RESUMO
Recently, we reported that auditory fear conditioning leads to the presynaptic potentiation at lateral amygdala to basal amygdala (LA-BA) synapses that shares the mechanism with high-frequency stimulation (HFS)-induced long-term potentiation (LTP) ex vivo. In the present study, we further examined the molecular mechanisms underlying the HFS-induced presynaptic LTP. We found that a presynaptic elevation of Ca2+ was required for the LTP induction. Interestingly, the blockade of presynaptic but not postsynaptic HCN channels with ZD7288 completely abolished LTP induction. While ZD7288 did not alter basal synaptic transmission, the blocker fully reversed previously established LTP, indicating that HCN channels are also required for the maintenance of LTP. Indeed, HCN3 and HCN4 channels were preferentially localized in the presynaptic boutons of LA afferents. Furthermore, an inhibition of either GABAB receptors or GIRK channels eliminated the inhibitory effect of HCN blockade on the LTP induction. Collectively, we suggest that activation of presynaptic HCN channels may counteract membrane hyperpolarization during tetanic stimulation, and thereby contributes to the presynaptic LTP at LA-BA synapses.
Assuntos
Complexo Nuclear Basolateral da Amígdala , Potenciação de Longa Duração , Sinapses , Transmissão Sináptica , Terminações Pré-SinápticasRESUMO
The lateral amygdala (LA) is a main sensory input site from the cortical and thalamic regions. In turn, LA glutamatergic pyramidal neurons strongly project to the basal amygdala (BA). Although it is well known that auditory fear conditioning involves synaptic potentiation in the LA, it is not clear whether the LA-BA synaptic transmission is modified upon auditory fear conditioning. Here we found that high-frequency stimulation ex vivo resulted in long-term potentiation (LTP) with a concomitant enhancement of neurotransmitter release at LA-BA synapses. Auditory fear conditioning also led to the presynaptic facilitation at LA-BA synapses. Meanwhile, AMPA/NMDA current ratio was not changed upon fear conditioning, excluding the involvement of postsynaptic mechanism. Notably, fear conditioning occluded electrically induced ex vivo LTP in the LA-BA pathway, indicating that the conditioning and electrically induced LTP share common mechanisms. Our findings suggest that the presynaptic potentiation of LA-BA synapses may be involved in fear conditioning.
Assuntos
Complexo Nuclear Basolateral da Amígdala/fisiologia , Condicionamento Clássico/fisiologia , Medo/fisiologia , Neurotransmissores/metabolismo , Sinapses/fisiologia , Estimulação Acústica , Tonsila do Cerebelo/metabolismo , Tonsila do Cerebelo/fisiologia , Animais , Complexo Nuclear Basolateral da Amígdala/citologia , Complexo Nuclear Basolateral da Amígdala/metabolismo , Potenciação de Longa Duração/fisiologia , Masculino , Neurônios/citologia , Neurônios/metabolismo , Neurônios/fisiologia , Ratos Sprague-Dawley , Receptores de AMPA/metabolismo , Receptores de AMPA/fisiologia , Sinapses/metabolismo , Transmissão Sináptica/fisiologiaRESUMO
This paper presents a case study of continuous productivity improvement of an automotive parts production line using Internet of Everything (IoE) data for fault monitoring. Continuous productivity improvement denotes an iterative process of analyzing and updating the production line configuration for productivity improvement based on measured data. Analysis for continuous improvement of a production system requires a set of data (machine uptime, downtime, cycle-time) that are not typically monitored by a conventional fault monitoring system. Although productivity improvement is a critical aspect for a manufacturing site, not many production systems are equipped with a dedicated data recording system towards continuous improvement. In this paper, we study the problem of how to derive the dataset required for continuous improvement from the measurement by a conventional fault monitoring system. In particular, we provide a case study of an automotive parts production line. Based on the data measured by the existing fault monitoring system, we model the production system and derive the dataset required for continuous improvement. Our approach provides the expected amount of improvement to operation managers in a numerical manner to help them make a decision on whether they should modify the line configuration or not.
RESUMO
To perform advanced operations with unmanned aerial vehicles (UAVs), it is crucial that components other than the existing ones such as flight controller, network devices, and ground control station (GCS) are also used. The inevitable addition of hardware and software to accomplish UAV operations may lead to security vulnerabilities through various vectors. Hence, we propose a security framework in this study to improve the security of an unmanned aerial system (UAS). The proposed framework operates in the robot operating system (ROS) and is designed to focus on several perspectives, such as overhead arising from additional security elements and security issues essential for flight missions. The UAS is operated in a nonnative and native ROS environment. The performance of the proposed framework in both environments is verified through experiments.
RESUMO
To improve vehicle safety, vehicular ad hoc networks (VANETs) periodically broadcast safety messages known as beacons. Consequently, it becomes safety critical to guarantee the timely reception of periodic beacons under the time-varying environments of VANET. However, existing approaches typically measure the packet delivery ratio, which is a time-average metric that does not consider the temporal behavior associated with beacon reception. In this paper, to properly reflect the temporal aspect of beacon reception, we propose a congestion control algorithm, Beacon inter-reception time Ensured Adaptive Transmission (BEAT). The proposed algorithm tightly regulates the beacon inter-reception time compared to conventional techniques, which can significantly improve vehicle safety. Our simulation results demonstrate the effectiveness of the proposed scheme.
RESUMO
Drones are broadening their scope to various applications such as networking, package delivery, agriculture, rescue, and many more. For proper operation of drones, reliable communication should be guaranteed because drones are remotely controlled. When drones experience communication failure due to bad channel condition, interference, or jamming in a certain area, one existing solution is to exploit mobility or so-called spatial retreat to evacuate them from the communication failure area. However, the conventional spatial retreat scheme moves drones in random directions, which results in inefficient movement with significant evacuation time and waste of battery lifetime. In this paper, we propose a novel spatial retreat technique that takes advantage of cooperation between drones for resilient networking, which is called cooperative spatial retreat (CSR). Our performance evaluation shows that the proposed CSR significantly outperforms existing schemes.
RESUMO
Underwater Acoustic Sensor Network (UASN) comes with intrinsic constraints because it is deployed in the aquatic environment and uses the acoustic signals to communicate. The examples of those constraints are long propagation delay, very limited bandwidth, high energy cost for transmission, very high signal attenuation, costly deployment and battery replacement, and so forth. Therefore, the routing schemes for UASN must take into account those characteristics to achieve energy fairness, avoid energy holes, and improve the network lifetime. The depth based forwarding schemes in literature use node's depth information to forward data towards the sink. They minimize the data packet duplication by employing the holding time strategy. However, to avoid void holes in the network, they use two hop node proximity information. In this paper, we propose the Energy and Depth variance-based Opportunistic Void avoidance (EDOVE) scheme to gain energy balancing and void avoidance in the network. EDOVE considers not only the depth parameter, but also the normalized residual energy of the one-hop nodes and the normalized depth variance of the second hop neighbors. Hence, it avoids the void regions as well as balances the network energy and increases the network lifetime. The simulation results show that the EDOVE gains more than 15 % packet delivery ratio, propagates 50 % less copies of data packet, consumes less energy, and has more lifetime than the state of the art forwarding schemes.
RESUMO
Hearing loss is a common communication disorder caused by various environmental and genetic factors. Hereditary hearing loss is very heterogeneous, and most of such cases involve sensorineural defects in the auditory pathway. There are currently 57 known autosomal dominant non-syndromic hearing loss (DFNA) loci, and the causative genes have been identified at 22 of these loci. In the present study, we performed a genome-wide linkage analysis in a Korean family segregating autosomal dominant hearing loss. We observed linkage on chromosome 1p34, and at this locus, we detected a novel mutation consisting of an 18 nucleotide deletion in exon 4 of the KCNQ4 gene, which encodes a voltage-gated potassium channel. We carried out a functional in vitro study to analyze the effects of this mutation (c.664_681del) along with two previously described KCNQ4 mutations, p.W276S and p.G285C. Although the c.664_681del mutation is located in the intercellular loop and the two previously described mutations, p.W276S and p.G285C, are located in the pore region, all mutants inhibit normal channel function by a dominant negative effect. Our analysis indicates that the intercellular loop is as significant as the pore region as a potential site of pathogenic effects on KCNQ4 channel function.
Assuntos
Sequência de Aminoácidos , Perda Auditiva/genética , Canais de Potássio KCNQ/genética , Deleção de Sequência , Linhagem Celular , Genes Dominantes , Ligação Genética , Haplótipos , Dados de Sequência Molecular , LinhagemRESUMO
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed in the central nervous system and play a regulatory role in neuronal excitability. In the present study, we examined a physiological role of HCN channels in the rat basolateral amygdala (BLA). In vitro electrophysiological studies showed that ZD7288 decreased spontaneous inhibitory postsynaptic current (sIPSC) without changing miniature IPSC (mIPSC). HCN channel blockade also attenuated feedback inhibitions in BLA principal neurons. However, blockade of HCN channel had little effects on spontaneous excitatory postsynaptic current (sEPSC) and mEPSC. Therefore, HCN channel appeared to decrease BLA excitability by increasing the action potential-dependent inhibitory control over the BLA principal neurons. Anxiety is reported to be influenced by neuronal excitability in the BLA and inhibitory synaptic transmission is thought to play a pivotal role in regulating overall excitability of the amygdala. As expected, blockade of HCN channels by targeted injection of ZD7288 to the BLA increased anxiety-like behavior under elevated plus maze test. Our results suggest that HCN channel activity can modulate the GABAergic synaptic transmission in the BLA, which in turn control the amygdala-related emotional behaviors such as anxiety.
Assuntos
Tonsila do Cerebelo/fisiologia , Ansiedade/fisiopatologia , Canais de Cátion Regulados por Nucleotídeos Cíclicos/fisiologia , Canais de Potássio/fisiologia , Transmissão Sináptica/fisiologia , Tonsila do Cerebelo/efeitos dos fármacos , Animais , Canais de Cátion Regulados por Nucleotídeos Cíclicos/antagonistas & inibidores , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização , Aprendizagem em Labirinto , Pirimidinas/farmacologia , Ratos , Ratos Sprague-Dawley , Transmissão Sináptica/efeitos dos fármacosRESUMO
Auditory fear memory is thought to be maintained by fear conditioning-induced potentiation of synaptic efficacy, which involves enhanced expression of surface AMPA receptor (AMPAR) at excitatory synapses in the lateral amygdala (LA). Depotentiation, reversal of conditioning-induced potentiation, has been proposed as a cellular mechanism for fear extinction; however, a direct link between depotentiation and extinction has not yet been tested. To address this issue, we applied both ex vivo and in vivo approaches to rats in which fear memory had been consolidated. A unique form of depotentiation reversed conditioning-induced potentiation at thalamic input synapses onto the LA (T-LA synapses) ex vivo. Extinction returned the enhanced T-LA synaptic efficacy observed in conditioned rats to baseline and occluded the depotentiation. Consistently, extinction reversed conditioning-induced enhancement of surface expression of AMPAR subunits in LA synaptosomal preparations. A GluR2-derived peptide that blocks regulated AMPAR endocytosis inhibited depotentiation, and microinjection of a cell-permeable form of the peptide into the LA attenuated extinction. Our results are consistent with the use of depotentiation to weaken potentiated synaptic inputs onto the LA during extinction and provide strong evidence that AMPAR removal at excitatory synapses in the LA underlies extinction.
Assuntos
Tonsila do Cerebelo/anatomia & histologia , Tonsila do Cerebelo/fisiologia , Medo , Animais , Encéfalo/metabolismo , Eletrodos , Eletrofisiologia/métodos , Endocitose , Masculino , Peptídeos/química , Ratos , Ratos Sprague-Dawley , Receptores de AMPA/metabolismo , Sinapses/metabolismo , Sinaptossomos/metabolismoRESUMO
The myristoylated zeta inhibitory peptide (ZIP), which was originally developed as a protein kinase C/Mζ (PKCζ/PKMζ) inhibitor, is known to produce the loss of different forms of memories. However, ZIP induces memory loss even in the absence of PKMζ, and its mechanism of action, therefore, remains elusive. Here, through a kinome-wide screen, we found that glycogen synthase kinase 3 beta (GSK-3ß) was robustly activated by ZIP in vitro. ZIP induced depotentiation (a cellular substrate of memory erasure) of conditioning-induced potentiation at LA synapses, and the ZIP-induced depotentiation was prevented by a GSK-3ß inhibitor, 6-bromoindirubin-3-acetoxime (BIO-acetoxime). Consistently, GSK-3ß inhibition by BIO-acetoxime infusion or GSK-3ß knockdown by GSK-3ß shRNA in the LA attenuated ZIP-induced disruption of learned fear. Furthermore, conditioned fear was decreased by expression of a non-inhibitable form of GSK-3ß in the LA. Our findings suggest that GSK-3ß activation is a critical step for ZIP-induced disruption of memory.
Assuntos
Peptídeos Penetradores de Células/farmacologia , Medo/fisiologia , Glicogênio Sintase Quinase 3 beta/metabolismo , Aprendizagem/fisiologia , Lipopeptídeos/farmacologia , Memória/fisiologia , Proteína Quinase C/antagonistas & inibidores , Animais , Medo/efeitos dos fármacos , Aprendizagem/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Modelos Animais , Fosforilação , Ratos , Ratos Sprague-Dawley , Transdução de SinaisRESUMO
Parkinson's disease (PD) is a neurodegenerative disorder associated with loss of striatal dopamine, secondary to degeneration of midbrain dopamine (mDA) neurons in the substantia nigra, rendering cell transplantation a promising therapeutic strategy. To establish human induced pluripotent stem cell-based (hiPSC-based) autologous cell therapy, we report a platform of core techniques for the production of mDA progenitors as a safe and effective therapeutic product. First, by combining metabolism-regulating microRNAs with reprogramming factors, we developed a method to more efficiently generate clinical-grade iPSCs, as evidenced by genomic integrity and unbiased pluripotent potential. Second, we established a "spotting"-based in vitro differentiation methodology to generate functional and healthy mDA cells in a scalable manner. Third, we developed a chemical method that safely eliminates undifferentiated cells from the final product. Dopaminergic cells thus express high levels of characteristic mDA markers, produce and secrete dopamine, and exhibit electrophysiological features typical of mDA cells. Transplantation of these cells into rodent models of PD robustly restores motor function and reinnervates host brain, while showing no evidence of tumor formation or redistribution of the implanted cells. We propose that this platform is suitable for the successful implementation of human personalized autologous cell therapy for PD.
Assuntos
Células-Tronco Pluripotentes Induzidas , Atividade Motora , Doença de Parkinson Secundária , Recuperação de Função Fisiológica , Transplante de Células-Tronco , Animais , Autoenxertos , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Células-Tronco Pluripotentes Induzidas/patologia , Células-Tronco Pluripotentes Induzidas/transplante , Masculino , Doença de Parkinson Secundária/metabolismo , Doença de Parkinson Secundária/patologia , Doença de Parkinson Secundária/terapia , Ratos , Ratos NusRESUMO
During development, cortical interneurons (cINs) are generated from the ventral telencephalon, robustly migrate to the dorsal telencephalon, make local synaptic connections, and critically regulate brain circuitry by inhibiting other neurons. Thus, their abnormality is associated with various brain disorders. Human pluripotent stem cell (hPSC)-derived cINs can provide unlimited sources with which to study the pathogenesis mechanism of these disorders as well as provide a platform to develop novel therapeutics. By employing spinner culture, we could obtain a >10-fold higher yield of cIN progenitors compared to conventional culture without affecting their phenotype. Generated cIN spheres can be maintained feeder-free up to 10 months and are optimized for passaging and cryopreservation. In addition, we identified a combination of chemicals that synchronously matures generated progenitors into SOX6+KI67- migratory cINs and extensively characterized their maturation in terms of metabolism, migration, arborization, and electrophysiology. When transplanted into mouse brains, chemically matured migratory cINs generated grafts that efficiently disperse and integrate into the host circuitry without uncontrolled growth, making them an optimal cell population for cell therapy. Efficient large-scale generation of homogeneous migratory cINs without the need of feeder cells will play a critical role in the full realization of hPSC-derived cINs for development of novel therapeutics.
RESUMO
Astrocyte ion channels participate in ionic homeostasis in the brain. Inward rectifying potassium channels (Kir channels) in astrocytes have been particularly implicated in K(+) homeostasis because of their high open probability at resting potential and their increased conductance at high concentrations of extracellular K(+). We examined the expression of the Kir2.1 subunit, one of the Kir channel subunits, in the mouse brain by immunohistochemistry. Kir2.1 channels were widely distributed throughout the brain, with high expression in the olfactory bulb and the cerebellum. Interestingly, they were abundantly expressed in astrocytes of the olfactory bulb, while astrocytes in other brain regions including the hippocampus did not show any detectable expression. However, Kir2.1 channel-expressing cells were dramatically increased in the hippocampus by kainic acid-induced seizure and the cells were glial fibrillary acidic protein (GFAP)-positive, which confirms that astrocytes in the hippocampus express Kir2.1 channels under pathological conditions. Our results imply that Kir2.1 channels in astrocyte may be involved in buffering K(+) against accumulated extracellular K(+) caused by neuronal hyperexcitability under phathophysiological conditions.
Assuntos
Astrócitos/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Potássio/metabolismo , Subunidades Proteicas/metabolismo , Convulsões/fisiopatologia , Animais , Astrócitos/citologia , Agonistas de Aminoácidos Excitatórios/metabolismo , Hipocampo/citologia , Hipocampo/metabolismo , Homeostase , Ácido Caínico/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos DBA , Técnicas de Patch-Clamp , Canais de Potássio Corretores do Fluxo de Internalização/genética , Subunidades Proteicas/genética , Convulsões/induzido quimicamenteRESUMO
[This corrects the article on p. 210 in vol. 11, PMID: 28572760.].
RESUMO
There has been a longstanding debate on whether original fear memory is inhibited or erased after extinction. One possibility that reconciles this uncertainty is that the inhibition and erasure mechanisms are engaged in different phases (early or late) of extinction. In this study, using single-session extinction training and its repetition (multiple-session extinction training), we investigated the inhibition and erasure mechanisms in the prefrontal cortex and amygdala of rats, where neural circuits underlying extinction reside. The inhibition mechanism was prevalent with single-session extinction training but faded when single-session extinction training was repeated. In contrast, the erasure mechanism became prevalent when single-session extinction training was repeated. Moreover, ablating the intercalated neurons of amygdala, which are responsible for maintaining extinction-induced inhibition, was no longer effective in multiple-session extinction training. We propose that the inhibition mechanism operates primarily in the early phase of extinction training, and the erasure mechanism takes over after that.
Assuntos
Tonsila do Cerebelo/fisiologia , Extinção Psicológica , Medo , Córtex Pré-Frontal/fisiologia , Animais , Condicionamento Clássico , RatosRESUMO
The mechanism of tinnitus suppression after cochlear implantation (CI) in single-sided deafness (SSD) is not fully understood. In this regard, by comparing pre- and post-CI quantitative electroencephalography (qEEG), we explored cortical changes relevant to tinnitus improvement. In SSD patients who underwent CI, qEEG data were collected: (1) before CI, (2) 6 months post-operatively with CI-on, and (3) 30 min after CI-off and source-localized cortical activity/functional connectivity analyses were performed. Compared to the pre-operative baseline, the CI-on condition demonstrated significantly decreased activity in the right auditory- and orbitofrontal cortices (OFC) for the delta frequency band as well as decreased connectivity between the auditory cortex/posterior cingulate cortex for the delta/beta2 bands. Meanwhile, compared to the CI-off condition, the CI-on condition displayed decreased activity in the right auditory cortices/OFC for the delta band, and in bilateral auditory cortices, left inferior frontal cortex/OFC for the gamma band. However, qEEG analyses showed no significant differences between the CI-off and baseline conditions. CI induced overall decreased cortical activity and functional connectivity. However, judging from no differences between the CI-off and baseline conditions, CI-induced cortical activity and functional connectivity changes are not by cortical plastic changes, but by dynamic peripheral reafferentation.
RESUMO
In this paper, we deal with the problem of assuring medical-grade quality of service (QoS) for real-time medical applications in wireless healthcare systems based on IEEE 802.11e. Firstly, we show that the differentiated channel access of IEEE 802.11e cannot effectively assure medical-grade QoS because of priority inversion. To resolve this problem, we propose an efficient channel access algorithm. The proposed algorithm adjusts arbitrary inter-frame space (AIFS) in the IEEE 802.11e protocol depending on the QoS measurement of medical traffic, to provide differentiated near-absolute priority for medical traffic. In addition, based on rigorous capacity analysis, we propose an admission control scheme that can avoid performance degradation due to network overload. Via extensive simulations, we show that the proposed mechanism strictly assures the medical-grade QoS and improves the throughput of low-priority traffic by more than several times compared to the conventional IEEE 802.11e.
Assuntos
Algoritmos , Atenção à Saúde , Alarmes Clínicos , Redes de Comunicação de Computadores , Eletrocardiografia , Frequência Cardíaca/fisiologia , Humanos , Tecnologia sem FioRESUMO
Various auditory tones have been used as conditioned stimuli (CS) for fear conditioning, but researchers have largely neglected the effect that different types of auditory tones may have on fear memory processing. Here, we report that at lateral amygdala (LA) synapses (a storage site for fear memory), conditioning with different types of auditory CSs (2.8 kHz tone, white noise, FM tone) recruits distinct forms of long-term potentiation (LTP) and inserts calcium permeable AMPA receptor (CP-AMPAR) for variable periods. White noise or FM tone conditioning produced brief insertion (<6 hr after conditioning) of CP-AMPARs, whereas 2.8 kHz tone conditioning induced more persistent insertion (≥6 hr). Consistently, conditioned fear to 2.8 kHz tone but not to white noise or FM tones was erased by reconsolidation-update (which depends on the insertion of CP-AMPARs at LA synapses) when it was performed 6 hr after conditioning. Our data suggest that conditioning with different auditory CSs recruits distinct forms of LA synaptic plasticity, resulting in more malleable fear memory to some tones than to others.
Assuntos
Tonsila do Cerebelo/fisiologia , Medo/fisiologia , Estimulação Acústica , Animais , Condicionamento Psicológico , Técnicas In Vitro , Potenciação de Longa Duração , Masculino , Plasticidade Neuronal , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Receptores de AMPA/metabolismo , SomRESUMO
Inositol 1,4,5-trisphosphate 3-kinase A (IP3K-A) is a molecule enriched in the brain and neurons that regulates intracellular calcium levels via signaling through the inositol trisphosphate receptor. In the present study, we found that IP3K-A expression is highly enriched in the central nucleus of the amygdala (CeA), which plays a pivotal role in the processing and expression of emotional phenotypes in mammals. Genetic abrogation of IP3K-A altered amygdala gene expression, particularly in genes involved in key intracellular signaling pathways and genes mediating fear- and anxiety-related behaviors. In agreement with the changes in amygdala gene expression profiles, IP3K-A knockout (KO) mice displayed more robust responses to aversive stimuli and spent less time in the open arms of the elevated plus maze, indicating high levels of innate fear and anxiety. In addition to behavioral phenotypes, decreased excitatory and inhibitory postsynaptic current and reduced c-Fos immunoreactivity in the CeA of IP3K-A KO mice suggest that IP3K-A has a profound influence on the basal activities of fear- and anxiety-mediating amygdala circuitry. In conclusion, our findings collectively demonstrate that IP3K-A plays an important role in regulating affective states by modulating metabotropic receptor signaling pathways and neural activity in the amygdala.