CONSISTENT CORTICAL RESPONSES FROM SUBCORTICALY DELIVERED ELECTRICAL STIMULI - A Study Oriented to Visual Prostheses

1973 ◽  
Vol 82 (4) ◽  
pp. 473-485 ◽  
Author(s):  
Richard Walloch ◽  
David DeWeese ◽  
Robert Brummett ◽  
Jack Vernon

In the guinea pig the effects of electrical stimulation of the inner ear were measured by recording the evoked potentials at the auditory cortex. The cortical evoked responses to electrical stimuli greatly resembled those resulting from auditory stimuli in the same ears. The similarity was in wave shape, latency, duration, sharpness of thresholds, etc. It was also possible to produce evoked cortical responses when the electrical stimuli were delivered to ears suffering from severe acoustic trauma. These ears were so traumatized by acoustic over-stimulation that they were totally unresponsive to sound. In addition, it was possible to produce electrically evoked cortical responses in ears suffering from drug induced damage. The damage was of sufficient long standing as to produce extensive degeneration in the spiral ganglion. The damage was verified histologically and was severe enough to produce a 90% loss of the spiral ganglion cells. Similar electrical stimulation has been carried out in one human subject with normal hearing. Using sinusoidal electrical currents of approximately 10–100 microamperes, hearing sensations were produced only for stimulus frequencies between 4,000 Hz and 10,000 Hz. The intent had been to place a chronic electrode on the round window membrane of a normal human ear. When the same electrode was used to record the alternating current (a.c.) cochlear potential the resulting data were so insensitive as to suggest that the electrode placement had been less than ideal. Exploration revealed the electrode to have been on the floor of the fossula of the cochlea fenestra. A repeat procedure, with improved visualization, located a new chronic electrode on the round window membrane. Recordings and stimulations are currently in progress with that electrode.


Author(s):  
I. V. Cheretaev ◽  
D. R. Khusainov ◽  
E. N. Chuyan ◽  
M. Yu. Ravaeva ◽  
A. N. Gusev ◽  
...  

The purpose of the review is to summarize current literature data and the results of our own research on the analgesic and anti-inflammatory effects of acetylsalicylic acid, as well as the physiological mechanisms underlying them. This acid is the most studied reference representative of salicylates, which is convenient to consider the physiological effects characteristic in general for this group of chemical and medicinal products. Acetylsalicylic acid has analgesic properties against thermal pain and pain caused by electrical stimuli, as well as a pronounced anti-inflammatory effect. The realization of these properties depends on the peculiarities of aspirin metabolism in the body, ion and synaptic mechanisms for controlling the functional state of the cell, neurotransmitter systems of the сentral nervous system, and mechanisms of peripheral and сentral analgesia. Analgesic properties of acetylsalicylic acid founded not only in normal, but also in ultra-small doses. Various physical and especially chemical factors significantly change their effects. This increases the interest in studying the analgesic activity of salicylates and their physiological mechanisms, since such studies can serve as a basis for creating new non-steroidal anti-inflammatory drugs with low toxicity and high safety for patients, and improve the strategy of their practical use. Currently, the most detailed study of the physiological mechanism of analgesic and anti-inflammatory action of aspirin and its main metabolite – salicylic acid. However, it should be note that despite the abundance of existing data obtained in scientific studies of the effects of aspirin and its practical use, there are a number of unexplained aspects of the action of this drug, the mechanism of which has not yet been deciphered. The continuing interest in the effects and mechanisms of action of this drug and in connection with the expansion of its use evidenced by a consistently high number of scientific publications on aspirin in the most famous foreign and domestic publications. At the same time, the number of publications about aspirin is an order of magnitude higher than about any other drug known to humanity.


2021 ◽  
pp. 147248
Author(s):  
Niels T. Haumann ◽  
Massimo Lumaca ◽  
Marina Kliuchko ◽  
Jose L. Santacruz ◽  
Peter Vuust ◽  
...  

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1217
Author(s):  
Jang Ho Ha ◽  
Jae Hyun Lim ◽  
Ji Woon Kim ◽  
Hyeon-Yeol Cho ◽  
Seok Geun Jo ◽  
...  

Blended hydrogels play an important role in enhancing the properties (e.g., mechanical properties and conductivity) of hydrogels. In this study, we generated a conductive blended hydrogel, which was achieved by mixing gelatin methacrylate (GelMA) with collagen, and silver nanowire (AgNW). The ratio of GelMA, collagen and AgNW was optimized and was subsequently gelated by ultraviolet light (UV) and heat. The scanning electron microscope (SEM) image of the conductive blended hydrogels showed that collagen and AgNW were present in the GelMA hydrogel. Additionally, rheological analysis indicated that the mechanical properties of the conductive GelMA–collagen–AgNW blended hydrogels improved. Biocompatibility analysis confirmed that the human umbilical vein endothelial cells (HUVECs) encapsulated within the three-dimensional (3D), conductive blended hydrogels were highly viable. Furthermore, we confirmed that the molecule in the conductive blended hydrogel was released by electrical stimuli-mediated structural deformation. Therefore, this conductive GelMA–collagen–AgNW blended hydrogel could be potentially used as a smart actuator for drug delivery applications.


Biology ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 135
Author(s):  
Pau Urdeitx ◽  
Mohamed H. Doweidar

Mechanical and electrical stimuli play a key role in tissue formation, guiding cell processes such as cell migration, differentiation, maturation, and apoptosis. Monitoring and controlling these stimuli on in vitro experiments is not straightforward due to the coupling of these different stimuli. In addition, active and reciprocal cell–cell and cell–extracellular matrix interactions are essential to be considered during formation of complex tissue such as myocardial tissue. In this sense, computational models can offer new perspectives and key information on the cell microenvironment. Thus, we present a new computational 3D model, based on the Finite Element Method, where a complex extracellular matrix with piezoelectric properties interacts with cardiac muscle cells during the first steps of tissue formation. This model includes collective behavior and cell processes such as cell migration, maturation, differentiation, proliferation, and apoptosis. The model has employed to study the initial stages of in vitro cardiac aggregate formation, considering cell–cell junctions, under different extracellular matrix configurations. Three different cases have been purposed to evaluate cell behavior in fibered, mechanically stimulated fibered, and mechanically stimulated piezoelectric fibered extra-cellular matrix. In this last case, the cells are guided by the coupling of mechanical and electrical stimuli. Accordingly, the obtained results show the formation of more elongated groups and enhancement in cell proliferation.


IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Eva Ignatious ◽  
Sami Azam ◽  
Mirjam Jonkman ◽  
Friso De Boer

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