Energy Is Delight The Pleasures and Pains of Brain Regulatory Systems
Authors: Panksepp Jaak 
Published: November 2023

Abstract
Mammals can survive only if they maintain relative constancy of various bodily processes, including oxygen and carbon dioxide content in blood, body water levels, salt and energy balance, and body temperature. Complex brain and body systems sustain these constancies, and the overall concept used to describe this ability is homeostasis. Some people prefer the word heterostasis, since the level of regulation sometimes changes as a function of environmental conditions as well as internal bodily cycles (e.g., 24-hour rhythms). Homeostasis is sustained by a diversity of mechanisms ranging from rapid physiological changes, such as reflexive modification of breathing rate as a function of oxygen need (which is actually signaled to the brain by carbon dioxide buildup in the bloodstream), to instinctual behavioral tendencies, such as an animal’s urge to seek resources needed for longer-term survival, including food, water, warmth, and micronutrients such as vitamins and minerals. Bodily needs instigate distinct forms of bodily arousal and psychological feelings of distress such as hunger, thirst, and coldness. Animals have exquisite sensory systems to identify the most important items they need-for example, the ability to taste sweetness identifies foods laden with sugar, and saltiness identifies sources of sodium. It is commonly believed that color vision evolved, in part, to help primates identify the ripest fruit. The needed items that cannot be identified by taste-for instance, many vitamins and other micronutrients-can usually be regulated via learned selection of foodstuffs, based on their postingestive consequences. Most interesting from the affective point of view are the intrinsic brain mechanisms that mediate pleasure and displeasure to provide an intrinsic guide for food selection. The pleasures of sensation arise from the interactions of many sensory systems with poorly understood hedonic mechanisms of the brain. Sensations generate pleasure or displeasure in direct relation to their influence on the homeostatic equilibrium of the body. For instance, if one is depleted of energy resources, foods taste better than when the body is already replete with energy. Although it is difficult to study internally experienced pleasures and displeasures in animals, for an accurate description of certain brain functions it will be essential to conceptualize how such processes are elaborated by specific neural circuits. A variety of distinct pleasures may arise from essentially the same types of neuro-chemical systems, such as the release of endogenous opioids. Likewise, regulation requires some type of set-point mechanisms, resembling the thermostats that control furnaces in our homes, which help specify deviations from physiological equilibrium and thereby promote SEEKING behaviors. To highlight general principles of how regulatory processes operate, in the present chapter I will focus largely on the physiological, behavioral, and psychological mechanisms that help sustain body energy balance. In more than a poetic sense, energy is delight.