained in a wide variety of studies. The meta-analytic conclusion that some areas play or do not play their anticipated role, does not invalidate their role, and this role may or may not show up in fMRI analysis. For example, the amygdala was repeatedly shown to play a role in processing of emotional stimuli, and brain imaging studies of autism are consistent with this. However, patients with Urbach-Wiethe syndrome have a major deficit of the basolateral amygdala, yet show no signs of autistic behavior. There are many more examples illustrating that there is no rigid link between a brain area and a functional deficit. But the suggestion of attributing functions to a network rather that to a single area is likely to beg the question. Another approach to emotions is needed. It must be possible to avoid naive naturalism and extreme psychologism.
Emotions are mind organs
Emotions are mind/body adaptations, evolved in natural and social contexts (in a partly species-specific way). As emotions serve different goals, they have evolved next to each other and inhabit brain/body resources in different ways to fit their goals (Panksepp Reference Panksepp1998). Yet in contrast to many approaches, different emotions are interdependent and interrelated. We do not believe that emotions must await neuroanatomical dissection to prove that they operate as cooperating distinct entities, even if functional distinctions can be made and appear in clinical symptoms. We know that this is unrealistic with current functional neuroimaging techniques. For example, different emotions produce different facial expressions in a predictable way, although we can reasonably assume that we are unable at the moment to distinguish between motor activity associated with angry versus fearful expressions. In the very same way, the visceral activation and the associated feeling will be different between disgust and anger, but it is unlikely that these emotional experiences can be disentangled spatially by their cortical somatosensory responses. In our view, emotions entail a distributed neural system, and focusing on its components, whether from a locationist or from a psychological constructionist perspective, is equally and inherently reductionist. First, psychological constructivism reduces emotions to a sum of parts, ignoring that a particular neural component exerts its function in relation to and sometimes driven by the other components of the individual emotion system (e.g., Benuzzi et al. Reference Benuzzi, Lui, Duzzi, Nichelli and Porro2009; Liang et al. Reference Liang, Zebrowitz and Aharon2009). This emotion-specific connectivity pattern is an essential and mandatory characteristic of emotions. Second, by attributing a specific psychological operation to a gross anatomical component, the degrees of freedom of the functional contribution of this component to a particular emotional state are reduced. For example, the amygdala may signal motivational salience in some instances but may critically contribute to the fear response in others. Patients with epilepsy caused by sclerosis of the amygdala, for example, may experience intense fear during their seizures, in the absence of any relevant object (Van Paesschen et al. Reference Van Paesschen, King, Duncan and Connelly2001). Third, emotion-specific activation at the cellular level in monkey studies (Kuraoka & Nakamura Reference Kuraoka and Nakamura2007) somewhat contradicts the postulation of generic regional operations that is made by psychological constructivism.
Just as organs have different functions in the body, emotions serve different functions in the mind. The traditional terminology of basic emotions as states is indeed inappropriate to catch these functions. They encompass not just a network of brain areas, as these activation peaks are the tip of the iceberg. Beneath the neurofunctional facts revealed by brain imaging studies of neurotypical subjects, are structural facts, inhibitory and excitatory modulations in dynamic networks, endocrinological signatures, behavioral engrams laid down by phylogenetic and ontogenetic experience, and so on. Most importantly in this context, the function of an organ, in this case the minds' emotions, needs to be understood in relation to the others and of the whole. Just as the body cannot be reduced to a collection of independent organs, the emotions operate in concert, and whether in health or in sickness, they need to be considered together. Balanced or unbalanced, the interaction between the emotion organs makes and breaks the self. One may still call this “psychologism,” but then any view on emotions is “psychologism.”