scholarly journals Memristive Artificial Synapses for Neuromorphic Computing

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Wen Huang ◽  
Xuwen Xia ◽  
Chen Zhu ◽  
Parker Steichen ◽  
Weidong Quan ◽  
...  

AbstractNeuromorphic computing simulates the operation of biological brain function for information processing and can potentially solve the bottleneck of the von Neumann architecture. This computing is realized based on memristive hardware neural networks in which synaptic devices that mimic biological synapses of the brain are the primary units. Mimicking synaptic functions with these devices is critical in neuromorphic systems. In the last decade, electrical and optical signals have been incorporated into the synaptic devices and promoted the simulation of various synaptic functions. In this review, these devices are discussed by categorizing them into electrically stimulated, optically stimulated, and photoelectric synergetic synaptic devices based on stimulation of electrical and optical signals. The working mechanisms of the devices are analyzed in detail. This is followed by a discussion of the progress in mimicking synaptic functions. In addition, existing application scenarios of various synaptic devices are outlined. Furthermore, the performances and future development of the synaptic devices that could be significant for building efficient neuromorphic systems are prospected.

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.


1987 ◽  
Vol 252 (6) ◽  
pp. H1183-H1191
Author(s):  
C. Iadecola ◽  
P. M. Lacombe ◽  
M. D. Underwood ◽  
T. Ishitsuka ◽  
D. J. Reis

We studied whether adrenal medullary catecholamines (CAs) contribute to the metabolically linked increase in regional cerebral blood flow (rCBF) elicited by electrical stimulation of the dorsal medullary reticular formation (DMRF). Rats were anesthetized (alpha-chloralose, 30 mg/kg), paralyzed, and artificially ventilated. The DMRF was electrically stimulated with intermittent trains of pulses through microelectrodes stereotaxically implanted. Blood gases were controlled and, during stimulation, arterial pressure was maintained within the autoregulated range for rCBF. rCBF and blood-brain barrier (BBB) permeability were determined in homogenates of brain regions by using [14C]iodoantipyrine and alpha-aminoisobutyric acid (AIB), respectively, as tracers. Plasma CAs (epinephrine and norepinephrine) were measured radioenzymatically. DMRF stimulation increased rCBF throughout the brain (n = 5; P less than 0.01, analysis of variance) and elevated plasma CAs substantially (n = 4). Acute bilateral adrenalectomy abolished the increase in plasma epinephrine (n = 4), reduced the increases in flow (n = 6) in cerebral cortex (P less than 0.05), and abolished them elsewhere in brain (P greater than 0.05). Comparable effects on rCBF were obtained by selective adrenal demedullation (n = 7) or pretreatment with propranolol (1.5 mg/kg iv) (n = 5). DMRF stimulation did not increase the permeability of the BBB to AIB (n = 5). We conclude that the increases in rCBF elicited from the DMRF has two components, one dependent on, and the other independent of CAs. Since the BBB is impermeable to CAs and DMRF stimulation fails to open the BBB, the results suggest that DMRF stimulation allows, through a mechanism not yet determined, circulating CAs to act on brain and affect brain function.


2015 ◽  
Vol 370 (1677) ◽  
pp. 20140201 ◽  
Author(s):  
Kristine Krug ◽  
C. Daniel Salzman ◽  
Scott Waddell

Causal methods to interrogate brain function have been employed since the advent of modern neuroscience in the nineteenth century. Initially, randomly placed electrodes and stimulation of parts of the living brain were used to localize specific functions to these areas. Recent technical developments have rejuvenated this approach by providing more precise tools to dissect the neural circuits underlying behaviour, perception and cognition. Carefully controlled behavioural experiments have been combined with electrical devices, targeted genetically encoded tools and neurochemical approaches to manipulate information processing in the brain. The ability to control brain activity in these ways not only deepens our understanding of brain function but also provides new avenues for clinical intervention, particularly in conditions where brain processing has gone awry.


Neuromorphic computing is a non-von Neumann architecture which is also referred to as artificial neural network and that allows electronic system to function in the same manner as that of the human brain. In this paper we have developed neural core architecture analogous to that of the human brain. Each neural core has its own computational element neuron, memory to store information and local clock generator for synchronous functioning of neuron along with asynchronous input-output port and its port controller. The neuron model used here is a tailor-made of IBM TrueNorth’s neuron block. Our design methodology includes both synchronous and asynchronous circuit in order to build an event-driven neural network core. We have first simulated our design using Neuroph studio in order to calculate the weights and bias value and then used these weights for hardware implementation. With that we have successfully demonstrated the working of neural core using XOR application. It was designed in VHDL language and simulated in Xilinx ISE software.


Author(s):  
M. V. Zueva

Cognitive decline characterizes normal physiological aging and is aggravated by the development of age-related neurodegenerative pathology and traumatic brain damage (TBI). Te review analyzes widely discussed in the scientifc literature non-drug methods of rehabilitation of patients with TBI and elderly people suffering from cognitive decline, including the paradigm of enrichment of the environment, cognitive and physical training and various types of stimulation therapy and their shortcomings. Special attention is paid to the advantages of fractal stimulation of the brain by complex-structured optical signals and sensory stimuli of another modality. It is assumed that the use of new approaches to neurorehabilitation, which increase the potential of neuroplasticity will also allow strengthening the therapeutic and learning impacts of any other methods of training and treating the brain.


Author(s):  
James A. Anderson

Brains and computers were twins separated at birth. In 1943, it was known that action potentials were all or none, approximating TRUE or FALSE. In that year, Walter Pitts and Warren McCulloch wrote a paper suggesting that neurons were computing logic functions and that networks of such neurons could compute any finite logic function. This was a bold and exciting large-scale theory of brain function. Around the same time, the first digital computer, the ENIAC, was being built. The McCulloch-Pitts work was well known to the scientists building ENIAC. The connection between them appeared explicitly in a report by John von Neumann on the successor to the ENIAC, the EDVAC. It soon became clear that biological brain computation was not based on logic functions. However, this idea was believed by many scientists for decades. A brilliant wrong theory can sometimes cause trouble.


1987 ◽  
Vol 253 (4) ◽  
pp. R666-R670 ◽  
Author(s):  
M. Chesler ◽  
R. P. Kraig

Modulation of intracellular pH is widely implicated in the control of cell growth and metabolism, yet little is known about intracellular pH and brain function. To determine how stimulation of brain may affect the intracellular pH of mammalian glial cells, rat cortical astrocytes were studied for the first time in vivo using pH-sensitive electrodes of submicron caliber. Stimulation of the cortical surface caused a cytoplasmic alkaline shift of tenths of a pH within seconds. Cessation of induced electrical activity was followed by pH recovery and a small acid rebound. Recordings obtained during cortical-spreading depression revealed similar but generally larger intracellular pH shifts. Production of metabolic acids is known to occur when the brain is stimulated and has led to the long-held presumption that brain cells accordingly become more acidic. The observation that glia initially become more alkaline during electrical activity is thus paradoxical. The correlation of glial alkalinization with evoked electrical activity suggests that modulation of intracellular pH of glia may have important functional implications.


Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 166 ◽  
Author(s):  
Valerio Milo ◽  
Gerardo Malavena ◽  
Christian Monzio Compagnoni ◽  
Daniele Ielmini

Neuromorphic computing has emerged as one of the most promising paradigms to overcome the limitations of von Neumann architecture of conventional digital processors. The aim of neuromorphic computing is to faithfully reproduce the computing processes in the human brain, thus paralleling its outstanding energy efficiency and compactness. Toward this goal, however, some major challenges have to be faced. Since the brain processes information by high-density neural networks with ultra-low power consumption, novel device concepts combining high scalability, low-power operation, and advanced computing functionality must be developed. This work provides an overview of the most promising device concepts in neuromorphic computing including complementary metal-oxide semiconductor (CMOS) and memristive technologies. First, the physics and operation of CMOS-based floating-gate memory devices in artificial neural networks will be addressed. Then, several memristive concepts will be reviewed and discussed for applications in deep neural network and spiking neural network architectures. Finally, the main technology challenges and perspectives of neuromorphic computing will be discussed.


2021 ◽  
Author(s):  
Jorge Luis-Islas ◽  
Monica Luna ◽  
Benjamin Floran ◽  
Ranier Gutierrez

AbstractHow do animals experience brain manipulations? Optogenetics has allowed us to manipulate selectively and interrogate neural circuits underlying brain function in health and disease. However, in addition to their evoked physiological functions, it is currently unknown whether mice could perceive arbitrary optogenetic stimulations. To address this issue, mice were trained to report optogenetic stimulations to obtain rewards and avoid punishments. It was found that mice could perceive optogenetic manipulations regardless of the brain area modulated, their rewarding effects, or the stimulation of glutamatergic, GABAergic, and dopaminergic cell types. We named this phenomenon optoception. Our findings reveal that mice’s brains are capable of “monitoring” their self-activity via interoception, opening a new way to introduce information to the brain and control brain-computer interfaces.One Sentence SummaryBrain manipulations are perceived


2021 ◽  
Vol 15 ◽  
Author(s):  
Zhong-Hao Zhang ◽  
Guo-Li Song

Selenium (Se) and its compounds have been reported to have great potential in the prevention and treatment of Alzheimer’s disease (AD). However, little is known about the functional mechanism of Se in these processes, limiting its further clinical application. Se exerts its biological functions mainly through selenoproteins, which play vital roles in maintaining optimal brain function. Therefore, selenoproteins, especially brain function-associated selenoproteins, may be involved in the pathogenesis of AD. Here, we analyze the expression and distribution of 25 selenoproteins in the brain and summarize the relationships between selenoproteins and brain function by reviewing recent literature and information contained in relevant databases to identify selenoproteins (GPX4, SELENOP, SELENOK, SELENOT, GPX1, SELENOM, SELENOS, and SELENOW) that are highly expressed specifically in AD-related brain regions and closely associated with brain function. Finally, the potential functions of these selenoproteins in AD are discussed, for example, the function of GPX4 in ferroptosis and the effects of the endoplasmic reticulum (ER)-resident protein SELENOK on Ca2+ homeostasis and receptor-mediated synaptic functions. This review discusses selenoproteins that are closely associated with brain function and the relevant pathways of their involvement in AD pathology to provide new directions for research on the mechanism of Se in AD.


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