GluK1 kainate receptors regulate synaptic population activity and plasticity in the amygdala

Kainaattireseptorit säätelevät hermosolujen toimintaa aivoissa (Li, H., & Rogawski, M. A. (1998), Braga, M. F. et al. (2004), Lerma & Marques (2013), Carta, M (2014)). Mantelitumakkeessa näiden reseptorien on osoitettu vaikuttavan synaptiseen signalointiin ja plastisuuteen, sekä glutamaatin ja γ-aminobutyyrihapon (GABA) vapautumiseen synaptisesta päätteestä (Li, H. et al. (2001). Braga, M. F. et al. (2003), Braga, M. F. et al. (2009), Aroniadou-Anderjaska, V. et al. (2012), Negrete‐Díaz, J. V. et al. (2012)), mutta niiden vaikutusta mantelitumakkeen hermoverkkojen kehitykseen ei tunneta. Tässä tutkielamssa halusimme ymmärtää kuinka GluK1 kainaatti reseptorit säätelevät synaptista populaatio aktiivisuutta ja plastisuutta kehittyvässä mantelitumakkeessa, mittaamaalla solunulkoisia kenttäpotentiaaleja P15-18 ikäisten Wistar Han rottien aivoleikkeistä. Koska solunulkoisia kenttäpotentiaaleja ei usein mitata mantelitumakkeesta, määritimme mittaamamme kenttäpotentiaalin ominaisuudet farmakologisesti. Kun kenttäpotentiaalin validiteetti oli määritetty, kykenimme osoittamaan, että GluK1 kainaattireseptorien toiminnan esto S)-1-(2-Amino-2-karboxyethyyli)-3-(2-karboxy-5-fenyylithiofeny-3-yli-metyyli)-5-metyylipyrimidiini-2,4-dioni (ACET) ei aiheuttanut merkittäviä muutoksia kenttäpotentiaalissa. GluK1 aktivaatio GluK1 agonistilla RS-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) proprionihappolla (ATPA) madalsi kenttäpotentiaalin amplitudia, vaikuttamatta sen konduktiojyrkkyyteen, viitaten inhibitorisen signaloinnin lisääntymiseen hermoverkossa. Estämällä GABAergiset reseptorit pikrotoksiinilla (GABAA-reseptori antagonisti) ATPAn vaikutukset kenttäpotentiaalin amplitudiin vähenivät merkittävästi. Lisäksi, varmistimme että GluK1 aktivointi ATPAlla lisää inhibitorista signalointia mantelitumakkeessa, mitaamalla spontaanin inhibitorisen signaloinnin frekvenssiä kokosolun virtalukituksella. GluK1 aktivaatio kasvatti spontaanin inhibitorisen signaloinnin frekvenssiä merkittävästi mantelitumakkeen neuroneissa. Lopuksi kykenimme myös osoittamaan, että GluK1 kainaattireseptorien aktivointi ATPAlla estää pitkäkestoisen potentiaation (LTPn) muodostumista. Tuloksemme osoittavat, että GluK1 reseptorit olennaisesti säätelevät synaptista signalointia ja plastisuuttaa kehittyvässä mantelitumakkeessa.Kainate receptors are known to regulate neuronal function in the brain (Li, H., & Rogawski, M. A. (1998), Braga, M. F. et al. (2004), Lerma & Marques (2013), Carta, M (2014)). In the amygdala, they have been shown to affect synaptic transmission and plasticity, as well as glutamate and γ-aminobutyric acid (GABA) release (Li, H. et al. (2001). Braga, M. F. et al. (2003), Braga, M. F. et al. (2009), Aroniadou-Anderjaska, V. et al. (2012), Negrete‐Díaz, J. V. et al. (2012)), however, their role during development of the amygdala circuitry is not known. In the present study, we wished to understand how GluK1 kainate receptors regulate synaptic population activity and plasticity in the developing amygdala by using extracellular field recordings in P15-18 Wistar Han rat pup brain slices. Since field excitatory postsynaptic potentials (fEPSPs) are not commonly measured from the amygdala, we first sought to pharmacologically characterize the basic properties of the extracellular signal, recorded from the basolateral amygdala in response to stimulation of the external capsulae (EC). Having confirmed the validity of the fEPSP as a measure of postsynaptic population response, we were able to show that blocking GluK1 with (S)-1-(2-Amino-2-carboxyethyl)-3-(2-carboxy-5-phenylthiophene-3-yl-methyl)-5-methylpyrimidine-2,4-dione (ACET), a selective GluK1 antagonist, had no effect on the fEPSP. Furthermore, activation of GluK1 with RS-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA), a GluK1 agonist, reduced the amplitude of the fEPSP, without affecting its slope, suggesting an increase in inhibitory signaling within the network. Blocking GABAergic activity with GABAA- receptor antagonist picrotoxin significantly reduced the effects of ATPA. Additionally, the increase in inhibitory signaling due to the activation of GluK1 was confirmed with whole-cell voltage clamp, by measuring spontaneous inhibitory postsynaptic current (sIPSC) frequency. Activation of GluK1 heavily increased sIPSC frequency in the basolateral amygdala neurons. Finally, we were also able to show that activation of GluK1 with ATPA strongly attenuates LTP induction. These results show that GluK1 kainate receptors play a vital role in the modulation of synaptic transmission and plasticity in the developing amygdala

Comparing torsional and lateral vibration data for deep learning-based drive train gear diagnosis

Funding Information: This work was supported by Academy of Finland as part of the AI-ROT research project (grant number 335717) and by Business Finland as part of the GOOD research project (grant number 211862) . Publisher Copyright: © 2023 The Author(s)Deep learning-based fault diagnosis models have been demonstrated to recognise machine health conditions from vibration data. However, most related studies have focused on lateral vibration data, and mostly neglected torsional vibration data. Yet, torsional vibration data can provide an advantage in diagnosing gear faults. Torsional vibration is typically less noisy than lateral vibration data as it can be measured directly from the rotating components. To this end, this study presents a large gear fault dataset with artificial faults of varying severity acquired from a downscaled thruster test rig operated at a vast range of rotating speeds. The test rig was equipped with multiple torque transducers, rotary encoders and piezoelectric accelerometers. The lateral and torsional vibration data acquired with these sensors were evaluated with three popular convolutional neural networks in extensive ablation studies. An interpretability analysis was conducted based on amplitude spectra and Grad-CAM visualisations. The results demonstrate that torsional vibration can be an effective source of data for gear fault diagnosis. For example, the models diagnose the most difficult gear conditions using only one torque transducer more accurately than using three accelerometers mounted on the gear box. Furthermore, the highest accuracy in each ablation study related to experiments with combined lateral and torsional vibration data. In addition, the interpretability analysis showed that the lower frequencies had relatively higher amplitudes in torsional vibration than in lateral vibration. The interpretability analysis also indicates that the models reached higher classification accuracies with torsional vibration data due to the lower dominating frequencies. Overall, this study highlights the potential benefits of using torsional vibration data for deep learning-based fault diagnosis of gears.Peer reviewe

On-Shaft Wireless Vibration Measurement Unit and Signal Processing Method for Torsional and Lateral Vibration

Microelectromechanical systems accelerometers have opened new possibilities for vibration monitoring of a rotating machinery. They enable mounting accelerometers directly to the rotating component of the machine, e.g., shaft. This enables not only the measurement of a lateral vibration but also a torsional vibration of the machine. This increases the vibration data gathered from the machine by one measurement instrument. This article presents an on-shaft wireless universal measurement unit (UMU) with innovative combination of features, such as a high measurement range and easy mounting. The UMU has a two-sensor configuration where two accelerometers are mounted to the opposite sides of a shaft. This enables to utilize a novel signal processing method to separate torsional and lateral vibration from the data. The signal processing method combines and modifies methods presented in the published literature. The results presented in this article demonstrate that the UMU together with the presented signal processing method can measure frequencies of torsional and lateral vibration accurately. However, the amplitude comparison between the UMU and reference sensors cannot be done adequately because they are measuring either different components of the machine or different physical properties.Peer reviewe

Downregulation of kainate receptors regulating GABAergic transmission in amygdala after early life stress is associated with anxiety-like behavior in rodents

Early life stress (ELS) is a well-characterized risk factor for mood and anxiety disorders. GABAergic microcircuits in the amygdala are critically implicated in anxiety; however, whether their function is altered after ELS is not known. Here we identify a novel mechanism by which kainate receptors (KARs) modulate feedforward inhibition in the lateral amygdala (LA) and show that this mechanism is downregulated after ELS induced by maternal separation (MS). Specifically, we show that in control rats but not after MS, endogenous activity of GluK1 subunit containing KARs disinhibit LA principal neurons during activation of cortical afferents. GluK1 antagonism attenuated excitability of parvalbumin (PV)-expressing interneurons, resulting in loss of PV-dependent inhibitory control and an increase in firing of somatostatin-expressing interneurons. Inactivation of Grik1 expression locally in the adult amygdala reduced ongoing GABAergic transmission and was sufficient to produce a mild anxiety-like behavioral phenotype. Interestingly, MS and GluK1-dependent phenotypes showed similar gender specificity, being detectable in male but not female rodents. Our data identify a novel KAR-dependent mechanism for cell-type and projection-specific functional modulation of the LA GABAergic microcircuit and suggest that the loss of GluK1 KAR function contributes to anxiogenesis after ELS.Peer reviewe

Torque estimation in marine propulsion systems

Funding Information: This work was done within the Business Finland funded research project Reboot IoT Factory. The authors would like to thank the anonymous reviewers for their meticulous reviews and constructive comments, which were of great help to improve the manuscript. Publisher Copyright: © 2022 The AuthorsAn augmented Kalman filter for torque estimation in marine propulsion-system drive trains is presented. Propeller and motor excitations and torque responses are estimated based on a dynamical model of the system and inboard shaft measurements. Input excitations affecting marine propulsion systems are signals whose statistical properties vary between finite time intervals. Hence, in this paper, excitations are characterized as quasi-stationary signals with bounded power spectral density. Given that upper bounds on the spectral densities are known prior to estimation, it is shown that a linear time-invariant input-and-state observer, minimizing the worst-case power of the estimation errors, can be synthesized by conventional Kalman-filtering techniques. Experiments have been conducted on a laboratory-scale test bench to assess the applicability of the proposed observer for use in marine propulsion systems. The test bench was built to emulate the behavior of a full-scale propulsion system operated in ice and other high load conditions. Estimation results from a full-size underwater mountable azimuthing thruster are also presented. Experiment results show that torque excitations and torque responses at all locations of interest on the engine-propeller drivetrain can be estimated with high accuracy based on a few indirect measurements at convenient locations on the motor shaft.Peer reviewe

Aberrant cortical projections to amygdala GABAergic neurons contribute to developmental circuit dysfunction following early life stress

Publisher Copyright: © 2022 The Author(s)Early life stress (ELS) results in enduring dysfunction of the corticolimbic circuitry, underlying emotional and social behavior. However, the neurobiological mechanisms involved remain elusive. Here, we have combined viral tracing and electrophysiological techniques to study the effects of maternal separation (MS) on frontolimbic connectivity and function in young (P14-21) rats. We report that aberrant prefrontal inputs to basolateral amygdala (BLA) GABAergic interneurons transiently increase the strength of feed-forward inhibition in the BLA, which raises LTP induction threshold in MS treated male rats. The enhanced GABAergic activity after MS exposure associates with lower functional synchronization within prefrontal-amygdala networks in vivo. Intriguingly, no differences in these parameters were detected in females, which were also resistant to MS dependent changes in anxiety-like behaviors. Impaired plasticity and synchronization during the sensitive period of circuit refinement may contribute to long-lasting functional changes in the prefrontal-amygdaloid circuitry that predispose to neuropsychiatric conditions later on in life.Peer reviewe