Neuronal migration

Neuronal migration

The SVZ-OB pathway represents unique model to study neuronal migration in the adult brain.We are interested in molecular and cellular pathways that regulate long-ranging neuronal migration.We have previously shown that neuronal precursors use blood vessels for their faithful migration towards olfactory bulb. Not only neuroblasts use blood vessels as a physical scaffold, but they also receive molecular cues from the endothelial cells, such as BDNF, that foster their migration (Snapyan et al., 2009). We then demonstrated that vasculature-guided neuronal migration is induced in the ischemic striatum (Grade et al., 2013) and that astrocytes control vasculature development in the developing migratory stream via VEGF signalling (Bozoyan et al., 2012). We have also shown that extracellular matrix molecule, tenascin-R regulates radial migration in the adult, but not perinatal olfactory bulb (David et al., 2013).

Neuronal maturation

Once arrived into the olfactory bulb, neuronal precursors mature and integrate into the bulbar neuronal network. We are interested in the role of principal cells activity, as well as other bulbar cells, in the maturation and integration of adult-born neurons. We have found that principal cells' activity modulates early stages of maturation of adult-born interneurons, via activation of NMDA receptors (Breton-Provencher et al., 2014).

 

Using in vivo two-photon imaging, we have also uncovered a completely new form of structural plasticity in the adult olfactory bulb. We showed that mature spines of adult-born, but not pre-existing, neurons relocate over a few microns in the bulbar network in an activity-dependent manner. Spine relocation of adult-born neurons allows a fast reorganization of the bulbar network to odor-induced activity with functional consequences for odor information processing (Breton-Provencher et al., 2016).

Video by Inessa Stanishevskaya

Video by Inessa Stanishevskaya

Image by Mireille Massouh

Functional role of adult-born neurons

We combine morphological, electrophysiological and behavioral studies to understand the role of adult-born neurons in the bulbar network functioning and odor behavior. We have shown that ablation of adult-born neurons (Breton-Provencher et al., 2009) or modulation in the number of new cells in the olfactory bulb (David et al., 2013) affects bulbar network functioning and specific types of odor behavior.

 

We also aim at understanding what are specific properties that different subtypes of interneurons (Malvaut et al., 2017) and new neurons (Hardy et al., 2018) bring to the olfactory network and what is their role in the OB functioning and execution of selected olfactory behaviors.

Image by Frederic Cantin

Contact:

Armen Saghatelyan, PhD

armen.saghatelyan@fmed.ulaval.ca