Basic Emotions

[Petter]

https://www.psychologytoday.com/us/b...power-oxytocin

Despite the warm and fuzzy feelings it can bring about, not every effect of oxytocin is positive.

It’s possible that oxytocin can actually impair memory. A study published around the same time as the trust study found that when people got a dose of oxytocin spray, they performed worse on a word recall test than people who got a placebo spray.

Does that mean oxytocin makes us more forgetful? Interestingly, this might depend on your attachment style. This refers to your pattern of bonding with other people, including the way you deal with trust, autonomy, and intimacy. A recent study found that if your attachment style is more emotionally independent (that is, you find depending on others uncomfortable), oxytocin actually improves your ability to learn and recall a list of words. But oxytocin had a detrimental effect on the memories of those who were more willing to rely on others.

[Petter]

https://en.wikipedia.org/wiki/Social_grooming

Social grooming has been shown to be correlated with changes in endocrine levels within individuals. Specifically, there is a large correlation between the brain's release of oxytocin and social grooming. Oxytocin is hypothesized to promote prosocial behaviors due to its positive emotional response when released. Further, social grooming also releases beta-endorphins which promote physiological responses in stress reduction. These responses can occur from the production of hormones and endorphins, or through the growth or reduction in nerve structures. For example, in studies of suckling rats, rats who received warmth and touch when feeding had lower blood pressure levels than rats who did not receive any touch. This was found to be the result of an increased vagal nerve tone, meaning they had had a higher parasympathetic nervous response and a lower sympathetic nervous response to stimuli, resulting in a lower stress response. Social grooming is a form of innocuous sensory activation. Innocuous sensory activation, characterized by non-aggressive contact, stimulates an entirely separate neural pathway from nocuous aggressive sensory activation. Innocuous sensations are transmitted through the dorsal column-medial lemniscal system.

[Petter]

https://users.cs.northwestern.edu/~o...20emotions.pdf

Similarly, Panksepp's panic might be relabeled as distress, which can be found in many people's lists.

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https://i.imgur.com/Zll7W7N.jpg

[Petter]

https://www.nature.com/articles/s41583-023-00758-x

The sound of an infant crying can trigger the release of the neuropeptide oxytocin by hypothalamic neurons and drive maternal behaviours and physiological responses.




https://www.ncbi.nlm.nih.gov/pmc/art...MC4934120/#B30

Adult crying reflects both positive and negative emotions (Vingerhoets et al., 2001a). Bindra (1972) found that causes of crying often related to feelings of elation, dejection, or anguish. Similarly, Kottler (1996) identified physiological responses, redemption, connection to others, grief and loss, despair, joyful and aesthetic transcendence, anger and frustration, and manipulation of others, whereas Scheirs and Sijtsma (2001) identified distress, sadness, and joy (see Vingerhoets et al., 2001a for a review). Crying has intrapersonal and interpersonal functions. Theorists have argued that crying may be of intrapersonal therapeutic utility by facilitating emotional processing and acceptance of loss (Nelson, 2005; Hendriks et al., 2008). Interpersonally, crying is a key attachment behavior, intended to elicit care and comfort from close others throughout life (Bowlby, 1969; Nelson, 2005). Hendriks et al. (2008) argue that the social support elicited by crying fully explains its benefits.

[Petter]

https://pubmed.ncbi.nlm.nih.gov/25215491/

Animals display a range of innate social behaviors that play essential roles in survival and reproduction. While the medial amygdala (MeA) has been implicated in prototypic social behaviors such as aggression, the circuit-level mechanisms controlling such behaviors are not well understood. Using cell-type-specific functional manipulations, we find that distinct neuronal populations in the MeA control different social and asocial behaviors. A GABAergic subpopulation promotes aggression and two other social behaviors, while neighboring glutamatergic neurons promote repetitive self-grooming, an asocial behavior. Moreover, this glutamatergic subpopulation inhibits social interactions independently of its effect to promote self-grooming, while the GABAergic subpopulation inhibits self-grooming, even in a nonsocial context. These data suggest that social versus repetitive asocial behaviors are controlled in an antagonistic manner by inhibitory versus excitatory amygdala subpopulations, respectively. These findings provide a framework for understanding circuit-level mechanisms underlying opponency between innate behaviors, with implications for their perturbation in psychiatric disorders.

[Petter]

https://en.wikipedia.org/wiki/Endorphins

Endorphins inhibit transmission of pain signals by binding μ-receptors of peripheral nerves, which block their release of neurotransmitter substance P.

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euphoria/dysphoria vs. rage (?)

[Petter]

https://www.sciencedirect.com/scienc...06453021003243

Development of mild dysphoria was associated with high post-injury cortisol.





https://www.sciencedirect.com/scienc...65178194900183

Serum cortisol levels are related to moods of elation and dysphoria in new mothers.

[Petter]

https://en.wikipedia.org/wiki/Substance_P

Tachykinin / Substance P plays an evolutionarily conserved role in inducing aggressive behaviors. In rodents and cats, activation of hypothalamic neurons which release Substance P induces aggressive behaviors (defensive biting and predatory attack). Similarly, in fruit flies, tachykinin-releasing neurons have been implicated in aggressive behaviors (lunging).





https://www.medcentral.com/pain/chro...roscience-pain

Nociceptors are specialized sensory receptors responsible for transforming painful stimuli into electrical signals, which travel to the central nervous system via neurotransmitters. Several neurotransmitters are involved in carrying the nociceptive message. However, glutamate and substance P (SP) are the main neurotransmitters associated with the sensation of pain.

[Petter]

https://manifold.umn.edu/projects/a-...mkins-handbook (see Part I. Affect, The Negative)

Distress-anguish. Imagine a desolate, crying baby. Her mouth is open, yet the corners of her lips are pulled down, her eyebrows are arched, and the muscles around her eyes are contracted. For Tomkins, these facial states don’t express negative feeling that has originated elsewhere in the body; rather, the awareness of the feedback from these physiological events is the feeling of distress. These facial responses and the distressing feeling they engender are caused by a high level of unrelenting stimulation: the baby is pained, cold, overheated, hungry, alarmed by intense noise or light.

[Petter]

https://healthier.stanfordchildrens....ation-anxiety/

https://www.sciencedirect.com/topics...ation-distress

Separation Anxiety

Sometime in the middle of the first year, when infants understand that people exist even when they are out of sight (person permanence), they react to the everyday recurring disappearances of their parents by attempting to maintain proximity through the behaviors available to them, including crying, cooing, and crawling (Stayton et al., 1973). In manifesting these responses, infants not only indicate their desire to stay in proximity with the caregiver but also the development of ways to control distance and separation (Witherington et al., 2001). During this age, infants increasingly initiate interaction with their parents and actively protest when their primary caregiver departs, even for a moment. By the first birthday, behaviors that indicate separation distress are even more clearly detected, with infants tending to become agitated and upset upon separation (Tennes and Lampl, 1964).

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Distress is caused by pain or fear, so it is not a basic emotion.

[Petter]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5171207/ (see figure 1)

https://i.imgur.com/qMM3d3S.jpg

Euphoria and dysphoria are directly linked to pleasure ('liking') and pain. They do not activate the amygdala.

[Petter]

https://en.wikipedia.org/wiki/Oxytocin

Modulation of hypothalamic-pituitary-adrenal axis activity: oxytocin, under certain circumstances, indirectly inhibits release of adrenocorticotropic hormone and cortisol and, in those situations, may be considered an antagonist of vasopressin.

[...]

Human ingroup bonding: Oxytocin can increase positive attitudes, such as bonding, toward individuals classified as "in-group" members, whereas other individuals become classified as "out-group" members. Oxytocin has also been implicated in lying when lying would prove beneficial to other in-group members. In a study where such a relationship was examined, it was found that when individuals were administered oxytocin, rates of dishonesty in the participants' responses increased for their in-group members when a beneficial outcome for their group was expected. Both of these examples show the tendency of individuals to act in ways that benefit those considered to be members of their social group, or in-group.

[...]

Affecting generosity by increasing empathy during perspective taking: In a neuroeconomics experiment, intranasal oxytocin increased generosity in the Ultimatum Game by 80%, but had no effect in the Dictator Game that measures altruism.





https://pubmed.ncbi.nlm.nih.gov/35863332/

Oxytocin and vasopressin are peptide hormones secreted from the pituitary that are well known for their peripheral endocrine effects on childbirth/nursing and blood pressure/urine concentration, respectively. However, both peptides are also released in the brain, where they modulate several aspects of social behaviors. Oxytocin promotes maternal nurturing and bonding, enhances social reward, and increases the salience of social stimuli. Vasopressin modulates social communication, social investigation, territorial behavior, and aggression, predominantly in males. Both peptides facilitate social memory and pair bonding behaviors in monogamous species. Here we review the latest research delineating the neural circuitry of the brain oxytocin and vasopressin systems and summarize recent investigations into the circuit-based mechanisms modulating social behaviors. We highlight research using modern molecular genetic technologies to map, monitor activity of, or manipulate neuropeptide circuits. Species diversity in oxytocin and vasopressin effects on social behaviors are also discussed. We conclude with a discussion of the translational implications of oxytocin and vasopressin for improving social functioning in disorders with social impairments, such as autism spectrum disorder.





https://www.frontiersin.org/journals...017.00356/full

Vasopressin (VP) and oxytocin (OT) are distinct molecules; these peptides and their receptors [OT receptor (OTR) and V1a receptor (V1aR)] also are evolved components of an integrated and adaptive system, here described as the OT–VP pathway. The more ancient peptide, VP, and the V1aRs support individual survival and play a role in defensive behaviors, including mobilization and aggression. OT and OTRs have been associated with positive social behaviors and may function as a biological metaphor for social attachment or “love.” However, complex behavioral functions, including selective sexual behaviors, social bonds, and parenting require combined activities of OT and VP. The behavioral effects of OT and VP vary depending on perceived emotional context and the history of the individual. Paradoxical or contextual actions of OT also may reflect differential interactions with the OTR and V1aR. Adding to the complexity of this pathway is the fact that OT and VP receptors are variable, across species, individuals, and brain region, and these receptors are capable of being epigenetically tuned. This variation may help to explain experience-related individual and sex differences in behaviors that are regulated by these peptides, including the capacity to form social attachments and the emotional consequences of these attachments.





https://www.nature.com/articles/s41380-024-02590-w

Prosocial and moral behaviors have overlapping neural systems and can both be affected in a number of psychiatric disorders, although whether they involve similar neurochemical systems is unclear. In the current registered randomized placebo-controlled trial on 180 adult male and female subjects, we investigated the effects of intranasal administration of oxytocin and vasopressin, which play key roles in influencing social behavior, on moral emotion ratings for situations involving harming others and on judgments of moral dilemmas where others are harmed for a greater good. Oxytocin, but not vasopressin, enhanced feelings of guilt and shame for intentional but not accidental harm and reduced endorsement of intentionally harming others to achieve a greater good. Neither peptide influenced arousal ratings for the scenarios. Effects of oxytocin on guilt and shame were strongest in individuals scoring lower on the personal distress subscale of trait empathy. Overall, findings demonstrate for the first time that oxytocin, but not vasopressin, promotes enhanced feelings of guilt and shame and unwillingness to harm others irrespective of the consequences. This may reflect associations between oxytocin and empathy and vasopressin with aggression and suggests that oxytocin may have greater therapeutic potential for disorders with atypical social and moral behavior.





https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9075672/

Is oxytocin a trust hormone? Salivary oxytocin is associated with caution but not with general trust

Studies on the association between trust and oxytocin, a neuropeptide of the central nervous system, have not reached a consensus, thereby challenging the possibility of a direct association between the two. However, previous studies have not examined how oxytocin is correlated with trust, based on its categorization into different factors in the field of social science. For instance, based on Yamagishi’s trust theory, trust can be categorized into two factors: general trust and caution. General trust refers to beliefs about the trustworthiness of others, whereas caution refers to the belief that caution is needed when dealing with high social uncertainty. In this study, to examine the relationship between these two factors and oxytocin, we analyzed data of 197 adults (men = 98, women = 99; mean age = 41.7 years; standard deviation for age = 10.4 years) and examined the relationships between these two factors of trust and endogenous salivary oxytocin levels. We found that oxytocin was positively correlated with caution rather than with general trust thereby suggesting that oxytocin plays a role in regulating caution rather than general trust among the components of trust. The present study demonstrated that salivary oxytocin level can act as a biomarker that partially predicts one’s trust, especially as reflected by caution.





https://www.psychologytoday.com/us/b...trust-molecule

Researchers have also been interested in behavioral effects of oxytocin. In animals, oxytocin has been demonstrated to play a role in pair bonding of animals. Based on these findings, a number of studies have explored whether oxytocin increases trust in humans. Based on some preliminary evidence, Paul Zak actually dubbed oxytocin “The Trust Molecule.”

[...]

When you put this all together, it appears that there is no good reason to think that oxytocin is directly related to trust. That does not mean that oxytocin has no influence on human behavior. It is just that the actual relationship between oxytocin and behavior is likely to be complicated. It will probably interact with situations and other aspects of people’s brain structure.

[Petter]

(see post #517 and #519)

https://link.springer.com/article/10...29-019-01945-2

The orbitofrontal cortex represents the reward value of stimuli (Rolls 2000, 2014a, 2018a, 2019a, b; Tremblay and Schultz 1999; Rolls et al. 1989; Small et al. 2001). It is in a sense an output region for all the sensory systems, including taste, olfaction, visual, auditory, and somatosensory, that represents ‘what’ a stimulus is, and uses that information to build what are frequently multimodal representations but in value space rather than in ‘what’ or stimulus identity space. Orbitofrontal cortex neurons focus on reward value representations for stimuli and know little about actions.

The orbitofrontal cortex sends inputs to the ACC about the value of stimuli, that is, about goals including the value of outcomes (the reward received) and the expected value. The ACC in combination with the midcingulate motor area, which contains representations of actions, interfaces actions to outcomes (rewards or punishers received) using action–outcome learning, and also takes into account the cost of actions to obtain the goal when selecting actions (Rushworth et al. 2012; Kolling et al. 2016; Rolls 2019a). The anterior and midcingulate cortical areas are thus relevant to emotion, for they implement the instrumental goal-directed actions that the instrumental reinforcers involved in emotion produce (Rolls 2014a, 2019a, b). In the context of its representations of value, damage to the anterior cingulate areas does influence emotion (Rolls 2014a, 2019a).

The ACC operates as a system that performs goal-directed actions to obtain rewards and avoid punishers, and takes into account the outcomes received after actions, in that it is sensitive to devaluation of the goal, and will not select an action if the goal has been devalued. This is in contrast to the basal ganglia, which implement a stimulus–motor response mapping which becomes automated as a habit after much learning, and is not sensitive to devaluation of the goal (Rolls 2014a, 2019a, b).

[...]

In these studies, the anterior cingulate activations were linearly related to the subjective pleasantness or unpleasantness of the stimuli, providing evidence that the ACC represents value on a continuous scale (Fig. 4), which is characteristic of what is found in the sending region, the orbitofrontal cortex (Rolls 2019a, b). Moreover, evidence was found that there is a common scale of value in the pregenual cingulate cortex, with the affective pleasantness of taste stimuli and of thermal stimuli delivered to the hand producing identically scaled BOLD activations (Grabenhorst et al. 2010a). The implication is that the ACC contains a value representation used in decision-making, but that the decision itself may be made elsewhere. Decisions about actions that reflect the outcomes represented in the ACC may be made further posterior towards the midcingulate cortex. Decisions about the value of stimuli may be made in the medial prefrontal cortex area 10 (or ventromedial prefrontal cortex, VMPFC) as shown by fMRI evidence (Grabenhorst et al. 2008b; Rolls and Grabenhorst 2008; Rolls et al. 2010a, b). Consistent with this, in macaques single neurons in the ventromedial prefrontal cortex rapidly come to signal the value of the chosen offer, suggesting the circuit serves to produce a choice (Strait et al. 2014), consistent with the attractor model of decision-making (Rolls et al. 2010a, b; Rolls 2014a, 2016a). [...] The ventromedial prefrontal cortex receives inputs from the orbitofrontal cortex (and also from the ACC).



https://academic.oup.com/book/46855/chapter/413761343

https://i.imgur.com/38TSEW0.gif

Figure 11.1

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LN (OFC): reward value

SN (pgACC and sgACC): emotional awareness, assessment of internal emotional states, evaluation of cost-benefit tradeoffs to guide action selection, autonomic regulation

CON (dACC/aMCC): action-outcome evaluation, error-detection, repeat a choice or switch, willed control of actions

CEN (PFC and BA10): decision-making

[Petter]

https://psychiatryonline.org/doi/pdf...np.23.2.jnp121

An unusual aspect of this region is the presence of Von Economo neurons (spindle neurons), found only in cingulate (pACC and MCC) and insular cortices (Figure 2). Von Economo neurons are present in great apes and humans, but in no other primates. They are more numerous in humans, possibly representing an evolutionary advantage. Von Economo neurons differ from pyramidal neurons in both size and shape (Figure 2). They are much larger than pyramidal neurons, suggesting faster transmission of information between brain regions, and possibly more connections. They are long, straight neurons, with single, long, apical and basal dendrites, which may indicate that they receive and integrate input from fewer neurons than pyramidal neurons. It has been suggested that Von Economo neurons perform an adaptive function by helping humans and great apes act quickly on an instinctual/intuitive level in social situations. Others have speculated that they may provide fast communication with the anterior insula as part of a salience network [or CON].

[Petter]

https://www.frontiersin.org/journals...3.1127143/full

Ultimately, BA8 can generally be considered as a decision maker which is important in weighing uncertainty (Volz et al., 2004, 2005). However, what is important to consider is that the contexts differ in their activations based on who else they are structurally and functionally connected to.

[...]

Differently, as we discuss further in the next section, area 8BM is a central executive network (CEN) region which is anatomically located between two SMA regions. Area 8BM may likely facilitate the motor planning and execution of goal-directed behaviors through interacting with numerous higher order networks and the motor system along the medial frontal lobe (Mandonnet et al., 2017; Briggs et al., 2021a).

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https://i.imgur.com/uQyFQe7.jpg

[Petter]

https://journals.sagepub.com/doi/10....73858417708284 (Oxytocin and Vasopressin: Powerful Regulators of Social Behavior)

https://en.wikipedia.org/wiki/Oxytocin

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1. Oxytocin stimulates uterine contractions in childbirth and lactation after childbirth. It also affects the production of testosterone. These physiological effects do not directly change behavior and emotion.

2. Oxytocin and vasopressin have effects on social cognition/memory.

3. "Oxytocin can induce anti-stress-like effects such as reduction of blood pressure and cortisol levels. It increases pain thresholds, exerts an anxiolytic-like effect and stimulates various types of positive social interaction. In addition, it promotes growth and healing." (pain and fear/anxiety)

[Petter]

https://en.wikipedia.org/wiki/Emotion#Components

Tenderness/love is not a basic emotion.

[Petter]

social cognition (DMN, LN, SN) <--> theory of mind and empathy

[Petter]

https://www.ox.ac.uk/research/how-cu...rive-behaviour

Cuteness may help to facilitate well-being and complex social relationships by activating brain networks associated with emotion and pleasure and triggering empathy and compassion. When we encounter something cute, it ignites fast brain activity in regions such as the orbitofrontal cortex, which are linked to emotion and pleasure. It also attracts our attention in a biased way: babies have privileged access to entering conscious awareness in our brains.

As a result, we like looking at babies and other cute things. Research has shown that people would rather look at cute baby faces than adult faces and that they would rather adopt or give a toy to babies with cuter faces. Studies have also shown that even babies and children prefer cute baby faces and that cuteness affects both men and women, even if they are not parents. Cute babies also spur us to action: research reveals that people will expend extra effort to look longer at cute baby faces.

[Petter]

decision-making

https://i.imgur.com/gx7yLv9.png

1. reward value / delayed reward: LN (OFC)

2. reward vs. effort: SN (pgACC and adACC) ...... action ---> excitement and fear (emotional value)

3. uncertainty and volatility: CON (dACC and dmPFC/BA8)

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(CEN = FPN + CON)

[Petter]

https://en.wikipedia.org/wiki/Emotion#Differentiation

Emotions: predispositions to a certain type of action in response to a specific stimulus, which produce a cascade of rapid and synchronized physiological and cognitive changes.

[Petter]

goal-directed behavior

maximize pleasure ('liking') and minimize pain/discomfort

approach a reward <--> excitement

avoid a threat <--> fear

approach a reward and a threat <--> anger

[Petter]

habit <--> goal-directed behavior <--> classical conditioning (---> an emotional response)

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https://i.imgur.com/Kzl3rmt.jpg

https://i.imgur.com/5n9Z6Zj.png

[Petter]

https://www.sciencedirect.com/topics...r-conditioning

Classical conditioning is a process of learning whereby the expressed fear response to a neutral conditioned stimulus (specific environmental features) is paired to an aversive unconditioned stimulus (traumatic experience). As a result, the conditioned stimulus is able to evoke the entire spectrum of responses (behavioral, autonomic, and endocrine) that generally only occur in the face of danger.

[Petter]

https://edition.cnn.com/2015/10/29/h...ear/index.html

Innate fears

We are born with only two innate fears: the fear of falling and the fear of loud sounds.

A 1960 study evaluated depth perception among 6-to-14-month-old infants, as well as young animals. Researchers placed the subjects on a platform that had plexiglass just beyond its edge to it to see how many of the subjects would actually step over the “visual cliff.” Most of the subjects – both children and animals – didn’t go “over” and step out on to the plexiglass. The fear of falling is an instinct necessary for the survival of many species.

When you hear loud sounds, you most likely will react with a fight or flight type response. It’s called “your acoustic startle reflex,” said Seth Norrholm, a translational neuroscientist at Emory University. Norrholm explained that if a sound is loud enough “you’re going to duck down your head. Loud noises typically means startling. That circuitry is innate.” It’s a response we have, that signals something dangerous may be around the corner.




https://en.wikipedia.org/wiki/Visual_cliff

This shows that when healthy infants are able to crawl, they can perceive depth. However, results do not indicate that avoidance of cliffs and fear of heights is innate.

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The startle reflex is not an emotion.

[Petter]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8228195/

Understanding Emotions: Origins and Roles of the Amygdala

[...]

According to Sterling’s allostasis model, the design of efficient predictive regulation depends on the brain’s ability for sensing the current state, integrating this information with prior knowledge to optimize regulatory decisions, and on relaying current sensory information to higher-order brain levels so that today’s learning becomes tomorrow’s “prior knowledge” [67]. In his “carrot and stick” model of allostatic anticipatory regulation, the “carrot” component is the midbrain reward system, whereas the “stick” component is the amygdala, as it integrates a large number of lower level physiological signals from the entire body, such as steroid hormones and peptides that regulate blood pressure, hypothalamic and brain stem signals containing visceral information (e.g., from the nucleus of the solitary tract), and signals from serotonergic neurons of the raphe nuclei of the PAG that modulate arousal levels and mood [67]. The amygdala is heavily and reciprocally connected with the hippocampus and vmPFC and these pathways provide a constant flow of information on needs and past dangers to design a plan of action. Figuratively speaking, the amygdala reports its “concerns” to the PFC, which decides what to do and performs planning for the future [67]. As posited, especially by Friston, the brain is, therefore, an organ intended for predictive regulation, the active prediction and interpretation of input sensory information [68]. The theory of constructed emotion is based on the concept of predictive coding, which assumes that the brain is an interface that creates internal models at different functional levels and that any function of the brain (perception, cognition, emotion) arises from, comparing the current model and input sensory signals [69]. In regard to interoceptive feelings, expectations and predictions of one’s own bodily states make a significant part of conscious emotional experience [4,69]. However, according to the constructed emotion theory, the key difference from Damasio’s assumptions is that the brain creates emotions from predictions that subsequently trigger physical events in the body (and not the opposite, as is assumed by the somatic marker theory).

Feldman Barrett explains that the primary, innate emotions in the first six months of life arise from physiological processes and interoception. According to the theory of constructed emotion, these states, however, should not be marked as emotions, as they are simply information about the state of bodily functions that contain insufficient detail for a child to act upon in the first six months of life. The child will be able to act purposefully (of its own volition) only with the maturation and activation of the corticospinal tract, a process which begins at about 6 months of age. More precisely, according to this theory, emotions are just brain predictions that connect bodily states to events in the environment so that the person knows how to (re)act. Only sometimes, as a by-product of these predictions, emotions arise.

[...]

Studies in humans have confirmed the key role of the amygdala in fear conditioning as well as in various forms of psychopathological behavior [13]. Thus, damage of the amygdala in humans disables fear conditioning, while reduced volume of the right amygdala, along with reduced volume of BNST and other associated structures, have been documented in some sexual offenders [76]. However, the amygdala does not function independently of other structures, but is part of larger neural circuits involving sensory systems, the motor system, the hippocampus (that provides contextual information) and the PFC (responsible for regulation of amygdala reactivity, so that hypofunction of the PFC will lead to amygdala hyperreactivity). The amygdala contributes to these fear circuits in two ways: directly, by detecting the threat on an unconscious level and regulating behavioral and physiological responses, and indirectly, through cognitive systems, in the emergence of a conscious feeling of fear. Moreover, there are two main afferent pathways that lead to the amygdala: a faster “low-road pathway” that reaches the amygdala directly from the sensory nuclei of the thalamus without prior cortical processing (without reaching the level of consciousness) and activates the amygdala in a 12 ms time-frame, and a slower “high-road pathway” that activates the amygdala through the thalamus and cerebral cortex [73,74,77].

[...]

After passing the LA, sensory signals are processed in virtually all parts of the amygdala (BLA, CE, IN, etc.) and the generated information is further integrated with various other afferent signals. Conditioned impulses then leave the CE and BM. The CE is considered to provide the main efferent projections of the amygdala, including those to the BNST and PBN [158,159]. However, efferent projections, especially to the neocortex, hippocampus, and ventral striatum, emerge from the BLA and BM as well. In a simplified view, the CE “converts” emotionally important sensory stimuli into a physiological response (changes in heart rate, changes in blood pressure, sweating, tremor, and somatic sensations) and modulates behavior. The final response is the result of processing of much complex and context-dependent information, which is provided by the hippocampo–entorhinal input (see below) [99].

see figure 10

https://i.imgur.com/PTTRIc5.png

[Petter]

(see post #471)

https://www.cambridge.org/core/journ...1EF15EEDA5035A

Evolution of circuits regulating pleasure and happiness with the habenula in control

The habenula, which in humans is a small nuclear complex within the epithalamus, plays an essential role in regulating the intensity of reward-seeking and adversity-avoiding behavior in all vertebrate ancestors by regulating the activity of ascending midbrain monoaminergic tracts.

https://www.nature.com/articles/nrn2866

Stress resulting from prolonged exposure to aversive stimuli may cause hyperactivity of lateral habenula neurons and immune responses in the medial habenula. These responses may lead to a general suppression of motor activity and other behavioural changes through modulation of the activity of dopamine and serotonin neurons. (sadness)

It is speculated that the habenula evolved as a general motor controller devoted to circadian control of behaviour and that it has subsequently acquired the ability to control value-based decision-making as more brain areas formed connections to, and received projections from, the habenula.

[Petter]

https://academic.oup.com/scan/articl...93?login=false

Many animal species communicate using a variety of highly conspicuous signals, including acoustic, tactile, olfactory and visual displays that have been tuned by natural selection to impact the listener in a reliable way (Smith, 1977 ; Dawkins and Krebs, 1978 ). Among primates, the visual and auditory domains have become the two most prominently involved in social communications. There is, for example, a general assumption that facial expressions convey a variety of information about an individual's motivation, intentions and emotions (van Hooff, 1967 ; Ekman, 1997 ; Parr, et al ., 2002 ). As such, facial expressions are critically important for coordinating social interaction, facilitating group cohesion and maintaining individual social relationships (Parr et al ., 2002 ). Despite the importance of facial expressions in the evolution of complex societies, there is little work comparing either the form or function of facial expression across distinct phylogenetic groups. Moreover, apart from a handful of excellent ethograms that describe the communication repertoires for a variety of species, including chimpanzees, bonobos, rhesus monkeys, capuchin monkeys and canids (Hinde and Rowell, 1962 ; van Hooff, 1962 , 1967 , 1973 ; Andrew, 1963 ; Goodall, 1968 ; Fox, 1969 ; Bolwig, 1978 ; Weigel, 1979 ; de Waal, 1988 ; Preuschoft and van Hooff, 1997 ; Redican, 1982 ; Parr, et al ., 2005 ), there has been little attempt to standardize the description of their facial and vocal displays in a manner that facilitates comparative and evolutionary studies.

Fridlund ( 1994 ) has proposed that facial expressions are best understood as communicative signals and as such, researchers should focus on their functional consequences during social interaction, or how they impact the listener. Moreover, the only way to fully understand why facial expressions have evolved to convey a specific meaning is to compare similar facial expressions between evolutionarily related species, examining any factors that may have influenced their social function, including ecological pressures and social factors like dominance style and social organization (Preuschoft and van Hooff, 1997 ). Some facial expressions appear to be well represented across diverse taxonomic groups, making them good models for understanding social and emotional function, while others appear to be species-specific. The bared-teeth display, also referred to as the fear grin, or grimace, is one of the most conspicuous and well-studied facial expressions in ethology and has been reported in a variety of mammalian species from canids to primates. Research has shown, however, that the communicative function of this expression can differ quite broadly depending on the species, their type of social organization and social context. In wolves, for example, retraction of the lips horizontally over the teeth results in a ‘submissive grin’ which is used by cubs and subordinates when actively greeting adult conspecifics, or humans (Fox, 1969 ). Antithetical to this expression is a vertical lip retraction which is given by dominant animals during aggressive interactions, very similar facial movements but with vastly different social functions (Darwin, 1872 ; Fox, 1969 ).

Among primates, the function of the bared-teeth also has different meanings depending on the species and their type of social organization. Among macaques species that have despotic social systems characterized by strict, linear dominance hierarchies, i.e. rhesus monkeys, the bared-teeth display appears to be a signal of submission, or rank recognition in that it is only given by subordinates to higher ranking individuals (van Hooff, 1976 ; de Waal and Luttrell, 1985 ). This expression has been referred to as a formal signal of dominance in the rhesus monkey because it is highly ritualized in appearance and has long-term predictability in determining dominance relationships despite short-term variation in social contexts (de Waal and Luttrell, 1985 ). In this study, bared-teeth displays performed by subordinate individuals occurred most often in response to the approach of a dominant monkey, and the most frequent response was for the subordinate to withdraw from any social interaction (de Waal and Luttrell, 1985 ). However, the meaning of the bared-teeth display is quite different when used by species with more egalitarian social systems, including some macaques, mandrills, Gelada baboons and chimpanzees (van Hooff, 1967 ; Preuschoft and van Hooff, 1997 ). In these species, the bared-teeth display is more appeasing and functions to increase social attraction and affiliation. It communicates benign intent in that the signaler wishes no harm, and that there is no risk of aggression (van Hooff, 1967 ; van Hooff, 1976 ; Waller and Dunbar, 2005 ). It can also occur during affiliative contexts, such as grooming, sexual solicitation and reconciliations, and thus functions to increase affiliative tendencies and reduce proximity between individuals (van Hooff, 1973 ; Preuschoft and van Hooff, 1997 ; Parr et al ., 2005 ; Waller and Dunbar, 2005 ).

Numerous authors have gone on to propose that the bared-teeth display is homologous with the human smile, meaning that they are the result of common evolutionary descent (van Hooff, 1972 ; Preuschoft and van Hooff, 1997 ; Waller and Dunbar, 2005 ). This conclusion is based in part on the physical similarity in the appearance of the bared-teeth display and the human smile, which are both characterized by retraction of the lip corners exposing, in most cases, the upper and lower teeth. However, the homology is also based on similarity in the social function of these expressions, indicating appeasement, reassurance, increasing social bonding, and thus its important role in facilitating social cohesion among primates (Preuschoft and van Hooff, 1997 ). These examples suggest that while similar appearing expressions can often have different meanings, or serve different social functions, depending on the species and their type of social organization, they share a common evolutionary root. Therefore, in order to understand the evolution of human emotional expressions, like the smile, it is extremely informative to take a comparative approach and evaluate whether the form and function of these expressions are uniquely human, present in many related species, or perhaps only shared by very closely related species, like Hominoids (Fridlund, 1994 ). The picture is less clear for other expressions, and only a few other direct comparisons have been made, i.e. homology between human laughter and the nonhuman primate ‘play face’ (Preuschoft and van Hooff, 1967; van Hooff, 1972 ). This is undoubtedly due to the fact that researchers, to date, have lacked a common language, or standardized system that could be used to identify potential homologues. Ideally, any assessment of homology should be based on something other than physical appearance, so a consideration of the underlying musculature is important (Waller et al ., 2006 ). Among primates, it is highly likely that many expressions may share a common ancestry, and thus a comparative treatment is warranted, even if the expressions look different in terms of their characteristic features.

[Petter]

https://emotion.wisc.edu/wp-content/...ly-infancy.pdf

Emotional Development in Early Infancy, Katharine M. Banham Bridges, 1932

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After observing the behavior of babies under one month of age, the writer felt more than ever convinced that the infant does not start life with 3 fully matured pattern reactions, such as have been mentioned by behaviorists and named fear, rage and love.

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It is a moot question whether "distress" is an original emotion or it is a very early differentiated reaction to disagreeably painful and unsatisfying experiences. It may be that it is a part of the general emotional response of excitement which copes more satisfactorily with obnoxious stimuli.