Human facial movements transmit a wealth of dynamic signals that provide crucial information about people’s emotional states. The temporal dynamics of facial expressions of emotion are optimised to hierarchically transmit biologically rooted and socially adaptive signals over time. We begin this chapter by formally defining these signals and by offering an overview of recent advances in research methods that improving our understanding of them. We then describe how the ability to decode such biologically relevant social signals emerges early in life and evolves throughout adolescence. Next, we discuss how experience, culture, and individual differences shape the decoding of facial expressions of emotion, before moving towards differences in processing static and dynamic facial expressions of emotion. Finally, we elaborate on the use of more ecologically valid experimental designs, cross-cultural studies, and understanding the roots of individual differences in facial expression processing to improve future knowledge in the field.

Experiencing emotions is part of human nature and our daily life. Sometimes, emotions can be too intense and we need or want to control them. Emotion regulation (ER) is a term that describes management of emotional experiences, regardless of whether we downregulate negative emotions or upregulate positive ones. Conscious, cognitive efforts to regulate an emotion have been subsumed under this term, as well as unconscious, implicit regulation of emotion. Effective ER has been associated with a number of positive outcomes, such as an increased general well-being, improved performance at work and in personal and professional relations, and, most importantly, enhanced mental and physical health. In contrast, deficits in ER are observed in severe psychological disorders, such as depression and anxiety. Consequently, understanding the neural underpinnings of ER has become one of the most popular topics in affective neuroscience throughout the last two decades.

When thinking about emotional expressions, most would probably envision facial expressions (e.g., smiling, scowling) or vocalizations (e.g., crying, laughter). Here we focus on the emotional postures and movements of the body – an important, but fairly understudied, signal for emotion perception. During emotional episodes, humans often position and move their bodies in consistent ways that may (or may not) signal their underlying feelings and future actions. We briefly review the historical antecedents of this literature, as well as current knowledge on the neural processing, developmental trajectory, and cultural differences in the emotional perception of body language. We continue by examining the role of the body as a contextualizing agent for disambiguating facial expressions, as well as their inverse relationship – from faces to bodies. Future directions and speculations about how this emerging field may evolve are discussed.

Psychiatric disorders are highly comorbid and are not separated by sharp biological boundaries. Understanding the common mechanisms that explain symptom overlap in mental disorders is therefore clearly needed. Here, we briefly review impaired emotional processing and emotional dysregulation in affective disorders, with a special focus on unipolar depression. Affective disorders are characterized by abnormal emotion intensity, changes in the temporal dynamics of emotion and difficulties to influence the trajectory of emotions. Disruptions in emotion processing and emotional regulation are underlined at the neural level by abnormal interactions between cortical and limbic structures in terms of increased variance in functional connectivity. Emotional processes are also tightly linked to cognitive processes, which constitute main targets for therapeutic interventions in affective disorders.

Social adaptation requires humans to respond to others’ nonverbal emotional cues by selecting and executing adaptive motor responses. In this chapter, we provide a general overview of how visual perception of others’ emotional expressions, particularly threatening faces and bodies, promotes rapid processing and elaboration of multiple opportunities for action, at different levels of complexity. Notably, we will highlight how subcortical and cortical neural pathways interact to flexibly orchestrate our social behavior in response to threatening expressions, ranging from simple stimulus-driven reactions to more elaborated goal-directed actions. We will review recent findings from research on humans and other animals and discuss clinical implications, as well as future challenges and perspectives.

Positron emission tomography (PET) is the most sensitive technique for imaging of human physiology and molecular pathways in vivo. Here we provide an overview of PET instrumentation and modelling and illustrate how different PET techniques can be used for mapping the molecular basis of the human emotion circuit. We first cover the principles of PET imaging and the most common imaging targets, modelling methods, and experimental designs in brain PET. We then describe how metabolic studies and neuroreceptor mapping of the endogenous dopamine, opioid, serotonin, and cannabinoid systems have contributed to our understanding of the emotional brain. Finally, we review the recent state-of-the art developments in PET-fMRI and total-body PET, and discuss how these techniques can transform the landscape of systems-level biological imaging of the emotion circuits across the brain and periphery.

Functional magnetic resonance imaging (fMRI) is a noninvasive technique widely used in research to identify and characterize the neural correlates of human cognitive and affective processes. Here we provide a brief introduction to the physical and physiological bases of fMRI, as well as a description of some of the main analysis approaches. These include traditional approaches, such as those based on univariate general linear models, as well as more recent ones, including multivariate methods and connectivity measures. We discuss how these different techniques can be used to answer different, complementary scientific questions, providing some examples to illustrate this. We end with a discussion of some of the key issues, both in terms of experimental design and data acquisition, analysis, and interpretation, that should be considered when planning an fMRI study and that can be of particular interest to those new to the technique.

Decades of research demonstrate cultural variation in different aspects of emotion, including the focus of emotion, expressive values and norms, and experiential ideals and values. These studies have focused primarily on Western and East Asian cultural comparisons, although recent work has included Latinx samples. In this chapter, we discuss why studying culture is important for studies of emotion and what neuroscientific methods can contribute to our understanding of culture and emotion. We then describe research that uses neuroscientific methods to explore both cultural differences and similarities in emotion. Finally, we discuss current challenges and outstanding questions for future research.

This chapter introduces peripheral physiological measures of emotion as important tools for studying emotion in affective neuroscience. It examines responses across three systems: skeletal muscle activity, autonomic nervous system (cardiovascular and electrodermal), and respiration. It surveys measurement modalities, derived metrics, their neural control, timescales of expected response, and prominent findings in recent literature, linking them to central nervous system activity throughout. The chapter concludes by highlighting outstanding questions and future challenges in the field of peripheral physiological measures of emotion.

This chapter explores the interplay between emotions and memory, highlighting the interrelations between regulatory and memory processes. In the first section we describe how, through indirect and direct influences, emotions impact every phase of the episodic memory cycle: encoding, consolidation, and retrieval. Whereas many of these influences are attributed to the amygdala and hippocampus, recent work has emphasized the role of a broad network of regions, extending well beyond these medial temporal lobe regions. In the second section, we focus on the role of the dorsomedial prefrontal cortex in adjusting the content, emotionality, and narrative context at each phase of the episodic memory cycle. In the third section, we discuss the reciprocal interactions between emotions and memory: Our memories serve as triggers for emotions and can be used as an emotion regulation device, while our emotions and emotion regulation goals can likewise influence our memories. The final section highlights broad directions for future research.

Large-scale neural activity during emotional processes can be measured noninvasively and in real time using electroencephalography (EEG) and magnetoencephalography (MEG). Both methods have been applied to the study of human affect, yielding information regarding the time course and cerebral correlates of emotional processes. This chapter aims to provide the reader with an understanding of how EEG and MEG may be used in affective neuroscience, including current trends and new methods in this rapidly expanding field. To this end, we discuss the neurophysiological mechanisms and physical origin of electromagnetic brain signals, highlighting methodological challenges and paradigmatic applications of EEG and MEG in affective neuroscience. We also illustrate methodological approaches used by affective neuroscientists, including experimental designs, data-recording procedures, and analytical methods. The chapter concludes by noting major challenges and future directions for EEG and MEG studies in affective neuroscience research.

Adolescence is marked by both normative changes in neural systems associated with emotion and increased sensitivity to social influences, especially from peers. Whereas the influences of caregiver emotion socialization practices on the emotional development of youths are well-studied, less is understood about how socialization through peer contexts impacts adolescents’ emotions. In this chapter, we first describe the neurobiological shifts that influence emotional processing during this developmental stage. We then review a growing literature linking caregiver and peer socialization to the development of emotion and related neurocircuitry. To emphasize the role of individual differences in emotional development, we situate these literatures within the differential susceptibility framework, which recognizes that adolescents’ neural sensitivity to social information may alter the degree to which caregiver and peer influences modulate emotional behaviors, skills, and experiences. We conclude by describing several perspectives for this emerging area of research, bridging developmental, social, and affective neuroscience.

Human affective science has advanced rapidly over the past decades, emerging as a central topic in the study of the mind. This handbook provides a comprehensive and authoritative road map to the field, encompassing the most important topics and methods. It covers key issues related to basic processes including perception of, and memory for, different types of emotional information, as well as how these are influenced by individual, social, and cultural factors. Methods such as functional neuroimaging are also covered. Evidence from clinical studies of brain disease such as anxiety and mood disorders shed new light on the functioning of emotion in all brains. In covering a dynamic and multifaceted field of study, this book will appeal to students and researchers in neuroscience, psychology, psychiatry, biology, medicine, education, social sciences, and philosophy.

The connection between olfaction and emotions has been established across many subjects. Considering the anatomy of the olfactory system, the canonical targets of olfactory projection neurons are part of and associated with nonolfactory neural circuits, widely summarized as the limbic system. Presumably, partly due to this strong connection between olfaction and the limbic system, odors can directly evoke emotions and result in emotional autobiographical memories. Accordingly, odors have been used to modify emotions via nocturnal exposure, active inhalation, and olfactory training. Odor pleasantness impacts these beneficial effects. The valence of odors changes resting state functional connectivity in regions associated with emotions, memory, motivation, and action control. Considering all the above, olfactory loss negatively influences human behaviors in various life domains, including ingestion, hazard avoidance, and social communication, often resulting in a reduced quality of life and well-being, which in turn may be associated with depressive disorders.