Group
Basal ganglia
Also called Basal nuclei
Your action selector: says "go" to one move and "no-go" to all the rest.
The basal ganglia are a group of deep nuclei (clusters of nerve cells) that help decide which action to do and which to hold back. At any moment you could do many things, so they lift the brake on the one you pick and keep the others on hold. Their main input part, the striatum, is made of the caudate and putamen, plus the nucleus accumbens lower down. They also turn repeated actions into habits, and when they go wrong, movement becomes too little (Parkinson's disease) or too much (Huntington's disease).
Where it is
Deep inside each half of the brain, curled around the thalamus and tucked under the cortex.
What it does
Picking one action
Many possible moves compete at once. The basal ganglia pick a winner and keep the rest on hold.
The "go" pathway
In the direct pathway, the striatum quiets the output brake, the internal globus pallidus. That frees the thalamus to push the chosen move forward.
The "no-go" pathway
In the indirect pathway, signals detour through the external globus pallidus and subthalamic nucleus to press the brake harder and stop unwanted moves.
Building habits
With practice, they bundle steps into smooth routines, so you can tie your shoes or drive home without thinking.
Learning from rewards
Bursts of dopamine tell the striatum "that went well, do it again", strengthening actions that led to good outcomes.
Think of it as a traffic cop at a busy crossing, waving one car through while holding up a hand to all the others.
Inside the basal ganglia
- Caudate nucleusA C-shaped nucleus with a long tail that helps you learn, plan and chase goals.
- PutamenThe shell-shaped hub where practiced movements become smooth, automatic habits.
- Globus pallidusThe "pale globe": the gatekeeper that holds movements in check until it is time.
- Nucleus accumbensThe brain's reward hotspot, turning "I like that" into "I want more".
- Subthalamic nucleusA small brake that can shout "wait!", and a top target for Parkinson's therapy.
Works with
- Substantia nigra pars compactaSupplies the dopamine that boosts "go" and quiets "no-go".
- Motor stripSends movement plans in and receives the final verdict back through the thalamus.
- Prefrontal cortexRuns parallel loops through the basal ganglia for planning and decisions.
- ThalamusThe relay the basal ganglia keep under a brake, releasing it when an action is chosen.
- Subthalamic nucleusThe emergency brake of the circuit, key to the "no-go" pathway.
- Medium spiny neuronThe main cell of the striatum, which collects signals and casts the first vote.
When it goes wrong
Parkinson's disease
The dopamine cells that feed the striatum slowly die. The "go" signal weakens, so movement becomes slow, small and stiff, often with a resting tremor.
Huntington's disease
An inherited illness damages the striatum early. It causes jerky, dance-like movements called chorea, along with mood and thinking changes.
Tics and compulsions
Studies link Tourette syndrome and obsessive-compulsive disorder to loops that run through the basal ganglia.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- The main output of the basal ganglia is a brake. It holds the thalamus back nearly all the time, and a movement happens when that brake is briefly lifted.
- By the time Parkinson's disease is diagnosed, a large share of the dopamine cells feeding the basal ganglia have usually already been lost.
- Dopamine here can rise before a reward arrives, just from a cue that predicts it, like the ping of a message you have been waiting for.
Where the name comes from
"Basal" means "at the base", because they sit low and deep in the brain. "Ganglia" is Greek for "knots" or "swellings". Since that word usually means nerve clusters outside the brain, many scientists prefer "basal nuclei".
Learn it in a lesson
- The basal gangliaChoosing which movement goes. A short guided lesson in 3D.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the basal ganglia?
Show the answer
Picking one action. Many possible moves compete at once. The basal ganglia pick a winner and keep the rest on hold.
Picking one action. Many possible moves compete at once. The basal ganglia pick a winner and keep the rest on hold.
The basal ganglia is part of which larger structure?
Show the answer
Inside the brain. It belongs to the deep parts of the brain.
Inside the brain. It belongs to the deep parts of the brain.
Which part fits this description? "Like a traffic cop at a busy crossing, waving one car through while holding up a hand to all the others."
Show the answer
Basal ganglia. It is the basal ganglia. Your action selector: says "go" to one move and "no-go" to all the rest.
Basal ganglia. It is the basal ganglia. Your action selector: says "go" to one move and "no-go" to all the rest.
These parts now come back in your daily review, just before you would forget them.
Practice these parts in 3DSources
- Neuroanatomy, Basal Ganglia, StatPearls, NCBI Bookshelf
- 13.2 The Central Nervous System, OpenStax, Anatomy and Physiology 2e
- 14.3 Neural Circuitry of Drug Reward, OpenStax, Introduction to Behavioral Neuroscience
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Explore the basal ganglia in 3D
Turn it around, zoom inside and see how it connects to the rest of the brain, then test yourself with quick quizzes.
Open it in 3D