A new study published by the team of Naguib Mechawar,
Ph.D., a researcher at the Douglas Institute (CIUSSS
de l’Ouest-de-l’île-de-Montréal) and Associate
Professor in the Department of Psychiatry at McGill
University, suggests that the integration of new
neurons in the adult brain is a phenomenon more
generally compromised in the brains of depressed
patients. This new work confirms that neurogenesis
in the human olfactory bulb is a marginal phenomenon
in adults. These findings shed light on the special
features of the human brain.
We already knew about the existence of neurogenesis
in the adult brain, the process through which new
neurons are produced and integrated throughout the
course of life, mainly in two brain regions, the
hippocampus and the olfactory bulb (OB). So far,
however, this knowledge has relied mainly on studies
in rodents. In humans, although neurogenesis in the
adult hippocampus is no longer a matter of debate,
the presence of neurogenesis in the OB has remained
controversial.
The work of the doctoral candidate Marissa Maheu on
Naguib Mechawar’s team breaks new ground. Based on
post-mortem brain samples from the Douglas-Bell
Canada Brain Bank, it shows the presence of only a
few immature cells within each olfactory tract,
which is the migration path to the OB. However, the
comparison of brain tissue from healthy people with
samples from depressed, suicidal individuals,
suggests that migration and maturation of these
cells is affected in depressed patients.
“While previous evidence from animals and humans has
suggested that neuronal proliferation or survival
might be altered in depression, this is the first
evidence implicating changes in neuronal maturation
and migration in the disorder,” explains Dr.
Mechawar.
Given that the phenomenon of neurogenesis in the
adult hippocampus has already been implicated in
depression, these new data, published in the journal
Frontiers in Neuroanatomy, is an important step
towards understanding depression.
This work was funded by the Canadian Institutes of
Health Research (CIHR) and the Fonds de recherche du
Québec-Santé (FRQS).
For more information
Increased doublecortin (DCX) expression and
incidence of DCX-immunoreactive multipolar cells in
the subventricular zone-olfactory bulb system of
suicides
http://dx.doi.org/10.3389/fnana.2015.00074
McGill University
MDN |