Ionic movements in cell membranes in relation to the activity of the nervous system

Author(s):  
Hans H. Ussing
2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Dongshin Kim ◽  
Jang-Sik Lee

Abstract Emulating neurons/synapses in the brain is an important step to realizing highly efficient computers. This fact makes neuromorphic devices important emerging solutions to the limitations imposed by the current computing architecture. To mimic synaptic functions in the brain, it is critical to replicate ionic movements in the nervous system. It is therefore important to note that ions move easily in liquids. In this study, we demonstrate a liquid-based neuromorphic device that is capable of mimicking the movement of ions in the nervous system by controlling Na+ movement in an aqueous solution. The concentration of Na+ in the solution can control the ionic conductivity of the device. The device shows short-term and long-term plasticity such as excitatory postsynaptic current, paired-pulse facilitation, potentiation, and depression, which are key properties for memorization and computation in the brain. This device has the potential to overcome the limitations of current von Neumann architecture-based computing systems and substantially advance the technology of neuromorphic computing.


During the course of an investigation into the central nervous systems of squids and cuttlefish, Professor J. Z. Young (1936 a , b ) noticed certain transparent tubular structures in the peripheral nerves. These must have seemed too large to be nerve fibres, and in a subsequent article Young (1944) remarked that he first took them to be blood vessels. However, on examining them more closely, he was able to prove that the tubes were, in fact, nerve fibres of exceptional size. Like many important discoveries, this was not an entirely new observation. It had been known since the time of Remak (1843) that Crustacea possessed giant nerve fibres, but with one exception the still larger fibres in cephalopods seem not to have been recognized as such. As Young pointed out, the exception was L. W. Williams who wrote a monograph on the squid which was published in 1909. In this monograph, Williams referred briefly to the large fibres in the nervous system. Williams did not commit himself as to the size of the fibres, but it is clear that he must have seen them. Thus he remarked that ‘The very size of the nerve processes has prevented their discovery, since it is well nigh impossible to believe that such a large structure can be a nerve fibre.’


2019 ◽  
Vol 42 ◽  
Author(s):  
Kevin B. Clark

Abstract Some neurotropic enteroviruses hijack Trojan horse/raft commensal gut bacteria to render devastating biomimicking cryptic attacks on human/animal hosts. Such virus-microbe interactions manipulate hosts’ gut-brain axes with accompanying infection-cycle-optimizing central nervous system (CNS) disturbances, including severe neurodevelopmental, neuromotor, and neuropsychiatric conditions. Co-opted bacteria thus indirectly influence host health, development, behavior, and mind as possible “fair-weather-friend” symbionts, switching from commensal to context-dependent pathogen-like strategies benefiting gut-bacteria fitness.


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