Corpus callosum

Vanessa Siffredi explores why the corpus callosum is central to typical brain development, yet some children born without it or with callosal abnormalities develop comparably to their peers. The talk connects callosal structure and communication between hemispheres with cognition, attention, executive function, memory, language and socio-emotional development. Structural and functional neuroimaging studies of typical development and callosal dysgenesis examine how developing brains compensate for alterations in this major white-matter pathway. Siffredi is affiliated with CHUV and UNIL; Carole

Glioblastomas (GB) are the most malignant primary brain tumors with median survival of about 17 month despite extensive treatment. Molecular heterogeneity and the tumor microenvironment contribute to the challenges in treating GBs. Glioma-associated microglia and macrophages, comprising 30-50% of non-neoplastic cells in the microenvironment, play a crucial role in facilitating tumor growth and inducing tissue necrosis. However, the intricate interplay between these immune and glioma cells remains poorly understood.This study focuses on understanding the dynamic role of microglia during gliobla

The corpus callosum (CC) is a wide and thick nerve tract in the brain. It is the largest white matter structure in the human brain, measuring approximately 250mm in length, and consisting of 200-300 million myelinated axons. According to the World Health Organization (WHO), the world's population is getting older. Aging is one of the main risk factors for neurodegenerative diseases. Brain aging involves mitochondrial dysfunction, dysregulated energy metabolism, altered neuronal activity, and inflammation. Changes in white matter metabolism during aging are poorly understood. In this study, we

Emerging evidence suggests that intrauterine exposures to maternal factors such as to maternal pre-pregnancy body mass index (MBMI) impacts the neurodevelopment of the offspring in a region-specific way, possibly contributing to future obesity risk of the offspring. Our study investigates the associations between MBMI and neonatal global white matter integrity in 157 infant-mother dyads from FinnBrain Birth Cohort Study (www.finnbrain.fi). Following TBSS (Tract-based Spatial Statistics) skeletonization, associations between MBMI and mean diffusivity values were assessed using a voxel-wise non-

The neural basis of abnormal social behavior in autism spectrum disorder (ASD) remains incompletely understood and previous studies has highlighted that altered myelination could be involved in the pathophysiology of ASD. We have characterized the myelination process during development in the cntnap2-/- mouse model of ASD. We observed that oligodendrocyte differentiation and myelination are transiently impaired during cortical development in cntnap2-/- mice. Thus, we observed a reduction in myelinated fibers, the number of nodes of Ranvier and the proportion of mature oligodendrocytes in somat

…development, with a focus on neonatal corpus callosum (CC) integrity. Leveraging data from the FinnBrain Birth Cohort Study, we involved 40 mother-infants dyads. We conducted DTI imaging on 2-5-week-old infants to estimate fractional anisotropy (FA) values in CC regions (Genu, Body, and Splenium) and evaluated maternal prenatal cortisol levels through hair cortisol concentration (HCC). The latter reflects cortisol concentration over the last five months of pregn

Focal cortical dysplasia (FCD) is a regional malformation of cortical development frequently associated with pharmacoresistant epilepsy. It is caused by somatic mutations affecting the mTOR signaling pathway within excitatory neurons. At the cellular level, FCD manifests as the emergence of dysmorphic neurons, disrupted neuronal migration, and consequent alterations in neuronal circuitry, accompanied by seizure occurrence. It has been demonstrated that physiological neuronal activity stimulates oligodendrocyte lineage cells (OLCs) to proliferate, differentiate, and myelinate. We hypothesize th

…the hemispheres is routed through the corpus callosum, how and which microcircuits are key in integrating it across development is not well understood. Here we identify an essential role for layer 1 NDNF+ inhibitory cells of mice in controlling the bilaterally evoked whisker stimulation in layer (L)4 before,

Exploring the molecular aspects of the human brain’s structural arrangement can provide insights into its underlying functional mechanisms. The search for differences in white matter regions often focuses on measuring myelin layer thicknesses or parameters of diffusion tensor imaging. Lipids are vital components of cell membranes and are involved in important physiological functions such as signal transmission, maintaining membrane structure, and supporting the development of neurons. This research involved analyzing the distribution of lipids in different areas of the human brain, specificall

Pinnipeds, semi-aquatic mammals of the order Carnivora, transitioned to the marine environment approximately 25 Mya. This transition was associated with many unique evolutionary pressures, including those affecting the brain. Here we investigate how a semi-aquatic lifestyle may have altered brain morphology in extant pinnipeds using magnetic resonance imaging (MRI) and gross anatomical observations on three spotted seals (Phoca largha, a Phocid) and three Steller sea lions (Eumetopias jubatus, an Otariid).Based on available data, we compared our observations on the semi-aquatic pinnipeds, to b

Adenosine A1 receptor (A1AR) signaling exerts important functions in the central nervous system (CNS). Among all CNS cell types, oligodendrocyte (OL) lineage cells possess the highest A1AR expression levels. However, in vivo data regarding the functions of A1ARs in OL lineage cells remain elusive. Here, we first generated NG2-CreERT2xA1ARfl/fl conditional knockout (cKO) mice to specifically delete A1ARs from oligodendrocyte precursor cells (OPCs) upon tamoxifen administration. Immunohistochemical analysis for OL lineage markers PDGFRα, APC CC1, as well as BrdU incorporation detected unaltered

…of a reduction of the volume of the corpus callosum in male children that have experienced child maltreatment and female children that have experienced sexual abuse. In this study, we aim to expand this finding to a broader population of trauma-survivors who experienced childhood neglect and/or potentially tr

The corpus callosum enables the transfer of information between cerebral hemispheres. In the context of somatosensory stimuli, each hemisphere predominantly processes information originating from the contralateral side of the body through thalamocortical innervation. To a lesser extent, information from the ipsilateral side is also processed and relies on the involvement of callosal axons. We aim to understand the role of these callosal axons in ipsilateral signaling. To study this, we employ the mice whisker system due to its clear somatotopical organization by which the input from a whisker

Seizure suppression by deep brain stimulation (DBS) applies high frequency stimulation (HFS) to grey matter to block seizures. In this presentation, I will present the results of a different method that employs low frequency stimulation (LFS) (1 to 10Hz) of white matter tracts to prevent seizures. The approach has been shown to be effective in the hippocampus by stimulating the ventral and dorsal hippocampal commissure in both animal and human studies respectively for mesial temporal lobe seizures. A similar stimulation paradigm has been shown to be effective at controlling focal cortical sei

…the basic circuit logic by which the corpus callosum operates remains poorly understood. To reveal the logic of bilateral integration and

…and projection fiber, namely: the corpus callosum, the fornix and the corona radiata. Ovine samples from three different subjects have been imaged using scanning electron microscope combined with focused ion beam milling. Particular focus has been given to the axons. For each tract, a 3D reconstruction of relat

The corpus callosum is the largest fibre tract in the brain of placental mammals and connects the two cerebral hemispheres. Corpus callosum dysgenesis is a developmental brain disorder that is commonly genetic and occurs in approximately 1:4000 live births. It is easily diagnosed by MRI or prenatal ultrasound and is found in isolation or together with other brain anomalies, or with other organ system defects in a large number of different congenital syndromes. Callosal dysgenesis is a structural brain wiring disorder that can impact brain function and cognition in heterogeneous ways. We aim to