Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Intra- and extra-axonal axial diffusivities in the white matter: which
  one is faster?   A two-compartment model of diffusion in white matter, which accounts for
intra- and extra-axonal spaces, is associated with two plausible mathematical
scenarios: either the intra-axonal axial diffusivity is higher than the
extra-axonal (Branch 1), or the opposite (Branch 2). This duality calls for an
independent validation of compartment axial diffusivities, to determine which
of the two cases holds. The aim of the present study was to use an
intracerebroventricular injection of a gadolinium-based contrast agent to
selectively reduce the extracellular water signal in the rat brain, and compare
diffusion metrics in the genu of the corpus callosum before and after
gadolinium infusion. The diffusion metrics considered were diffusion and
kurtosis tensor metrics, as well as compartment-specific estimates of the
WMTI-Watson two-compartment model. A strong decrease in genu T1 and T2
relaxation times post-Gd was observed (p < 0.001), as well as an increase of
48% in radial kurtosis (p < 0.05), which implies that the relative fraction of
extracellular water signal was selectively decreased. This was further
supported by a significant increase in intra-axonal water fraction as estimated
from the two-compartment model, for both branches (p < 0.01 for Branch 1, p <
0.05 for Branch 2). However, pre-Gd estimates of axon dispersion in Branch 1
agreed better with literature than those of Branch 2. Furthermore, comparison
of post-Gd changes in diffusivity and dispersion between data and simulations
further supported Branch 1 as the biologically plausible solution, i.e. the
intra-axonal axial diffusivity is higher than the extra-axonal one. This result
is fully consistent with other recent measurements of compartment axial
diffusivities that used entirely different approaches, such as diffusion tensor
encoding.

23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an