Adult neurogenesis

Adult neurogenesis is the production of new neurons in the adultbrain. In many species (e.g. fish and birds) it is a common process, butin mammals it is an exception. Mammalian adult neurogenesis takes
place primarily in two regions: the SVZ/olfactory bulb system and thehippocampus (as well as the striatum and the hypothalamus in somespecies). It is a highly complex, polygenic process that recapitulates

Created by Abcam in collaboration with Gerd Kempermann*

Neurogenesis in
the adult olfactory bulb

aspects of brain development in the otherwise non-neurogenicadult brain, and originates from local precursor cells that reside in
defined neurogenic niches. In the hippocampus, adult neurogenesis
is regulated by behavior and activity. Finally, adult neurogenesis
contributes to specific types of plasticity in the different regions, withregeneration not being its primary purpose.

Neurogenesis in
the adult hippocampus

Adult neurogenesis in the striatum

Adult neurogenesis in the neocortex

Normally in humans and rabbits and very limited
after ischemia in mice and rats.

Occurs in mammals only during prolonged postnatal
generation of Layer VI neurons, and limited postischemic neurogenesis (Layer II).

Progenitor
cell division(expansion)

Migrationand exit fromthe cell cycle

Diﬀerentiation,
neurite extension,selection, survival
and maturation?

Subventricular Zone (SVZ)

Diﬀerentiation

Type-1

Neurite extension,selection andsurvival, maturation.

Type-3Type-2At least seven typesof new interneurons
in the granular andperiglomerular layer
are produced.

Olfactory
bulb

Stem cell
division

StriatumFirst synaptic input(tonic, GABAergic,excitatory)

Period of low
threshold for
LTP induction
and highexcitabilityPrecursor cell stages

Lasting synaptic
input (glutamatergic,excitatory)
To CA3

New neuron

GFAP

Dentate gyrus

Switch toradial migration

Newgranulecells

BLBP
Nestin, Sox2
DCX, PSA-NCAM
Calretinin, Tuc4

(chain migration)

Incoming axons fromthe olfactory
recepter neurons
connect in theolfactory glomeruli.

Entorhinal
cortexA

A cellPrecursor cell stages

B

Neuronal lineage
GFAP, Sox2
Nestin, BLBPCC

C cellProgenitor cell
division (Expansion)

B

B cellStem cell
division

Adult neurogenesis in the hypothalamus

3rdventricle
Potentiallyneurogenic
lateral zoneA
Calretinin, (TH)New
neuronNeuN

Gli1*, Nkx2.1**Precursor cells in the SVZ are regionalized: wall areas withspeciﬁc transcription factor proﬁles give rise to diﬀerent
types of neurons in the olfactory bulb.

Oligodendrocytic lineage
Olig2

Simpliﬁed sequence of marker expression

MBP, O4

Stem cells (B) send
their process tothe ventricularsurface in a uniquepinwheel formation.

YXX’

Dentate gyrus

Spatial context

CA3

Forgetting

Horizontal view

Neurogenic
ventral zone

TanycyteMedianeminence*Correspondance to: Gerd Kempermann, M.D., German Center for Neurodegenerative Diseases (DZNE) Dresden and CRTD – Center for Regenerative Therapies Dresden, Technische Universität Dresden, e-mail: gerd.kempermann@dzne.de or gerd.kempermann@tu-dresden.de

Orthogonalization
and avoidanceof catastrophic
interference

CA1

Time stamp

EGFR, Dlx
DCX, PSA-NCAM, Ascl1

Function

A population of tanycytes in the median eminence of the 3rdventricle can give rise to new hypothalamic neurons in mice.
Additonal precursors might arise in the lateral wall of the ventricle.

Postmitotic stages

Pax6*, Gsx2*

PDGFRαNeuN

Simpliﬁed sequence of marker expression

Migration

Calbindin

Connectivity
Adult hippocampal
neurogenesis adds
new excitatory
granule cells thatlink synapses 1 and2 in the tri-synaptic
backbone ofhippocampal circuitry.

Flexible re-learning(Behavioral)
and updating
Pattern separation

Regulation
Stress and age

Homeostatic
baseline situation

Cognitive
demand, locomotor
activity, and seizures

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