Biology subjects

Dadarwal, R.

Publications and source records attributed to Dadarwal, R..

3 recordsLinked to original sources

bioRxiv2021

Fusion of quantitative susceptibility maps and T1-weighted images improve braintissue contrast in primates

Recent progress in quantitative susceptibility mapping (QSM) has enabled the accurate delineation of submillimeter scale subcortical brain structures in humans. The simultaneous visualization of cortical, subcortical, and white matter structure remains, however, challenging, utilizing QSM data solely. Here we present TQ-SILiCON, a fusion method that enhances the contrast of cortical and subcortical structures and provides an excellent white matter delineation by combining QSM and conventional T1-weighted (T1w) images. In this study, we first applied QSM in the macaque monkey to map iron-rich subcortical structures. Implementing the same QSM acquisition and analysis methods allowed a similar accurate delineation of subcortical structures in humans. However, the QSM contrast of white and cortical gray matter was not sufficient for an appropriate segmentation. Applying automatic brain tissue segmentation to TQ-SILiCON images of the macaque improved the classification of subcortical brain structures as compared to the single T1 contrast by maintaining a good white to cortical gray matter contrast. Furthermore, we validated our dual-contrast fusion approach in humans and similarly demonstrated improvements in automated segmentation of cortical and subcortical structures. We believe the proposed contrast will facilitate translational studies in nonhuman primates to investigate the pathophysiology of neurodegenerative diseases that affect subcortical structures such as the basal ganglia in humans. HighlightsO_LIThe subcortical gray matter areas of macaque monkeys are reliably mapped by QSM, much as they are in humans. C_LIO_LICombining T1w and QSM images improves the visualization and segmentation of white matter, cortical and subcortical structures in the macaque monkey. C_LIO_LIThe proposed dual contrast TQ-SILiCON provides a similar image quality also in humans. C_LIO_LITQ-SILiCON facilitates comparative and translational neuroscience studies investigating subcortical structures. C_LI

neuroscience↗

bioRxiv2020

A collaborative resource platform for non-human primate neuroimaging

Neuroimaging non-human primates (NHPs) is a growing, yet highly specialized field of neuroscience. Resources that were primarily developed for human neuroimaging often need to be significantly adapted for use with NHPs or other animals, which has led to an abundance of custom, in-house solutions. In recent years, the global NHP neuroimaging community has made significant efforts to transform the field towards more open and collaborative practices. Here we present the PRIMatE Resource Exchange (PRIME-RE), a new collaborative online platform for NHP neuroimaging. PRIME-RE is a dynamic community-driven hub for the exchange of practical knowledge, specialized analytical tools, and open data repositories, specifically related to NHP neuroimaging. PRIME-RE caters to both researchers and developers who are either new to the field, looking to stay abreast of the latest developments, or seeking to collaboratively advance the field.

neuroscience↗

bioRxiv2020

Circuits in the absence of cortical layers: increased callosal connectivity in reeler mice revealed by brain-wide input mapping of VIP neurons in barrel cortex

The neocortex is composed of layers. Whether layers constitute an essential framework for the formation of functional circuits is not well understood. We investigated if neurons require the layer organization to be embedded into brain-wide circuits using the reeler mouse. This mutant is characterized by a migration deficit of cortical neurons so that no layers are formed. Still, neurons retain their properties and reeler mice show little cognitive impairment. We focused on VIP neurons because they are known to receive strong long-range inputs and have a typical laminar bias towards upper layers. In reeler these neurons are more distributed across the cortex. We mapped the brain-wide inputs of VIP neurons in barrel cortex of wildtype and reeler mice with rabies virus tracing. Innervation by subcortical inputs was not altered in reeler, in contrast to the cortical circuitry. Numbers of long-range ipsilateral cortical inputs were reduced in reeler, while contralateral inputs were strongly increased. Reeler mice had more callosal projection neurons. Hence, the corpus callosum was larger in reeler as shown by structural imaging. We argue that in the absence of cortical layers, circuits with subcortical structures are maintained but cortical neurons establish a different network capable to preserve cognitive functions.

neuroscience↗