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2021 ◽  
Author(s):  
Alexandra Gastone Guilabert ◽  
Benjamin Ehret ◽  
Moritz O. Buchholz ◽  
Gregor F.P. Schuhknecht

To compute spiking responses, neurons integrate inputs from thousands of synapses whose strengths span an order of magnitude. Intriguingly, in mouse neocortex, the small minority of 'strong' synapses is found predominantly between similarly tuned cells, suggesting they are the synapses that determine a neuron's spike output. This raises the question of how other computational primitives, such as 'background' activity from the majority of synapses, which are 'weak', short-term plasticity, and temporal synchrony contribute to spiking. First, we combined extracellular stimulation and whole-cell recordings in mouse barrel cortex to map the distribution of excitatory postsynaptic potential (EPSP) amplitudes and paired-pulse ratios of excitatory synaptic connections converging onto individual layer 2/3 (L2/3) neurons. While generally net short-term plasticity was weak, connections with EPSPs > 2 mV displayed pronounced paired-pulse depression. EPSP amplitudes and paired-pulse ratios of connections converging onto the same neurons spanned the full range observed across L2/3 and there was no indication that strong synapses nor those with particular short-term plasticity properties were associated with particular cells, which critically constrains theoretical models of cortical filtering. To investigate how different computational primitives of synaptic information processing interact to shape spiking, we developed a computational model of a pyramidal neuron in the rodent L2/3 circuitry: firing rates and pairwise correlations of presynaptic inputs were constrained by in vivo observations, while synaptic strength and short-term plasticity were set based on our experimental data. Importantly, we found that the ability of strong inputs to evoke spiking critically depended on their high temporal synchrony and high firing rates observed in vivo and on synaptic background activity - and not primarily on synaptic strength, which in turn further enhanced information transfer. Depression of strong synapses was critical for maintaining a neuron's responsivity and prevented runaway excitation. Our results provide a holistic framework of how cortical neurons exploit complex synergies between temporal coding, synaptic properties, and noise in order to transform synaptic inputs into output firing.


2021 ◽  
Vol 0 (0) ◽  
pp. 1-16
Author(s):  
Esmaeil Akbari ◽  
◽  
Narges Hosseinmardi ◽  
Motahareh Rouhi Ardeshiri ◽  
◽  
...  

The basolateral amygdala (BLA) has substantial effects on the neuronal transmission and synaptic plasticity processes through the dentate gyrus. Orexin neuropeptides play different roles in the sleep/wakefulness cycle, feeding, learning, and memory. The present study was conducted to investigate the function of the orexin receptors of the BLA in the hippocampal local interneuron circuits. For this, paired-pulse responses from dentate gyrus (DG) region were recorded. Within the procedure, SB-334867-A (12μg/0.5μl), and, TCS-OX2-29 (10μg/0.5μl (orexin 1 and 2 receptors antagonists, respectively), were administered into the both side of the BLA areas of the rat brain. Dimethyl sulfoxide (DMSO) was used as the solvent in the control animals with the volume of 0.5μl. Our data indicated that the paired-pulse (PP) responses were not affected by the inactivation of the orexin receptors of the BLA.


2021 ◽  
Author(s):  
Melissa Kirkovski ◽  
Aron T. Hill ◽  
Nigel C. Rogasch ◽  
Takashi Saeki ◽  
Bernadette M. Fitzgibbon ◽  
...  

2021 ◽  
Author(s):  
Qi Qin ◽  
Miaocheng Zhang ◽  
Suhao Yao ◽  
Xingyu Chen ◽  
Aoze Han ◽  
...  

Abstract In the Post-Moore Era, the neuromorphic computing has been mainly focused on breaking the von Neumann bottlenecks. Memristor has been proposed as a key part for the neuromorphic computing architectures, which can be used to emulate the synaptic plasticities of human brain. Ferroelectric memristor is a breakthrough for memristive devices on account of its reliable-nonvolatile storage, low-write/read latency, and tunable-conductive states. However, among the reported ferroelectric memristors, the mechanisms of resistive-switching are still under debate. In addition, the research of emulation of the brain synapses using ferroelectric memristors needs to be further investigated. Herein, the Cu/PbZr0.52Ti0.48O3 (PZT)/Pt ferroelectric memristors have been fabricated. The devices are able to realize the transformation from threshold switching behaviors to resistive switching behaviors. The synaptic plasticities, including excitatory post-synaptic current (EPSC), paired-pulse facilitation (PPF), paired-pulse depression (PPD), and spike time-dependent plasticity (STDP) have been mimicked by the PZT devices. Furthermore, the mechanisms of PZT devices based on the interface barrier and conductive filament models have been investigated by first-principles calculation. This work may contribute to the applications of ferroelectric memristors in neuromorphic computing systems.


2021 ◽  
Author(s):  
Koya Yamashiro ◽  
Kanako Siiya ◽  
Koyuki Ikarashi ◽  
Yasuhiro Baba ◽  
Tomomi Fujimoto ◽  
...  

Abstract Injuries are inevitable for athletes, and when injuries end up causing chronic pain, they usually force athletes to withdraw from training. Chronic pain is known to be caused by plastic changes in the brain; thus, the purpose of this study was to assess the somatosensory evoked potential (SEP) and the paired-pulse inhibition (PPI) in athletes suffering from chronic pain as compared to pain-free athletes. Twenty track and field (T&F) athletes, that were also undergraduate students, were recruited for this study. These athletes (12 men; 8 women) were divided into two groups of 10 based on their self-reporting of actively experiencing chronic pain (defined as pain that persisted for more than 3 months) or not. Both SEP and PPI in the primary somatosensory cortex (SI) were elicited by constant current square-wave pulses (of 0.2 ms duration) that were delivered to the right median nerve by an electrical stimulator through a surface bar electrode with a cathode proximal. Paired-pulse stimulation was set at interstimulus intervals of 30 and 100 ms. Subjects were randomly presented with 1,500 single- and paired-pulse stimuli at 2 Hz. Our measurements demonstrated a trend toward a lower N20 and P25 amplitude as well as a disinhibition of the PPI_30 ms in the athletes suffering from chronic pain. These findings suggest that chronic pain may modulate excitatory and inhibitory function of the SI in athletes as well as in patients suffering from complex regional pain syndrome or fibromyalgia.


2021 ◽  
Vol 429 ◽  
pp. 119243
Author(s):  
Salvatore Di Marco ◽  
Laura Pilati ◽  
Angelo Torrente ◽  
Salvatore Ferlisi ◽  
Filippo Brighina

2021 ◽  
Vol 132 (8) ◽  
pp. e15
Author(s):  
C. Nettekoven ◽  
J. Pieczewski ◽  
V. Neuschmelting ◽  
K. Jonas ◽  
R. Goldbrunner ◽  
...  

Author(s):  
John Rothwell ◽  
Ricci Hannah

Transcranial magnetic stimulation (TMS) can be viewed as interacting with voluntary movement in two ways: it can used to probe the excitability of central nervous system (CNS) pathways before, during, and after a movement; alternatively, it can be used to interfere with movement and give information about the role of different cortical areas in different aspects of a task. This chapter concentrates on the role of single and paired pulse TMS methods that have been covered in detail in previous chapters. Long lasting effects of repetitive TMS (rTMS) are described in later chapters. Almost all of the TMS measures described in previous chapters differ in subjects at rest and during tonic voluntary activity.


Author(s):  
Daniel T. Corp ◽  
Hannah G.K. Bereznicki ◽  
Gillian M. Clark ◽  
George J. Youssef ◽  
Peter J. Fried ◽  
...  

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