Brain lateralization probed by water diffusion at the atomic to micrometric scale

F Natali,J Peters,C Stelletta,E L Barbier,A Cupane,G Leduc,J Ollivier,C Dolce,B Demé

doi:10.1038/s41598-019-51022-1

Abstract

Combined neutron scattering and diffusion nuclear magnetic resonance experiments have been used to reveal significant interregional asymmetries (lateralization) in bovine brain hemispheres in terms of myelin arrangement and water dynamics at micron to atomic scales. Thicker myelin sheaths were found in the left hemisphere using neutron diffraction. 4.7 T dMRI and quasi-elastic neutron experiments highlighted significant differences in the properties of water dynamics in the two hemispheres. The results were interpreted in terms of hemisphere-dependent cellular composition (number of neurons, cell distribution, etc.) as well as specificity of neurological functions (such as preferential networking).

Highlights

An important topic in the study of the neural basis of brain functions is the interregional asymmetry between the left and the right hemisphere and its relation to the factors that modulate cognitive specialization in the brain, such as language and motor control
In terms of functional principles, these patterns appear to support the fact that the left hemisphere plays a leading role in highly demanding specific processes, such as language and motor actions, which may require specialized networks, whereas the right hemisphere is responsible for more general processes, such as integration tasks, which may require a more general level of interconnection
Diffraction peaks can be seen at Q = 0.078 Å−1 (A1) for RH and Q = 0.074 Å−1 (A2) for LH that correspond to the second order Bragg reflections of ordered multilamellar structures of the myelin sheath, with repeat distances of d1 = 161 Å (RH) and d2 = 170 Å (LH)

Summary

Introduction

An important topic in the study of the neural basis of brain functions is the interregional asymmetry between the left and the right hemisphere and its relation to the factors that modulate cognitive specialization in the brain, such as language and motor control. In terms of functional principles, these patterns appear to support the fact that the left hemisphere plays a leading role in highly demanding specific processes, such as language and motor actions, which may require specialized networks, whereas the right hemisphere is responsible for more general processes, such as integration tasks, which may require a more general level of interconnection. Neuroimaging studies have suggested that asymmetries in water diffusivity in the brain may exist[16,17] This asymmetry could be due to either a greater neuronal attenuation or a greater number of reciprocal connections with neighboring brain regions on the side with reduced diffusivity. Estrogens may affect diffusivity; they have been found to influence cerebral water diffusion by accelerating myelination in the immature rat brain[18]

Methods

Results

Discussion

Conclusion