FIGURE 9 - uploaded by Amir Maghoul
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(a) the schematic of Ranvier node between the 2-nerve segment of nerve fiber, (b) the effect of Ranvier node length on transmittance coefficient for LL nerve fiber(c) the effect of Ranvier node length on transmittance coefficient for LM nerve fiber.
Source publication
Electrical signaling is known as the means for inter-cellular connectivity among neural cells. However, there are some indications that optical phenomena can occur in the neuronal cells based on biochemical processes in intra-or extracellular reactions. Also, external optical signals can be used to manipulate engineered neural cells for performing...
Contexts in source publication
Context 1
... effect of the Ranvier node is simulated to understand its influence on the optical spectrum in the transmission band. At the start, the length of the structure is 27µm for simulation, as shown in Fig.9(a). We aim to assess the size effect of the Ranvier gap on photon transitions. ...
Context 2
... size of the Ranvier gap for the rat is given as 0.7µm, 1.08µm, and 1.4µm [8]. The simulated results for LL and LM structures indicate that there is a downward trend in all results, as demonstrated in Fig.9(b),(c), which are derived from becoming close to the cut-off wavelength. ...
Context 3
... blue shift is due to the variation of the structure's optical properties derived from manipulating the mode index of the bounded medium [52]. In detail, adding the Ranvier node between segments and changing size in the architecture of Fig.9(a) causes new modes to be imposed on the electromagnetic radiation profile of construction. ...
Context 4
... manipulation causes modal dispersion on the structure; therefore, the interconnection of two nerve segments across the fiber creates a remarkable distortion on the spectral response due to new generated modes and path loss. In the LM architecture, as seen in Fig.9(c), myelin dispersion, in addition to modal dispersion, is also motivated, and severe fluctuations appear in the transmission band. ...
Citations
... Recent research findings have not only verified the feasibility of optical communication in neural circuits but also provided an important basis for establishing a theoretical model of optical communication between nerve fibers (Kumar et al., 2016;Zangari et al., 2018;Zarkeshian et al., 2018;Ambrosetti et al., 2022). Moreover, experimental results have shown that near infrared laser photons induce glutamate release from nerve terminals, and the quantum energy level of glutamate modulate neural biophotonic activity and transmission (Amaroli et al., 2018;Xiang et al., 2020;Han et al., 2021;Maghoul et al., 2021). In the present study, reduced biophotonic activities and spectral blueshift induced by glutamate were found in synaptosomes and brain slices from AD and VaD model animals, indicating that this biophoton imaging technology is accurate and effective in assessing functional changes in synapses and neural circuits. ...
Background
Although clinically, Alzheimer’s disease (AD) and vascular dementia (VaD) are the two major types of dementia, it is unclear whether the biophotonic activities associated with cognitive impairments in these diseases share common pathological features.
Methods
We used the ultraweak biophoton imaging system (UBIS) and synaptosomes prepared by modified percoll method to directly evaluate the functional changes in synapses and neural circuits in AD and VaD model animals.
Results
We found that biophotonic activities induced by glutamate were significantly reduced and spectral blueshifted in synaptosomes and brain slices. These changes could be partially reversed by pre-perfusion of the ifenprodil, a specific antagonist of the GluN2B subunit of N-methyl-D-aspartate receptors (NMDARs).
Conclusion
Our findings suggest that AD and VaD pathology present similar but complex changes in biophotonic activities and transmission at synapses and neural circuits, implying that communications and information processing of biophotonic signals in the brain are crucial for advanced cognitive functions.
... Their treatment to estimate transmission across inter-neuron distances demonstrated that biophoton transmission along myelinated axons is possible within realistic expectations of these optical imperfections. This has sparked various theoretical studies 13,[36][37][38][39][40][41] , and the possibility of myelin sheath waveguides has been well-supported through subsequent simulations. Another biophoton-motivated simulation study 13 considered (optical spectral range) mode propagation in the context of a myelinated axon model containing the detailed multi-lamellar structure of the myelin sheath. ...
In neuroscience, it is of interest to consider all possible modes of information transfer between neurons in order to fully understand processing in the brain. It has been suggested that photonic communication may be possible along axonal connections, especially through the myelin sheath as a waveguide, due to its high refractive index. There is already a good deal of theoretical and experimental evidence for light guidance in the myelin sheath; however, the question of how the polarization of light is transmitted remains largely unexplored. It is presently unclear whether polarization-encoded information could be preserved within the myelin sheath. We simulate guided mode propagation through a myelinated axon structure with multiple Ranvier nodes. This allows both to observe polarization change and to test the assumption of exponentiated transmission loss through multiple Ranvier nodes for guided light in myelin sheath waveguides. We find that the polarization can be well preserved through multiple nodes and that transmission losses through multiple nodes ae approximately multiplicative. These results provide an important context for the hypothesis of neural information transmission facilitated by biophotons, strengthening the possibility of both classical and quantum photonic communication within the brain.
... To improve the excitation efficiency of electrophysiological activity in individual axons by electromagnetic sources, it is important to know how localized electromagnetic waves propagate along the nerve fiber. Analyses of the dispersion properties of eigenmodes supported by a single axon were made in the cases where a myelin sheath was present [18][19][20][21] or absent [22,23] on the surface of the axon. Transmission of electromagnetic signals by a single axon in the terahertz and infrared ranges was also studied, both in the presence and absence of a propagating electrical nerve impulse [19][20][21][22][23]. ...
... Analyses of the dispersion properties of eigenmodes supported by a single axon were made in the cases where a myelin sheath was present [18][19][20][21] or absent [22,23] on the surface of the axon. Transmission of electromagnetic signals by a single axon in the terahertz and infrared ranges was also studied, both in the presence and absence of a propagating electrical nerve impulse [19][20][21][22][23]. It is obvious that the presence of multiple axons in a nerve fiber can significantly affect the dispersion properties and field structures of electromagnetic waves guided by the nerve compared to those of a single axon. ...
... As a result, only the lowest dipole eigenmode with m = 1 remains to exist for relatively long wavelengths, up to the infrared range. Although nonsymmetric waves with m = 1 can exist in a wide wavelength interval, they have not received sufficient attention in previous works [18][19][20][21], in which the propagation of axisymmetric eigenmodes of a single axon was mostly considered. ...
... Different values for the length and radius of the myelinated axon have been measured 1,7,14 . Besides, g-ratio was expressed as a relationship between the radius of the axon and the thickness of the myelin sheath according to Eq. 1. ...
... Besides, g-ratio was expressed as a relationship between the radius of the axon and the thickness of the myelin sheath according to Eq. 1. The g-ratio for different nerve fibers varies between 0.6 and 0.8 7,14 . Therefore, according to Ref. 14 , the length of the myelinated axon was roughly 27μm 14 . ...
... The g-ratio for different nerve fibers varies between 0.6 and 0.8 7,14 . Therefore, according to Ref. 14 , the length of the myelinated axon was roughly 27μm 14 . The axon radius is 0.4μm 14 www.nature.com/scientificreports/ ...
Light and optical techniques are widely used for the diagnosis and treatment of neurological diseases as advanced methods. Understanding the optical properties of nervous tissue and nerve cells is vital. Using light sources in these methods raises significant challenges, such as finding the place of light transmission in nerve fibers that could be an appropriate substrate for neural signaling. The myelinated axons are a promising candidate for transmitting neural signals and light due to their waveguide structures. On the other hand, with the emergence of diseases such as multiple sclerosis and disorders within the production and transmission of nerve signals, because of the demyelination, understanding the properties of the myelinated axon as a waveguide is obtaining additional necessity. The present study aims to show that the myelinated axon’s refractive index (RI) profile plays an essential role in transmitting the beams in it. According to the nerve fiber, RI profile and its similarity to depressed core fiber with lower RI of the core compared to the cladding, the behaviors of the nerve fiber based on anti-resonant reflecting optical waveguide structure are investigated by taking into account the realistic optical imperfections. Light launching to the myelin sheath and axon is shown by introducing the axon and myelin sheath as a waveguide in the presence of both axon and myelin with bends, myelin sheath variation, and node of Ranvier.
... Employing electrical signals for nerve stimulation in the brain is very common; however, this method is inefficient for micro/nanoscale brain tissue because of incompatibility between wavelengths in kHz and sample size [19], [20]. By focusing on deep brain stimulation, particular mechanisms have emerged that deal with the implications of light manipulations for neural communication applications -optogenetic [21], upconversion techniques [22], [23], photon communication [24]- [26]-ranging from Terahertz (THz) to the optical frequencies [19], [27]. Modern optical techniques used to obtain a wavelength range corresponding to the thickness of myelin to virtualize a multilayer myelin nanostructure are being developed as part of breakthrough new knowledge in the field of neurophotonics [18]- [20], [28]. ...
... As mentioned above, the interference of electromagnetic modes in the nerve's configuration plays a decisive role in the conduction and transition of photons in the nerve [25], [26]. The simulated results indicate manipulating the nerve's geometrical configuration leads to modal interference during photon transmission in the myelinated axon, which can have a destructive or constructive impact on the outgoing signal in the neuronal communication system. ...
The myelin sheath, as an insulation layer in nerve cells, plays an essential role in neural communication and signal conduction. Loss of myelin, referred to as demyelination, is associated with many mental disorders. Detecting the tiny demyelinated parts in nerve fibers can provide early diagnosis of some mental disorders and create effective treatment plans. This paper establishes a new engineering approach for differentiation between demyelinated and myelinated axons by analyzing spectral responses resulting from the optical simulation framework. We propose computational modeling on the photonic communication of nerve fibers and develop a graphene-based neurophotonic device that can be used to detect the regions demyelinated on the nerve fiber. We first model a nanoscale thin-film configuration of the multilayered myelinated axon to evaluate photons transmission in the nerve fibers under geometric defects as demyelination. Then, the nerve’s optical characteristics are achieved by focusing on the reflectance of light incidence on the nerve model with the change of the demyelination size to distinguish demyelinated—from myelinated nerves by the spectral contrast. Undertaking the different levels of demyelination progression, we theoretically explore the variations of effective refractive index using an analytical solution technique. Ultimately, we design a nanostructure configured with silicon dioxide, graphene, and gold nanoparticles to function as a biochip recognizing myelinated axon damage under the surface plasmon effect. This device can promote a practical procedure to distinguish nanoscale demyelinated and myelinated axons, which can be utilized for neural sensing of tiny brain tissues as a neurophotonic needle.
