Stochastic Model of Central Synapses: Slow Diffusion of Transmitter

... information about the experimentally observed time course of glutamate in the cleft the effective diffusion coefficient Dnet is estimated as Dnet 0 20–50 nm2 ms − 1, implying a strong reduction compared with free diffusion in aqueous solution. The tortuosity of the cleft and interactions with transp ...

... information about the experimentally observed time course of glutamate in the cleft the effective diffusion coefficient Dnet is estimated as Dnet 0 20–50 nm2 ms − 1, implying a strong reduction compared with free diffusion in aqueous solution. The tortuosity of the cleft and interactions with transp ...

Medial medullary syndrome

... entire neuraxis is important prior to treatment. • Most commonly located in the posterior fossa, classically arising from the floor of the 4th ventricle and often protruding out the foramen of Luschka (“plastic tumor”). • Demonstrates heterogeneous neuroimaging characteristics due to propensity to h ...

... entire neuraxis is important prior to treatment. • Most commonly located in the posterior fossa, classically arising from the floor of the 4th ventricle and often protruding out the foramen of Luschka (“plastic tumor”). • Demonstrates heterogeneous neuroimaging characteristics due to propensity to h ...

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... orientation . This information is contained in the diffusion tensor, a mathematic model of diffusion in three-dimensional space. The tensor model of diffusion consists of a 3x3 matrix derived from diffusivity measurements in at least six noncollinear directions. Fractional anisotropy (FA) is an inde ...

... orientation . This information is contained in the diffusion tensor, a mathematic model of diffusion in three-dimensional space. The tensor model of diffusion consists of a 3x3 matrix derived from diffusivity measurements in at least six noncollinear directions. Fractional anisotropy (FA) is an inde ...

White matter tract alterations in fragile X

... 1991]. Histologic examinations, however, detected abnormalities in the dendritic structure and density, as well as immature synapses in subjects with fragile X syndrome. These were also observed in FMR1 knockout mice [Rudelli et al., 1985; Hinton et al., 1991; Comery et al., 1997; Irwin et al., 2001 ...

... 1991]. Histologic examinations, however, detected abnormalities in the dendritic structure and density, as well as immature synapses in subjects with fragile X syndrome. These were also observed in FMR1 knockout mice [Rudelli et al., 1985; Hinton et al., 1991; Comery et al., 1997; Irwin et al., 2001 ...

Clinical Investigative Study Detectability of Neural Tracts and Nuclei

... adjacent to the fourth ventricle.12 In various pathological conditions or diseases, the degenerated neural tracts or nuclei can be depicted as areas of high signal intensity on conventional T2WI images.13–16 However, the depiction of these anatomical structures in the brainstem is limited to specifi ...

... adjacent to the fourth ventricle.12 In various pathological conditions or diseases, the degenerated neural tracts or nuclei can be depicted as areas of high signal intensity on conventional T2WI images.13–16 However, the depiction of these anatomical structures in the brainstem is limited to specifi ...

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... per volume per second. Note that when T = 0, the steady state correlation transport equation is reduced to the steady state photon transport equation (see, for example, books by Ishimaru,12 Case and Zweifel,13 Davison and Sykes,14 and Glasstone and Edlund 1S for discussions of the transport equation ...

... per volume per second. Note that when T = 0, the steady state correlation transport equation is reduced to the steady state photon transport equation (see, for example, books by Ishimaru,12 Case and Zweifel,13 Davison and Sykes,14 and Glasstone and Edlund 1S for discussions of the transport equation ...

Multimodality Imaging

... cancer centers worldwide and is bringing together researchers and engineers from the far-ranging fields of molecular pharmacology to nanotechnology engineering. The rapid growth of in vivo multimodality imaging arises from the convergence of established fields of in vivo imaging technologies with mo ...

... cancer centers worldwide and is bringing together researchers and engineers from the far-ranging fields of molecular pharmacology to nanotechnology engineering. The rapid growth of in vivo multimodality imaging arises from the convergence of established fields of in vivo imaging technologies with mo ...

In Vivo Evaluation of White Matter Integrity and Anterograde

... tensor MRI (DTI) and manganese-enhanced MRI (MEMRI) at a high magnetic field strength, in combination with spectraldomain optical coherence tomography (OCT), with an aim to develop an in vivo model system for characterizing the spatiotemporal patterns of white matter integrity changes in the visual ...

... tensor MRI (DTI) and manganese-enhanced MRI (MEMRI) at a high magnetic field strength, in combination with spectraldomain optical coherence tomography (OCT), with an aim to develop an in vivo model system for characterizing the spatiotemporal patterns of white matter integrity changes in the visual ...

differential diagnosis of corpus callosum lesions

... • In acute intoxication, patients may develop progressive white matter demyelination which is variable, ranging from discrete perivascular CC foci to axonal destruction. • Imaging: MRI is not specific, including high signal in T2 and FLAIR sequences as well as a diffusion restriction in the CC. ...

... • In acute intoxication, patients may develop progressive white matter demyelination which is variable, ranging from discrete perivascular CC foci to axonal destruction. • Imaging: MRI is not specific, including high signal in T2 and FLAIR sequences as well as a diffusion restriction in the CC. ...

Axonal integrity predicts cortical reorganisation following cervical injury

... (CST), whose integrity is critical for manual dexterity,7 are less well understood. In particular, three key questions remain unanswered: (1) Can CST integrity and demyelination be measured comprehensively? (2) How do microstructural changes in CST relate to macroscopic changes (ie, cord area)? (3) ...

... (CST), whose integrity is critical for manual dexterity,7 are less well understood. In particular, three key questions remain unanswered: (1) Can CST integrity and demyelination be measured comprehensively? (2) How do microstructural changes in CST relate to macroscopic changes (ie, cord area)? (3) ...

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... DT-MRI measures the random motion of water molecules in vivo. In free water, diffusion is isotropic, that is the movement of water molecules is equal in all directions. Conversely, in the brain’s WM the motion of water molecules is restricted by axonal membranes and myelin, so diffusion is not equal ...

... DT-MRI measures the random motion of water molecules in vivo. In free water, diffusion is isotropic, that is the movement of water molecules is equal in all directions. Conversely, in the brain’s WM the motion of water molecules is restricted by axonal membranes and myelin, so diffusion is not equal ...

Current Trends in the Imaging of Diffuse Axonal Injury

... by measuring fractional anisotropy (FA) Fractional anisotropy is the degree of alignment of the underlying nerve fibers (ratio: 0 to 1) ...

... by measuring fractional anisotropy (FA) Fractional anisotropy is the degree of alignment of the underlying nerve fibers (ratio: 0 to 1) ...

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... are 0.74, 0.73, and 0.76, corresponding to the anisotropy factors of 0.32, 0.49, and 0.92, respectively. These values are slightly different from that of 0.67 predicted by Eq. 共4兲 and closer to the value of 0.7104 given by the Milne problem for isotropic scattering. As expected, for this index-match ...

... are 0.74, 0.73, and 0.76, corresponding to the anisotropy factors of 0.32, 0.49, and 0.92, respectively. These values are slightly different from that of 0.67 predicted by Eq. 共4兲 and closer to the value of 0.7104 given by the Milne problem for isotropic scattering. As expected, for this index-match ...

Estimation of glucose diffusion coefficient in scleral tissue

... 6. ESTIMATION OF DIFFUSION COEFFICIENT For estimation of diffusion coefficient we used experimental data for the collimated transmittance and gravimetrical ...

... 6. ESTIMATION OF DIFFUSION COEFFICIENT For estimation of diffusion coefficient we used experimental data for the collimated transmittance and gravimetrical ...

The optics and performance of dual-focus fluorescence correlation

... collection efficiency function (CEF). For rapidly rotating molecules with rotational diffusion times much faster than their fluorescence decay time, the MDF is well approximated by the simple product of the excitation light intensity distribution with the CEF, and we will limit our considerations t ...

... collection efficiency function (CEF). For rapidly rotating molecules with rotational diffusion times much faster than their fluorescence decay time, the MDF is well approximated by the simple product of the excitation light intensity distribution with the CEF, and we will limit our considerations t ...

Connectivity of the human pedunculopontine nucleus region and

... which has directional organization, diffusion varies in different directions, and in areas of coherent fiber organization the principal diffusion direction corresponds to the underlying fiber direction.3,4 Therefore, by following estimates of the principal direction of diffusion it is possible to re ...

... which has directional organization, diffusion varies in different directions, and in areas of coherent fiber organization the principal diffusion direction corresponds to the underlying fiber direction.3,4 Therefore, by following estimates of the principal direction of diffusion it is possible to re ...

Sisay M THESIS - Addis Ababa University Institutional Repository

... The diffusion coefficient of a substance in a fluid can be predicted theoretically or found from empirical correlations. It can also be obtained experimentally. Optical methods are among the wide variety of techniques available. They apply to transparent fluids and are based on the fact that the con ...

... The diffusion coefficient of a substance in a fluid can be predicted theoretically or found from empirical correlations. It can also be obtained experimentally. Optical methods are among the wide variety of techniques available. They apply to transparent fluids and are based on the fact that the con ...

Cerebral Diffusion Tensor MR Tractography in Tuberous Sclerosis

... white matter lesions, and subependymal nodules.12,13,16 Because larger tuber volume was correlated with more severe DTI change of white matter tracts,16 studying the white matter therefore may be a reasonable way to assess the load of brain abnormality in tuberous sclerosis complex. However, in many ...

... white matter lesions, and subependymal nodules.12,13,16 Because larger tuber volume was correlated with more severe DTI change of white matter tracts,16 studying the white matter therefore may be a reasonable way to assess the load of brain abnormality in tuberous sclerosis complex. However, in many ...

Physics and its applications in non-stroke brain

... Diffusion Coefficient (ADC). Mobile molecules experience a substantial loss of signal that is related to the diffusion coefficient and spin-spin relaxation time (T2) of tissue, as well as the pulse sequence parameters chosen by the operator (eg, b value and excitation time). ADC is a value that desc ...

... Diffusion Coefficient (ADC). Mobile molecules experience a substantial loss of signal that is related to the diffusion coefficient and spin-spin relaxation time (T2) of tissue, as well as the pulse sequence parameters chosen by the operator (eg, b value and excitation time). ADC is a value that desc ...

Thermodynamic Limits of Spatial Resolution in Active Thermography

... optics. The resolution is the minimal size of a structure which can be detected at a certain depth. If an embedded structure at a certain depth in a sample is suddenly heated, e.g. by eddy current or absorbed light, an image of the structure can be reconstructed from the measured temperature at the ...

... optics. The resolution is the minimal size of a structure which can be detected at a certain depth. If an embedded structure at a certain depth in a sample is suddenly heated, e.g. by eddy current or absorbed light, an image of the structure can be reconstructed from the measured temperature at the ...

A non-invasive method to relate the timing of neural activity to white

... for the resampling. Inter-subject registration of individual FA maps to the Montreal Neurological Institute (MNI305) atlas (Collins et al., 1994) was performed using the average of the two 3D structural images. The resulting transformation was applied to individual FA volumes. The MNI-normalized FA ...

... for the resampling. Inter-subject registration of individual FA maps to the Montreal Neurological Institute (MNI305) atlas (Collins et al., 1994) was performed using the average of the two 3D structural images. The resulting transformation was applied to individual FA volumes. The MNI-normalized FA ...

A light scattering study of non equilibrium fluctuations

... transmitted light intensity. The detection plane is located at about z = 26 cm from the sample plane. As a sensor, we use a charge coupled device (CCD4000, Vosskühler, Germany) with 2048 × 2048 square pixels each of size 7.4 × 7.4 μm2 and a dynamic range of 12-bit. After reaching the steady-state of ...

... transmitted light intensity. The detection plane is located at about z = 26 cm from the sample plane. As a sensor, we use a charge coupled device (CCD4000, Vosskühler, Germany) with 2048 × 2048 square pixels each of size 7.4 × 7.4 μm2 and a dynamic range of 12-bit. After reaching the steady-state of ...

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... typical DLS experiments, as it is set by the time required by the scatterers to move over a distance q⫺1, where q is the wave vector. Thus, DWS is suitable for investigations of much slower dynamic processes, such as those developed in glassy systems, and this property of DWS opens a new field of ap ...

... typical DLS experiments, as it is set by the time required by the scatterers to move over a distance q⫺1, where q is the wave vector. Thus, DWS is suitable for investigations of much slower dynamic processes, such as those developed in glassy systems, and this property of DWS opens a new field of ap ...

P approximation for reflectance imaging with an oblique beam of arbitrary profile 1

... Instead of solving the RTE based boundary-value problems directly, one can obtain light distributions with a MC method by sampling a large number of photons undergoing stochastic processes of absorption and scattering. These processes are characterized by the probability distribution functions based ...

... Instead of solving the RTE based boundary-value problems directly, one can obtain light distributions with a MC method by sampling a large number of photons undergoing stochastic processes of absorption and scattering. These processes are characterized by the probability distribution functions based ...

# Diffusion MRI

Diffusion MRI (or dMRI) is a magnetic resonance imaging (MRI) method which came into existence in the mid-1980s. It allows the mapping of the diffusion process of molecules, mainly water, in biological tissues, in vivo and non-invasively. Molecular diffusion in tissues is not free, but reflects interactions with many obstacles, such as macromolecules, fibers, and membranes. Water molecule diffusion patterns can therefore reveal microscopic details about tissue architecture, either normal or in a diseased state.