All of this is actually much more complicated, which we'll get into later. So why does dopamine have such a scandalous reputation? It's because dopamine signaling is a key player in the brain's reward system, which influences us to do things that feel pleasurable, and to do them over and over. But that's only one of the numerous functions that dopamine performs in our bodies. It's also vital for important processes such as motor control, learning and memory. Malfunctions in the wiring that uses dopamine seems to play a role in numerous disorders, including Parkinson's and schizophrenia [source: Jiang ].
In this article we'll explain what dopamine is and how it works in our brains and bodies. We'll also explain what dopamine isn't, and try to dispel some of the myths that have arisen around the chemical.
As we previously explained, dopamine is one of more than chemicals known as neurotransmitters, which enable neurons in the brain to communicate with one another and manage everything that happens in our body [source: Purves et al.
Like all neurotransmitters, dopamine goes through a cycle, which begins with it being synthesized by a neuron called the presynaptic cell. That cell releases the dopamine and it floats out into the synapse, the gap between neurons , and then makes contact and binds with structures called receptors on the other neuron, which then transmit the signal to the second neuron. After the dopamine accomplishes its mission, it's rapidly removed and degrades. The effects of dopamine on your brain depend a lot on which neurons are involved and which receptors are binding the dopamine [sources: Brookshire , Purves et al.
As molecules go, dopamine is fairly compact, consisting of just 22 atoms. Only a tiny portion of the brain's billion or so neurons — as few as 20, — generate dopamine, most of them in midbrain structures such as the substantia nigra , which helps control movement, and the prefrontal cortex [sources: Angier , Deans ].
Those specialized neurons make dopamine by taking an amino aside called tyrosine and combining it with an enzyme, tyrosine hydroxylase.
Add another step to the chemical reaction and you would get a different neurotransmitter, norepinephrine [source: Deans ]. In terms of evolutionary history, dopamine has been around for a long time, and it's found in animals from lizards to humans. But people have a lot of dopamine and over time, we seem to have evolved to produce more and more of it, possibly because it helps enable us to be aggressive and competitive.
As evolutionary psychiatrist Emily Deans wrote in , "dopamine is what made humans so successful. Massachusetts Institute of Technology researchers have developed tiny probes — just 10 microns in diameter — that can be implanted in animal brains to track dopamine.
Because they're so small, they don't cause scar tissue to form, and can function for more than a year [source: Trafton ]. Dopamine's function at the most basic level is to enable signals to pass through synapses from one neuron to another. But that's the high-level view. Up closer, the networks that use dopamine are composed of vast numbers of neurons, and the effects of releasing dopamine can vary, depending upon what types of neurons are involved and which of the five different types of receptors are using the dopamine to connect the neurons.
The particular role the neurons are playing can also be a factor [source: Brookshire ]. Dopamine's effects depend upon which of the four pathways is used in the brain and body where it's working to facilitate communication. The first is the nigrostriatal tract , which has to do with motor control in the body. When neurons in that system stop working, it can lead to disorders such as Parkinson's.
Another is the mesocortical pathway , which runs from the ventral tegmental area to the dorsolateral frontal cortex in the brain. It's the pathway associated with planning, prioritizing, responsibility and other executive function activities. There's also the tuberinfundibular pathway , which connects the hypothalamus and the pituitary gland, and blocks the secretion of milk in the female breast.
Blocking this pathway of dopamine enables breastfeeding. Finally, there's the mesolimbic pathway , which is connected to the brain's limbic system, which controls reward and emotion, and includes the hippocampus and the medial frontal cortex. That's the pathway that gets the most attention, since it's connected with problems such as addiction[source: Deans ]. Dopamine plays a role in kidney and heart function, nausea and even psychosis.
Many treatments for schizophrenia target dopamine [source: Brookshire ]. Until recently, not much was known about the precise mechanisms by which neurons use dopamine.
It was thought that it mostly took place through something called volume transmission , in which dopamine spread slowly and nonspecifically across large areas of the brain, and in the process happened to make the right contacts with the certain neurons. But in , Harvard University medical researchers published a paper revealing that specialized sites on those cells release dopamine in an extremely fast —think milliseconds — and precise manner to target sites [source: Jiang ].
But all that probably seems ho-hum to you, so in the next section, let's get back to the role of dopamine in the brain's reward system and in pleasure. The earliest experiments involving dopamine function were performed back in the s and s by a researcher named James Olds, who discovered that when rats' brains received a jolt of electrical stimulation in a certain area, they'd keep performing an action such a yanking a lever over and over [source: Chen ]. Because dopamine played a role in transmitting the signals, scientists initially suspected that it had something to do with pleasure.
Lastly, the pyriform complex of the olfactory bulb is responsible for providing humans with the sense of smell. In the mesolimbic pathway, dopamine is released during pleasurable situations, causing arousal and influences behavior motivations to seek out the pleasurable activity or occupation and bind to dopaminergic receptors present in the nucleus accumbens and prefrontal cortex.
Increased activity in the projections to the nucleus accumbens play a major role in reinforcement and in more extreme cases with addictions. In the arcuate nucleus of the hypothalamus, dopamine neurons make up the tuberoinfundibular pathway which projects to the pituitary gland and inhibits the secretion of the hormone prolactin.
Dopamine produced by neurons in the arcuate nucleus are released in the hypothalamo-hypophysial blood vessels which supply the pituitary gland with dopamine to inhibit the production of prolactin. Quantitative Measurement of Dopamine Levels in Samples Assessing dopamine levels as they pertain to de-regulation of functions associated with certain portions of the brain is an attractive target for neuroscience research.
Enzo Life Sciences offers a Dopamine ELISA Kit , which is a colorimetric competitive immunoassay capable of quantifying dopamine in serum, plasma, tissue homogenates and other biological fluids. This kit is highly specific for human dopamine and has negligible cross-reactivity between detection of human dopamine and its analogues.
This highly sensitive immunoassay has a detection range that can detect as little as 1. Furthermore, this product was designed with high sensitivity, high lot-to-lot reproducibility, and low time-to-result and offers a simple protocol that can produce reliable, quantitative results for our end-users in less than 2 hours for up to 40 samples in duplicate. Enzo Life Sciences provides a wide variety of products for your Neuroscience and Immunology research needs.
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Nucleic Acid. Western Blot. New Products. Certificates of Analysis. Antibody Search Tool. Apoptosis Detection Guide. Flow Cytometry Spectra Viewer. Flying Start New Lab Program. Customized Solutions For Your Workflow. Because of its roles in reward and reinforcement, dopamine also helps animals focus on things. But dopamine has a more sinister side. Drugs such as cocaine, nicotine and heroin cause huge boosts in dopamine.
And that prompts people to seek out those drugs again and again — even though they are harmful. By Bethany Brookshire January 17, at am. Story continues below video. The substantia nigra is very important for movement. And sure enough, this area of your brain is actually dark grey or black!
The reason: Cells that produce dopamine also make another chemical that stains the area a dark color. Neuroscientifically Challenged These two brain areas are very thin and tiny. Brain Concussion patients should avoid screen time for first two days By Kathiann Kowalski November 10, Psychology Will you learn better from reading on screen or on paper?
By Avery Elizabeth Hurt October 18, Tech A sense of touch could upgrade virtual reality, prosthetics and more By Kathiann Kowalski October 7, Sorry, your blog cannot share posts by e-mail.
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