Motivation and the Brain
How is motivation represented in our brains?
What motivates people to do the things that they do? Or fail to do? Why do some people make the same bad decisions repeatedly? These are complex, baffling questions, and the answers are often elusive.
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Walk into a bookstore and stand in the self-help section. Every published self-help topic somehow touches on the theme of motivating people to make better decisions, avoid dysfunctional behaviors, and create thinking patterns that lead to more productive, healthier lives.
Classes outside of psychology and philosophy even focus on the processes involved with better decision making. Business students, for example, take a class called Decision Sciences. The Business School at Columbia University in New York has an entire center devoted to decisions called “The Center for Decision Sciences.” It states as its core purpose “to help students understand consumer behaviors, the implications of decision making on public policy, and the neurological underpinnings of judgment and decision making.”
But what exactly are the neurological underpinnings associated with decisions? Are there neurons connected in networks that directly affect motivation? In other words, how do the brain and its neuronal networks and anatomical structures combine to form motivations and ensuing behaviors?
These questions form the core of what neuroscientists and neuropsychologists specializing in the study of motivation desire to know, empirically examining, analyzing, and probing how the “mind” facilitates motivation - and its close relatives called emotions. (For more information see human emotions and the brain).
But investigating the human mind for clues to motivation has only recently taken significant strides in areas of scientific study. Those strides came along with the introduction of neuroimaging technologies that give researchers real-time, live images of the working brain. Using these neuroimaging devices in combination with motivational tests and tasks, researchers now study motivation in ways unheard of only a decade ago.
Studying motivation and behavior
Up until recently, researchers used animals exclusively to study motivation. Setting up a system of rewards, punishments, and reinforcers, psychologists used animals to motivate behaviors in terms of reaching for rewards or avoiding punishments.
Pavlov’s dogs are the classic example for conditioned learning. Ivan Petrovich Pavlov, the Russian physiologist, psychologist, and physician, studied how dogs salivated when shown food they knew to be appetizing. Hence, they had to previously taste the food, find it likable, and when presented with the food again, they would salivate. Dogs could also be conditioned to salivate with a light or tone. If Pavlov presented a light or tone each time he gave the dogs the tasty food, they would soon begin salivating simply at the sight or sound of the stimulus. He called the stimulus a “reinforcer.”
In Pavlov’s example, the food is the primary or unconditioned reinforcer, and the tone or light is the secondary or conditioned reinforcer. Primary reinforcers motivate behavior without any learning while secondary reinforcers only motivate after learning – or conditioning - takes place.
Scientists furthered Pavlov’s findings by training animals such as rats to perform a certain action to receive a reward or punishment. They trained rats to press a lever to obtain food pellets, for example. This is called instrumental learning.
From these animal experiments, neuroscientists have extrapolated primary and secondary reinforcers of human behaviors. Humans learn cues that lead to positive and negative outcomes, becoming motivated by actions and behaviors that produce positive results. Individuals also quickly learn what elicits negative outcomes, and try to decrease or avoid behaviors leading to adverse results.
However, research studies using humans have remained obscure mainly as a result of ethical consequences. For example, keeping food from humans, or punishing them with options such as electric shock to teach them to avoid certain behaviors are not viable options.
The social context also plays a part in human learning. For instance, in some experimental situations, humans will make choices to avoid looking stupid. However, neuropsychologists now use effective tools to measure human motivation.
The Iowa Gambling Task is one such example, now the most widely used tool for understanding how humans use rewards and punishments to alter behavior.
The Iowa Gambling Task
In the Iowa Gambling Task, researchers use four decks of cards and play money. Test participants select cards from the decks, which, unknown to them, are marked accordingly: two decks are high risk; two decks are low risk.
Researchers tell participants that each time they select a card that they will win game money, but occasionally selecting a card will cause them to lose some money.
The high-risk decks offer the highest money rewards but also the greatest penalties. The object is to earn as much money as possible, and participants quickly learn that by selecting from the high-risk decks they earn large amounts of money, but can lose the largest amounts as well. Over the course of the game, participants will earn the most and have the lowest amount of penalties by selecting from the low-risk decks.
Normal participants selecting cards from each deck learn after about 40 or 50 selections which decks have the steadiest income with the least penalties. However, test participants with damage or lesions to the brain’s prefrontal cortex region in the frontal lobes, also called the orbitofrontal cortex (OFC) because it’s above the eye’ orbits, continue to select from the bad decks.
Some neuroscientists credit these results to the fact that those with OFC dysfunction don’t connect behaviors to future consequences – also apparent in their daily lives. However, these results are still being debated in the scientific community, with many still not convinced in a direct causal link between OFC dysfunction and consequence planning.
A number of neuropsychological researchers use the Iowa Gambling Task in combination with functional magnetic resonance imaging, or fMRI, to observe the brain regions as they complete the Iowa Gambling Task using different research paradigms. For instance, some observe only normal volunteers while others observe those with psychiatric disorders such as schizophrenia and obsessive-compulsive disorder.
A scientific workaround
However, using fMRI to test participants in terms of primary reinforcers such as food or drink presents some difficulties for scientists because the fMRI machines require participants to lay as still as possible.
They have found a way around this limitation by devising studies that activate taste and smell senses. Scientists know that the orbitofrontal cortex (OFC) contains taste and smell receptors, so they devise experiments that test “sensory-specific satiety” using these receptors.
For example, eating one cookie makes you desire another, and another, until after a certain number of cookies they are no longer appealing. One study gave participants a large meal, and afterwards used the smells of foods eaten during the meal during an fMRI study. The response of the OFC during the presence of the smells became increasingly reduced, pointing to evidence that the OFC is involved in the motivation to keep doing something.
Other researchers have moved away from using food as a primary reinforcer in studies, turning instead to the use of financial rewards. Money is not a primary reinforcer because it does not meet a physiological need; however, it is a strong motivator of behavior.
Since the late 1990s, a series of experiments using money as a reward has shown activation in the following brain areas: the midbrain, thalamus, dorsal and ventral striatum, and OFC. (For more information on the anatomy of the brain, see the Basics of Brain Structure.)
Amygdala damage, emotions and motivation
As noted in the following article on Emotions, studies done on those with brain injuries to the amygdala, a sub cortical structure of the limbic system, exhibit dysfunctional emotional processing.
Similarly, studies on motivation – specifically conditioned learning – show that some patients with damage to the amygdala have impairments in conditioned learning concerning both positive and negative reinforcers. Researchers today are investigating this link between the amygdala and motivation – and how damage to this deep brain structure simultaneously causes emotional impairments.
Motivated to study motivations
If you are interested in why and how people become motivated, and you wish to work in the fields of either Neuropsychology or Neuroscience, you should consider an undergraduate or graduate degree in psychology. Advancements in technology have made the study of human motivation and the brain some of the most timely and needed research for today’s complex and changing society.
Most careers investigating motivation focus on research and require at least a Ph.D. Public and private laboratories hire those with advanced degrees in the neurosciences.
Contact schools offering degrees in psychology for more information about a career in this field.
Rewards, Motivation and Learning
Rewards motivate learning, according to the 2006 Neuron article “Remembrance of Rewards.” Or, at the very least, an area of brain circuitry might help turn motivations into memory, said Cognitive Neuroscientist Alison Adcock and colleagues in the journal article.
In this study, these researchers revealed specific reward-related regions of the brain that alert other regions, aiding learning and memory formation.
Adcock, now an assistant professor at the Duke Institute for Brain Sciences in North Carolina, used fMRI to scan the brains of volunteers as they participated in two types of reward-related tasks.
The first task tried identifying the brain area responsible for anticipating rewards. The researchers showed participants circles or squares that contained an amount of money the subjects could win or lose. The amounts ranged from no money to $5, and to earn the money participants had to press a button immediately when shown a target. Neuroimaging during this task showed increased activity in the mesolimbic brain region as participants anticipated rewards - an area also associated with emotional processing.
The second task attempted to measure how this mesolimbic region also facilitated memory processing. The scientists showed participants “value” symbols associated with differing scenes. One symbol might be worth $5 while another was only worth ten cents, and the participants had to try and remember the symbols and the corresponding scenes. The next day the participants returned to pick out scenes from groupings of scenes, and not surprisingly, the high-value scenes were remembered more than the low-value scenes. But what the researchers did find remarkable was that the recall of the symbols activated areas of the mesolimbic region as well as the hippocampus. The hippocampus located in the medial temporal lobe (MTL), is known for higher-order processes such as learning and memory.
Participants who showed the greatest activity in the mesolimbic and MTL regions exhibited the best memory recall. The study summarized the findings as demonstrating that organisms’ “expectations and motivation interact with events in the physical world to influence learning.” The researchers concluded that anticipatory activation of the mesolimbic circuitry may help translate motivation into memory.