Control of timing, rate and bursts of hippocampal place cells by dendritic and somatic inhibition

Royer, S챕bastien,Zemelman, Boris V,Losonczy, Attila,Kim, Jinhyun,Chance, Frances,Magee, Jeffrey C,Buzs찼ki, Gy철rgy Nature Publishing Group, a division of Macmillan P 2012 NATURE NEUROSCIENCE Vol.15 No.5

A consortium of inhibitory neurons control the firing patterns of pyramidal cells, but their specific roles in the behaving animal are largely unknown. We performed simultaneous physiological recordings and optogenetic silencing of either perisomatic (parvalbumin (PV) expressing) or dendrite-targeting (somatostatin (SOM) expressing) interneurons in hippocampal area CA1 of head-fixed mice actively moving a treadmill belt rich with visual-tactile stimuli. Silencing of either PV or SOM interneurons increased the firing rates of pyramidal cells selectively in their place fields, with PV and SOM interneurons having their largest effect during the rising and decaying parts of the place field, respectively. SOM interneuron silencing powerfully increased burst firing without altering the theta phase of spikes. In contrast, PV interneuron silencing had no effect on burst firing, but instead shifted the spikes' theta phase toward the trough of theta. These findings indicate that perisomatic and dendritic inhibition have distinct roles in controlling the rate, burst and timing of hippocampal pyramidal cells.

Removal and potential recovery of rare earth elements from mine water

A. Royer-Lavallée,C.M. Neculita,L. Coudert 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.89 No.-

Recovery of rare earth elements (REE) from acid mine drainage (AMD) could be an alternative to theirconventional mining, given that REE are relatively highly concentrated in AMD. Their pre-concentration,through AMD active or passive treatment, and further recovery seem promising from both an economicand environmental point of view. This review thoroughly discusses sorption and precipitation as mainprocesses for REE removal from synthetic and real mine water. Nanofiltration and bioaccumulation arealso presented as pre-concentration steps prior to the treatment. Promising sorbents especially includebiosorbents, but the scientific literature on this topic remains sparse. Even fewer studies coverprecipitation as a technique for REE removal from mine water, but its high removal efficiency justifiesfurther research. Large-scale experiments for REE recovery from active or passive AMD remediationsystems have already been conducted and this emerging practice has shown economic benefits. Furtherresearch is needed to test the performance of these systems.

Segregated Cell Populations Enable Distinct Parallel Encoding within the Radial Axis of the CA1 Pyramidal Layer

Tristan Geiller,Sebastien Royer,최준식 한국뇌신경과학회 2017 Experimental Neurobiology Vol.26 No.1

Numerous studies have implicated the hippocampus in the encoding and storage of declarative and spatial memories. Several models have considered the hippocampus and its distinct subfields to contain homogeneous pyramidal cell populations. Yet, recent studies have led to a consensus that the dorso-ventral and proximo-distal axes have different connectivities and physiologies. The remaining deep-superficial axis of the pyramidal layer, however, remains relatively unexplored due to a lack of techniques that can record from neurons simultaneously at different depths. Recent advances in transgenic mice, two-photon imaging and dense multisite recording have revealed extensive disparities between the pyramidal cells located in the deep and the superficial layers. Here, we summarize differences between the two populations in terms of gene expression and connectivity with other intra-hippocampal subregions and local interneurons that underlie distinct learning processes and spatial representations. A unified picture will emerge to describe how such local segregations can increase the capacity of the hippocampus to compute and process numerous tasks in parallel.

Protein Conformational Dynamics of Homodimeric Hemoglobin Revealed by Combined Time-Resolved Spectroscopic Probes

Choi, Jungkweon,Muniyappan, Srinivasan,Wallis, John T.,Royer Jr., William E.,Ihee, Hyotcherl WILEY-VCH Verlag 2010 CHEMPHYSCHEM -WEINHEIM- Vol.11 No.1

<B>Graphic Abstract</B> <P>Allosteric regulation: The protein kinetics of the R–T transition of homodimeric hemoglobin (HbI) in solution are investigated using combined spectroscopic probes (see figure). The comparative results using both transient absorption spectroscopy and transient grating techniques show that the former can be blind to the overall quaternary structural change. <img src='wiley_img/14394235-2010-11-1-CPHC200900822-content.gif' alt='wiley_img/14394235-2010-11-1-CPHC200900822-content'> </P>

Traveling Theta Waves along the Entire Septotemporal Axis of the Hippocampus

Patel, J.,Fujisawa, S.,Berenyi, A.,Royer, S.,Buzsaki, G. Cell Press 2012 Neuron Vol.75 No.3

A topographical relationship exists between the hippocampus-entorhinal cortex and the neocortex. However, it is not known how these anatomical connections are utilized during information exchange and behavior. We recorded theta oscillations along the entire extent of the septotemporal axis of the hippocampal CA1 pyramidal layer. While the frequency of theta oscillation remained same along the entire long axis, the amplitude and coherence between recording sites decreased from dorsal to ventral hippocampus (VH). Theta phase shifted monotonically with distance along the longitudinal axis, reaching ~180<SUP>o</SUP> between the septal and temporal poles. The majority of concurrently recorded units were phase-locked to the local field theta at all dorsoventral segments. The power of VH theta had only a weak correlation with locomotion velocity, and its amplitude varied largely independently from theta in the dorsal part. Thus, theta oscillations can temporally combine or segregate neocortical representations along the septotemporal axis of the hippocampus.

Differential Representation of Landmark and Self-Motion Information along the CA1 Radial Axis: Self-Motion Generated Place Fields Shift toward Landmarks during Septal Inactivation

Fattahi, Mohammad,Sharif, Farnaz,Geiller, Tristan,Royer, Sé,bastien Society for Neuroscience 2018 The Journal of neuroscience Vol.38 No.30

<P>Spatial location in the environment can be defined in relation to specific landmarks or in relation to the global context, and is estimated from both the sensing of landmarks and the inner sense of cumulated locomotion referred to as path-integration. The respective contribution of landmark and path-integration to place-cell activity in the hippocampus is still unclear and complicated by the fact that the two mechanisms usually overlap. To bias spatial mechanisms toward landmark or path-integration, we use a treadmill equipped with a long belt on which male mice run sequentially through a zone enriched and a zone impoverished in visual-tactile cues. We show that inactivation of the medial septum (MS), which is known to disrupt the periodic activity of grid cells, impairs mice ability to anticipate the delivery of a reward in the cue-impoverished zone and transiently alter the spatial configuration of place fields in the cue-impoverished zone selectively: following MS inactivation, place fields in the cue-impoverished zone progressively shift backward and stabilize near the cues, resulting in the contraction of the spatial representation around cues; following MS recovery, the initial spatial representation is progressively restored. Furthermore, we found that place fields in the cue-rich and cue-impoverished zones are preferentially generated by cells from the deep and superficial sublayers of CA1, respectively. These findings demonstrate with mechanistic insights the contribution of MS to the spread of spatial representations in cue-impoverished zones, and indicate a segregation of landmark-based and path-integration-assisted spatial mechanisms into deep and superficial CA1, respectively.</P>

Genetic transformation and evaluation of two sweet sorghum genotypes for resistance to spotted stemborer, Chilo partellus (Swinhoe)

K. B. R. S. Visarada,G. Shyam Prasad,Monique. Royer 한국식물생명공학회 2016 Plant biotechnology reports Vol.10 No.5

Sweet sorghum is a climate smart crop with multiple uses. The crop is susceptible to attack by the spotted stemborer, Chilo partellus (Swinhoe). This causes deadheart formation, leading to lodging of plants and consequent high economic losses. Lack of stable sources of resistance make any genetic enhancement through breeding difficult. We report a study to build up host plant resistance using transgenic technology by introducing two different classes of Bt genes (cry1Aa and cry1B) into two elite sweet sorghum genotypes of India (SSV84 and RSSV9). We devised tissue culture methods to suit the genotypes of our interest, SSV84 and RSSV9, and employed two methods of genetic transformation: the particle bombardment and in planta method of Agrobacterium. Modification of in vitro culture methods involved subculture every 3 days in the initial stages of culture and the use of precultured embryos as target tissues. For the in planta method, a floral dip for 1 h in Agrobacterium suspension supplemented with Lcysteine and Tween-20 was used. Sixteen transgenic events were generated; inheritance, integration and stable expression of the transgenes till the T4 generation were confirmed. The amount of Bt Cry1Aa protein at 25–30 days of growth ranged from 24.8 to 72.8 ng/g of fresh leaf tissue. We recorded 78.4 % larval mortality, reduced leaf damage (3.0 out of 9.0) and reduced feeding (41.0 %) over the controls in insect feed assays. Stable inheritance and expression in the in planta-derived transgenics are presented.

Inhibition of Nuclear Factor κB Activation and Cyclooxygenase-2 Expression by Aqueous Extracts of Hispanic Medicinal Herbs

Robert A. Orlando,Amanda M.,Lucy A. Hunsaker,Carolina R.,Robert E. Royer,David L. Vander Jagt,Dorothy J. Vander Jagt 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.4

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a primary choice of therapy for diseases with a chronic inflammatory component. Unfortunately, long-term NSAID therapy is often accompanied by severe side effects, including cardiovascular and gastrointestinal complications. Because of this, there is critical need for identification of new and safer treatments for chronic inflammation to circumvent these side effects. Inflammatory diseases have been successfully remedied with natural herbs by many cultures. To better understand the potential of natural herbs in treating chronic inflammation and to identify their mechanism of action, we have evaluated the anti-inflammatory activities of 20 medicinal herbs commonly used in the Hispanic culture. We have established a standardized method for preparing aqueous extracts (teas) from the selected medicinal herbs and screened for inhibition of tumor necrosis factor-α-induced activation of nuclear factor κB (NF-κB), which is the central signaling pathway of the inflammatory response. A number of herbal teas were identified that exhibited significant anti-inflammatory activity. In particular, tea from the herb commonly called laurel was found to be an especially potent inhibitor of NF-κB-dependent cyclooxygenase-2 gene expression and prostaglandin E2 production in cultured murine macrophages. These findings indicate that laurel tea extract contains potent anti-inflammatory compounds that function by inhibiting the major signal transduction pathway responsible for inducing an inflammatory event. Based on these results, laurel may represent a new, safe therapeutic agent for managing chronic inflammation.

Pyramidal Cell-Interneuron Interactions Underlie Hippocampal Ripple Oscillations

Stark, E.,Roux, L.,Eichler, R.,Senzai, Y.,Royer, S.,Buzsaki, G. Cell Press 2014 Neuron Vol.83 No.2

High-frequency ripple oscillations, observed most prominently in the hippocampal CA1 pyramidal layer, are associated with memory consolidation. The cellular and network mechanisms underlying the generation, frequency control, and spatial coherence of the rhythm are poorly understood. Using multisite optogenetic manipulations in freely behaving rodents, we found that depolarization of a small group of nearby pyramidal cells was sufficient to induce high-frequency oscillations, whereas closed-loop silencing of pyramidal cells or activation of parvalbumin- (PV) or somatostatin-immunoreactive interneurons aborted spontaneously occurring ripples. Focal pharmacological blockade of GABA<SUB>A</SUB> receptors abolished ripples. Localized PV interneuron activation paced ensemble spiking, and simultaneous induction of high-frequency oscillations at multiple locations resulted in a temporally coherent pattern mediated by phase-locked interneuron spiking. These results constrain competing models of ripple generation and indicate that temporally precise local interactions between excitatory and inhibitory neurons support ripple generation in the intact hippocampus.

Effect of Cryoprotectant and Freeze-Drying Process on the Stability of W/O/W Emulsions

Choi, M. J.,Brianç,on, S.,Bazile, D.,Royere, A.,Min, S. G.,Fessi, H. Taylor Francis 2007 Drying Technology Vol.25 No.5

<P> In order to protect a hydrophilic drug and to prolong its further delivery, the formulation of multiple emulsions could be worthy. However, the double emulsions are not stable, their structure can change, leading to the formation of a single emulsion as the destruction of the system, and the drug can release easily from the globules in liquid state. The freeze-drying technology could be used to produce dry emulsion, the powder form being much more stable. The aim of this work was to study the influence of a cryoprotectant and a freeze-drying process on the stability of W/O/W emulsions. Samples were frozen at two different freezing rate (νf = 0.55°C/min and 1.25°C/min) and successively dried at two different sublimation temperature (Ts = - 10°C and - 20°C). The particle size distributions were measured by granulometer and UV spectrophotometer was performed to investigate the leakage of internal constituent. The glass transition temperature (Tg) of the double emulsions was analyzed by DSC. The particle sizes became even smaller after freeze drying, except when &kgr;-carrageenan is used as a cryoprotectant. In that case, the particles became aggregated after freeze drying, whatever the process conditions. The mean size is considerably reduced when the globules are diluted at low concentration in glucose and trehalose solution. When the concentration is increased, the size distribution is not significantly affected. The leakage of the internal aqueous phase to the external one during freeze drying was measured as an indicator of the structure stability. It is affected by the nature of the cryoprotectant and the conditions of the freeze-drying process. The leakage of the internal phase was smaller when cycle III (νf = 1.25°C/min, Ts = - 10°C) was processed. From our experiments, we suppose that the water transfer from the inner phase to the outer aqueous phase results in the diminution of the globules size in double emulsion. The Tg of the double emulsions diluted with trehalose and glucose were determined at - 33.8°C and - 47.1°C. In contrast, the Tg of double emulsion with &kgr;-carrageenan and HES did not appear.</P>