Summary
Deep nuclei that select and initiate actions, disrupted in Parkinson's and Huntington's diseases.
In depth
Direct and indirect pathways facilitate or inhibit movements via the thalamus. Dopamine modulates both. Parkinson's causes bradykinesia and rigidity; Huntington's causes involuntary movement. Deep brain stimulation helps.
The striatum receives cortical input; output nuclei inhibit the thalamus. Dopamine from substantia nigra modulates activity. Disorders cause too little or too much movement.
Remember: Parkinson's is hypokinetic; Huntington's is hyperkinetic.
The basal ganglia comprise the striatum (caudate and putamen), globus pallidus, subthalamic nucleus and substantia nigra. They form loops with the cortex and thalamus for selecting and initiating actions, habits, and reinforcement learning. The direct pathway releases inhibition on the thalamus (go signal, D1 receptors), the indirect pathway increases inhibition (no-go, D2 receptors), and the hyperdirect pathway via the subthalamic nucleus stops actions.
Disorders: Parkinson disease (tremor, rigidity, slowness, due to loss of nigral dopamine), Huntington disease (loss of striatal neurons gives chorea), Tourette syndrome, OCD and dystonia. Deep brain stimulation of the subthalamic nucleus can relieve Parkinson symptoms dramatically. Dopamine signals teach the striatum which actions pay off.
Key idea: the basal ganglia act like a gate, deciding which movement to allow.
Frequently asked questions
What is Basal Ganglia?
Deep nuclei that select and initiate actions, disrupted in Parkinson's and Huntington's diseases.
Which area of biology covers Basal Ganglia, and how advanced is it?
Basal Ganglia is one of the 54 topics in Neuroscience. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Dopamine Pathways, Cerebellum and Motor Learning, Pain Pathways.
Can you give an example of Basal Ganglia?
The substantia nigra is the source of dopamine to the striatum.
What should I learn before Basal Ganglia?
Work through the Beginner topics in Neuroscience first, such as Nervous System, Neuron, Central and Peripheral Nervous Systems, then return to Basal Ganglia. Advanced topics assume the Intermediate vocabulary.
What topics are related to Basal Ganglia?
The closest topics to Basal Ganglia are Dopamine Pathways, Cerebellum and Motor Learning, Pain Pathways, Neural Circuits and Oscillations. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Basal Ganglia?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Basal Ganglia. To practise the whole of Neuroscience, use the Neuroscience quiz.
How is Basal Ganglia different from Dopamine Pathways?
Basal Ganglia: Deep nuclei that select and initiate actions, disrupted in Parkinson's and Huntington's diseases. Dopamine Pathways: Dopamine circuits mediate reward, motivation and movement; loss of its neurons causes Parkinson's disease. Read both side by side and note what each one explains.
How should I study Basal Ganglia step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Dopamine Pathways and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.