Publications by authors named "RAMAKRISHNAN C"

Motor output results from the coordinated activity of neural circuits distributed across multiple brain regions that convey information to the spinal cord via descending motor pathways. Yet the organizational logic through which supraspinal systems target discrete components of spinal motor circuits remains unclear. Here, using viral transsynaptic tracing along with serial two-photon tomography, we have generated a whole-brain map of monosynaptic inputs to spinal V1 interneurons, a major inhibitory population involved in motor control.

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Background: Web-based advance care planning (ACP) interventions offer a promising solution to improve ACP engagement, but none are specifically designed to meet the needs of patients with heart failure and their caregivers.

Objective: We aimed to develop and assess the usability and acceptability of a web-based ACP decision aid called "My Voice," which is tailored for patients with heart failure and their caregivers.

Methods: This study's team and advisory board codeveloped the content for both patient and caregiver modules in "My Voice.

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Neuronal activity promotes the proliferation of healthy oligodendrocyte precursor cells (OPC) and their malignant counterparts, gliomas. Many gliomas arise from and closely resemble oligodendroglial lineage precursors, including diffuse midline glioma (DMG), a cancer affecting midline structures such as the thalamus, brainstem and spinal cord. In DMG, glutamatergic and GABAergic neuronal activity promotes progression through both paracrine signaling and through bona-fide neuron-to-glioma synapses.

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Objective: The study aimed to assess coronavirus disease 2019 (COVID-19) knowledge among dental patients seeking treatment at a tertiary care center.

Materials And Methods: A cross-sectional study was conducted at the Government Dental College Thrissur to assess dental patients' COVID-19 awareness. Patients over 18 who attended the dental department and agreed to participate were included after obtaining the informed consent.

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Article Synopsis
  • A population of neurons in the ventral tegmental area (VTA) co-transmit two neurotransmitters, glutamate and GABA, but their inputs and functions are not fully understood.
  • Using advanced tracing techniques in mice, researchers discovered that these neurons receive diverse inputs from various brain regions, with significant inputs from the superior colliculus and lateral hypothalamus.
  • Optical activation of these inputs revealed that lateral hypothalamus involvement leads to active behavior, while superior colliculus stimulation results in brief activation and freezing behavior, indicating the complex integration of signals by VTA neurons related to motivation and behavior.
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Background: Hypertension is a major public health challenge, globally. Recently, we reported findings from cluster randomized trial in 8 primary care clinics in Singapore and showed that a multicomponent "SingHypertension" intervention comprising 1) motivational conversation by trained nurses, 2) telephone-based follow-ups, 3) standardized algorithm with single-pill combination (SPC) antihypertensive medications, and 4) subsidy on SPC antihypertensive drugs was effective on improving BP control. This paper presents the acceptability of SingHypertension multicomponent intervention among the key stakeholders.

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A series of eleven public concerts (staging chamber music by Ludwig van Beethoven, Brett Dean, Johannes Brahms) was organized with the goal to analyze physiological synchronies within the audiences and associations of synchrony with psychological variables. We hypothesized that the music would induce synchronized physiology, which would be linked to participants' aesthetic experiences, affect, and personality traits. Physiological measures (cardiac, electrodermal, respiration) of 695 participants were recorded during presentations.

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The parasubthalamic nucleus (PSTN) is activated by refeeding after food deprivation and several PSTN subpopulations have been shown to suppress feeding. However, no study to date directly addressed the role of PSTN neurons activated upon food access in the control of ensuing food consumption. Here we identify consumption latency as a sensitive behavioral indicator of PSTN activity, and show that, in hungry mice, the ensemble of refeeding-activated PSTN neurons drastically increases the latency to initiate refeeding with both familiar and a novel, familiar food, but does not control the amount of food consumed.

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Behavioral states such as sleep and wake are highly correlated with specific patterns of rhythmic activity in the cortex. During low arousal states such as slow wave sleep, the cortex is synchronized and dominated by low frequency rhythms coordinated across multiple regions. Although recent evidence suggests that GABAergic inhibitory neurons are key players in cortical state modulation, the circuit mechanisms coordinating synchronized activity among local and distant neocortical networks are not well understood.

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Ventral tegmental area (VTA) glutamatergic neurons participate in reward, aversion, drug-seeking, and stress. Subsets of VTA VGluT2+ neurons are capable of co-transmitting glutamate and GABA (VGluT2+VGaT+ neurons), transmitting glutamate without GABA (VGluT2+VGaT- neurons), or co-transmitting glutamate and dopamine (VGluT2+TH+ neurons), but whether these molecularly distinct subpopulations show behavior-related differences is not wholly understood. We identified that neuronal activity of each VGluT2+ subpopulation is sensitive to reward value but signaled this in different ways.

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The anterior cingulate cortex plays a pivotal role in the cognitive and affective aspects of pain perception. Both endogenous and exogenous opioid signaling within the cingulate mitigate cortical nociception, reducing pain unpleasantness. However, the specific functional and molecular identities of cells mediating opioid analgesia in the cingulate remain elusive.

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Background and objectives Direct pulp capping (dPC) is a therapeutic process that involves the application of a protective chemical to an exposed pulp with the intent to facilitate the restoration and preservation of its vitality and function. Despite numerous proposed solutions, researchers have yet to find a dependable, non-absorbable bioactive pulp capping substance that constantly activates cellular healing processes, consequently preserving pulpal vitality over an extended period of time. The objective of this study was to assess and contrast the efficacy of a novel tricalcium silicate cement and calcium hydroxide in preserving the long-term health of the dental pulp following dPC using clinical and radiographic observations.

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Introduction: The increased use of soft drinks leads to a high prevalence of dental erosion (DE), and the use of polymers can decrease tooth demineralization by a carbonated drink. Assessment of the effect of food-approved polymers such as highly esterified pectin (HP), propylene glycol alginate (PGA), and gum arabic (GA) on their efficiency to reduce enamel demineralization on addition with a commercially available carbonated drink was the main objective of this study.

Materials And Methods: For this study, 300 premolar teeth were studied for enamel erosion and were divided into five groups consisting of 60 samples in each group.

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Prefrontal cortical (PFC) circuits provide top-down control of threat reactivity. This includes ventromedial PFC (vmPFC) circuitry, which plays a role in suppressing fear-related behavioral states. Dynorphin (Dyn) has been implicated in mediating negative affect and maladaptive behaviors induced by severe threats and is expressed in limbic circuits, including the vmPFC.

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Endocannabinoid (eCB)-mediated suppression of inhibitory synapses has been hypothesized, but this has not yet been demonstrated to occur in vivo because of the difficulty in tracking eCB dynamics and synaptic plasticity during behavior. In mice navigating a linear track, we observed location-specific eCB signaling in hippocampal CA1 place cells, and this was detected both in the postsynaptic membrane and the presynaptic inhibitory axons. All-optical in vivo investigation of synaptic responses revealed that postsynaptic depolarization was followed by a suppression of inhibitory synaptic potentials.

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Prefrontal cortical (PFC) circuits provide top-down control of threat reactivity. This includes ventromedial PFC (vmPFC) circuitry, which plays a role in suppressing fear-related behavioral states. Dynorphin (Dyn) has been implicated in mediating negative affect and mal-adaptive behaviors induced by severe threats and is expressed in limbic circuits, including the vmPFC.

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Background: For patients on dialysis with poor quality of life and prognosis, dialysis withdrawal and subsequent transition to palliative care is recommended. This study aims to understand multi-stakeholder perspectives regarding dialysis withdrawal and identify their information needs and support for decision-making regarding withdrawing from dialysis and end-of-life care.

Methods: Participants were recruited through purposive sampling from eight dialysis centers and two public hospitals in Singapore.

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Sexual reproduction of Toxoplasma gondii, confined to the felid gut, remains largely uncharted owing to ethical concerns regarding the use of cats as model organisms. Chromatin modifiers dictate the developmental fate of the parasite during its multistage life cycle, but their targeting to stage-specific cistromes is poorly described. Here we found that the transcription factors AP2XII-1 and AP2XI-2 operate during the tachyzoite stage, a hallmark of acute toxoplasmosis, to silence genes necessary for merozoites, a developmental stage critical for subsequent sexual commitment and transmission to the next host, including humans.

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Parkinson's disease (PD) targets some dopamine (DA) neurons more than others. Sex differences offer insights, with females more protected from DA neurodegeneration. The mammalian vesicular glutamate transporter VGLUT2 and ortholog dVGLUT have been implicated as modulators of DA neuron resilience.

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Astrocytes play active roles at synapses and can monitor, respond, and adapt to local synaptic activity. While there is abundant evidence that astrocytes modulate excitatory transmission in the hippocampus, evidence for astrocytic modulation of hippocampal synaptic inhibition remains more limited. Furthermore, to better investigate roles for astrocytes in modulating synaptic transmission, more tools that can selectively activate native G protein signaling pathways in astrocytes with both spatial and temporal precision are needed.

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With concurrent global epidemics of chronic pain and opioid use disorders, there is a critical need to identify, target and manipulate specific cell populations expressing the mu-opioid receptor (MOR). However, available tools and transgenic models for gaining long-term genetic access to MOR+ neural cell types and circuits involved in modulating pain, analgesia and addiction across species are limited. To address this, we developed a catalog of MOR promoter (MORp) based constructs packaged into adeno-associated viral vectors that drive transgene expression in MOR+ cells.

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KCR channelrhodopsins (K-selective light-gated ion channels) have received attention as potential inhibitory optogenetic tools but more broadly pose a fundamental mystery regarding how their K selectivity is achieved. Here, we present 2.5-2.

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Animals must continually evaluate stimuli in their environment to decide which opportunities to pursue, and in many cases these decisions can be understood in fundamentally economic terms. Although several brain regions have been individually implicated in these processes, the brain-wide mechanisms relating these regions in decision-making are unclear. Using an economic decision-making task adapted for rats, we find that neural activity in both of two connected brain regions, the ventrolateral orbitofrontal cortex (OFC) and the dorsomedial striatum (DMS), was required for economic decision-making.

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Multicellular biological systems, particularly living neural networks, exhibit highly complex organization properties that pose difficulties for building cell-specific biocompatible interfaces. We previously developed an approach to genetically program cells to assemble structures that modify electrical properties of neurons in situ, opening up the possibility of building minimally invasive cell-specific structures and interfaces. However, the efficiency and biocompatibility of this approach were challenged by limited membrane targeting of the constructed materials.

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