The Emotional Brain

Introduction

Why do some people float through life in a sea of tranquility while others ride an emotional roller coaster? What explains why a traumatic experience leaves one person with lasting psychological scars yet another emerges relatively unscathed? These questions about the remarkable variation in human emotional experience lie at the heart of affective neuroscience—the scientific study of how emotions are generated and regulated in the brain. For Dr. Eliza Bliss-Moreau, a 2018 recipient of the American Psychological Association's Distinguished Scientific Award for Early Career Contributions to Psychology, finding answers requires looking beyond humans to our closest animal relatives ^{4 8} .

Bliss-Moreau, now a Chancellor's Leadership Professor at UC Davis and core scientist at the California National Primate Research Center, has dedicated her career to understanding the biological and evolutionary mechanisms that generate emotions across species ^{1 3} . Her award-winning work, noted by the APA for its "interdisciplinary and ethical nature," spans behavioral neuroscience, psychophysiology, and evolutionary processes, enhancing our understanding of the neural and environmental determinants of social and emotional behavior ⁸ . By studying monkeys and humans in tandem, her research is uncovering fundamental truths about what makes us emotional beings—from womb to tomb.

A New Lens on Animal Emotion: Rethinking Old Assumptions

Traditional approaches to animal emotion have largely operated under the assumption that emotions are biologically hardwired, evolutionarily conserved across species, and manifest in discrete, recognizable patterns of behavior and physiology. Under this view, humans can accurately "read" animal emotions by applying our own emotional concepts and observations ⁶ . Bliss-Moreau's work challenges this perspective by adopting an alternative framework known as Theories of Constructed Emotion ⁶ .

This constructivist approach represents a paradigm shift in how scientists study emotion across species. Rather than assuming emotions like fear, anger, or joy are universal entities that different species express in similar ways, the constructivist view proposes that emotions emerge from more fundamental psychological ingredients—core affect (characterized by valence and arousal), attention, conceptual knowledge, and language (in humans) ^{2 6} . These ingredients combine in flexible ways to create the rich tapestry of our emotional experiences.

"The constructivist view changes the questions we ask about animal emotion," explains Bliss-Moreau in her influential paper ⁶ . Instead of asking "Do animals feel fear?"—which assumes fear is a single, identifiable state—her research asks which basic ingredients of fear-like states are present in different species, how they develop across the lifespan, and how they combine to create adaptive emotional responses ² . This approach allows scientists to study emotion across phylogeny without imposing human concepts on non-human animals, leading to more accurate and ethically informed models of animal wellbeing ^{2 6} .

Decoding the Power of Touch: A Key Experiment Unveiled

One of Bliss-Moreau's most fascinating recent studies, led by Ph.D. candidate Joey Charbonneau and published in the Proceedings of the National Academy of Sciences, examines how nonhuman primates process affective touch—the slow, gentle, pleasurable touch that plays a crucial role in social bonding and development ⁹ . What makes this research particularly remarkable is its surprising challenge to conventional wisdom about consciousness and sensation.

Results and Analysis: Consciousness Not Required

The findings challenged fundamental assumptions about how the brain processes pleasurable touch. Surprisingly, anesthetized monkeys showed distinct brain activation patterns in response to affective versus discriminative touch, with affective touch activating regions known to process social and emotional information in awake humans and monkeys ⁹ . This suggests that the rewarding aspects of affective touch transcend species boundaries and—most remarkably—do not require consciousness.

The research also revealed significant age-related differences in how touch is represented in the brain. Older monkeys showed altered brain activity patterns in response to discriminative—but not affective—touch, suggesting that the neural circuits supporting this basic social reward remain more stable across the lifespan than those supporting simple tactile discrimination ⁹ . This finding has profound implications for understanding how social connection and wellbeing might be maintained even as other sensory and cognitive functions decline with age.

The implications of these findings extend far beyond basic neuroscience. Understanding these mechanisms could inform treatments for conditions where affective processing is impaired, such as autism spectrum disorder, or where social bonds are crucial for wellbeing, such as Alzheimer's disease and other neurodegenerative conditions ⁹ . By revealing that the building blocks of social pleasure are more fundamental than previously thought—embedded deep in our neurobiology and shared with our primate relatives—this work opens new pathways for promoting social health across the lifespan.

The Scientist's Toolkit: Essential Resources for Affective Research

The groundbreaking work emerging from Bliss-Moreau's laboratory relies on a sophisticated array of methodological approaches and resources. This multidisciplinary "toolkit" enables the team to study emotion across species and throughout the lifespan with unprecedented precision. Their research is characterized by what they call a "multi-method, multi-species, multilevel approach" that integrates techniques from social psychology, physiological psychology, neuroscience, primatology, and systems science ^{2 3 7} .

Bliss-Moreau's research program is supported by substantial funding from the National Institutes of Health, including multiple grants from the National Institute on Aging focused on interoception, Alzheimer's disease modeling, and social relationships in aging ⁵ . This funding enables the long-term, lifespan approaches that are essential for understanding how emotions develop and change from "womb to tomb" ² . Additional support from the National Eye Institute and National Institute of Mental Health allows the lab to explore connections between visual disorders, neurodevelopmental diseases, and emotional processing ⁵ .

Conclusion: From Animal Models to Human Wellbeing

Eliza Bliss-Moreau's award-winning research represents a transformative approach to understanding one of humanity's most fundamental experiences: our emotional lives. By blending innovative theoretical frameworks with rigorous multispecies methods, her work is revealing the deep evolutionary roots of emotion while respecting the unique manifestations of emotional experiences across species.

The implications of this research extend far beyond academic interest. By developing objective measures of animal wellbeing that don't rely on human perception, Bliss-Moreau's work promises to improve the lives of both humans and animals ² . Her studies of fetal Zika virus infection are illuminating the neurodevelopmental challenges facing affected children, while her aging research offers new hope for maintaining social and emotional health throughout our lives ^{2 8} .