A Floating Gate Memory with U-Shape Recessed Channel for Neuromorphic Computing and MCU Applications

We have simulated a U-shape recessed channel floating gate memory by Sentaurus TCAD tools. Since the floating gate (FG) is vertically placed between source (S) and drain (D), and control gate (CG) and HfO2 high-k dielectric extend above source and drain, the integrated density can be well improved, while the erasing and programming speed of the device are respectively decreased to 75 ns and 50 ns. In addition, comprehensive synaptic abilities including long-term potentiation (LTP) and long-term depression (LTD) are demonstrated in our U-shape recessed channel FG memory, highly resembling the biological synapses. These simulation results show that our device has the potential to be well used as embedded memory in neuromorphic computing and MCU (Micro Controller Unit) applications.

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Postsynaptic Application of a cAMP Analogue Reverses Long-Term Potentiation in Hippocampal CA1 Pyramidal Neurons

Journal of Neurophysiology ◽

10.1152/jn.2002.87.6.3018 ◽

2002 ◽

Vol 87 (6) ◽

pp. 3018-3032 ◽

Cited By ~ 15

Author(s):

Nikolai Otmakhov ◽

John E. Lisman

Keyword(s):

Molecular Mechanisms ◽

Competitive Inhibition ◽

Drug Application ◽

Specific Effect ◽

Long Term Potentiation ◽

Term Potentiation ◽

Camp Analogue ◽

And Control ◽

Dependent Processes

The molecular mechanisms that underlie the maintenance of long-term potentiation (LTP) remain unclear. We have examined the influence of postsynaptic cAMP-dependent processes on LTP maintenance in CA1 hippocampal cells. After LTP induction, drugs affecting cAMP-dependent processes were perfused into the cell through a patch pipette. A cAMP analogue, Rp-cAMPS (4 mM), dramatically decreased the amplitude of potentiated synaptic responses. The amplitude of responses in the control pathway was also decreased but to a lesser extent, indicating a specific effect on the potentiation process. This specific effect was not due to the larger amplitude of potentiated responses, was not use-dependent and, unlike other factors that affect LTP maintenance, did not depend on the delay (2, 10, or 25 min) of drug application after LTP induction. Lower concentrations of Rp-cAMPS (1.0 and 0.4 mM) also produced an inhibitory effect but reduced the LTP and control pathways comparably. One possible action of Rp-cAMPS is competitive inhibition of protein kinase A (PKA). Surprisingly, a potent and noncompetitive PKA inhibitor, regulatory type II subunit of PKA, produced only a weak depression of potentiated and control responses indicating there must be other targets for Rp-cAMPS. Moreover, Sp-8-OH-cAMPS, which is an activator of PKA, and Rp-8-OH-cAMPS, which is a weak inhibitor of PKA, both produced effects similar to those of Rp-cAMPS. We conclude that there are postsynaptic cyclic nucleotide-dependent processes that can specifically alter the mechanisms that maintain LTP and that are not primarily dependent on PKA.

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Design and Characterization of Semi-Floating-Gate Synaptic Transistor

Micromachines ◽

10.3390/mi10010032 ◽

2019 ◽

Vol 10 (1) ◽

pp. 32 ◽

Cited By ~ 1

Author(s):

Yongbeom Cho ◽

Jae Yoon Lee ◽

Eunseon Yu ◽

Jae-Hee Han ◽

Myung-Hyun Baek ◽

...

Keyword(s):

Long Term Potentiation ◽

Spike Timing ◽

Floating Gate ◽

Total System ◽

Charge Trap ◽

Tunneling Mechanism ◽

Integration Density ◽

Term Potentiation ◽

Short And Long Term

In this work, a study on a semi-floating-gate synaptic transistor (SFGST) is performed to verify its feasibility in the more energy-efficient hardware-driven neuromorphic system. To realize short- and long-term potentiation (STP/LTP) in the SFGST, a poly-Si semi-floating gate (SFG) and a SiN charge-trap layer are utilized, respectively. When an adequate number of holes are accumulated in the SFG, they are injected into the nitride charge-trap layer by the Fowler–Nordheim tunneling mechanism. Moreover, since the SFG is charged by an embedded tunneling field-effect transistor existing between the channel and the drain junction when the post-synaptic spike occurs after the pre-synaptic spike, and vice versa, the SFG is discharged by the diode when the post-synaptic spike takes place before the pre-synaptic spike. This indicates that the SFGST can attain STP/LTP and spike-timing-dependent plasticity behaviors. These characteristics of the SFGST in the highly miniaturized transistor structure can contribute to the neuromorphic chip such that the total system may operate as fast as the human brain with low power consumption and high integration density.

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Evoked field responses, recurrent inhibition, long-term potentiation and immobility-related nonrhythmical EEG in the dentate gyrus of fimbria-fornix-lesioned and control rats

Brain Research Bulletin ◽

10.1016/0361-9230(91)90090-7 ◽

1991 ◽

Vol 26 (4) ◽

pp. 525-532 ◽

Cited By ~ 17

Author(s):

Antti Valjakka ◽

Keijo Lukkarinen ◽

Esa Koivisto ◽

Risto Lammintausta ◽

Mauno M. Airaksinen ◽

...

Keyword(s):

Dentate Gyrus ◽

Long Term Potentiation ◽

Recurrent Inhibition ◽

Term Potentiation ◽

And Control

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Specific nanoscale synaptic reshuffling and control of short-term plasticity following NMDAR- and P2XR-dependent Long-Term Depression

10.1101/759191 ◽

2019 ◽

Author(s):

Benjamin Compans ◽

Magalie Martineau ◽

Remco V. Klaassen ◽

Thomas M. Bartol ◽

Corey Butler ◽

...

Keyword(s):

Synaptic Transmission ◽

Molecular Mechanisms ◽

Super Resolution ◽

Long Term Potentiation ◽

Global Changes ◽

Short Term ◽

Long Term Depression ◽

Term Potentiation ◽

And Control

Long-Term Potentiation (LTP) and Long-Term Depression (LTD) of excitatory synaptic transmission are considered as cellular basis of learning and memory. These two forms of synaptic plasticity have been mainly attributed to global changes in the number of synaptic AMPA-type glutamate receptor (AMPAR) through a regulation of the diffusion/trapping balance at the PSD, exocytosis and endocytosis. While the precise molecular mechanisms at the base of LTP have been intensively investigated, the ones involved in LTD remains elusive. Here we combined super-resolution imaging technique, electrophysiology and modeling to describe the various modifications of AMPAR nanoscale organization and their effect on synaptic transmission in response to two different LTD protocols, based on the activation of either NMDA receptors or P2X receptors. While both type of LTD are associated with a decrease in synaptic AMPAR clustering, only NMDAR-dependent LTD is associated with a reorganization of PSD-95 at the nanoscale. This change increases the pool of diffusive AMPAR improving synaptic short-term facilitation through a post-synaptic mechanism. These results demonstrate that specific dynamic reorganization of synapses at the nanoscale during specific LTD paradigm allows to improve the responsiveness of depressed synapses.

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