GABAergic neurons.
One tends to think of the nervous system in terms of chains of excitatory signals that tell neurons to fire. The signals that say "Don't fire" also have a major role. Inhibitory signals damp overall neural activity and also fine-tune the responses of particular circuits. The primary carrier of these signals is the inhibitory transmitter known as GABA.
Gottlieb
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DI
D000818:Animals; D001569:Benzodiazepines / Q000494:pharmacology; D002490:Central Nervous System / Q000166:cytology / Q000502:physiology; D005968:Glutamate Decarboxylase / Q000235:genetics; D006801:Humans; D009433:Neural Inhibition; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D011963:Receptors, GABA-A / Q000235:genetics / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism / Q000502:physiology*
D011963:Receptors, GABA-A; D001569:Benzodiazepines; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase