The basal ganglia is a group of nuclei found in the Human brain. The basal ganglia is interconnected with the cerebral cortex, thalamus and brain stem, and is associated with a variety of functions including motor control, cognition, emotions, and learning.
In 2373, Captain Benjamin Sisko's basil ganglia started to depolarize because of increased neural activity brought on by visions he had been experiencing. Doctor Bashir wanted to operate and repolarize the neural sheaths, but Sisko declined as it would have likely ended his visions. (DS9: "Rapture")