Mammals and birds have evolved three primary, discrete, interrelated emotion-motivation systems in the brain for mating, reproduction, and parenting: lust, attraction, and male-female attachment. Each emotion-motivation system is associated with a specific constellation of neural correlates and a distinct behavioral repertoire. Lust evolved to initiate the mating process with any appropriate partner; attraction evolved to enable individuals to choose among and prefer specific mating partners, thereby conserving their mating time and energy; male-female attachment evolved to enable individuals to cooperate with a reproductive mate until species-specific parental duties have been completed. The evolution of these three emotion-motivation systems contribute to contemporary patterns of marriage, adultery, divorce, remarriage, stalking, homicide and other crimes of passion, and clinical depression due to romantic rejection. This article defines these three emotion-motivation systems. Then it discusses an ongoing project using functional magnetic resonance imaging of the brain to investigate the neural circuits associated with one of these emotion-motivation systems, romantic attraction.

The nucleus accumbens, a site within the ventral striatum, plays a prominent role in mediating the reinforcing effects of drugs of abuse, food, sex, and other addictions. Indeed, it is generally believed that this structure mandates motivated behaviors such as eating, drinking, and sexual activity, which are elicited by natural rewards and other strong incentive stimuli. This article focuses on sex addiction, but we hypothesize that there is a common underlying mechanism of action for the powerful effects that all addictions have on human motivation. That is, biological drives may have common molecular genetic antecedents, which if impaired, lead to aberrant behaviors. Based on abundant scientific support, we further hypothesize that dopaminergic genes, and possibly other candidate neurotransmitter-related gene polymorphisms, affect both hedonic and anhedonic behavioral outcomes. Genotyping studies already have linked gene polymorphic associations with alcohol and drug addictions and obesity, and we anticipate that future genotyping studies of sex addicts will provide evidence for polymorphic associations with specific clustering of sexual typologies based on clinical instrument assessments. We recommend that scientists and clinicians embark on research coupling the use of neuroimaging tools with dopaminergic agonistic agents to target specific gene polymorphisms systematically for normalizing hyper- or hypo-sexual behaviors.

Hypersexuality has been defined as abnormally increased sexual activity. Epidemiological and clinical studies have shown that this non-paraphilic condition consists of "excessive" sexual behaviors and disorders accompanied by personal distress and social and medical morbidity. It is a very controversial and political topic in terms of how best to categorize it as similar or not similar to addictive behaviors including substance abuse. Hypersexual disorder is conceptualized as a non-paraphilic sexual desire disorder with impulsivity. Pathophysiological perspectives include dysregulation of sexual arousal and desire, sexual impulsivity, and sexual compulsivity. The nucleus accumbens, situated within the ventral striatum, mediates the reinforcing effects of drugs of abuse, such as cocaine, alcohol, nicotine, and food as well as music. Indeed, it is believed that this structure mandates behaviors elicited by incentive stimuli. These behaviors include natural rewards like feeding, drinking, sexual behavior, and exploratory locomotion. An essential rule of positive reinforcement is that motor responses will increase in magnitude and vigor if followed by a rewarding event. Here, we are hypothesizing that there is a common mechanism of action (MOA) for the powerful effects drugs, music, food, and sex have on human motivation. The human drive for the three necessary motivational behaviors "hunger, thirst, and sex" may all have common molecular genetic antecedents that, if impaired, lead to aberrant behaviors. We hypothesize that based on a plethora of scientific support hypersexual activity is indeed like drugs, food, and music that activate brain mesolimbic reward circuitry. Moreover, dopaminergic gene and possibly other candidate neurotransmitter-related gene polymorphisms affect both hedonic and anhedonic behavioral outcomes. There is little known about both the genetics and epigenetics of hypersexuality in the current literature. However, we anticipate that future studies based on assessments with clinical instruments combined with genotyping of sex addicts will provide evidence for specific clustering of sexual typologies with polymorphic associations. There have been some studies using electrophysiological techniques that do not support the view that hypersexuality is indeed similar to substance abuse and other behavioral addictions. The authors are also encouraging both clinical and academic scientists to embark on research using neuroimaging tools to examine natural dopaminergic agonistic agents targeting specific gene polymorphisms to "normalize" hypersexual behavior.

and brain scan experiments using fMRI have shown that it activates reward areas in the brain. One prominent evolutionary theory developed by the anthropologist Romance and romantic love encompass a number of ideas about love, which are interrelated for historical and cultural reasons: passionate feelings of attraction—a mental state of "being in love", with focused attention (salience) towards a specific individual for courtship or pair bonding; the cultural practice or idealization of initiating intimate relationships for feelings like these, over more Romantic love is believed to have evolved in hominids about 4.4 or 2 million years ago (depending on the theory), although the exact time has not been identified yet. It has been associated with a suite of psychological characteristics, and brain scan experiments using fMRI have shown that it activates reward areas in the brain. One prominent evolutionary theory developed by the anthropologist Helen Fisher states that romantic love is a brain system evolved for mammalian mate choice (also called courtship attraction), an aspect of sexual selection, for focusing energy on a preferred mating partner. In most species, courtship attraction is only brief (lasting minutes, hours, days or weeks), but Fisher believed that over the course of evolutionary time, it became prolonged and intensified in humans. Another prominent theory states that romantic love re-purposed brain systems which were originally for mother–infant bonding, via an evolutionary process called co-option (or exaptation). Both types of love share similar features (preoccupation, exclusivity of focus, longing for reciprocity and idealization), and brain scans have shown overlapping areas. It has been claimed on the basis of certain ethnographic reports that romantic love is limited to Western culture, and does not exist in tribal societies throughout the world. For example, the anthropologist Audrey Richards lived among the Bemba people in the 1930s, and once told them a folk story about a young prince who "climbed glass mountains, crossed chasms, and fought dragons, all to obtain the hand of a maiden he loved". The Bemba, however, became bewildered by the story, prompting an old chief to ask the question "Why not take another girl?" Margaret Mead studied the Samoans, and also believed that deep attachments between individuals were a foreign idea to such societies: "Romantic love as it occurs in our civilisation, inextricably bound up with ideas of monogamy, exclusiveness, jealousy and undeviating fidelity does not occur in Samoa." The tribal mentality, according to Nathaniel Branden, is that the family ought to exist for the optimization of physical survival. The individual is subordinate to the tribe…