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All parts of the brain › Brain chemicals › GABA

Where is GABA made in the brain?

GABA (gamma-aminobutyric acid) is the brain’s chief inhibitory messenger, its brake: it makes the cells it reaches less likely to fire. Neurons throughout the brain make it, from glutamate. Lit are the cell groups built almost wholly of GABA neurons: the striatum (about 90% of its neurons), the globus pallidus, the Purkinje cells of the cerebellar cortex and the thalamus’s reticular nucleus. [1][2][3][4]

The 3D brain needs JavaScript. The lists below still say where GABA is made and where it is sent.

Lit: the main sources of GABA (blue) and where they send it (orange).

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Its main sources are lit in blue, where they send GABA in orange. Drag to turn, pinch or scroll to zoom; tap a part or a “light” button to name it on its own; .

Made by neurons throughout the brain; lit: the cell groups the cited source names as its main sources. GABA’s principal role is lowering how readily neurons fire, throughout the nervous system; in the neocortex alone 20–30% of neurons are interneurons, which in the brain and spinal cord are mainly inhibitory, using GABA or glycine. The lit parts are the ones built largely of GABA cells, whose output runs to other parts. [1][5] Lit in blue: the caudate nucleus, putamen, globus pallidus, cerebellum and thalamus. The Purkinje cells and reticular nucleus are not separate shapes in this atlas; lit: the parts that hold them, the cerebellum and thalamus. [3][4]

Lit in orange: the midbrain and superior colliculus, where its fibres end. The fibres themselves are not drawn: the two colours show where the cells are and where they send GABA, not the routes in between. [6]

Main sources: lit in blue

  • Striatum, lit as the caudate nucleus and putamen: About 90% of its neurons are medium spiny neurons, inhibitory cells that use GABA; the other 10% are interneurons, several kinds of them GABA cells too. [2]
  • Globus pallidus, lit as the globus pallidus: Both its segments are tonically active inhibitory nuclei: the external one sends GABA to the subthalamic nucleus, the internal one holds the thalamus in check. [2][7]
  • Purkinje cells, in the cerebellum: Some of the largest neurons in the brain, lined up in one layer of the cerebellar cortex; they mainly release GABA. The cells are not shapes in this atlas, so the whole cerebellum is lit. [3]
  • Thalamic reticular nucleus, in the thalamus: A thin capsule round the outer side of the thalamus, separated from it by the external medullary lamina; all its cells use GABA. It has no shape of its own here, so the whole thalamus is lit. [4]

Sent to: lit in orange

  • Substantia nigra, lit as the midbrain (direct pathway): Its pars reticulata, with the internal globus pallidus, receives the striatum’s direct pathway. It is not a separate shape here, so the midbrain is lit. [2][7]
  • Superior colliculus (basal ganglia output): The internal globus pallidus and the substantia nigra pars reticulata project to its deep layer, which controls fast eye movements (saccades). [2]
  • Not lit as targets: the thalamus and the subthalamic nucleus. The internal globus pallidus sends GABA to the thalamus and the external one to the subthalamic nucleus, but the thalamus is lit in blue as a source, and the subthalamic nucleus lies between it and the midbrain. [2][7]
  • Inside lit parts, so not lit apart: the deep cerebellar nuclei, the dentate nucleus among them, which receive the Purkinje cells’ GABA within the cerebellum. [3][8]

The pathways, as the sources name them

  • Direct pathway, from the striatum straight to the internal globus pallidus and the substantia nigra pars reticulata. These two output nuclei constantly brake the thalamus; when the striatum’s direct-pathway cells fire, they silence that brake, so the thalamus can drive the motor cortex and a movement is released. [2] See What part of the brain controls movement?
  • Indirect pathway, from the striatum to the external globus pallidus, then on to the subthalamic nucleus (not lit; see above). A chain of brakes: indirect-pathway cells quiet the external pallidum, which frees the subthalamic nucleus to excite the output nuclei, and they in turn hold the thalamus and movement back. [2] See What part of the brain controls movement?
  • Basal ganglia output, from the internal globus pallidus and the substantia nigra pars reticulata to the thalamus and the deep layer of the superior colliculus. The globus pallidus’s principal direct outputs go to the thalamus and the substantia nigra; the internal segment and the pars reticulata also reach the colliculus that steers saccades. [7][2] See What part of the brain controls eye movements?
  • Purkinje cells → deep cerebellar nuclei, from the cerebellar cortex to the deep cerebellar nuclei in the cerebellum’s own white matter (inside the lit cerebellum). This inhibitory projection is the cerebellar cortex’s sole output; the deep nuclei then carry the cerebellum’s output to the rest of the brain. [3][8] See What part of the brain controls balance?
  • Reticular nucleus → thalamic nuclei, from the capsule round the thalamus inwards to the other (dorsal) thalamic nuclei, inside the lit thalamus. The only thalamic nucleus that never projects to the cerebral cortex: it modulates the signals the other nuclei pass on to it. [4]

Good to know

  • Made from glutamate: one enzyme, glutamate decarboxylase (GAD), with the active form of vitamin B6 as its cofactor, turns the brain’s main excitatory messenger into its main inhibitory one. [1]
  • How the brake works: GABA-A receptors are chloride channels. When chloride flows in, the cell is pushed further from firing; even when its voltage barely moves, the open channels shunt away excitation arriving at the same time. [1]
  • Not always a brake: in the developing brain GABA mainly excites, because immature neurons hold more chloride; its role switches to inhibition as the brain matures. [1]
  • One inhibitory cell can still excite: the striatum’s direct-pathway cells are inhibitory, yet by silencing a brake they end up exciting their final target, the thalamus. [2]
  • First made in a laboratory in 1883 and long known only from plants and microbes; in 1957 Canadian researchers identified it as the factor in brain and spinal cord extracts that quieted crayfish neurons. [1]

What it takes part in

Each lit with every part that takes part: What part of the brain controls movement? · What part of the brain controls balance? · What part of the brain controls eye movements?

Its main sources, each on its own page: Striatum; Globus pallidus; Purkinje cells, in the cerebellum; Thalamic reticular nucleus, in the thalamus.

Sources

  1. Wikipedia: GABA
  2. Wikipedia: Medium spiny neuron
  3. Wikipedia: Purkinje cell
  4. Wikipedia: Thalamic reticular nucleus
  5. Wikipedia: Interneuron
  6. BodyParts3D 4.0 (3D model measured on this page), © DBCLS, CC BY-SA 2.1 Japan
  7. Wikipedia: Globus pallidus
  8. Wikipedia: Cerebellum

Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); GABA is made by neurons all through the brain, so the lit parts are its main sources as the cited sources name them, not the only places it is made. Real brains vary.