The basal ganglia are the oldest structure in your brain, one that has been coordinating movement, motivation, and reward for some 560 million years. Read on to find out how it works and what kind of substances can affect it.
What Are the Basal Ganglia?
The basal ganglia are a group of specialized brain cells located deep in the middle of the brain. Their most important roles are to orchestrate movement, regulate feelings of reward, and govern other instinctual needs. These are very old functions and concerns on the evolutionary time scale: the basic structure of the basal ganglia has been the same for almost all of vertebrate evolution [1, 2].
The largest structure in the basal ganglia, the striatum (composed of the caudate, putamen, and nucleus accumbens in the image above), receives signals from parts of the brain using dopamine. It then sends out new signals using GABA [1].
Your Reptilian Brain
One interesting theory from the 60s gave rise to the popular concept of the reptilian brain. While most scientists were focusing on the conscious, thinking brain, the neuroscientist Paul MacLean set out to understand the structures that underlie our more primitive, unconscious actions. “Instinct has been kind of a dirty word for some time,” he announced back then [3].
MacLean coined the term “Triune Brain”. He was also the first to come up with the term limbic system, which we frequently use today. According to the triune model, your brain is divided into 3 layers or parts [3]:
- The reptilian brain or your basal ganglia, the most primitive part of the brain that governs balance and where your basic instincts reside.
- The limbic system or the old mammalian brain, which governs your emotions, social behavior, and some aspects of memory.
- The neocortex, or the human brain, which directs complex processes like language, abstract thinking, advanced cognition, and planning.
It was first thought that this structure originated from ancient lizards, hence the popular reptilian brain idea. However, even the lamprey, a primitive fish used to model some of the earliest vertebrates, uses the same basal ganglia pathways as we do to move, breathe, and swallow. So, the emergence of this part of the brain seems to predate reptiles [1, 2].
As modern research has uncovered much more about the brain in the meantime, this theory has become outdated. It’s not precise, and there are several important exceptions to it. But it helped scientists initially understand some aspects of brain anatomy and behavior.
Functions of the Basal Ganglia
This section will explore how the basal ganglia works when everything is running smoothly. To learn more about what happens when this part of the brain becomes dysfunctional, check out this post.
Movement
The basal ganglia allow us to very precisely control our bodies by preventing unwanted movement.
When you decide to move a part of your body, the signal travels to a part of the basal ganglia called the caudate nucleus. This elongated C-shaped structure (see the red structure in the image below) uses the neurotransmitter GABA to send the signal to another part of the basal ganglia called the pars reticulata [1, 4].
Neurons in the pars reticulata inhibit movement. GABA is always “inhibitory.” As such, its job in this context is to momentarily deactivate (or pause) activity in the pars reticulata for movement to take place [1, 4].
Motivation and Decision-making
Dopamine in the basal ganglia controls motivation by encouraging feel-good sensations over unpleasant ones. Essentially, we avoid situations that result in lower dopamine, and we seek to repeat situations that result in higher dopamine [5].
This makes sense from an evolutionary perspective. If humans didn’t instinctively avoid the “down” of low dopamine, they probably wouldn’t have survived to tell the tale. Problems arise, however, once addictive drugs come into the picture. They can hijack our dopaminergic reward system by overloading the basal ganglia with dopamine and creating a euphoric high [5].
As an extension of this function, the basal ganglia also help us make decisions. Just like the more strong-willed of us will make responsible, hard decisions when faced with a dilemma, your basal ganglia will be working on the seemingly more basic life decisions in the background. They will assign values to different possible actions based on the probability of receiving a reward [6].
Working Memory
The basal ganglia may help filter information, selecting what is and what is not important for the brain to process. Their job is to save the brain from an unnecessary burden. If they need to, they will shut off irrelevant information before it reaches your conscious brain [7].
Learning
Unsurprisingly – given their role in decision-making and working memory – the basal ganglia also help you learn and build habits. By reinforcing behaviors with either good or bad feelings (reward or punishment), the basal ganglia help us figure out what to do in situations we’ve encountered before [8, 6].
The reinforcement can be guised as anything from a social reaction (people frown or smile in response to your behavior), material goods (treats, toys, money), or specific events (injury, fear, pleasure, etc.).
The basal ganglia also control curiosity and the desire (or lack thereof) for new experiences [9].
Natural Substances that May Affect Basal Ganglia Function
It is extremely important to seek medical advice if you believe that you may have a neurological disorder or dysfunction. Your doctor will determine an accurate diagnosis and appropriate treatment or management plan, which may or may not include some of the strategies below. Never use any of the following substances or strategies in place of what your doctor prescribes.
Possibly Effective
1) Coffee
Caffeine blocks adenosine receptors and increases the number of dopamine receptors in the striatum of the basal ganglia. It may also directly increase dopamine release in the nucleus accumbens. Together, these effects explain how coffee wakes you up and keeps you going [10, 11, 12, 13].
Moderate amounts of caffeine have shown the potential to help prevent and slow down the progression of Parkinson’s disease, though clinical trials are scarce. Talk to your doctor before attempting to use caffeine as part of a Parkinson’s management strategy [14].
Caffeine is most often consumed in coffee, but you can also find it in tea and chocolate [15].
However, caffeine can promote tolerance and poor health outcomes like high blood pressure. We advise against overusing caffeine for any health purpose unless your doctor specifically recommends it.
2) Cannabis
Cannabis contains many active compounds called cannabinoids; the most important and abundant of these are tetrahydrocannabinol (THC) and cannabidiol (CBD) [16, 17].
The striatum of the basal ganglia contains cannabinoid receptors that are sensitive to THC and CBD. After exposure to THC, the nucleus accumbens releases dopamine. Because of this, cannabis is under investigation for its potential in people with movement disorders, such as Parkinson’s disease and Tourette Syndrome, which are caused by disrupted dopamine pathways [18, 19, 20, 21, 22].
At lower doses, THC may also reduce anxiety, possibly through its action on cannabinoid receptors in the striatum. However, at higher doses and over a long period of time, THC can decrease the overall function of the dopamine system and increase anxiety. On the other hand, CBD has lessened anxiety at all doses that have been studied; some researchers have suggested that it may also protect the brain from the potential negative effects of THC [23, 24, 25, 26].
Remember that cannabis is illegal in much of the United States and other parts of the world. We advise against using cannabis without the specific recommendation of a medical professional.
Insufficient Evidence
The substances in this section have some human evidence to back them up, but existing studies are controversial or contradictory in some way. Further evidence is required in order to justify using these substances for any benefit to the basal ganglia.
3) Tyrosine
The amino acid tyrosine is converted into dopamine and norepinephrine (catecholamines) in the brain. Tyrosine is considered a non-essential amino acid because our bodies can make it from a different amino acid, phenylalanine [27, 28, 29, 30].
Dietary and supplemented tyrosine effectively raises available tyrosine in the blood. In people with low dopamine. Some researchers have therefore suggested that tyrosine supplements may help restore neurotransmitter function in those who are deficient [31, 32].
However, there is little if any evidence that supplementing with tyrosine raises levels of catecholamines in the brain, especially if you are already producing enough.
Tyrosine-Rich Foods
Tyrosine can be taken as a supplement, but it is also available in protein-rich foods like [33]:
- Meat (beef, lamb, pork, chicken)
- Eggs
- Cheese and other dairies
- Beans
- Soybeans
- Nuts
- Whole grains
Eating a diet rich in protein can help prevent any deficiencies in tyrosine.
4) Ginkgo biloba
In one clinical study, ginkgo extract injections prevented the striatum from releasing too much dopamine after an injury. In another study of rats with suppressed dopamine release, ginkgo extract returned dopamine levels to near normal. These results suggest a role for ginkgo in protecting nervous tissue from damage [34, 35, 36].
A few clinical trials on ginkgo in ADHD have been mixed. Some studies have found a significant improvement in children and adolescents taking ginkgo extracts, while others have found that it is not effective enough to justify replacing conventional therapies. Most researchers agree that further clinical studies are required [37, 38, 39].
Ginkgo extract is also being investigated in models ADHD. Some researchers believe that it may be used alone or in combination with standard ADHD treatments, but further research is required to fully understand how it works and how useful it might be [39].
Animal & Cell Studies (Lacking Evidence)
No clinical evidence supports the approaches listed below to improve basal ganglia function. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
5) Green Tea
Green tea contains a group of chemicals called polyphenols which reduce the activity of dopamine transporters and protect the striatum from damage [40, 41].
Polyphenols from green tea are the subject of new research in the context of disorders affecting the basal ganglia, including anxiety, OCD, bipolar disorder, Parkinson’s disease, and movement disorders caused by stroke. This research has been limited to cells and animals so far, with researchers arguing that clinical trials are warranted [42, 43, 44, 41].
6) Ashwagandha
Also known as Indian ginseng, ashwagandha is an important herb in traditional Indian medicine. It is often taken to improve the symptoms of stress, anxiety, and insomnia [45].
Ashwagandha affects multiple neurotransmitter pathways, including the GABA and dopamine systems in the striatum. It improved symptoms in animal models of Parkinson’s and Huntington’s diseases [46, 47, 48].
In one study, ashwagandha extract reduced behavioral symptoms and damage to the basal ganglia (striata) in a rat model of Parkinson’s disease [49].
7) Rhodiola rosea
An extract of Rhodiola rosea – also known as rose root, Arctic root, or king’s crown – is being investigated in models of ADHD.
In one study, researchers gave Rhodiola rosea extract to a group of rats and measured their brain activity, including in the striatum of the basal ganglia. They found that Rhodiola rosea extract produced similar brain changes as methylphenidate, the active ingredient in Ritalin [50].
Rhodiola rosea is also a promising ingredient of a natural complementary treatment for Parkinson’s disease. Extracts of Rhodiola rosea, red wine, green tea, and dwarf periwinkle, in combination, are being investigated in combination with Parkinson’s medication [51].
8) Sideritis scardica
Like Rhodiola rosea, an extract of Sideritis – also known as ironwort, mountain wort or shepherd’s tea – is also being investigated in models of ADHD. When researchers gave Sideritis extract to a group of rats, it produced similar brain changes as the ADHD drug methylphenidate [50].
Effect of Drugs on the Basal Ganglia
It is extremely important to seek medical advice if you believe that you may have a neurological disorder or dysfunction. Your doctor will determine an accurate diagnosis and appropriate treatment or management plan.
We strongly recommend against using any drug without a doctor’s prescription.
Drugs that Increase Dopamine
1) L-Dopa and Dopamine Agonists
Levodopa, often called L-Dopa, has been used to treat Parkinson’s disease since its discovery in the 1960s. In fact, L-Dopa is so effective at decreasing the movement problems caused by Parkinson’s that a strong positive reaction to L-Dopa is used to help diagnose the disease [52].
The movement problems caused by Parkinson’s disease arise when dopamine levels are too low. L-Dopa is converted into dopamine in the brain, which compensates for this decrease and reduces symptoms [52, 53].
Over the course of five to ten years, L-Dopa can cause problems of its own. People who develop Parkinson’s disease earlier in life often suffer from dyskinesia, a chorea-like movement problem caused by long-term L-Dopa exposure. Because of this, early-onset Parkinson’s is usually treated with dopamine agonists for up to ten years before switching to L-Dopa [52].
Dopamine agonists include drugs like amantadine, which make dopamine receptors in the basal ganglia more sensitive. These sensitized receptors have an increased reaction to the decreased dopamine already present in the brain [52].
L-Dopa and dopamine agonists are also used to treat restless leg syndrome [54].
Read this post to learn about natural ways to increase your dopamine, especially if you struggle with low motivation, poor focus, and struggle in social situations.
2) ADHD Medication
Ritalin
Methylphenidate is the active ingredient in Ritalin, Concerta, Daytrana, and some other ADHD medication. The action of methylphenidate is complicated and acts on multiple pathways in the brain. In the basal ganglia, it increases the amount of available dopamine and activates dopamine receptors. Both of these actions will intensify dopamine’s effects. This improves focus and reduces the symptoms of ADHD [55, 56].
Adderall
Amphetamine is the active ingredient in Adderall. Amphetamine also has a complicated mechanism of action and, like methylphenidate, activates dopamine receptors in the basal ganglia. An increased response to dopamine improves focus in people with ADHD [57, 58].
3) Antidepressants
Some antidepressants act on receptors in the striatum of the basal ganglia. For example, sertraline, the active ingredient in Zoloft, increases the amount of available serotonin and dopamine in the striatum [59, 60, 61].
Fluoxetine, the active ingredient in Prozac, protects against damage to the striatum and substantia nigra [62].
Maintaining healthy serotonin levels will not only improve your mood, but will also contribute to good emotional balance, happiness, and wellness. Some safe supplements that boost dopamine include l-tryptophan, 5-HTP, vitamin D (or sun exposure), probiotics, and omega-3 fatty acids. This is just the tip of the iceberg, though. If you want to dive deeper check out this post.
4) Mood Stabilizers
Mood stabilizers like valproate, carbamazepine, and lamotrigine reduce the symptoms of bipolar disorder, in part, by supporting the function of the basal ganglia and increasing available dopamine [63, 64, 65, 66].
These drugs have complex mechanisms and are also prescribed to prevent seizures. In such cases, increased dopamine in the basal ganglia can produce side effects including tremor, tics, and other movement problems [66, 67].
It’s important to know that most of these mood stabilizers (and the majority of anti-seizure drugs) also work by stimulating GABA. Changes in basal ganglia activity in people with anxiety may also be linked to GABA imbalances.
Many strategies for treating anxiety, high stress, irritability, and insomnia increase GABA. Uncover more about GABA in this post.\
Other Drugs that Increase GABA
1) Benzodiazepines
Benzodiazepines, or benzos, are tranquilizing drugs that act on the nucleus accumbens region of the basal ganglia [68].
The basal ganglia’s exact role in sleep regulation is still being studied, but the striatum contains many GABA receptors. Benzos bind to these receptors and reduce the amount of GABA required to activate them. GABA is an inhibitory neurotransmitter: it slows down brain activity, helps you relax, and regulates sleep [69, 70, 71].
Benzos also increase the amount of dopamine available to the brain: they increase how often dopamine is released but decrease the amount released each time [72].
Benzos are often prescribed to treat anxiety disorders, schizophrenia, and insomnia, but they may increase suicide risk in the people who take them [73, 72, 74].
2) Ambien
Zolpidem, sold as Ambien, is used to treat insomnia and other sleeping problems and may be used to treat Parkinson’s disease. In one case study, it also improved all symptoms of Wilson disease. [75, 76, 77, 78].
Zolpidem binds to and activates the same receptors as benzodiazepines, mainly in a region of the basal ganglia called the globus pallidus [79].
Drugs that Block Dopamine
1) Tetrabenazine
Tetrabenazine is used to treat chorea and tics in people with Huntington’s disease and Tourette syndrome, respectively [80, 81].
Tetrabenazine has a complicated mechanism, but its main action decreases the amount of dopamine in the striatum of the basal ganglia [80].
2) Antipsychotics
Antipsychotic drugs are a group of compounds used to treat a variety of psychotic disorders including schizophrenia [82].
Many drugs in this class block dopamine receptors in the basal ganglia, including:
Of these, risperidone also affected glutamate receptors in the basal ganglia. Some subtypes of glutamate receptor increased in response to risperidone, and some subtypes decreased [90].
All of the above medications except clozapine may have side effects that resemble the motor symptoms of Parkinson’s disease. Clozapine avoids this side effect because it only blocks dopamine receptors for a short time [89].
In one study, people taking antipsychotic drugs like risperidone to treat their schizophrenia switched to an atypical drug called olanzapine. Before the switch, these people all had basal ganglia structures up to 20% larger than normal. After the switch, their basal ganglia all returned to a normal size [91].
Melatonin, lithium, and 5-HT also lower dopamine activity.
Limitations and Caveats
Most if not all of the natural substances and pharmaceutical drugs listed in this article affect parts of the brain other than the basal ganglia. These effects should also be considered before they are supplemented or added to an existing regimen. Always consult your doctor before using supplements, especially if you are taking medication for mental illness or movement conditions.
Our knowledge of the human brain is still limited. Our understanding of the role of the basal ganglia in learning, the regulation pathways of these neurons, and the mechanisms of effect of various drugs continues to evolve. The recommendations and conclusions in this article are therefore subject to change.
Further Reading
Takeaway
The basal ganglia are sometimes called the reptilian brain, as scientists thought we inherited them from a lizard ancestor. In fact, they may go back to an even older evolutionary ancestor. Rooted deep within the brain, the basal ganglia orchestrate some of your most basic instincts and help control your balance and movement.
Your basal ganglia use two main neurotransmitters to communicate: GABA and dopamine. Imbalances or damage in the basal ganglia can affect the harmony of these important brain messengers. Some safe lifestyle interventions and supplements may be able to correct milder imbalances. Ultimately, however, only a qualified neurologist can assess the function of your basal ganglia and brain.
