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Optical Cochlear Implants
Published in Francesco S. Pavone, Shy Shoham, Handbook of Neurophotonics, 2020
C. P. Richter, Y. Xu, X. Tan, N. Xia, N. Suematsu
Cochlear implants (CIs) are considered one of the most successful neural prostheses. Today about 500,000 severe-to-profoundly deaf individuals have received a CI to restore some of their hearing. While some patients communicate over the phone in different languages, others receive little benefit from CIs. For all of the users, however, noisy listening environments and music perception constitute a challenge. It has been argued that performance could be improved by reducing the interaction between neighboring electrode contacts and subsequently creating more independent channels for stimulation. More selective stimulation with electric current can be achieved through multipolar stimulation. Multiple electrode contacts are used to narrow the current field and to achieve more spatially selective stimulation (Bierer et al., 2002; Mens et al., 2005; Snyder et al., 2004; Srinivasan et al., 2010). A different approach to increase the number of different pitch percepts is current steering (Koch et al., 2006; Nogueira et al., 2017; Wu et al., 2016). Neighboring electrodes are used simultaneously to “steer” the current to selected neuron populations, which sit between the two stimulating electrodes to introduce virtual channels (Berenstein et al., 2008; Choi et al., 2009; Koch et al., 2006; Landsberger et al., 2009; van den Honert et al., 2007). More recently, the use of photons has been suggested as a novel approach to evoke responses from small populations of neurons (Boyden et al., 2005; Hernandez et al., 2014; Izzo et al., 2006a; Wells et al., 2005). Depending on the tissue, photons can be delivered without direct contact between the optical source and the target structure. Light beams can be focused, allowing for selective irradiation of neural tissue and introducing a larger number of independent channels for stimulation. The underlying assumption for favoring optical energy to stimulate neuron populations over electrical current relates to the finding that optical radiation can be delivered more selectively to groups of target neurons (Moreno et al., 2011; Richter et al., 2011a). It is anticipated that with optical stimulation, neural prostheses with enhanced neural fidelity can be developed. In this chapter, we discuss some design parameters required for an optical cochlear implant.
Enhanced bone marrow stem cell attachment and differentiation on PCL/CNT substrate
Published in Inorganic and Nano-Metal Chemistry, 2019
Maryam Mehdizadeh Omrani, Mojtaba Ansari, Soheila Salahshour Kordestani, Nasim Kiaie, Amir Salati
It is known that cell viability and proliferation are a consequence of suitable cell adhesion to the substrate.[45] SEM images in Figure 3 show that CNT substrate covered with PCL (PCL/CNT) show better differentiation and proliferation than other samples. Neuronal differentiation is confirmed with changing morphology into neuron-like cells (an appearance with multipolar elongations). This result is probably due to the electrical conductivity of carbon nanotubes which can cause better differentiation of neurons. Betterment of cell adhesion might be due to the improvement of protein adsorption. The adsorption of proteins onto substrate plays an important role in cellular behavior because adsorption of favorable proteins from culture media onto substrate causes cell growth and proliferation.[46,47] Hence, the protein adsorption of substrates was evaluated in this project.
Neuroprotective effect of peanut against oxidative stress in streptozotocin-induced diabetic rats
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Norhan H. Mohamed, Hassan Elsayad, Yasser M. Elsherbini, Mohamed E. Abdraboh
Histologically, the cerebral cortex of male albino rats of the control group and peanut-supplemented group exhibited the morphology of normal six layers. The thick molecular layer had normal histological features with the presence of few cells and dense plexus of nerve fibers. Meanwhile, The external pyramidal and granular layers were characterized by the presence of numerous pyramidal and granular cells with few pyramidal and granular cells at the internal pyramidal and internal granular layers. The pyramidal cell had a multipolar shape with basophilic cytoplasm and a large, rounded vesicular nucleus. The granular cells were characterized by large open-face nuclei with little cytoplasm and prominent nucleolus (Figure 1a).