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Scientific Dream Interpretation and Analysis |
SP r = √SSxSSy |
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Scientific Dream Interpretation and Analysis |
SP r = √SSxSSy |
The limbic system is a complex set of structures that lies on both sides and underneath the thalamus, just under the cerebrum. It includes the hypothalamus, the hippocampus, the amygdala, and several other nearby areas. It appears to be primarily responsible for our emotional life, and has a lot to do with the formation of memories.
Boeree
"Limbic" is from "limbus" (border) around the corpus callosum and brainstem). THE LIMBIC "SYSTEM" is principally a SUBCORTICAL (basal forebrain; paleocortical) circuit involving several distinct structures (neuronal pools) BUT also involving a cortical structure (cingulate gyrus) and the HYPOTHALAMUS. The subcortical structures are the SEPTUM ( just under forward end of the corpus callosum), AMYGDALA (in the ventral surface near the temporal lobe), and HIPPOCAMPUS (begins near the amygdala and swerves up into brain). It extends from the orbitofrontal area (ventral surface of the frontal lobes) to the cingulate gyrus (in front of the corpus callosum onto the medial aspect of the cerebral hemisphere). To pass posterior down to the ventromedial part of the temporal lobe to the hippocampal gyrus and pyriform area and uncus.
Before the hippocampus can catalogue and file information, that information has to be filtered through the thalamus.The thalamus sends information to the part of the brain that deals with that type of information; in other words, as information comes in via our five senses (hearing, sight, smell, taste and touch) it gets sent to the appropriate part of the brain for that type of information. If the brain decides the information is a keeper, the factual portion is sent to the hippocampus, and the emotional component – if there is one – gets sent to the amygdala.
Our five senses take in information where it first reaches a part of the brain called the thalamus, and from there to the sensory processing areas of the neocortex.
The neocortex is the seat of thought; it contains the centers that put together and comprehend what the senses perceive. It is the thinking part of the brain. Normally, the neocortex processes information perceived, and from there sends out the appropriate response. However, scientists have discovered a bundle of neurons leading directly from the thalamus to the amygdala, something like a neural short cut or back alley.
The amygdala is the brain's specialist for emotional matters. Interestingly enough the amygdala is like our brains security alarm monitoring system. Through the emotions before we even have a chance to 'think' about things, it detects potential danger and can trigger a physical response in us. When it sounds an alarm of, say, fear, it sends urgent messages to every other major part of the brain: it triggers the secretion of the body's flight of fight response hormones, mobilizes the center for movement and activates the cardiovascular system, the muscles and the gut.
The shortcut between thalamus and amygdala allows the amygdala to receive some direct inputs from the five senses and start a response before they are fully registered by the neocortex. This is often what happens in heroic rescues where a bystander sees someone in danger and instantly springs into action without thinking about the danger to their selves. It also explains the reaction of a parent, say in an emergency, who will often act to save their child at the cost of their own life. This same pattern (shortcut from thalamus to amydala) also explains sudden outbursts of anger, those moments when we say, "I don't know what came over me… I suddenly just lost it." This is referred to as an 'emotional hijacking.
Anne Bercht made this observation: "That this can often explain the 'triggers' we experience after our spouse has been unfaithful. For example, during the months following my husband's affair, while we were in what I call 'the fighting phase,' one night the level of frustration in an argument my husband and I were having had reached out of control proportions. In a desperate attempt to be heard, my husband was restraining me. He wasn't hurting my physically, but he was keeping me from leaving. I had become so upset, that I had completely shut down. I was trying to break free. For me it felt frightening.
Years later, during a much milder argument, my husband had put his arms out in the exact same fashion as he had during the traumatic argument in our affair recovery period. It had resulted in my 'losing it.' I found myself screaming hysterically. Later, realizing that my response had been completely inappropriate to the situation, I realized, I had suffered a 'trigger,' or an emotional hijacking. "I was only putting my arms out to give you a hug," my bewildered husband said regarding the experience. Such an incidence is a mild form of post traumatic stress disorder."
Anne Bercht also mentions another person who reported a similar experience, which might also be labeled as an emotional hijacking. She was on holidays with her husband having a nice time, when someone mentioned the name of the city, where her husband's affair partner resided. Instantly and without warning she burst into tears.
The connections between the amygdala and the neocortex are the hub of the battles between head and heart. This circuitry explains why emotion is so crucial to effective thought, both in making wise decisions and in simply allowing us to think clearly.
Take the power of emotions to disrupt thinking itself, something those recovering from infidelity seem to experience much of. Neuroscientists use the term 'working memory' for the capacity of attention that holds in mind the facts essential for completing a given task or problem, like the elements of a reasoning problem on a test. The prefrontal cortex is the brains region responsible for 'working memory.' But circuits from the limbic brain to the prefrontal lobes mean that the signals of strong emotion - anxiety, anger, and the like - can create neural static, sabotaging the ability of the prefrontal lobe to maintain working memory. That is why when we are emotionally upset we say we "just can't think straight." The role of emotions, scientists have discovered, is significant in 'rational' decision-making.
Dr. Antonio Damasio, a neurologist at the University Of Iowa College Of Medicine, has made careful studies of just what is impaired in patients with damage to the amydala, the emotional thinking part of the brain. He discovered that their decision-making ability was terribly flawed even though their cognitive/thinking abilities were not damaged at all. These people continually made disastrous choices in their business and personal lives, and could even obsess endlessly over simple decisions such as when to make an appointment. Evidence such as this leads Dr. Damasio to the counter-intuitive position that feelings are typically INDISPENSABLE for rational decisions; they point us in the proper direction. The emotions, then, matter for rationality.
Bercht
In mammals limbic system consists of:
a. olfactory bulbs
b. septum pellucidum
c. fornix (fibers that pass from beneath corpus callosum to the mammillary bodies of the hypothalamus)
d. cingulum (cerebral gyrus just above corpus callosum)
e. hippocampus (in floor of lateral ventricle near amygdaloid nucleus)
f. mammillary bodies (mainly olfactory reflexes)
g. hypothalamus (connects to pituitary gland or hypophysis), the main outflow to autonomic system (and thus non-cognitive emotional displays
Neuro-notes.
1. Phylogenetically, the limbic lobe is the oldest part of the cerebral cortex (Willis 1998D:247).
2. The limbic system includes the amygdala, anterior thalamic nucleus, cingulate gyrus, fornix, hippocampus, hypothalamus, mammillary bodies, medial forebrain bundle, prefrontal lobes, septal nuclei, and other areas and pathways of the brain. The hypothalamus, a key player, mediates nonverbal behaviors through the brain-stem reticular nuclei. When excited, the reticular nuclei arouse cerebral as well as spinal circuits. (N.B.: An important two-way link between the limbic system and brain stem is the medial forebrain bundle.)
Givens
AMYGDALA
1. An almond-shaped structure in the CNS involved in producing and responding to nonverbal signs of anger, avoidance, defensiveness, and fear.
2. A small mass of gray matter that inspires aversive cues, such as the freeze reaction, sweaty palms, and the tense-mouth display.
3. A primeval arousal center, originating in early fishes, which is central to the expression of negative emotions in man.
-Nonverbal Dictionary
AMYGDALA (also see Dream Therapy)
responds to perceived affect in others. Not only is the amygdala of the brain responsible for many of our emotions, it also is what allows us to interpret emotions in others by looking at their facial expressions. According to a study out of Iowa, people with damage in the amygdala region (paired also with damage to the front of the temporal lobe) can't "read" the emotion of a person's face. (Schmolck, H & Squire, L. 2001. Neuropsychology, vol. 15(1), 30 - 38.)
ENDOCRINE modulation of amygdala.
"Do you ever wonder how the brain determines its response to emotional stimuli? Researchers have now shown a correlation between secretin, a hormone found in gut and brain tissue, and how the brain responds to affective stimuli.
Studies using magnetic resonance imaging (MRI) methods have found that individuals with a range of behavioral disorders including schizophrenia, depression, bipolar illness and autism have abnormal amygdala activation in response to facial emotions and other social stimuli. The amygdala, a part of the limbic brain, has emerged as one of the most critical areas influencing how we respond emotionally. It has also been shown to play an important role in emotional learning and in the attribution of emotional significance to stimuli. These MRI findings point to amygdala dysfunction as a potential neurobiological factor in the development of these disorders.
Recent evidence suggests that secretin may modulate the functional response of the amygdala. "We wanted to test the hypothesis that administration of secretin alters amygdala responsiveness to affective stimuli in healthy adult males," notes study author Deborah Yurgelun-Todd, PhD, of McLean Hospital and Harvard Medical School, Belmont, Mass.
The ability to detect and measure the effects of secretin in the brain is important in three ways. It is consistent with animal studies that report altered amygdala response after secretin administration. It also indicates that administration of this agent can be monitored using neuroimaging methods, therefore providing an important method for studying both brain and behavioral effects of secretin. Finally, and perhaps most promising given that abnormalities of amygdala function have been implicated in a variety of behavioral and psychiatric disorders, studies of secretin effects may lead to new treatment interventions for these often debilitating disorders.
"Results of our study support the hypothesis that secretin alters amygdala responsiveness to affective stimuli," concludes Yurgelun-Todd. Inducing these changes in the amygdala may be achieved through a variety of pathways."
HIGHER NEURAL INFLUENCES.
There is evidence that the experience of joy requires a prefrontal cortex. And there is laterality: patients with right lobe dysfunction were prone to laughing and episodes of euphoria while left side dysfunction might lead to pathological crying and depression. This suggests that the left side is involved with positive affect --happiness-- while the right side is involved with negative affect --fear. Do optimists have hightened left-side function? Increased activity when experiencing pleasant pictures or music, suggests so, while right side is more active when being showm unpleasant stimuli. Babies that express a separation cry, have lower left-side activity and higher right-side activity then more placid babies.
STRESS CONNECTION? Perhaps left-siders can handle stress better ... students tend to have better immune function when they take exams, presumably because the stress resulted in smaller drop in immune system's killer cells. (Brain Briefings, 2000. v 22)
HYPOTHALAMUSis a key structure involved in homeostatic control of the internal milieu of the body. Drives and motivation are organized here and "energized" by affective information from the rest of the limbic system. It does that by means of its neuroendocrine role (via the pituitary gland) as well as by its influence on the autonomic nervous system (which helps regulate body temperature, the cardiovascular system, and food and water intake)
Greenberg
The hypothalamus is a small part of the brain located just below the thalamus on both sides of the third ventricle. (The ventricles are areas within the cerebrum that are filled with cerebrospinal fluid, and connect to the fluid in the spine.) It sits just inside the two tracts of the optic nerve, and just above (and intimately connected with) the pituitary gland.
The hypothalamus is one of the busiest parts of the brain, and is mainly concerned with homeostasis. Homeostasis is the process of returning something to some “set point.” It works like a thermostat: When your room gets too cold, the thermostat conveys that information to the furnace and turns it on. As your room warms up and the temperature gets beyond a certain point, it sends a signal that tells the furnace to turn off.
The hypothalamus is responsible for regulating your hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger and aggressive behavior, and more. It also regulates the functioning of the parasympathetic and sympathetic nervous systems, which in turn means it regulates things like pulse, blood pressure, breathing, and arousal in response to emotional circumstances.
The hypothalamus receives inputs from a number of sources. From the vagus nerve, it gets information about blood pressure and the distension of the gut (that is, how full your stomach is). From the reticular formation in the brainstem, it gets information about skin temperature. From the optic nerve, it gets information about light and darkness. From unusual neurons lining the ventricles, it gets information about the contents of the cerebrospinal fluid, including toxins that lead to vomiting. And from the other parts of the limbic system and the olfactory (smell) nerves, it gets information that helps regulate eating and sexuality. The hypothalamus also has some receptors of its own, that provide information about ion balance and temperature of the blood.
In one of the more recent discoveries, it seems that there is a protein called leptin which is released by fat cells when we overeat. The hypothalamus apparently senses the levels of leptin in the bloodstream and responds by decreasing appetite. It would seem that some people have a mutation in a gene which produces leptin, and their bodies can’t tell the hypothalamus that they have had enough to eat. However, many overweight people do not have this mutation, so there is still a lot of research to do!
The hypothalamus sends instructions to the rest of the body in two ways. The first is to the autonomic nervous system. This allows the hypothalamus to have ultimate control of things like blood pressure, heartrate, breathing, digestion, sweating, and all the sympathetic and parasympathetic functions.
The other way the hypothalamus controls things is via the pituitary gland. It is neurally and chemically connected to the pituitary, which in turn pumps hormones called releasing factors into the bloodstream. As you know, the pituitary is the so-called “master gland,” and these hormones are vitally important in regulating growth and metabolism.
HippocampusThe hippocampus consists of two “horns” that curve back from the amygdala. It appears to be very important in converting things that are “in your mind” at the moment (in short-term memory) into things that you will remember for the long run (long-term memory). If the hippocampus is damaged, a person cannot build new memories, and lives instead in a strange world where everything they experience just fades away, even while older memories from the time before the damage are untouched! This very unfortunate situation is fairly accurately portrayed in the wonderful movie Memento.
Amygdala (also see Dream Therapy)Area of brain found to play key role in initiating memory storage
The amygdalas are two almond-shaped masses of neurons on either side of the thalamus at the lower end of the hippocampus. When it is stimulated electrically, animals respond with aggression. And if the amygdala is removed, animals get very tame and no longer respond to things that would have caused rage before. But there is more to it than just anger: When removed, animals also become indifferent to stimuli that would have otherwise have caused fear and even sexual responses.
Flee, freeze or fight. A response to a threat is based on experience and memory. Now scientists have discovered that an area of the brain, the amygdala, which was thought to store painful and emotion-related memories, also initiates memory storage in other brain regions.
There has been a growing debate on the function of the amygdala [pronounced uh-MIG duh-luh], an almond-shaped sub-cortical structure in the temporal lobe. It receives electrical signals carrying auditory information through axons traveling one way from the medial geniculate (MG) nucleus in the thalamus.
New research published in the Jan. 1 issue of the Journal of Neuroscience suggests that the amygdala plays a pivotal role in the initial process of storing memory elsewhere in the brain. The amygdala appears to decide which experiences are important enough to store a decision based on the emotional significance of the events in a decoding process that affects both learning and memory.
"Our data show that a disabled amygdala leads to a breakdown of learning-related changes in other parts of the brain," said Michael Gabriel, a professor of psychology at the University of Illinois Beckman Institute for Advanced Science and Technology. "Specifically, disabling the amygdala blocks learning-related changes in the sensory pathway, the media geniculate nucleus. These changes are essential for the ability to discriminate between important and unimportant sounds."
Amy Poremba of the National Institute of Mental Health in Bethesda, Md., is the co-author of the study. The National Institutes of Health funded the project through a grant to Gabriel, whose lab uses technology that allows for the simultaneous tracking of firing neurons in several places of the brain. In the study, involving 26 male rabbits, researchers temporarily disabled the amygdala. Rabbits with unaltered brains were able to learn the consequences of two differently sounding tones: one that resulted in nothing and another followed in five seconds by a mild shock to the feet. Rabbits that correctly learned the consequences could avoid the shock by moving the wheel under their feet. Those with blocked amygdalas failed to learn such a response to the shock-predicting tone.
In a follow-up study to appear later in the same journal, the researchers blocked the auditory cortex, through which return signals travel from the amygdala to the medial geniculate. Again, rabbits failed to differentiate the tones.
Instead of just getting input from the medial geniculate, Gabriel said, the amygdala appears to send signals back to the medial geniculate, allowing neurons to decipher the significance of the sounds. "This work puts the amygdala in the middle of the circuitry, in a very prominent position in terms of relevance toward learning," Gabriel said. The findings, he added, also are consistent with a theory originally formulated by James L. McGaugh of the University of California at Irvine. The new data, however, show how the theory is implemented in terms of the activity in the brain circuit.
Besides the hypothalamus, hippocampus, and amygdala, there are other areas in the structures near to the limbic system that are intimately connected to it:
The cingulate gyrus is the part of the cerebrum that lies closest to the limbic system, just above the corpus collosum. It provides a pathway from the thalamus to the hippocampus, seems to be responsible for focusing attention on emotionally significant events, and for associating memories to smells and to pain.
The septum, which lies in front of the thalamus, has areas that seem to be centers for orgasm.
The ventral tegmental area of the brain stem (just below the thalamus) consists of dopamine pathways that seem to be responsible for pleasure. People with damage here tend to have difficulty getting pleasure in life, and often turn to alcohol, drugs, sweets, and gambling.
The basal ganglia (including the caudate nucleus, the putamen, the globus pallidus, and the substantia nigra) lie over and to the sides of the limbic system, and are tightly connected with the cortex above them. They are responsible for repetitive behaviors, reward experiences, and focusing attention.
The prefrontal cortex, which is the part of the frontal lobe which lies in front of the motor area, is also closely linked to the limbic system. Besides apparently being involved in thinking about the future, making plans, and taking action, it also appears to be involved in the same dopamine pathways as the ventral tegmental area, and plays a part in pleasure and addiction.
Amygdala
Emotions and the Brain: Love
Are we finally getting good enough at biochemistry to understand the mystery and magic.of romance?
by Steven Johnson
Scientists who study the brain have traditionally spent far more time exploring the neural pathways of negative emotional responses: On our current map of the mind, the regions of fear are clearly delineated. Not so the kingdom of love and attachment, which has been a vast terra incognita until recently. But a new portrait of love has begun to emerge, and at its center lies a fascinating hormone called oxytocin that may well follow in the footsteps of serotonin, which shot into the popular consciousness a dozen years ago as Prozac was introduced. We are entering an age of brain biochemistry that can grasp the undecipherable.love.
In March of 1998, a psychology professor at the University of California at Los Angeles named Shelley Taylor attended a guest lecture at the university's Westwood campus. The topic was stress and the fight-or-flight instinct, a subject she knew a thing or two about, having studied human stress response for 20 years. At one point in the lecture, the speaker told a story about the levels of aggression he had witnessed in laboratory rats placed in stressful situations. After they had been repeatedly shocked with an electrical charge, the rats began to bite and claw each other to death.
"That went off like a lightbulb in my head, because it's not at all descriptive of what we typically see in human studies," Taylor recalls, sitting in her campus office, a Los Angeles cityscape hovering behind the pine branches outside her window. "I went back to my lab group, and I said, 'What do you make of these disjunctions between the animal studies and what we see in humans?' And one of them said, 'You know, the animal studies are all based on males. They hardly ever include females, because females cycle so rapidly.' And then someone else said, 'You know, I think that's true for the human literature as well.' So we started looking through the literature to see how well female responses to stress were represented, and the answer was very poorly. Prior to 1995, females constituted 17 percent of participants. There were virtually no studies where you had enough female participation to do a comparative study."
The lack of gender parity was not just a political issue. For decades, the scientific literature on stress response revolved around a fundamental causal chain: Introduce a stressor.a lunging predator, say, or a rival stealing your food supply.and the body initiates the now-famous fight-or-flight response. Confronted with stress, the theory went, our bodies instinctively primed themselves to strike back or run away. Fight or flight was compatible with the old Darwinian nature-red-in-tooth-and-claw stereotypes, but it didn't leave much room for an equally common human response to traumatic events: reaching out to loved ones. A parent reacting to a sudden threat will often put himself or herself in greater danger if it means protecting a child or a partner. That selfless behavior makes perfect sense to anyone who has felt parental or romantic love, but under the fight-or-flight paradigm, the behavior seems anomalous.
Taylor suspected that the fight-or-flight response was only half the story, and that gender differences might help shed light on the other half. "I said to my group, 'OK, let's start from scratch. What are women doing? Is fight or flight a reasonable description of women's response to stress?' And within seconds, all of us had an immediate response: No. Because what differentiates female responses to stress from those of males is that female responses have to incorporate the protection of offspring, at least for the period of time that there are offspring. Our idea was that fight behavior works fine if you're an individual, but if you're trying to protect young, fighting just isn't going to work. The same goes for flight.only ungulates like deer have offspring that are capable of fleeing shortly after birth." Two years after attending that guest lecture, Taylor had formulated a new theory, in the form of an essay published in Psychological Review titled "Behavioral Responses to Stress in Females." Fight or flight was one way of dealing with stress, she acknowledged, but there was another option: tend and befriend. You can combat threats by literally going to combat with them, or you can lean on your friends and family for support.
Taylor believes the tending instinct is more commonly expressed in women. "There was recently a meta-review of 28 different studies, and 26 of them found that women sought social support more than men. Short of childbirth, there is no sex difference in humans that looks like that. With most sex differences.men have a slight spatial advantage, women have a linguistic advantage.when you actually look at the curves, there's an enormous overlap." But when it comes to seeking out social bonds in the face of stress, the contrast is emphatic.
Taylor and her team even had a solid hunch about the brain chemistry behind the tending instinct. Researchers had long since detected the release of the peptide oxytocin during some of the key life experiences that involve intense emotional attachment: birth, breast-feeding, and sexual climax. In recent years, higher oxytocin levels had been linked to stressful experiences as well. While oxytocin was present in both male and female brains, evidence suggested that estrogen enhanced the peptide's effects, making it less powerful in males because of testosterone levels. If there was a biologically grounded tending instinct, oxytocin probably played a role.
Taylor's "tend or befriend" enjoyed its 15 minutes as a media sound bite following the publication in 2002 of her book The Tending Instinct, but the underlying concept was more than just a passing slogan. The idea that brain circuitries devoted to affiliation and social bonds may well be as sophisticated as our fear mechanisms had been percolating for almost a decade.
Johnson
The two faces of oxytocin
By Tori DeAngelis
Monitor on Psychology
February 2008, Vol 39, No. 2
Oxytocin is produced mainly in the hypothalamus, where it is either released into the blood via the pituitary gland, or to other parts of the brain and spinal cord, where it binds to oxytocin receptors to influence behavior and physiology.
New studies are adding to a body of literature that shows oxytocin plays a key role in maternal bonding and social affiliation-what Taylor has labeled the "tend and befriend" response, as opposed to the "fight or flight" response. In line with years of animal research linking oxytocin to mothers' ability to care for their infants, a study in the November Psychological Science (Vol. 18, No. 11, pages 965-970), demonstrates this association for the first time in people.
Because of its role in birth and lactation, oxytocin was originally considered a "female" hormone, but it is now known to be present and important in both sexes.
DeAngelis
The New York Times
May 31, 2005
Watching New Love as It Sears the Brain
By BENEDICT CAREY
Now for the first time, neuroscientists have produced brain scan images of this fevered activity, before it settles into the wine and roses phase of romance or the joint holiday card routines of long-term commitment.
In an analysis of the images appearing today in The Journal of Neurophysiology, researchers in New York and New Jersey argue that romantic love is a biological urge distinct from sexual arousal.
It is closer in its neural profile to drives like hunger, thirst or drug craving, the researchers assert, than to emotional states like excitement or affection. As a relationship deepens, the brain scans suggest, the neural activity associated with romantic love alters slightly, and in some cases primes areas deep in the primitive brain that are involved in long-term attachment.
The research helps explain why love produces such disparate emotions, from euphoria to anger to anxiety, and why it seems to become even more intense when it is withdrawn. In a separate, continuing experiment, the researchers are analyzing brain images from people who have been rejected by their lovers.
"When you're in the throes of this romantic love it's overwhelming, you're out of control, you're irrational, you're going to the gym at 6 a.m. every day - why? Because she's there," said Dr. Helen Fisher, an anthropologist at Rutgers University and the co-author of the analysis. "And when rejected, some people contemplate stalking, homicide, suicide. This drive for romantic love can be stronger than the will to live."
In the study, Dr. Fisher, Dr. Lucy Brown of Albert Einstein College of Medicine in the Bronx and Dr. Arthur Aron, a psychologist at the State University of New York at Stony Brook, led a team that analyzed about 2,500 brain images from 17 college students who were in the first weeks or months of new love. The students looked at a picture of their beloved while an M.R.I. machine scanned their brains. The researchers then compared the images with others taken while the students looked at picture of an acquaintance.
Functional M.R.I. technology detects increases or decreases of blood flow in the brain, which reflect changes in neural activity.
In the study, a computer-generated map of particularly active areas showed hot spots deep in the brain, below conscious awareness, in areas called the caudate nucleus caudate nucleus and the ventral tegmental area, which communicate with each other as part of a circuit.
These areas are dense with cells that produce or receive a brain chemical called dopamine, which circulates actively when people desire or anticipate a reward. In studies of gamblers, cocaine users and even people playing computer games for small amounts of money, these dopamine sites become extremely active as people score or win, neuroscientists say.
Yet falling in love is among the most irrational of human behaviors, not merely a matter of satisfying a simple pleasure, or winning a reward. And the researchers found that one particular spot in the M.R.I. images, in the caudate nucleus, was especially active in people who scored highly on a questionnaire measuring passionate love.
This passion-related region was on the opposite side of the brain from another area that registers physical attractiveness, the researchers found, and appeared to be involved in longing, desire and the unexplainable tug that people feel toward one person, among many attractive alternative partners.
This distinction, between finding someone attractive and desiring him or her, between liking and wanting, "is all happening in an area of the mammalian brain that takes care of most basic functions, like eating, drinking, eye movements, all at an unconscious level, and I don't think anyone expected this part of the brain to be so specialized," Dr. Brown said.
The intoxication of new love mellows with time, of course, and the brain scan findings reflect some evidence of this change, Dr. Fisher said.
In an earlier functional M.R.I. study of romance, published in 2000, researchers at University College London monitored brain activity in young men and women who had been in relationships for about two years. The brain images, also taken while participants looked at photos of their beloved, showed activation in many of the same areas found in the new study - but significantly less so, in the region correlated with passionate love, she said.
In the new study, the researchers also saw individual differences in their group of smitten lovers, based on how long the participants had been in the relationships. Compared with the students who were in the first weeks of a new love, those who had been paired off for a year or more showed significantly more activity in an area of the brain linked to long-term commitment.
Last summer, scientists at Emory University in Atlanta reported that injecting a ratlike animal called a vole with a single gene turned promiscuous males into stay-at-home dads - by activating precisely the same area of the brain where researchers in the new study found increased activity over time.
"This is very suggestive of attachment processes taking place," Dr. Brown said. "You can almost imagine a time where instead of going to Match.com you could have a test to find out whether you're an attachment type or not."
One reason new love is so heart-stopping is the possibility, the ever-present fear, that the feeling may not be entirely requited, that the dream could suddenly end.
In a follow-up experiment, Dr. Fisher, Dr. Aron and Dr. Brown have carried out brain scans on 17 other young men and women who recently were dumped by their lovers. As in the new love study, the researchers compared two sets of images, one taken when the participants were looking at a photo of a friend, the other when looking at a picture of their ex.
Although they are still sorting through the images, the investigators have noticed one preliminary finding: increased activation in an area of the brain related to the region associated with passionate love. "It seems to suggest what the psychological literature, poetry and people have long noticed: that being dumped actually does heighten romantic love, a phenomenon I call frustration-attraction," Dr. Fisher said in an e-mail message.
One volunteer in the study was Suzanna Katz, 22, of New York, who suffered through a breakup with her boyfriend three years ago. Ms. Katz said she became hyperactive to distract herself after the split, but said she also had moments of almost physical withdrawal, as if weaning herself from a drug.
"It had little to do with him, but more with the fact that there was something there, inside myself, a hope, a knowledge that there's someone out there for you, and that you're capable of feeling this way, and suddenly I felt like that was being lost," she said in an interview.
And no wonder. In a series of studies, researchers have found that, among other processes, new love involves psychologically internalizing a lover, absorbing elements of the other person's opinions, hobbies, expressions, character, as well as sharing one's own. "The expansion of the self happens very rapidly, it's one of the most exhilarating experiences there is, and short of threatening our survival it is one thing that most motivates us," said Dr. Aron, of SUNY, a co-author of the study.
To lose all that, all at once, while still in love, plays havoc with the emotional, cognitive and deeper reward-driven areas of the brain. But the heightened activity in these areas inevitably settles down. And the circuits in the brain related to passion remain intact, the researchers say - intact and capable in time of flaring to life with someone new.
Carey