Motivation and emotion/Book/2021/Dopamine and motivational drive

Dopamine and motivational drive:
How does dopamine affect motivational drive?

Overview

Motivation is crucial to our everyday lives; it allows us to get out of bed in the morning, it is what allows humans to pursue short-term or long-term goals. Motivation and specifically the neurochemistry of motivation, is tightly woven within the science of movement. The same single molecule responsible for movement is also the main contributor to the senses of motivation. Even though nerves control the movement of muscular-skeletal tissue, the effector chemical that allows for this to happen is dopamine. In the brain, dopamine is responsible for many functions within living organisms, namely focus, movement, and the ability to produce motivation to overcome specific difficulties or barriers (Lodish et al., 2019). This molecule, dopamine, is at the heart of so many great things in life, namely relationships, learning, and creativity. However, this same molecule also resides at the centre of so many terrible aspects of life, such as addictions and certain forms of mental illnesses and mental diseases (Juárez Olguín et al., 2016). So, if there were ever a double-edged sword in the world of neuroscience or psychology, dopamine would be it. Thus, to understand the concepts behind motivation, it is crucial to look at the underlying dopamine systems and how they function; as there is a fundamental relationship between dopamine and the desire to exert effort.

This book chapter covers various critical concepts and theories that underlie both the natural and scientific aspects of the motivational drive. Precisely at the role of dopamine and why it is such a crucial component towards the composition of motivational drive[grammar?]. Furthermore, a range of discussion points based within the literature of psychology and neuroscience will dissect the relevant theories of motivational drive and what determines the proper functionality of a motivational system. This book chapter also looks at science-based methods and actionable tools that can help increase motivational drive and optimise dopaminergic levels within the human system. Decidedly, the theory that will be covered is reward subjectivity. These topics explain how dopamine affects motivational drive and how dopamine can be optimised to benefit motivational drive.

Focus questions:

What is dopamine?
What is motivation?
What is the connection between dopamine and motivation?
How can dopamine be optimised to foster motivational drive?

The fundamentals of dopamine

Dopamine is a naturally occurring neurochemical belonging to the catecholamine and monoamine families and is also the primary neurotransmitter involved in the limbic reward system within humans. Dopamine plays roles as both a neurotransmitter and a hormone in mammals and functions as neurotransmitters in echinoderms, non-vertebrates, lower vertebrates, molluscs, arthropods, nematodes, and is even found within the cells structures of particular plants (Liu et al., 2020). In the brain, dopamine functions as a stimulatory neurotransmitter that excites the electrochemical activity within and among various nerve cells that can lead to a myriad of states within living organisms such as pleasurable feelings, focus, motivation, and even movement (Lodish et al., 2019). This is because the neurotransmitter dopamine is uniquely synthesised within specific brain regions that can correlate to different body effects when stimulated. There are four distinct pathways within the synthesis and the division of dopamine; these pathways consist of the mesocortical pathway, nigrostriatal pathway, mesolimbic pathway, and the tuberoinfundibular pathway. To understand the landmarks and the correlating functions of these pathways, refer to Table 1. The entire composition of the dopamine pathways is known as the mesocorticolimbic system (Jaber et al., 1996).

Table 1.

The landmarks of the dopamine pathways and their responsibilities (Jaber et al., 1996)
Mesocortical pathway	Nigrostriatal pathway	Mesolimbic pathway	Tuberoinfundibular pathway
Landmarks: -Frontal lobe -Ventral tegmental area -Cerebral Cortex	Landmarks: -Substantia nigra -Striatum	Landmarks: -Ventral tegmental area -Nucleus accumbens -Amygdala -Hippocampus -Frontal cortex.	Landmarks: -Hypothalamus -Pituitary gland
Main responsibilities: - Cognitive functions -Motivational Salience	Main responsibilities: -Transportation of dopamine -Synthesis of dopamine -Motor function -Reward-related cognition -Associative learning	Main responsibilities: -Incentive salience -Pleasure response -Reward-related cognition -Reinforcement -Learning -Fear	Main responsibilities: -Transportation of dopamine -Synthesis of dopamine -Regulation of prolactin

Now that the fundamentals of dopamine and the correlating neural networks their functions have been covered, let us dive into the science of motivation.

New concepts of motivation

Motivation is a driving force (or forces) responsible for the initiation, persistence, direction, and vigour of goal-directed behaviour (Colman, 2009). Motivation is essential to know if someone will perform well; however, it is not the sole causation of the desire to act. So, if motivation is not the sole cause of action, then what does motivate people? Why do some people pursue excellence to reach their targets, while others merely show initiative to do anything? As with most questions that involve the human being, the answer is anything but simple. The following section will try to provide an answer to this perplexing question.

Temporal motivation theory

The fields of economics, decision making, sociology, and psychology share a common desire to understand our human nature—that is, our essential character, disposition, or temperament. This extensive, multidisciplinary interest in understanding who we are reflects enormous ramifications of the endeavour to understand what "truly" motivates us. Ironically, the understanding of motivational behaviour has been hindered by the extensive efforts from multiple fields of study. Consequently, a superabundance of motivational theories has since been produced that are pretty similar in their descriptions but seem to be postulated separately from the actual science of motivation. Thus, the theory of temporal motivation can aid in creating a stable and reliable theory that can help us understand the concepts of motivation and drive (Steel & König, 2006).[Summarise and abbreviate]

Temporal motivation theory (TMT) is an integrative theory of motivation that constructs many of its primary aspects from a range of major motivational theories, including expectancy theory, hyperbolic discounting, need theory and cumulative prospect theory. It was proposed by Piers Steel and Cornelius J. König in 2006; the theory emphasises time as a critical motivational factor and focuses on the impact of deadlines on the allotment of attention to particular tasks. Temporal motivation theory argues that as a deadline for completing an activity nears, that activity's perceived usefulness or benefit increases exponentially (Ide Bagus Siaputra, 2010).

TMT states that an individual’s motivation towards a task can be extracted from the following formulaː

$Motivation={Expectancy\times Value \over 1+Impulsiveness\times Delay}$

In this equation, motivation is considered as a yearning for a particular outcome. Expectancy represents self-efficacy and is viewed with the likelihood of success. The value represents the reward associated with the outcome of the motive; impulsiveness is considered to be one's ability to withstand urges; and delay represents the total amount of time until the realisation of the outcome (i.e., a deadline). The greater the individual's expectancy for completing the task, and the higher the value of the outcome associated with it, the higher the individual's motivation will be. In contrast, impulsivity and a more significant amount of time before a deadline reduce motivation (Steel & König, 2006).[How does this relate to dopamine?]

An example of temporal motivation theory.

Consider a student who has been given one month to write and edit an essay for his/her unit. Throughout the month, the student has two options: to study or to procrastinate. The student enjoys being laid back and taking life as it comes, but the student also needs to study to achieve a passing grade. At the start of the student’s study period (where there is a period of delay prior to the deadline), the reward of studying is not immediate (and hence has a level of low value); Therefore, the motivation to study will be lower than the motivation to relax. However, as the study period is reduced from several weeks to several days, the motivation to study will surpass the motivation to relax.

To understand this example further, suppose the student does not understand the material and does not feel confident that he/she will understand the concepts needed to write the essay ( expectancy or low self-efficacy). In addition, the student has just purchased a video game that has been dying to play (high value) and has a tough time resisting the urge to play it (high impulsiveness). With the essay deadline still a month away (long delay), the student’s motivation to study for the essay is likely to be low and, therefore, will play the video game instead. As the exam date approaches (shorter delay), studying motivation may increase, leading to abstinence from playing video games.

In the end, TMT addresses a range of dysfunctional separations of motivational science by combining lessons from various motivation theories. Importantly, this is not a complete model that accounts for all aspects of human behaviour but provides a stable framework of essential features derived from other motivational theories. Using TMT will allow for the extensive contributions from individual disciplines that may be more broadly communicated, such as the findings from cognitive psychology or self-regulatory disciplines demonstrating how motivation might be controlled or how motivational expectancies may alter with experience (Steel & König, 2006). This model can provide a common ground to enable the necessary dialogue towards motivational science.

Motivation: The dopamine connection

Dopamine is a chemical substance that sends messages between cells in the brain that are called neurons. Many neurons are correlated with the propagation of dopamine; however, dopamine plays a vital role in the model lighting areas of the brain that enable a wide variety of functions. The best known is movement, as dopamine deficiencies have been interrelated to contribute to Parkinson’s disease. For example, it has been shown that the Lentiviral-induced knockdown of dopamine with the nucleus accumbens of wild mice can completely eradicate the ability of locomotion (Mishra et al., 2018). However, dopamine goes way beyond movement, as one of the actions of dopamine is its ability to modulate areas of the brain involved with the ability to perceive reward reinforcement and enhance motivational states (Salamone & Correa, 2012).

Motivation management is primarily done through two brain structures known as the mesolimbic pathway and the mesocortical pathway.

The motivation-reward pathway: Dopamine functions in reward and pleasure seeking

Incentive salience or otherwise known as 'wanting', is a form of motivation that is generated by a robust and extensive set of neural structures that are dopamine dense, the main effector being the mesolimbic pathway or otherwise known as the limbic system. Rewards are often 'wanted' and 'liked', and those two words seem always to be used interchangeably among humans. However, neurocircuitry that moderates the operation of the psyche of humans in the pursuit of 'wanting' a specific reward is entirely separate from neurocircuitry that affects the degree to which a reward is 'liked'.

The limbic system's intricate functionality allows for the sensation of reward and pleasure; when dopamine spikes, it results in the excitation of the neurons found within the limbic system that results in the propagation of 'pleasurable feelings'. This is because dopamine acts as a 'rewiring' mechanism within the brain by which new information is taken into account when nuanced experiences arise. Thus to alleviate nuanced situations, the body needs to adapt to the circumstances by 'recalling' or 'creating' actions to deal with new stimuli that are present in the environment of a given being. If the theatrical event was dealt with, the limbic system goes into overdrive, promoting dopamine release and giving the person or animal the perception of a 'rewarding; experience. However, once the brain's modelling of the environment or circumstance has been updated, the reward derived from the initial experience will be processed as not as 'surprising'. This is due to the transient release of dopamine losing its effects in the prior experience as the brain has now adapted to recognising the nuanced experience and, therefore, will adapt swiftly to meet the demands of the experience again.

The motivation-reward pathway: The prefrontal cortex

The frontal cortex is the most recently evolved part of the brain, and its complexity in humans separates us significantly from our primate cousins, chimpanzees and many other species (Teffer & Semendeferi, 2012). At the front of the frontal cortex is the prefrontal cortex; this is the brains[grammar?] decider and does not fully mature in humans until their mid-20s (Rolls et al., 2010). Jonathan Cohen says, "the prefrontal cortex gives us the ability to orchestrate thought and action in accordance with internal goals" (Miller & Cohen, 2001). Thus, any damage infringed upon the prefrontal cortex disrupts the ability of animals to act in pursuit of a future goal, leaving them at the mercy of their environment (Goyal et al., 2008). The prefrontal cortex is a network of neural circuits that gets input regarding sensory information and has outputs generating motor responses. It is also in constant contact with a range of subcortical structures that process our internal information, such as motivational states, hunger and tiredness. The prefrontal cortex can be considered a venue to process information from all brain regions. During learning, reward-related signals — like dopamine — act on the prefrontal cortex to strengthen neural pathways that lead to desired outcomes. To explain this, let us look at a case study of a monkey called George.

Operant conditioning and George the monkey:

George, the monkey, has been put into a university science department for a study and is wired to an electroencephalogram. His enclosure contains a stone, a shell, and a train. Now, the researchers' rule is that every time George the monkey passes the stone to the researcher, he will get a bit of cucumber; but George, the monkey, does not know this. So, George explores, pushes the train, kicks the shell, and eventually takes the rock and gives it to the researcher. "There you go, buddy!" says the researcher as he hands George a piece of cucumber. Now, when the researchers look at the neurocircuitry results from George, they are completely shocked to see the results. George has had a massive surge of dopamine! As a response to solving the nuances of his environment, George's prefrontal cortex has now started piecing together a neural map that led to the attainment of his piece of cucumber, so when it comes to doing the task again, George is ready and rearing to go!

Cognitive control in humans and non-humans is brought by the prefrontal cortex sending excitatory signals to the relevant brain structures to solve a task. For example, neurons compete for activation in our visual cortex whilst inhibiting one another; this gives our vision contrast, depth and focus (Wise, 2004). So, for George, the monkey, he sees a train, a shell, and a rock; corresponding neurons in the visual cortex recognise the train, shell, and rock and this information gets sent to the prefrontal cortex. If George the monkey is hungry enough, the prefrontal cortex (aided by brain systems for memory) can recall that giving the rock to the researchers led to the attainment of the cucumber. So, suppose the researchers want to boost the attachment of reward involving the rock and George. In that case, they need to stimulate the excitatory signals within George's neurons to boost the relevant neural circuits while suppressing others that can lead to George being focused upon the rock. The theory of operant conditioning can explain this focusing mechanism; to understand how this focusing mechanism works, please turn to this famous psychological experiment conducted by Christopher Chabris and Daniel Simons:[Summarise and abbreviate]

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"Attention test" - Daniel Simons

The reasoning why most people miss the gorilla is due to the selective attention of the prefrontal cortex. The inhibition of using the prefrontal cortex requires lots of energy, so using it for everyday tasks can be unsustainable and mentally tolling (Kanoski et al., 2007).In evolutionary terms, the prefrontal cortex emerged to be a crucial component towards an animal's survival, as the prefrontal cortex created the ability to sustain behaviours automatically that would only benefit the promotion of survival (Hathaway & Newton, 2020). Furthermore, the prefrontal cortex and the concepts of survival are the main contributors that enabled the growth of motivation within humans and various other species (Murayama, 2018).

Pick a response

Dopamine and aversion: Concerning the last case study of George the monkey, dopamine can also be used as a critical effector in the motivation of avoiding a particular stimulus, as dopamine has even been shown to release in the experience of something un-pleasurable (de Jong et al., 2019). Now, let us consider that the researchers this time around wanted to teach George to be risk-averse. So what they do is hook George up to a shock collar after the prior experiments. The new rule is that every time George passes the rock to the researchers, he will get a slight shock. From learning about the functions of dopamine on motivational drive, what kind of behaviour might we see from George, the monkey?

	George continues to pass the rock to the researchers?
	George will no longer pass the rock to the researchers?
	George continues to see the rock as a positive reinforcement?
	George will now see the rock as a negative reinforcement?

Reward-prediction errors

Reward-prediction errors are the differences between received and predicted rewards. They are crucial for learning about rewards and make us strive for more rewards. The majority of dopamine neurons in the midbrain of humans, monkeys, and rodents signal a reward prediction error; they are activated by more the experience of attaining a reward than what was initially predicted (positive prediction error). After that, dopamine levels remain at a baseline for fully predicted rewards and show depressed activity with the nucleus accumbens (Schultz, 2016). The result of this error within the dopaminergic systems can lead to states of apathy and complacence.

By now, we know that dopamine stimulation generates learning and approach behaviour. We also know that encountering a better-than-predicted reward stimulates dopamine neurons. Thus, the dopamine stimulation arising from a natural reward may directly induce behavioural learning and actions (Schultz, 2016). Every time we see a reward, the responses of our dopamine neurons affect our behaviour. They are like “little devils” in our brain that drive us to rewards! This becomes even more troubling because of the particular dopamine response characteristics, namely the positive dopamine response (activation) to positive prediction errors: the dopamine activation occurs when we get more reward than predicted. However, any reward we receive automatically updates the prediction, and the previously larger-than-predicted reward becomes the norm and no longer triggers a dopamine prediction error surge (Schultz, 2016). The following reward then starts from a higher point of prediction and induces less or no prediction error response (To be succinct, this makes us less motivated). To continue getting the same prediction error, and thus the same dopamine stimulation, requires getting a more significant reward every time. The little devil not only drives us towards rewards, but it also drives us towards ever-increasing rewards (otherwise known as the hedonic treadmill).

Thus, the dopamine prediction error response may be a mechanism that underlies our drive always to want more rewards. This mechanism would explain why humans constantly seek to attain higher rewards and are never satisfied.

Now that the intertwining concepts of dopamine and motivational drive have been discussed, let us look at how dopamine can be optimised to ensure that motivational states do not become subject to reward-prediction errors.

How to control dopamine to optimise motivation and pleasure

Envision thisː

It is the middle of the afternoon, and it seems like the motivation for doing anything has wholly disappeared. Never mind working through the lengthy readings that need to be done for an upcoming essay — at this point, even the thought of starting the essay feels like an equivalent to running a marathon.

Now, there is a transparent image of this situation in mind; think of what might/should be done to combat this event and not fall behind on the essay.

Many people tend to give in to an unfocused mood or tend to peruse the endless cycle of scrolling through social media, or maybe they will sit down with their head down on a desk and beg the productivity angels to come down from the heavens to give a much-needed kick in the pants.

Fortunately, there is a better way to boost motivation, and it all has to do with the main focus of this chapterː, Dopamine. So, peel that forehead off the desk, and let us delve into a concept that can help optimise the release of dopamine positively.

Reward subjectivityː Enjoy your wins, but not all of them

Intermittent reinforcement is one of the most potent tools of the dopamine reward schedule that will ensure that motivational behaviour is upheld. Many scientific researchers discovered the intermittent reinforcement schedule long ago, namely B. F. Skinner and his colleagues (Cameron & Pierce, 1994). To export this concept and use it for good, think of pursuing a goal, whether it is an academic goal, financial goal, or a relationship goal. One of the things that can be done to ensure that the pursuit of this goal will remain on a stable path for a very long time and continue to promote better performance is to remove the feeling of reward subjectively (Peters & Büchel, 2010).

Let us say someone sets out a particular financial goal. They progress forward with the relevant planning and set out the sub-milestones that they need to achieve to reach the pinnacle of the actual goal. Understanding the concepts of reward-prediction errors has outlined that every time each of those sub-division goals has been attained, the amount of dopamine is not going to peak. It will diminish and create a craving for more stimulus that can halt the process of motivation. The key to avoiding this crash is to withhold from deriving pleasure out of succeeding in a particular goal or pursuit. Once the mechanisms behind dopamine have also been understood, it can help to hit new high points of performance because blunting the response to achievements allows for the modulation of dopamine to be used in a controlled manner that will ensure that it stays in cheque (Peters & Büchel, 2010).

Furthermore, doing this ensures balance within the path of continued pursuit, not just for one thing in particular, but for all pursuits, whether big or small. So, to make this crystal clear. Celebrate wins, but do not celebrate every win. That is one way to ensure that motivation can be encouraged to sustain the path of continuous progression.

Conclusion

Dopamine plays a critical role in motivating and modifying behaviour as it serves to invigorate patterns of behaviour that will aid the progression of survival. This book chapter has not only just examined the concepts of dopamine and motivation. However, it has also depicted how dopamine contributes to a range of effects in generating motivational drives. This was done successfully by recording information from separate studies on the concepts of dopamine and motivation, which revealed how dopamine relates to ongoing motor-associated activity and goal-directed behaviour. This chapter also discussed how dopamine can be optimised to foster states of motivation. Combining these findings revealed the extensive role dopamine has in producing motivational drive.

References

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External links

[Use alphabetical order. Use bullet-points and rename links so that they are more user-friendly per Tutorial 1.]

Awareness Test - YouTube

Robert Sapolsky - Intermittent reinforcement - YouTube

Reward prediction error: Current Biology (cell.com)

The Hedonic Treadmill - YouTube