Biology subjects

Migaud, M.

Publications and source records attributed to Migaud, M..

5 recordsLinked to original sources

bioRxiv2026

The olfactory ventricle: an overlooked and evolutionarily conserved feature of the mammalian brain

The olfactory ventricle (OV), an anterior extension of the lateral ventricular system into the olfactory bulbs, is generally considered a transient developmental structure that closes during early postnatal life. However, this view largely derives from a limited number of laboratory models, and the evolutionary distribution and cellular organization of the adult OV remain poorly understood. Here, we combined a comparative survey of mammalian neuroanatomy with phylogenetic analyses and cellular characterization of the OV across species. We compiled anatomical data for 154 mammalian species spanning 26 orders and 80 families, revealing widespread persistence of a patent OV into adulthood. Phylogenetic analyses supported OV presence as the ancestral mammalian state and indicated that its absence is phylogenetically structured and consistent with repeated secondary losses. Chiroptera displayed multiple lineage-specific losses, whereas variation within Muridae extended to the intraspecific level, with contrasting OV persistence among Mus musculus and Rattus norvegicus populations. Comparative histological analyses in sheep, Peromyscus maniculatus, and CD1 mice revealed that, despite marked interspecific differences in OV morphology, the persistent ventricular region retains a conserved cellular organization characterized by progenitor- and glial-associated markers, proliferative cells, immature neuronal populations, and a differentiated apical/ciliary interface. Although these observations do not establish local neuronal production or demonstrate that the OV constitutes an autonomous neurogenic niche, their convergence across species indicates that the persistent adult OV is not simply an anatomically residual lumen but a specialized component of mammalian olfactory bulb organization. Together, our findings identify the OV as an ancestral and widely conserved feature of the mammalian brain and provide an evolutionary and cellular framework for investigating the developmental mechanisms controlling its persistence and its potential contribution to adult olfactory neurogenesis and plasticity.

neuroscience↗

bioRxiv2022

1H-MRS characterization of metabolic changes induced by photoperiod in the sheep brain: a promising eye into in-vivo adult neurogenesis?

The hypothalamus is a central structure of the mammalian brain, which controls physiological, endocrine and metabolic brain homeostasis. Despite this essential role, little is known about the normal and altered neurochemical changes occurring within the hypothalamic structures. Here, the metabolism of the hypothalamus of ewes was investigated at 3T using proton magnetic resonance spectroscopy (1H-MRS). We used the sensitivity of these animals to photoperiod i.e. the ratio of day to night length, to investigate the hypothalamic metabolic changes and their relationship to hypothalamic adult neurogenesis. A longitudinal study involving 4 ewes per timepoint was conducted at 4 time points (P01, P02, P03 and P04) during long days (LD) and 4 time points during short days (SD). Significant metabolic changes were found between LD and SD at all time points in particular for glutamate (Glu), glutamine, myo-inositol and total N-acetyl-Aspartate (NAA). During SD, glutamate and glutamine concentrations were significantly smaller at P01 compared to all other time points while significant neurochemical changes occurred during the entire LD period. Neurochemical changes relative to P01 remained stable during LD and SD except for Glu and Gln which increased between P01 and P02 during SD. Relative metabolic changes were significantly higher on average for NAA and Glu and significantly smaller on average for total choline during SD compared to LD, respectively, paralleling the average changes in the numbers of neural stem cells and glial and oligodendrocyte progenitors found by immunohistochemistry. Despite important differences between MRS and immunohistochemistry in terms of spatial resolution, both techniques suggest complementary findings that should contribute to a better characterization of the hypothalamus during photoperiodism and adult neurogenesis. We conclude that 1H-MRS could be a promising non-invasive translational technique to investigate the existence of adult neurogenesis in-vivo in gyrencephalic brains.

neuroscience↗

bioRxiv2020

The sheep brain: an interesting translational model for functional MRI studies?

Biomedical investigations in clinically relevant animal models is of crucial interest for faster and appropriate transfer to human. The ovine model has already demonstrated its potential compared to rodents and non-human primates (NHP) in various studies: sheep possess a gyrencephalic brain, captivity is not an issue and can undergo magnetic resonance imaging (MRI) in routine clinical scanners (1.5T, 3T) under identical conditions using similar techniques to humans. To date, the effects of anesthesia have been poorly explored and only few functional MRI (fMRI) studies were conducted in sheep. Here, Blood Oxygen Level dependent fMRI and perfusion MRI were conducted in lambs and adult ewes at 3 T. Robust but weak BOLD responses to visual stimulation were found in the lateral geniculate nucleus (LGN) up to 3% isoflurane anaesthesia. BOLD responses were weaker in adult sheep than in lambs while relative cerebral blood volumes (rCBV) and relative cerebral blood flows (rCBF) were significantly higher in lambs than in adult sheep for both gray and white matter in accordance with previous findings in the human. Assessment of functional responses in healthy individuals under adequate physiological conditions is essential for robust translational studies.

neuroscience↗

bioRxiv2020

Detection of homozygous and hemizygous partial exon deletions by whole-exome sequencing

The detection of copy number variations (CNVs) in whole-exome sequencing (WES) data is important, as CNVs may underlie a number of human genetic disorders. The recently developed HMZDelFinder algorithm can detect rare homozygous and hemizygous (HMZ) deletions in WES data more effectively than other widely used tools. Here, we present HMZDelFinder_opt, an approach that outperforms HMZDelFinder for the detection of HMZ deletions, including partial exon deletions in particular, in typical laboratory cohorts that are generated over time under different experimental conditions. We show that using an optimized reference control set of WES data, based on a PCA-derived Euclidean distance for coverage, strongly improves the detection of HMZ deletions both in real patients carrying validated disease-causing deletions and in simulated data. Furthermore, we develop a sliding window approach enabling HMZDelFinder-opt to identify HMZ partial deletions of exons that are otherwise undiscovered by HMZDelFinder. HMZDelFinder_opt is a timely and powerful approach for detecting HMZ deletions, particularly partial exon deletions, in laboratory cohorts, which are typically heterogeneous.

bioinformatics↗

bioRxiv2020

Brain orchestration of pregnancy and maternal behavior in mice.

Reproduction induces changes within the brain to prepare for gestation and motherhood. However, the dynamic of these central changes and their relationships with the development of maternal behavior remain poorly understood. Here, we describe a longitudinal morphometric neuroimaging study in female mice between pre-gestation and weaning, using new magnetic resonance imaging (MRI) resources comprising a high-resolution brain template, its associated tissue priors (60-m isotropic resolution) and a corresponding mouse brain atlas (1320 regions of interest). Using these tools, we observed transient hypertrophies not only within key regions controlling gestation and maternal behavior (medial preoptic area, bed nucleus of the stria terminalis), but also in the amygdala, caudate nucleus and hippocampus. Additionally, unlike females exhibiting lower levels of maternal care, highly maternal females developed transient hypertrophies in somatosensory, entorhinal and retrosplenial cortices among other regions. Therefore, coordinated and transient brain modifications associated with maternal performance occurred during gestation and lactation.

neuroscience↗