Cortical area · one in each half of the brain
Dentate gyrus
Also called DG, Fascia dentata
The hippocampus's front door, and one of the few spots where new neurons may form.
The dentate gyrus is built around a tightly packed layer of millions of small neurons called granule cells. It is often seen as the first step inside the hippocampus for information arriving from the entorhinal cortex. According to one influential theory, its special skill is keeping similar memories apart, so today's parking spot does not get mixed up with yesterday's. It is also one of the very few places where new neurons keep forming in the adult brains of many animals, though how much this happens in adult humans is still debated.
Where it is
Deep in the hippocampus. Shaped like a V or U, it wraps like a cap around the end of the Cornu Ammonis, whose tip, sometimes called CA4, sits in its hollow.
What it does
Front door
It receives much of the hippocampus's incoming information from the entorhinal cortex, through a pathway called the perforant path.
Telling similar things apart
According to one influential theory, it makes the brain's codes for similar experiences more different from each other, a trick called pattern separation.
Staying mostly quiet
Only a small share of its granule cells seem to be active at any moment. In the same theory, this helps keep each memory's code distinct.
Passing it on
Its cells send signals to CA3 through mossy fibers, the next step in the hippocampus's main loop.
Making new neurons
In rodents and many other mammals, new granule cells are born here throughout adult life and join the existing circuits.
Think of it as a careful filing clerk who gives every new memory its own clearly labeled folder, so two similar days never get mixed up.
Works with
- Entorhinal cortexThe entorhinal cortex is its main source of input, passing along much of the sensory information from the cortex that the hippocampus uses.
- Cornu Ammonis (CA fields)Its output goes straight to the CA3 zone of the Cornu Ammonis, which is thought to link the details into a full memory.
- Dentate granule cellIts main neurons are small, oval granule cells, packed shoulder to shoulder in a tight layer.
- GlutamateIts granule cells use glutamate, an excitatory "go" signal, to excite the cells they talk to.
When it goes wrong
Epilepsy
In temporal lobe epilepsy, the mossy fibers of its granule cells sprout back into the layer that holds the granule cells' own branches, a place they normally avoid. This sprouting is one of the main hallmarks of the disease.
Stress and mood
In animals, long-term stress strongly holds back the birth of new neurons here, while short bursts of moderate stress can boost it. Depression has been linked to fewer new neurons, and scientists hope that boosting them could one day help treat mental illness.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- Exercise increases the number of new neurons born here, researchers have found, while the number tends to fall with age.
- Some studies suggest that hundreds of new neurons are added to the adult human dentate gyrus every day. But a 2018 study found that young neurons here drop sharply in the first year of life and could not find any in adults, so scientists still disagree.
- In rats, each granule cell connects with only 15 to 20 of CA3's main neurons, but through unusually large, powerful contacts.
Where the name comes from
Named for its tooth-like look: along one edge it has a row of small ridges, like teeth. This ridged edge is found only in humans and other higher primates.
Learn it in a lesson
- MemoryThe hippocampus and its circuit. 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 dentate gyrus?
Show the answer
Front door. It receives much of the hippocampus's incoming information from the entorhinal cortex, through a pathway called the perforant path.
Front door. It receives much of the hippocampus's incoming information from the entorhinal cortex, through a pathway called the perforant path.
The dentate gyrus is part of which larger structure?
Show the answer
Hippocampus. It belongs to the hippocampus.
Hippocampus. It belongs to the hippocampus.
Which part fits this description? "Like a careful filing clerk who gives every new memory its own clearly labeled folder, so two similar days never get mixed up."
Show the answer
Dentate gyrus. It is the dentate gyrus. The hippocampus's front door, and one of the few spots where new neurons may form.
Dentate gyrus. It is the dentate gyrus. The hippocampus's front door, and one of the few spots where new neurons may form.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- The dentate gyrus: fundamental neuroanatomical organization (dentate gyrus for dummies), Progress in Brain Research
- The mechanisms for pattern completion and pattern separation in the hippocampus, Frontiers in Systems Neuroscience
- 12.2 Neural Mechanisms and Circuitry of the Stress Response, OpenStax, Introduction to Behavioral Neuroscience
- Adult neurogenesis, Queensland Brain Institute, University of Queensland
- Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults, Nature
- Hippocampal dentation: structural variation and its association with episodic memory in healthy adults, Neuropsychologia
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