Motivation and emotion/Book/2018/Endorphins and motivation

Overview
 Case Study: 

Jerry Rice stares across the football field at the New York Giant's imposing defence. There is a break in play with only seconds left in the game and his team is trailing 17-13, while still being 78 yards away from the end-zone. It's going to take a miracle to win this game. Rice is the wide-receiver for the San Francisco 49ers and this is a crucial moment for his franchise in the National Football League (NFL). The two men assigned to cover him for this final play of the game are highly trained physical freaks, the best of the best in a sport where power and speed reign supreme.

Rice's team have saved their best play of the game for last. The quarterback launches a huge Hail Mary pass down-field and Rice sets out in pursuit. The two defenders that he has previously eyed off are both technically faster than him but this doesn't account for the huge amounts of fatigue that they are experiencing this late in the game. They are left in Rice's wake as he catches the pass and flies into the end-zone to score the game winning touchdown with one second left on the clock. The crowd goes wild and the 49ers win!

Jerry Rice's secret to success during his hall of fame career was his sickening work ethic. In a sport full of hard workers Rice out-worked the competition to the point that he was always the most superbly conditioned athlete on the field. His mornings began with daily punishing runs up a five mile hill no matter how much pain, fatigue or discomfort he was feeling ("Masters of Habit: The Deliberate Practice and Training of Jerry Rice", 2018).

By observing Rice's two decades as a professional athlete in the NFL - where he underwent a torturous daily training routine and subjected himself to strict dietary control - we can assume that he is a highly motivated (and disciplined) individual. We can also speculate on the nature of his motivation. Is it an intrinsic type of motivation where he enjoys the process of maintaining and/or gaining great physical condition to enable him to improve at his chosen field? Or perhaps it is more extrinsic and he is mainly motivated by sponsorship deals, trophies and magazine covers? These are subjective observations, however something that is less subjective as it relates to the state of motivation or motivated behaviours in humans is the observation of physiological mechanisms in the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). One such mechanism that may have affected Rice as he battled the pain of those 5 mile hill runs is the production of Endorphins in his body, widely implicated in a pain-relieving euphoric state colloquially called the "runners' high". Through this book chapter I will explore the effects of endorphins on motivational states and behaviours, with implications for self-help and future research also discussed.

What are endorphins?
Endorphins are "endogenous opioid peptides" (Li et al. 2012), meaning that they are hormones produced naturally in humans and other animals which have an opioid-like effect on the body. There are three classes of endorphins, however this book chapter will mostly focus on β-endorphins (Beta endorphins) as they are the most widely researched of these neuropeptides. β-endorphins are produced by the Anterior Pituitary Gland but it seems that other cells in the periphery of the body are also capable of β-endorphin synthesis (Sprouse-blum et al., 2010). The primary mechanisms of β-endorphin production in the body are:


 * The Hypothalamus releases Corticotropin-Releasing Hormone (CRH)
 * CRH prompts the Anterior Pituitary Gland to release a protein called Proopiomelanocortin (POMC)
 * POMC then modifies and forms β-endorphin (as well as other smaller proteins) which are released into the body

What do β-endorphins do?
β-endorphins bind to opioid receptors in the Peripheral Nervous System (PNS) and in the Central Nervous System (CNS), particularly μ-opioid receptors which then activate opioid pathways. This binding causes an inhibition of pain and particularly in the CNS, an inhibition of GABA which results in increased Dopamine production and potentially increased feelings of well-being (Sprouse-blum et al., 2010). The opioid receptors are found in parts of the brain that have previously been suggested to activate in response to motivational processes - the striatum, nucleus accumbens, medial prefrontal cortex, hippocampus, ventral tegmental area, hypothalamus, and amygdala (Callaghan, Rouine & O'Mara, 2018).

What is Motivation?
Motivation has been described as "an internal process that makes a person work towards a goal" (Callaghan, Rouine & O'Mara, 2018). It is the internal force that guides the intensity and direction of human behaviour.

Opponent Process Theory
The opponent-process theory, as described by Richard Solomon (1980), states that most stimuli experienced by the human brain (the “A process”) have a subsequent opposing force (the “B process”) which functions to compensate for the initial stimulus and bring the subject back to a healthy baseline. In the case of the presentation of a stressor as the “A process” it is thought that endorphins play a key role in mediating the “B process”. When an individual is repeatedly subjected to an unconditioned stimulus, reinforcer or an innate release, three major affective phenomena are frequently observed. First, affective or hedonic contrast. Second, affective or hedonic habituation (tolerance). Finally, withdrawal or abstinence syndrome (Solomon, 1980). These affective dynamics generate new motives for reinforcing operant behaviours, based on the hedonic attributes of withdrawal or abstinence syndromes (Solomon, 1980). Solomon (1980) suggests the brain is structured to oppose or suppress an assortment of emotional arousals or hedonic processes, whether they are pleasurable, adverse or generated by positive or negative reinforces. The opposing affective or hedonic processes are automatically set in motion by those stimulus patterns (Solomon, 1980, p. 698).

Hedonic Motivation and related concepts


Hedonic motivation is the desire or motivation to engage in behaviour that makes one feel good. Humans will generally be motivated to perform behaviour that they know will provide them with a reward, whether this is an intrinsic reward such as experiencing positive emotions or an extrinsic reward such as praise or money (Kaczmarek, 2017). As mentioned by Kaczmarek (2017) It is worth noting that experiencing pleasure and avoiding pain does not completely capture the scope of human motives and complementary sub-theories relating to hedonic motivation exist. Some theories such as the one described by Higgins (2006) acknowledge the strength of hedonistic motives while also rejecting the notion that these incentives act as a sole source of drive. Higgins (2006) proposes that the simple concept of pursuing pleasure and rejecting pain can be over-ridden by other motivational forces such as as goal attainment.

While humans attribute value to behaviours based on whether they bring us pleasure or pain, there are factors separate to this hedonic experience which also motivate behaviour. For example, the perceived value of the behaviour in terms of its relevance to one's goals is also thought to impact on what Higgins (2006) refers to as "Motivational Force" or the strength of an individual's engagement in a behaviour. This concept could explain why humans still engage in activities that don't provide them with immediate hedonic enjoyment, in fact we may participate in behaviours that some would deem downright unpleasant as long as we believe the activity helps us move closer to goal attainment. The motivating forces behind such goal attainment can be explained by cognitive concepts such as Eudaemonia and Self-Actualisation. These concepts state that humans will "do what needs to be done" (Waterman, 2008) and be driven to perform behaviours that help them to realise their potential.

Endorphins and human behaviour


Endorphin production seems to increase in response to different types of motivated behaviour.

Exercise
The endorphin hypothesis states that exercise causes the release of endorphins which leads to a positive mood-state. Various studies have confirmed that exercise results in increased levels of β-endorphin in the blood stream, with correlated increases in reported positive moods (Daley, 2008). In 2008, Boecker et al. took these findings one step further by using PET scans to observe increased endorphin production and opioid receptor activity in the frontolimbic region of the brains of participants after they completed a 2hr long distance run. This area of the brain is strongly linked with positive emotions and indeed the participants also reported higher levels of euphoria after their run (Boecker et al., 2008).

Despite the proven health benefits of regular exercise it can be considered an uncomfortable or aversive stimuli (Boutcher & Landers, 1988). The opponent-process theory of motivation described earlier in this chapter would support the requirement of the pain-relieving, mood-enhancing properties of endorphins as an "opponent-process" for the initial process of discomfort and CNS shock that can be induced by intense exercise. In this regard, perhaps endorphin production during exercise can be viewed as the 'B process' which helps bring the CNS back into homeostasis after the 'A process' of exercise-induced discomfort. It may be that endorphin production during and after exercise is designed as a "reward" to humans to incentivice participating in a beneficial yet arguably uncomfortable activity. While there may be various motives to begin and maintain an active lifestyle, of note is that some studies (e.g., Yan zi et al., 2015) suggest that people who engage in exercise purely for the mood-altering benefits may be able to maintain greater exercise participation than those who exercise for other reasons.

Eating
It was previously theorised that dopamine was responsible for the activation of the pleasurable reward state in the brain when enjoyable or "palatable" foods were consumed, therefore guiding hedonistic motivation to consume such foods. More recent research suggests that endogenous opioids such as endorphins are also involved in the reinforcement of eating behaviour (Barbano & Cador, 2006). It seems that dopamine's role in the brain may be more of a prepatory one, activating the motivational state to seek out food and restore homeostasis in the body. While endorphins then seem to function to elicit a pleasurable "reward state" in the brain during the consumption of desirable or "palatable" foods, to borrow the language used by Barbano & Cador (2006).This suggests that endorphins contribute hedonistic value to the consumption of palatable foods but may not necessarily play a role in the food approach behaviour which ensures that humans eat enough calories to survive and maintain homeostatic balance.

Conclusion
The effects of endorphins and specifically β-endorphins on motivation are difficult to summarise as endorphins seem to mainly be involved in the brain's experience of reward when presented with enjoyable stimuli and in the reduction of negative physiological symptoms arising from aversive stimuli such as pain and stress.

Where the mechanism of β-endorphins could prove useful is in the relief of depression. Major Depressive Disorder (MDD) is characterised by a loss of energy and motivation among other symptoms. β-endorphin increasing interventions such as exercise have been shown to improve the negative symptoms of depression and this could have implications for purposely modifying motivational states, although the exact physiological mechanisms require more investigation (Dinas, Koutedakis & Flouris, 2010).