Associative learning is often considered to require the physical presence of stimuli in the environment in order for them to be linked. This, however, is not a necessary condition for learning. ...Indeed, associative relationships can form between events that are never directly paired. That is, associative learning can occur by integrating information across different phases of training. Higher-order conditioning provides evidence for such learning through two deceptively similar designs - sensory preconditioning and second-order conditioning. In this review, we detail the procedures and factors that influence learning in these designs, describe the associative relationships that can be acquired, and argue for the importance of this knowledge in studying brain function.
The interhemispheric circuit connecting the left and the right mammalian brain plays a key role in integration of signals from the left and the right side of the body. The information transfer is ...carried out by modulation of simultaneous excitation and inhibition. Hemodynamic studies of this circuit are inconsistent since little is known about neurovascular coupling of mixed excitatory and inhibitory signals. We investigated the variability in hemodynamic responses driven by the interhemispheric circuit during optogenetic and somatosensory activation. We observed differences in the neurovascular response based on the stimulation site – cell bodies versus distal projections. In half of the experiments, optogenetic stimulation of the cell bodies evoked a predominant post-synaptic inhibition in the other hemisphere, accompanied by metabolic oxygen consumption without coupled functional hyperemia. When the same transcallosal stimulation resulted in predominant post-synaptic excitation, the hemodynamic response was biphasic, consisting of metabolic dip followed by functional hyperemia. Optogenetic suppression of the postsynaptic excitation abolished the coupled functional hyperemia. In contrast, light stimulation at distal projections evoked consistently a metabolic response. Our findings suggest that functional hyperemia requires signals originating from the cell body and the hemodynamic response variability appears to reflect the balance between the post-synaptic excitation and inhibition.
Applying design for manufacture and assembly (DfMA) principles in the construction industry has gained attention in recent years. Studies convey that the application of DfMA in construction projects ...can significantly enhance overall productivity. However, the literature on construction-oriented DfMA is still limited, and its application in real-life projects has been stifled due to various constraints. Following a design science research method, a systematic literature review was conducted to identify the construction-oriented DfMA implementation challenges. To address these challenges, a construction-oriented DfMA framework was theorized, verified in a project-based context, and validated through focus group discussions with off-site construction industry experts. In this study, 45 challenges were identified and categorized into eight main constraint categories: contractual, technological, procedural, cultural, commercial, geographical, financial, and technical/cognitive. The foremost challenges to the adoption of DfMA in construction projects seems to relate to the contractual and operational aspects and their associated stakeholders. This study provides insight into the challenges of implementing DfMA in the construction industry. The investigated challenges contribute to the theoretical and practice-based checklists of limitations for implementing DfMA methods and can inform future research. Finally, this paper introduces a framework for implementing DfMA and provides supporting field-based evidence for its application.
Introducing optogenetics into neurovascular research can provide novel insights into the cell-specific control of the hemodynamic response. To generalize findings from molecular approaches, it is ...crucial to determine whether light-activated circuits have the same effect on the vasculature as sensory-activated ones. For that purpose, rats expressing channelrhodopsin (ChR2) specific to excitatory glutamatergic neurons were used to measure neural activity, blood flow, hemoglobin-based optical intrinsic signal, and blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) during optogenetic and sensory stimulation. The magnitude of the evoked hemodynamic responses was monotonically correlated with optogenetic stimulus strength. The BOLD hemodynamic response function was consistent for optogenetic and sensory stimuli. The relationship between electrical activities and hemodynamic responses was comparable for optogenetic and sensory stimuli, and better explained by the local field potential (LFP) than the firing rate. The LFP was well correlated with cerebral blood flow, moderately with cerebral blood volume, and less with deoxyhemoglobin (dHb) level. The presynaptic firing rate had little impact on evoking vascular response. Contribution of the postsynaptic LFP to the blood flow response induced by optogenetic stimulus was further confirmed by the application of glutamate receptor antagonists. Overall, neurovascular coupling during optogenetic control of glutamatergic neurons largely conforms to that of a sensory stimulus.
Adult neurogenesis research in mammals presents a challenge as most stem cells and progenitors are located deep in opaque brain tissues. Here, we describe an efficient ferritin-based magnetic ...resonance imaging (MRI) reporter and its use to label mouse subventricular zone progenitors, enabling in vivo visualization of endogenous neuroblast migration toward the olfactory bulb. We quantify the effect of the ferritin transgene expression on cellular iron transport proteins such as transferrin receptor, divalent metal transporter and STEAP reductase. Based on these data, we elucidate key aspects of the cellular pathways that the reporter utilizes to load iron and form its superparamagnetic core. This MRI reporter gene platform can facilitate the non-invasive study of native or transplanted stem cell migration and associated neurogenic or therapeutic molecular events in live animals.
► We show that expression of ferritin up-regulates levels of iron import proteins. ► This effect increases iron storage and ferritin-based MRI reporter efficiency. ► We label murine subventricular zone progenitors with efficient ferritin reporter. ► We use MRI to visualize in vivo neuroblast migration towards the olfactory bulb.
Discrete architecture is recognized as a computational design approach which uses computation to generate algorithmically combinable aggregations. It is therefore a promising innovation for ...increasing design process productivity through the adaptability of the aggregations it generates. In the built environment, discrete design is usually identified with the modular method. It is a construction process based on the aggregation of different modules assembled according to well-defined connections to ensure the building’s integrity and functionality. It involves off-site manufacturing, and hence a controlled environment ensuring more predictability over weathering and change. But like in conventional construction practices, the fragmentation of modular construction processes hinders its productivity. As a result, this construction approach requires adequate technologies and communication tools to improve collaboration and productivity. This paper aims to address these requirements by adopting a BIM-driven computational approach to design processes and a robotic approach to prefabrication processes. It proposes a modular construction framework for design and production, and presents the results through a study adopting BIM-driven discrete design and robotic manufacturing.
MgMoO4 with hexagonal particles were prepared by combining high energy ball milling with heat treatment technique. The influence of the mechanochemical activation/heat-treatment on the phase, ...structural and morphology transformation were investigated by X-ray powder diffraction analysis (XRD), infrared spectroscopy (IR), differential scanning calorimetry (DSC), particle size distribution (PSD) and scanning electron microscope (SEM). Optical properties of the final product were studied by UV–Vis and photoluminescence (PL) measurements. Mechanochemical activation of the initial oxides for 10 h ball milling leads to a full amorphization of MoO3, only. The heat-treatment at different temperatures after 10 h milling time results to the phase formation of MgMoO4. The reaction started at 400 °C for 5 h and completed at 800 °C for 5 h. The calculated energy band gap value as prepared MgMoO4 is 2.03 eV and exhibits photoluminescence emission above 600 nm. The CIE chromaticity coordinates (x = 0.53 and y = 0.43) were found to lie in the orange region.
Purpose>According to the construction literature, the number of projects applying integrated project delivery (IPD) principles is expected to increase in the new-normal era. However, given that the ...pandemic is not yet fully over, accurate and measurable data are not yet available. Also, there is a lack of empirical studies that could provide guidelines as to the application of IPD principles at the various stages of construction projects. Thus, the goal of this paper is to address this knowledge gap through case studies.Design/methodology/approach>This paper follows a multi-step research methodology, namely, a literature review, case study and focus group discussions in the context of Canadian construction projects.Findings>Based on the conducted literature review and focus group discussions, the authors identified: (1) new challenges in the various stages of the construction projects' life cycle, (2) their related proximity aspects (technological, organizational, geographical and cognitive) and (3) IPD principles that can address the identified challenges within their associated proximities. The results show that IPD relational principles can improve a project's organizational and cognitive proximities, while IPD digital integrative principles can enhance a project's geographical and technological proximities.Originality/value>This study contributes to the theoretical checklists of challenges that the construction industry has experienced since the beginning of the pandemic, and to the practical guidelines of implementation of IPD principles to meet these challenges. The conducted case studies are timely and relevant, and their results provide new insights for key project stakeholders into the application of IPD to tackle new-normal challenges based on their proximity perspectives.
Behavioral change is paramount to adaptive behavior. Two ways to achieve alterations in previously established behavior are extinction and overexpectation. The infralimbic (IL) portion of the medial ...prefrontal cortex controls the inhibition of previously established aversive behavioral responses in extinction. The role of the IL cortex in behavioral modification in appetitive Pavlovian associations remains poorly understood. Here, we seek to determine if the IL cortex modulates overexpectation and extinction of reward learning. Using overexpectation or extinction to achieve a reduction in behavior, the present findings uncover a dissociable role for the IL cortex in these paradigms. Pharmacologically inactivating the IL cortex left overexpectation intact. In contrast, pre-training manipulations in the IL cortex prior to extinction facilitated the reduction in conditioned responding but led to a disrupted extinction retrieval on test drug-free. Additional studies confirmed that this effect is restricted to the IL and not dependent on the dorsally-located prelimbic cortex. Together, these results show that the IL cortex underlies extinction but not overexpectation-driven reduction in behavior, which may be due to regulating the expression of conditioned responses influenced by stimulus-response associations rather than stimulus-stimulus associations.
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