A short review on emotion processing: a lateralized network of neuronal networks

Abstract

Emotions are valenced mental responses and associated physiological reactions that occur spontaneously and automatically in response to internal or external stimuli, and can influence our behavior, and can themselves be modulated to a certain degree voluntarily or by external stimuli. They are subserved by large-scale integrated neuronal networks with epicenters in the amygdala and the hippocampus, and which overlap in the anterior cingulate cortex. Although emotion processing is accepted as being lateralized, the specific role of each hemisphere remains an issue of controversy, and two major hypotheses have been proposed. In the right-hemispheric dominance hypothesis, all emotions are thought to be processed in the right hemisphere, independent of their valence or of the emotional feeling being processed. In the valence lateralization hypothesis, the left is thought to be dominant for the processing of positively valenced stimuli, or of stimuli inducing approach behaviors, whereas negatively valenced stimuli, or stimuli inducing withdrawal behaviors, would be processed in the right hemisphere. More recent research points at the existence of multiple interrelated networks, each associated with the processing of a specific component of emotion generation, i.e., its generation, perception, and regulation. It has thus been proposed to move from hypotheses supporting an overall hemispheric specialization for emotion processing toward dynamic models incorporating multiple interrelated networks which do not necessarily share the same lateralization patterns.

Early Right Motor Cortex Response to Happy and Fearful Facial Expressions: A TMS Motor-Evoked Potential Study

“…However, meta-analytic neuroimaging work [5,7] indicates that both hemispheres are engaged during the processing of emotional faces and other stimuli. Emotions are the result of activations in networks which are interrelated, but may have differential lateralization patterns, and classical proposals such as the right-hemisphere dominance or valence/motivation lateralization could reflect different aspects of emotion processing [67]. A recent review highlights the possibility that the brain is right-biased in emotional and neutral face perception by default, however, task conditions can activate a more distributed and bilateral brain network [68].…”

Bifocal emotion regulation through acupoint tapping in fear of flying

“…Both aversive stimulus categories lead to robust activations in regions underlying emotional processing compared with neutral stimuli ( Chang et al, 2015 , Palomero-Gallagher and Amunts, 2022 , Pessoa, 2017 ). We additionally observe activation that is specific to phobia-related stimuli and fear-inducing stimuli, respectively.…”

Asymmetric Lateralization during Pain Processing

“…The "valence-specific hypothesis" based on the emotional perception claim that the right hemisphere would be responsible for the processing of negative emotions (and pain); therefore, positive emotions would be predominantly processed by the left hemisphere [6]. Recent findings suggest that both hypotheses are valid and responsible for specific components of the emotion (such as generation, perception, and regulation) [7,8]. Both scenarios posit that functional lateralization also occurs during pain perception, involving a differential recruitment of specific brain areas located in the right or left hemisphere, together with an asymmetrical distribution of neurotransmitter signaling pathways involved in pain.…”

“…Lateralization of positive and negative emotions (and pain) [8] might suggest an asymmetric distribution of neurotransmitter systems that matches the opposing effects of the EOS. This idea has been recently supported by a study examining symmetric areas of left and right brain biopsies from deceased subjects.…”