What kinds of arousal can a human brain experience?

What kinds of arousal can a human brain experience?

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I've been reading about the new phenomenon called "arousal addiction". The context in which this term is used is Internet, Porn and/or video game addiction(cummulatively Internet Addiction Disorder - IAD). Dopamine and Dopamine receptor D2 are sometimes mentioned, as being affected by exposure to a new, novel stimuli.

I'm interested if there are other forms of "arousal" that may involve more than just Dopamine. For example, I know that there are 4 neuromodulators in the human brain:

  • Dopamine
  • Serotonin
  • Choline
  • Noradrenaline

For example, if a person likes horror movies to the point of addiction, is it Dopamine, or is it Noradrenaline that the person enjoys? If a person is addicted to comfort foods, is it Dopamine or Serotonin?

Thank you!

Depends on what you mean by "addiction": defined, addiction usually requires both psychological and physiological dependence, but conversationally we sometimes only talk about psychological dependence (as in here, your muscles won't cramp up if you NEED a horror flick).

If a person enjoys horror movies, is it the suspense? Such a rush is caused by the well-known fight-or-flight catecholamine epinephrine (also known as adrenaline). This is the short-term stress response at play. Comfort foods are a whole other story, because it depends on the food as well. Carbohydrates can contribute to serotonin levels, yes, but I read a super-interesting study a couple years back about saturated fat causing a decrease in corticosteroid levels and this sought to explain why people eat fatty foods when they are stressed (I'll try to find this article for you). Tryptophan, an amino acid, is converted to serotonin, which is why turkey, milk, and other sources of trp can make one sleepy.

Awesome question! I'm going to try to learn more about this and find that article for you. Dopamine is the primary player in most conventional addiction-talk, as it's crucial to the reward circuitry that is usually discussed.

Technological Basics of EEG Recording and Operation of Apparatus

2.1.1 Brain Waves

Brain waves are oscillating electrical voltages in the brain measuring just a few millionths of a volt. There are five widely recognized brain waves, and the main frequencies of human EEG waves are listed in Table 2.1 along with their characteristics.

Table 2.1 . Characteristics of the Five Basic Brain Waves

Frequency bandFrequencyBrain states
Gamma (γ)&gt35 HzConcentration
Beta (β)12–35 HzAnxiety dominant, active, external attention, relaxed
Alpha (α)8–12 HzVery relaxed, passive attention
Theta (θ)4–8 HzDeeply relaxed, inward focused
Delta (δ)0.5–4 HzSleep

Brain wave samples for different waveforms are shown in Fig. 2.1 .

Figure 2.1 . Brain wave samples with dominant frequencies belonging to beta, alpha, theta, and delta bands and gamma waves.

Various regions of the brain do not emit the same brain wave frequency simultaneously. An EEG signal between electrodes placed on the scalp consists of many waves with different characteristics. The large amount of data received from even one single EEG recording makes interpretation difficult. The brain wave patterns are unique for every individual. 8

The Cannon-Bard and James-Lange Theories of Emotion

Recall for a moment a situation in which you have experienced an intense emotional response. Perhaps you woke up in the middle of the night in a panic because you heard a noise that made you think that someone had broken into your house or apartment. Or maybe you were calmly cruising down a street in your neighborhood when another car suddenly pulled out in front of you, forcing you to slam on your brakes to avoid an accident. I’m sure that you remember that your emotional reaction was in large part physical. Perhaps you remember being flushed, your heart pounding, feeling sick to your stomach, or having trouble breathing. You were experiencing the physiological part of emotion—arousal—and I’m sure you have had similar feelings in other situations, perhaps when you were in love, angry, embarrassed, frustrated, or very sad.

If you think back to a strong emotional experience, you might wonder about the order of the events that occurred. Certainly you experienced arousal, but did the arousal come before, after, or along with the experience of the emotion? Psychologists have proposed three different theories of emotion, which differ in terms of the hypothesized role of arousal in emotion (Figure 10.4 “Three Theories of Emotion”).

Figure 10.4 Three Theories of Emotion

The Cannon-Bard theory proposes that emotions and arousal occur at the same time. The James-Lange theory proposes the emotion is the result of arousal. Schachter and Singer’s two-factor model proposes that arousal and cognition combine to create emotion.

If your experiences are like mine, as you reflected on the arousal that you have experienced in strong emotional situations, you probably thought something like, “I was afraid and my heart started beating like crazy.” At least some psychologists agree with this interpretation. According to the theory of emotion proposed by Walter Cannon and Philip Bard, the experience of the emotion (in this case, “I’m afraid”) occurs alongside our experience of the arousal (“my heart is beating fast”). According to the Cannon-Bard theory of emotion , the experience of an emotion is accompanied by physiological arousal. Thus, according to this model of emotion, as we become aware of danger, our heart rate also increases.

Although the idea that the experience of an emotion occurs alongside the accompanying arousal seems intuitive to our everyday experiences, the psychologists William James and Carl Lange had another idea about the role of arousal. According to the James-Lange theory of emotion , our experience of an emotion is the result of the arousal that we experience. This approach proposes that the arousal and the emotion are not independent, but rather that the emotion depends on the arousal. The fear does not occur along with the racing heart but occurs because of the racing heart. As William James put it, “We feel sorry because we cry, angry because we strike, afraid because we tremble” (James, 1884, p. 190). A fundamental aspect of the James-Lange theory is that different patterns of arousal may create different emotional experiences.

There is research evidence to support each of these theories. The operation of the fast emotional pathway (Figure 10.3 “Slow and Fast Emotional Pathways”) supports the idea that arousal and emotions occur together. The emotional circuits in the limbic system are activated when an emotional stimulus is experienced, and these circuits quickly create corresponding physical reactions (LeDoux, 2000). The process happens so quickly that it may feel to us as if emotion is simultaneous with our physical arousal.

On the other hand, and as predicted by the James-Lange theory, our experiences of emotion are weaker without arousal. Patients who have spinal injuries that reduce their experience of arousal also report decreases in emotional responses (Hohmann, 1966). There is also at least some support for the idea that different emotions are produced by different patterns of arousal. People who view fearful faces show more amygdala activation than those who watch angry or joyful faces (Whalen et al., 2001 Witvliet & Vrana, 1995), we experience a red face and flushing when we are embarrassed but not when we experience other emotions (Leary, Britt, Cutlip, & Templeton, 1992), and different hormones are released when we experience compassion than when we experience other emotions (Oatley, Keltner, & Jenkins, 2006).

How We Remember, and Why We Forget

I remember my mother’s vegetable garden when I was a child, corn plants tall like skyscrapers. I remember when I fell out of a tree and everyone from the neighbor’s barbecue rushed over to see if I’d broken a bone. Remember, remember… the verb itself is poetic, connotating the essence of experience. The notion of memory is so intriguing that we’ve come up with more metaphors for it than for any other mental phenomenon. Early theories predicted a memory “engram,” a literal text written by the body to describe past experiences. Freud popularized descriptions of repressed memories, experiences physically buried in the depths of the subconscious. Modern descriptions are dominated by analogies to computers, in which the human brain is a hard disk that stores experience in electronic files and folders. Typical of biology, the truth is at once more complicated and more beautiful than any of these descriptions.

Fundamentally, memory represents a change in who we are. Our habits, our ideologies, our hopes and fears are all influenced by what we remember of our past. At the most basic level, we remember because the connections between our brains’ neurons change each experience primes the brain for the next experience, so that the physical stuff we’re made of reflects our history like mountains reflect geologic eras. Memory also represents a change in who we are because it is predictive of who we will become. We remember things more easily if we have been exposed to similar things before, so what we remember from the past has a lot to do with what we can learn in the future.

An understanding of memory is an understanding of the role of experience in shaping our lives, a critical tool for effective learning in the classroom and beyond. In this article we will explore how experiences become memories, and we’ll examine whether the way that we create and store memories can influence the way that we learn.

Immediate, Working, and Long-Term Memory
Scientists divide memory into categories based on the amount of time the memory lasts: the shortest memories lasting only milliseconds are called immediate memories, memories lasting about a minute are called working memories, and memories lasting anywhere from an hour to many years are called long-term memories.

Each type of memory is tied to a particular type of brain function. Long-term memory, the class that we are most familiar with, is used to store facts, observations, and the stories of our lives. Working memory is used to hold the same kind of information for a much shorter amount of time, often just long enough for the information to be useful for instance, working memory might hold the page number of a magazine article just long enough for you to turn to that page. Immediate memory is typically so short-lived that we don’t even think of it as memory the brain uses immediate memory as a collecting bin, so that, for instance, when your eyes jump from point to point across a scene the individual snapshots are collected together into what seems like a smooth panorama.

Declarative and Nondeclarative Memories
Another way to categorize memory is to divide memories about what something is from memories about how something is done. Skills like catching a baseball or riding a bicycle are called nondeclarative memories because we perform those activities automatically, with no conscious recollection of how we learned the skills. Declarative memories, on the other hand, are memories of facts and events that we can consciously recall and describe verbally.

Categorizing memory temporally and functionally makes sense from the clinical and biological perspective patients with various amnesias may have difficulty with one particular type of memory and not with others. Moreover, scientists have discovered that different brain structures are specialized to process each category of memory, suggesting that these categories are not merely convenient for discussion, but are based in the biology of how we remember. Understanding how memories are formed in each category and how some memories move amongst categories can help to focus strategies for improving memory and learning.

How Memories Are Made
Modern computers encode memory as a vast array of independent, digital bits of information that are “randomly accessible.” Functionally, this means that your computer can bring up your best friend’s phone number without accessing any information about what your best friend looks like or how you met. The human brain stores memory in a very different way recalling your best friend’s phone number may very well bring to mind your friend’s face, a pleasant conversation that you had, and the title of the movie that the two of you are going to see. While computer memories are discrete and informationally simple, human memories are tangled together and informationally complex.

Our memories are rich because they are formed through associations. When we experience an event, our brains tie the sights, smells, sounds, and our own impressions together into a relationship. That relationship itself is the memory of the event. Unlike computer memories, a human memory is not a discrete thing that exists at a particular location instead, it is an abstract relationship amongst thoughts that arises out of neural activity spread over the whole brain.

But how is the memory relationship actually made? The process from both a biological and a behavioral perspective is critically dependent on reinforcement. Reinforcement can come in the form of repetition or practice we remember that two plus two equals four because we’ve heard it so many times. Reinforcement can also occur through emotional arousal most people remember where they were when they heard that John F. Kennedy was shot because of the highly emotional content of that event. Arousal is also a product of attention, so memories can be reinforced independent of context by paying careful attention and consciously attempting to remember.

Remembering a New Face
Reinforcement is important in forming memories because it moves the memory relationship from short-lived categories to longer-lasting ones. For example, if you met a man called John Byrd at a party, you’d see his face, hear his name, and you’d be aware of the social context of the event. At first this information is loosely held in immediate memory, just long enough for the event to play itself out. Immediate memories are held in various modality-specific regions of the brain, meaning that immediate visual memory is probably held in visual parts of the brain, immediate auditory memory in auditory parts of the brain, and so on.

If you paid attention during the introduction, the relationship between sight, sound, and awareness is brought together into working memory, somewhere in the prefrontal lobe of the brain. When the event moves from immediate memory to working memory, certain features will be lost. You probably won’t remember background conversations from the party, and you may not remember the color of the Mr. Byrd’s shoes. The loss of distracting information is an important feature of human memory, and is critical for efficient storage and recollection of experiences.

At this point you might rehearse the event by saying the name to yourself, or by making up a mnemonic (John Byrd, who has a big hook nose like a bird). The mnemonic and the rehearsal cause the memory to move from working memory into long-term memory, a change that starts in the brain’s hippocampus. The process of converting working memory into long-term memory is called consolidation, and again, it is characterized by the loss of distracting information. Several days after meeting Mr. Byrd you may not be able to remember what color his tie was or whether he wore a wristwatch, but you will still remember his face, his name, and the person who introduced you to him. The consolidation phase of memory formation is sensitive to interruption if you are distracted just after meeting Mr. Byrd, you may have trouble remembering his name later.

So to recap, the event of meeting John Byrd started out in immediate memory, spread out in various modality-specific regions of the brain. Reinforcement through attention caused the relationship between sight, sound, and context to consolidate into working memory in the prefrontal lobe. Further reinforcement through practice caused more consolidation, and the most critical relationships in the event (the name, the face, and the context) were tied together in the hippocampus. From there, the memory relationship is probably stored diffusely across the cerebral cortex, but research on the actual location of memory relationships is still inconclusive.

Can Memory Be Improved?
The end result of all of this moving across categories is that humans are good at remembering a few complex chunks of information while computers are good at remembering many simple chunks of information. It is a lot easier for a person to remember four photographs in great detail than it is to remember a list of forty two-digit numbers quite the opposite for a computer. Also, because we form memories through consolidation, attention and emotional arousal work together to determine what features of an event are important, and therefore what features will be remembered.

From a practical perspective, that means that we can remember something best if we learn it in a context that we understand, or if it is emotionally important to us. It is a lot easier to remember that the hypophysial stalk connects the hypothalamus to the pituitary gland if you already know a lot about neurobiology. But it’s also an easy fact to remember if you’ve ever had a loved one who suffered from a tumor near that part of the brain.

Mnemonic strategies, contextual learning, repetitive rehearsal, and emotional arousal are all good ways to ensure that we remember the things that are important to us. By focusing our learning strategies on the strengths of the brain’s memory systems, we may be able to learn more information in a shorter amount of time in a way that is useful to our lives. That focus requires understanding the limitations of our memories the human brain is not good at remembering long lists of unrelated numbers, dozens of nonsense words, or lengthy grocery lists. While the brain has an extraordinary ability to remember many events in rich detail, the neurologically appropriate strategy for life’s most mundane memory tasks may require little more than pen and paper.

Ashish Ranpura earned his bachelor’s degree in neuroscience at Yale University, where he studied the cellular basis of learning and memory. He began his career in science journalism at National Public Radio’s “Science Friday,” and continues to be deeply interested in promoting public understanding of science. He is currently conducting research on cognitive development underlying number perception and arithmetical skills.

The Roots of Sexual Arousal and Sexual Orientation

Unlike members of other species that are genetically wired to be attracted to their sexual partners, humans learn the cues that guide them in choosing their sexual partners and that trigger sexual arousal. Genetically wired mechanisms must be directing the acquisition of those cues and organizing them in information structures that underlie human sexual behavior. Individual sexuality is a combination of the genetic mechanisms and information learned through personal experiences. This article focuses on the roots of human sexuality –on genetically embedded mechanisms, common to all humans, around which the wide variety of sexual behaviors is built. It proposes a model that defines the basic mechanisms and their role in developing individual sexuality. It is suggested that three brain areas host the root of human sexuality: the auditory area, which provides stimuli that serve as cues for the identification of a mate an emotional area, which provides cues for emotional arousal and a corporal area, which controls the physiological expressions of arousal. The amygdala is a main candidate for the emotional area, and the hypothalamus for the corporal area, but other areas may also provide those inputs. Experimental observations that support this model are discussed, and an outline of additional experiments for validating the model is proposed. If validated, the model would provide knowledge that fills a gap in the understanding of human sexuality –knowledge that would benefit individuals, the medical profession, and society as a whole.


Throughout their lives, individuals develop their behavioral and emotional patterns from roots that are genetically embedded in their brains. This article proposes a theory about the roots of sexual orientation and arousal, and outlines how innate learning mechanisms and individual experiences expand those roots to create the wide spectrum of human sexual emotions and behaviors.

At puberty, many people discover that their sexuality has emerged, without them even noticing how it was evolving. Asexual experiences during childhood have been processes by the brain and formed the adult sexual phenotype. This article focuses on pre-pubertal developmental mechanisms. The same general mechanisms continue also after puberty, but by then, additional factors, which depend on the mature sexual system, affect the outcome.

The sexual system of the newborn consists of “hardware” and “software”. The hardware is the immature sex organs, and the software is the immature brain programs that activate that hardware. Both parts evolve with time and experience, and at puberty the entire system becomes functional. Although it is not known how the software is encoded, it is apparently realized as synaptic weights between neurons that form neural networks. Neural networks process external stimuli and activate the physiological and mental components of the sexual system.

Classical conditioning is one of the innate mechanisms that the brain uses for acquiring and recording information in its neural networks. Three factors participate in classical conditioning (e.g. Pavlov's experiment): the unconditioned stimulus US(taste of food), the unconditioned response UR (salivation), and the conditioned stimulus CS (bell's ring). The unconditioned stimulus US and its response UR are already a part of the brain's information system. Then, the unconditioned stimulusUS triggers the unconditioned response UR in the presence of the conditioned stimulus CS. After the learning is complete, the CS too becomes a trigger of the UR. The UR is now called the conditioned response CR of the CS.

A CS that has become associated with an UR through conditioning may serve as theUS in a subsequent conditioning. For example, a whistle that has become associated by conditioning with the feeling of reward, can serve as the US in subsequent training of a dog, and associate other behaviors and stimuli with feeling rewarded. That is how root associations can be expanded to general behavior repertoires.

Classical conditioning is ubiquitous, and it ought to be genetic. It has been demonstrated that human adults can learn new sexual arousal cues by conditioning (1). Conditioning probably underlies the development of the software of the sexual system. Therefore, the innate sexual US's and UR's are the root of human sexuality they determine the sexuality of the individual. Unlike in Pavlov’s experiments, the innate sexual US's and UR's are not so self-evident. The sexual system is not functional at infancy. Its software and hardware develop during many years of personal experiences, till they mature at puberty. In adults, both root and conditioned stimuli commingle in triggering sexual behaviors. The purpose of this paper is to identify the root US's around which human sexuality develops.

The software of the sexual activities that the brain uses consists of input and output routines. They control the sexual activities and coordinate them with the external circumstances. The input routines, which are the focus of this article, determine the sexual orientation and what arouses a person.

Many attempts have been made to identify the US's that serve as the input cues to the root sexual orientation routines.

Chemical compounds whose production in men is different than in women were found, and if ingested they affect sexual behavior (2,3). However, it has not been demonstrated that humans naturally use those compounds, or in general, that humans depend on pheromones or olfactory signals to identify a mate or to get aroused (4).

Breast feeding apparently does not provide the root stimuli around which sexual orientation is built the distribution of sexual orientations among adults who were breast-fed does not seem different from that of formula-fed people.

Differences in the appearance of men and women, such as chest shape and facial hair, are affected by clothing and other social norms that may vary with time and location, so they cannot provide a universal root US's for sexual orientation.

Studies of the correlations between the sexual orientations of parents and the sexual identities of their children suggest that, in general, the sexual orientation of the parents is not a major factor that affects the sexual identities of their children (5,6). However, more studies of larger populations and of a wider variety of parental compositions are needed in order to sort out cause-effect relationships.

There are pre- and post-natal differences between the hormonal profiles of females and males. These differences are responsible for the development of the sex organs and for general gender-characteristic behaviors, but they do not seem to determine sexual orientation (7-10).

Several morphological and functional brain differences between the sexes have been observed (11), but their roles in sexual activities need clarification.

In homosexual men (HoM), the size of the suprachiasmatic nucleus is twice the size that it is in HeM, and this difference may be attributed to pre-natal hormonal differences.(12,13).

HoM, like HeW, have a smaller area in the frontal part of the hypothalamus (the INAH-3) than do HeM (14).

The anterior commissure of HoM is larger than that of HeM. This structure, which is larger in women than in men, connects the left and right temporal cortexes and is thus involved in sex differences related to cognitive abilities and language (15).

The hypothalamus of HoM, is not as responsive to a classic antidepressant (fluoxetine) as that of HeM, which points to a difference in the activity of the serotonergic system (16).

The progesterone derivative 4,16-androstadien-3-one (AND), whose concentration in men’s sweat is approximately 10 time greater than in women’s, and the estrogen-like steroid estra-1,3,5(10),16-tetraen-3-ol (EST), which was detected in women’s urine, elicited different responses, concurrent with sexual orientation, in the hypothalamus of HeW and HoM, but not it HeM. (2) and in HoW’s and HeW (3).

Brain areas that are activated during sexual stimulation have been mapped, using non-invasive methods. Numerous studied (17) use fMRI and PET scans. Others use electrical evoked potential, and some used MEG (18). A general experimental paradigm is comparing and contrasting activations that were triggered by sexual stimuli with activations of asexual stimuli or with a quiet baseline. Videos and still pictures are common visual stimuli in such experiments. The Achilles heel of visual stimulation is the multitude of factors that are involved in the experiments and the subjectivity of some of the criteria. Brain areas that handle cognitive, emotional, motivational and physiological information participate in the process in both men and women, including the thalamus, amygdala, inferior frontal lobe, orbital prefrontal cortex, medial prefrontal cortex, cingulate cortex, insula, corpus callossum, inferior temporal lobe, fusiform gyrus, occipitotemporal lobe, striatum, caudate, and globus pallidus (17). The level of activation of some of the areas depends on hormone levels, which vary with time and subject (19). The stimuli vary from one experiment to another, and the appraisal of the specific features that cause the arousal may be subjective (20). Overall, it is difficult to establish cause-effect sequences from these experiments. Nevertheless, it has been established that the ways that the brain processes sexual information varies according to the sex and the sexual orientation of the person. Some areas, such as the hypothalamus and the amygdala, appear to be more central to the processes than others (17). Areas associated with reward, such as the ventral striatum and centromedian thalamus, also responded in accordance with the sexual orientation of the person (21).

The Model

The root of sexual orientation

In many species, pheromones drive sexual attraction. In one mode of operation, a female releases a pheromone, and a male detects it. That triggers a sequence of activities in the male that leads him to the female. All this is possible because the releasing organs of the female and the detecting organs of the male are genetically designed to work together. In analogy, in order to uncover the roots of human sexual orientation, it is needed to identify a genetic human system that emits signals that depend on the sex of the emitter, and a receiving system that responds to those signals according to the sex of the receiver.

The auditory system fits these specifications. The voice of men is distinct from the voice of women, and this distinction is easily detected by the auditory system. Voice is one of the most reliable cues that humans use in order to recognize the sex of the speaker. Voice is a genetic, robust, universal cue that is not susceptible to surrounding factors. Therefore, it is suggested that voice is the enigmatic root US, around which sexual orientation is built by conditioning.

In a boy that will become a heterosexual men (HeM), the innate receiving sexual routine is genetically tuned to respond to women's voice. When the boy hears a woman’s voice, features of that woman are conditioned and become cues of the boy’s immature sexual-attraction-center. After puberty, these cues will trigger in this HeM sexual attraction to women. Similarly, in HeW, the voice detectors are tuned to men’s voice, in HoM they are tuned to men’s voice, in HoW they are tuned to women’s voice, and in BiW and BiM they are tuned to the voices of both men and women.

Evolvement of arousal cues

Identifying a potential mate of the desired sex is one goal of the sexual software. Another goal is triggering arousal towards that mate. The arousal software generates emotions that help trigger the physiological expressions of sexual arousal. It is plausible that the root arousal software, around which the mature software is built, deals with genetic emotions.

Fear is a genetic innate emotion that participates as the US and the UR in conditioning. It is the activated state of its default opposite, feeling safe. These two opposites can happen simultaneously, and when they do, an overall feeling of arousal may result. For example, fear and feeling-safe get mixed in a roller-coaster ride. The result is a kind of arousal. When watching a favorite team playing a close match, the fear of losing and the feeling of personal safety create a state of arousal. Such arousal feelings are different from pure fear and from pure safety. It has been suggested (22) that a combination of two feelings: fear of another person and, at the same time, feeling safe is a root of sexual arousal. This combination is called SWAP, for Safe With Another Person. In children, whose sexual system is still immature, feeling SWAP activates conditioning processes that acquire sexual arousal cues in asexual situations. For example, a child that is scared of a stranger clings to her mother’s leg. Features of the situation, such as touching a leg, become cues of SWAP. After puberty, in synergy with sexual orientation cues and in the appropriate ambiance and state of mind, touching the leg of her partner would trigger her sexual arousal.

Although feeling SWAP appears to be a root US of sexual arousal, it may, but it does not have to actually cause all adult arousals. This is a general property of all cues that serve as root US’s in conditioning. For example, a dog that due to conditioning feels rewarded by various stimuli, will still feel rewarded by food, the root US that was used in the training. Also, after puberty, physical erotic pleasures become operational, and they can serve as US's for learning arousal cues. Those cues do not have to depend on feeling SWAP. For example, a fragrance that one of the partners wears may become an arousal cue, due to its association with experienced sexual pleasures.

Prevalence of SWAP

The role of feeling SWAP in acquiring and in triggering arousal is elucidated by analyzing common observed behaviors and testimonials.

Starting at about three years of age, it is common for children to be apprehensive of becoming friends, or even associating with children of the opposite sex. At the same time, they feel safe with friends of their own sex. In fewer cases, children prefer associating with the opposite sex and avoid their own. It is possible that those SWAP feelings trigger conditioning of cues of sexual arousal and orientation in asexual interactions. Those cues could become part of the adult’s sexual repertoire. The same emotional tension between the need to feel safe with a partner and the concern of being rejected is a common ingredient of sexual arousal also in the adult. The acquisition of those cues is usually influenced also by explicit and implicit social interventions.

In general, there are two strategies for creating safety feelings in situations of feeling threatened by another person. One is taking control over that person. The other is surrendering. Both strategies create a feeling of safety in the presence of fear, which is SWAP. The theme of controlling a partner or being controlled, which generates the feeling of SWAP, which creates arousal, is common in a wide spectrum of sexual interactions. In “milk-and-honey” interactions, body-language messages, such as sexual positions, is one way of enacting that theme. In “off-the-main-stream” interactions, it is expressed in games of dominance, submission and sadomasochism. Those arousing games are played with the consent of the players and do not interfere with their wellbeing. In paraphilia, those emotions take over the perpetrators and interfere with their wellbeing and with the rights and wellbeing of others (23,24). In dysfunctional situations, other emotions, such as guilt and shame, which have traits of fear in them, interfere with the creation of SWAP and muffle the arousal.

The Loci

The roots of sexual arousal and orientation reside in inter-related brain areas that handle three kinds of information: sensory, emotional, and corporal. According to the proposed model, the auditory system is a main provider of sensory stimuli that identify the sex of a potential partner. The amygdala and the hypothalamus are two of the centers that are involved in generating the characteristic feelings and in triggering the bodily responses of sexual activity (25, 26). The details of the innate connectivity between those three areas determine the root US’s and UR’s around which individual sexuality is developed. The first developmental stage occurs from childhood to puberty, and it relies on asexual individual experiences. During this period, asexual cues that are typical to the child’s surroundings are collected and assembled in information structures that will serve as sexual cues for the adult. Different innate connectivity patterns between those brain areas cause different mature sexual orientations. After puberty, centers that are directly related to sexual activity and pleasure join in and provide additional US’s and UR’s around which individual sexuality continues to develop.

Feasibility of the Model

Several observations support the feasibility of the model. The basilar membrane creates a tonotopical representation of the incoming sound. High pitch components cause stronger vibrations at the narrow end of the membrane. As the frequency of the sound decreases, the stronger vibrations shift towards the wide end of the membrane. Hair cells translate the vibrations of the membrane into electrical signals that propagate to the brain. The auditory tract and parts of the auditory cortex are also organized tonotopically (27). Thus, various brain areas receive information about the spectrum of the sound, and this information could be used for identifying the sex of a speaker.

The inner ear shows sexual dimorphism. The cochleae of human females are 8-13% shorter than those of males (28). Otoacoustic emission (OAE) is sound generated by the cochlea in response to external sound. It enhances features if the incoming sound. It was found that there are sex differences in OAE even in newborns, and that in adult women there is a correlation between such differences and sexual orientation (28).

Auditory evoked potentials, which are presumed to correspond to populations of neurons from the auditory nerve through auditory cortex, showed differences in mean latency or amplitude that correlate with sex and with sexual orientation of women (29).

According to the model, an amygdala, a hypothalamus, or any area of a similar role that is innervated heavier by high-pitch neurons would respond stronger to women. Areas that are innervated heavier by low pitch neurons would respond stronger to men. Such connectivity dimorphism may be created by pre- and post-natal genetic and hormonal factors that regulate neurogenesis, cell migration, cell differentiation, cell death, axon guidance and synapsogenesis. Sex differences in cell positions in the developing pre-optic area and the hypothalamus suggest that cell migration may be one target for early molecular actions that impact brain development and sexual differentiation (30-32). Other morphological changes in the hypothalamus and the preoptic areas have been correlated with sex and sexual orientations (14) The amygdala is involved in processing emotions, in particular fear, and in retaining long-term memory of emotionally-arousing events. Sex related differences in the hemispheric lateralization of processing emotional arousal by the amygdala were observed (33). Sex related differences were found in the relative size of the amygdala and hippocampus (34).The amygdala is larger relative to total cerebral size in men compared with women, and in boys compared with girls (35).

Testing the model

The model suggests that the auditory system provides the US’s stimuli around which individual sexuality evolves. However, people born with dysfunctional inner ear and auditory neural networks still develop their sexuality before puberty. This is an indication that the model describes a sufficient, but not necessary condition for the development of individual sexuality. Combinations of other factors, such as social, visual, olfactory and tactile, may act in parallel to the auditory stimuli. The relative role of auditory versus other cues may be assessed by comparing populations of intact and hearing impaired people.

Although human voice is an innately embedded feature that is used for identifying the sex of a speaker, it is not known which parts of the auditory system separate this cue from the rest of the sounds. In the last trimester of pregnancy, human fetuses already respond to the voice of their mother differently than to the voice of men (36). So, any part of the auditory system, from the inner ear to the auditory cortex, may be a candidate for the role of providing the cues to the sexual system.

A similar situation exists also in the two other parts of the model the amygdala and the hypothalamus. These structures are involved in the integration of emotional and corporal information that is directly related to sexual activity. However, they themselves have bi-directional connections with higher and lower brain areas. So, even though they are primary candidates, other brain structures may also be involved in hosting the roots of sexuality.

Although the connectivity between auditory, emotional and corporal brain centers determines the root of human sexuality, reward centers may also have effect on the evolving sexuality. Reward centers affect the rate at which information is recorded. If a reward center favors one voice pitch over another, this could affect the formation of connections between the auditory and the two other centers of the model.

Off-the-shelf brain imaging, EEG, MEG and histological methodologies and techniques, such as those used in the references quoted here, could be used for validating the model. The correlation between the frequency of sound and activated cortical and sub cortical brain areas could be further explored using those and other methods. In particular, responses of brain areas to men’s and women’s voice could be mapped and sequenced. This includes responses to voice in both asexual and sexual contexts. The role of different emotions in triggering brain sexual response centers could also be further investigated. If the model is validated, it would shed light on one of the oldest, fundamental, unresolved questions: why humans do it as they do it?


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Some types of arousal can lead to unhealthy choices, study finds

You might want to avoid food shopping right after a heavy workout or drinking after an intense day of high-powered negotiations, according to a new study in the Journal of Consumer Research.

"While happy people make better and healthier choices, this is dependent on the intensity of the positive feelings experienced. In other words, the level of arousal accompanying the positive mood state can interfere with the beneficial effect of positive mood on resistance to temptation," write authors Alexander Fedorikhin (Indiana University) and Vanessa M. Patrick (University of Houston).

In three studies, the authors found that arousal interfered with the effects of positive mood to influence resistance to tempting food. In one study, the authors asked some participants to watch a positive but calm movie clip while another set of participants watched a positive but arousing movie clip. All participants were then asked to choose between two snacks: a cup of grapes and a cup of M&Ms.

"The results showed that those participants who watched the arousing movie clip were more likely to choose M&Ms than those who watched the calm clip. Moreover, when participants who watched the calm movie clip would choose M&Ms, they were more likely to carefully regulate or monitor the amount of M&Ms they ate," the authors write.

In another study, the researchers added exercise to the mix. Participants who watched the calm movie and performed a light exercise on a stepstool were more likely to choose M&Ms than those who were sedentary.

The authors also proposed that a shortage of mental energy leads to less-healthy choices. To test this theory, the researchers had some people in each group remember a 7-digit number and assigned others a 2-digit number. The people with the larger number were more likely to choose M&Ms.

"In order to resist temptations and make choices that are healthy and have longterm benefits, a person needs to be both in a positive frame of mind and have the available mental energy needed to make good choices," the authors conclude.

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Sexual Function in Men and Women, Overview

Orgasm/Satisfaction Orgasm

Orgasm for an individual can be anything from a genital or autonomic reflex with rhythmic muscle contractions to a total mind and body experience and can occur without muscular contractions or ejaculation. For some, it is a feeling of warmth, tingling, euphoria, and a state of total awareness and survives even the complete disconnection of the genitals from the brain via spinal cord severance. Sexual satisfaction does not require orgasm however, it is known that orgasm reinforces the learning and desire for repetition of sexual behavior in men and women. The capability of experiencing orgasm for men and women can vary according to suitable circumstances and partners. Sexual arousal and orgasm may also occur without experiencing any satisfaction or pleasure. The lack of orgasm in women is a very common complaint, affecting 25–30% of younger women and 20–25% of older women. The symptom of anorgasmia in women is classified into two categories: new onset and never had an orgasm. New-onset anorgasmia is most often due to medication side effects, testosterone deficiency, medical illness, surgery, chronic pain, orthopedic injury, genital/perineal injury, or new sexual problems of the partner or new-onset anger or betrayal by the partner. The etiology of new-onset ejaculatory delay or lack of ejaculation in men is most often due to medication side effects. Treatment can include hormone treatment, elimination of the offending medication or change to a different medication, and sex and/or couples therapy. Lifelong eja culatory or orgasmic inhibition in men and women is most often due to psychological issues, relationship issues, or an undiagnosed medical or neurological condition. Appropriate medical and/or psychological treatment is often successful.

Damage to the pons can result in serious problems as this brain area is important for connecting areas of the brain that control autonomic functions and movement. Injury to the pons may result in sleep disturbances, sensory problems, arousal dysfunction and coma. Locked-in syndrome is a condition resulting from damage to nerve pathways in the pons that connect the cerebrum, spinal cord, and cerebellum. The damage disrupts voluntary muscle control leading to quadriplegia and the inability to speak. Individuals with locked-in syndrome are consciously aware of what is going on around them but are unable to move any parts of their bodies except for their eyes and eyelids. They communicate by blinking or moving their eyes. Locked-in syndrome is most commonly caused by decreased blood flow to the pons or bleeding in the pons. These symptoms are often the result of blood clot or stroke.

Damage to the myelin sheath of nerve cells in the pons results in a condition called central pontine myelinolysis. The myelin sheath is an insulating layer of lipids and proteins that help neurons conduct nerve impulses more efficiently. Central pontine myelinolysis can result in difficulty swallowing and speaking, as well as paralysis.

A blockage of the arteries that supply blood to the pons can cause a type of stroke known as lacunar stroke. This type of stroke occurs deep within the brain and typically only involves a small portion of the brain. Individuals suffering from a lacunar stroke may experience numbness, paralysis, loss of memory, difficulty in speaking or walking, coma, or death.

What is the function of the various brainwaves?

Ned Herrmann is an educator who has developed models of brain activity and integrated them into teaching and management training. Before founding the Ned Herrmann Group in 1980, he headed management education at General Electric, where he developed many of his ideas. Here is his explanation.

It is well known that the brain is an electrochemical organ researchers have speculated that a fully functioning brain can generate as much as 10 watts of electrical power. Other more conservative investigators calculate that if all 10 billion interconnected nerve cells discharged at one time that a single electrode placed on the human scalp would record something like five millionths to 50 millionths of a volt. If you had enough scalps hooked up you might be able to light a flashlight bulb.

Even though this electrical power is very limited, it does occur in very specific ways that are characteristic of the human brain. Electrical activity emanating from the brain is displayed in the form of brainwaves. There are four categories of these brainwaves, ranging from the most activity to the least activity. When the brain is aroused and actively engaged in mental activities, it generates beta waves. These beta waves are of relatively low amplitude, and are the fastest of the four different brainwaves. The frequency of beta waves ranges from 15 to 40 cycles a second. Beta waves are characteristics of a strongly engaged mind. A person in active conversation would be in beta. A debater would be in high beta. A person making a speech, or a teacher, or a talk show host would all be in beta when they are engaged in their work.

The next brainwave category in order of frequency is alpha. Where beta represented arousal, alpha represents non-arousal. Alpha brainwaves are slower, and higher in amplitude. Their frequency ranges from 9 to 14 cycles per second. A person who has completed a task and sits down to rest is often in an alpha state. A person who takes time out to reflect or meditate is usually in an alpha state. A person who takes a break from a conference and walks in the garden is often in an alpha state.

The next state, theta brainwaves, are typically of even greater amplitude and slower frequency. This frequency range is normally between 5 and 8 cycles a second. A person who has taken time off from a task and begins to daydream is often in a theta brainwave state. A person who is driving on a freeway, and discovers that they can't recall the last five miles, is often in a theta state--induced by the process of freeway driving. The repetitious nature of that form of driving compared to a country road would differentiate a theta state and a beta state in order to perform the driving task safely.

Individuals who do a lot of freeway driving often get good ideas during those periods when they are in theta. Individuals who run outdoors often are in the state of mental relaxation that is slower than alpha and when in theta, they are prone to a flow of ideas. This can also occur in the shower or tub or even while shaving or brushing your hair. It is a state where tasks become so automatic that you can mentally disengage from them. The ideation that can take place during the theta state is often free flow and occurs without censorship or guilt. It is typically a very positive mental state.

The final brainwave state is delta. Here the brainwaves are of the greatest amplitude and slowest frequency. They typically center around a range of 1.5 to 4 cycles per second. They never go down to zero because that would mean that you were brain dead. But, deep dreamless sleep would take you down to the lowest frequency. Typically, 2 to 3 cycles a second.

When we go to bed and read for a few minutes before attempting sleep, we are likely to be in low beta. When we put the book down, turn off the lights and close our eyes, our brainwaves will descend from beta, to alpha, to theta and finally, when we fall asleep, to delta.

It is a well known fact that humans dream in 90 minute cycles. When the delta brainwave frequencies increase into the frequency of theta brainwaves, active dreaming takes place and often becomes more experiential to the person. Typically, when this occurs there is rapid eye movement, which is characteristic of active dreaming. This is called REM, and is a well known phenomenon.

When an individual awakes from a deep sleep in preparation for getting up, their brainwave frequencies will increase through the different specific stages of brainwave activity. That is, they will increase from delta to theta and then to alpha and finally, when the alarm goes off, into beta. If that individual hits the snooze alarm button they will drop in frequency to a non-aroused state, or even into theta, or sometimes fall back to sleep in delta. During this awakening cycle it is possible for individuals to stay in the theta state for an extended period of say, five to 15 minutes--which would allow them to have a free flow of ideas about yesterday's events or to contemplate the activities of the forthcoming day. This time can be an extremely productive and can be a period of very meaningful and creative mental activity.

In summary, there are four brainwave states that range from the high amplitude, low frequency delta to the low amplitude, high frequency beta. These brainwave states range from deep dreamless sleep to high arousal. The same four brainwave states are common to the human species. Men, women and children of all ages experience the same characteristic brainwaves. They are consistent across cultures and country boundaries.

Research has shown that although one brainwave state may predominate at any given time, depending on the activity level of the individual, the remaining three brain states are present in the mix of brainwaves at all times. In other words, while somebody is an aroused state and exhibiting a beta brainwave pattern, there also exists in that person's brain a component of alpha, theta and delta, even though these may be present only at the trace level.

It has been my personal experience that knowledge of brainwave states enhances a person's ability to make use of the specialized characteristics of those states: these include being mentally productive across a wide range of activities, such as being intensely focused, relaxed, creative and in restful sleep.

Socialization for the development of the brain

Socialization challenges the brain and keeps it active. It’s vital, especially in the more advanced stages of life, and can prevent mental impairment caused by low brain activity.

To reap these benefits, we must try to be as social as possible. We should interact with others through conversations, although writing is also a great option.

Those who tend to keep to themselves can try the following things to socialize more:

Watch the video: Πώς μπορούμε να αναπτύξουμε νέους νευρώνες στον εγκέφαλο. TED (May 2022).