scholarly journals Measuring and Modelling the Emergence of Order in the Mouse Retinocollicular Projection

2019 ◽  
Author(s):  
Daniel Lyngholm ◽  
David C. Sterratt ◽  
J. J. Johannes Hjorth ◽  
David J. Willshaw ◽  
Stephen J. Eglen ◽  
...  
Keyword(s):  
Molecular Model ◽  
Activity Patterns ◽  
Theoretical Work ◽  
Contour Analysis ◽  
Common View ◽  
Retinotopic Maps ◽  
Retinocollicular Projection ◽  
Developmental Dynamics ◽  
Anterior Posterior

AbstractIn the formation of retinotopic maps both experimental and theoretical work implicate guidance molecules and patterned neuronal activity. A common view is that molecular cues define and activity cues refine mappings. Important insights have come from studies of the retinocollicular projection in transgenic mice, in which cues have been modified either in isolation or in combination. Mostly these have generated descriptions of endpoint mappings. The dynamics of map formation remain under-explored experimentally and computationally. We have quantified changes in the ordering of the mouse retinocollicular projection with age after making local collicular injections of fluorescent microspheres. Contour analysis shows that, at birth (P0), cells from over 80% of the retina converge on a given collicular locus; this percentage falls gradually to P4 then rapidly approaches adult values by P12. Paired injections reveal how the segregation of labelled cells depends both on injection site separation and relative orientation and also age. At P0, large anterior-posterior separations failed to produce segregated label: segregation improved with a similar timecourse to convergence to reach near adult-values by P12. An implementation of a combined activity-molecular model captures these segregation dynamics.The developmental dynamics were then studied in the nAChR-β2−/− mouse, which has altered patterns of retinal activity in the first postnatal week that results in a more diffuse adult retinal projection. Surprisingly, both measures of map refinement (convergence and segregation) remain largely constant and imprecise in the first postnatal week – only subsequently does the projection begin to refine. Substituting nAChR-β2−/− activity patterns for wild-type patterns [5] into the model failed to capture the biology: refinement was initially faster. By reducing the relative importance of the gradients’ contribution to the model energy (to 15% of normal) we were able to mimic the delayed refinement observed in vivo. Our model therefore predicts the altered activity patterns may affect readout of guidance cues.

Anterior mesendoderm induces mouse Engrailed genes in explant cultures

Development ◽  
1993 ◽  
Vol 118 (1) ◽  
pp. 139-149 ◽  
Author(s):  
S.L. Ang ◽  
J. Rossant
Keyword(s):  
Direct Evidence ◽  
Neural Tissue ◽  
Explant Culture ◽  
Neural Plate ◽  
Explant Cultures ◽  
Neural Marker ◽  
Engrailed Genes ◽  
Anterior Posterior

We have developed germ layer explant culture assays to study the role of mesoderm in anterior-posterior (A-P) patterning of the mouse neural plate. Using isolated explants of ectodermal tissue alone, we have demonstrated that the expression of Engrailed-1 (En-1) and En-2 genes in ectoderm is independent of mesoderm by the mid- to late streak stage, at least 12 hours before their onset of expression in the neural tube in vivo at the early somite stage. In recombination explants, anterior mesendoderm from headfold stage embryos induces the expression of En-1 and En-2 in pre- to early streak ectoderm and in posterior ectoderm from headfold stage embryos. In contrast, posterior mesendoderm from embryos of the same stage does not induce En genes in pre- to early streak ectoderm but is able to induce expression of a general neural marker, neurofilament 160 × 10(3) M(r). These results provide the first direct evidence for a role of mesendoderm in induction and regionalization of neural tissue in mouse.

scholarly journals Nasal Chemosensory-Stimulation Evoked Activity Patterns in the Rat Trigeminal Ganglion Visualized by In Vivo Voltage-Sensitive Dye Imaging

PLoS ONE ◽  
2011 ◽  
Vol 6 (10) ◽  
pp. e26158 ◽  
Author(s):  
Markus Rothermel ◽  
Benedict Shien Wei Ng ◽  
Agnieszka Grabska-Barwińska ◽  
Hanns Hatt ◽  
Dirk Jancke
Keyword(s):  
Trigeminal Ganglion ◽  
Activity Patterns ◽  
Voltage Sensitive Dye ◽  
Evoked Activity ◽  
Voltage Sensitive Dye Imaging

scholarly journals Oxytocin shapes spontaneous activity patterns in the developing visual cortex by activating somatostatin interneurons

2019 ◽  
Author(s):  
Paloma P Maldonado ◽  
Alvaro Nuno-Perez ◽  
Jan Kirchner ◽  
Elizabeth Hammock ◽  
Julijana Gjorgjieva ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Spontaneous Activity ◽  
Sensory Processing ◽  
Activity Patterns ◽  
Network Activity ◽  
Synaptic Connections ◽  
Pairwise Correlations ◽  
Early Brain Development

SummarySpontaneous network activity shapes emerging neuronal circuits during early brain development, however how neuromodulation influences this activity is not fully understood. Here, we report that the neuromodulator oxytocin powerfully shapes spontaneous activity patterns. In vivo, oxytocin strongly decreased the frequency and pairwise correlations of spontaneous activity events in visual cortex (V1), but not in somatosensory cortex (S1). This differential effect was a consequence of oxytocin only increasing inhibition in V1 and increasing both inhibition and excitation in S1. The increase in inhibition was mediated by the depolarization and increase in excitability of somatostatin+ (SST) interneurons specifically. Accordingly, silencing SST+ neurons pharmacogenetically fully blocked oxytocin’s effect on inhibition in vitro as well its effect on spontaneous activity patterns in vivo. Thus, oxytocin decreases the excitatory/inhibitory ratio and modulates specific features of V1 spontaneous activity patterns that are crucial for refining developing synaptic connections and sensory processing later in life.

Myotomal slow muscle function of rainbow trout Oncorhynchus mykiss during steady swimming.

1998 ◽  
Vol 201 (10) ◽  
pp. 1659-1671 ◽  
Author(s):  
L Hammond ◽  
J D Altringham ◽  
C S Wardle
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Body Length ◽  
Muscle Activation ◽  
Activity Patterns ◽  
The Body ◽  
Entire Body ◽  
Negative Power ◽  
Rainbow Trout Oncorhynchus Mykiss

Strain and activity patterns were determined during slow steady swimming (tailbeat frequency 1.5-2.5 Hz) at three locations on the body in the slow myotomal muscle of rainbow trout Oncorhynchus mykiss using sonomicrometry and electromyography. Strain was independent of tailbeat frequency over the range studied and increased significantly from +/-3.3 % l0 at 0.35BL to +/-6 % at 0.65BL, where l0 is muscle resting length and BL is total body length. Muscle activation occurred significantly later in the strain cycle at 0.35BL (phase shift 59 degrees) than at 0.65BL (30 degrees), and the duration of activity was significantly longer (211 degrees at 0.35BL and 181 degrees at 0.65BL). These results differ from those of previous studies. The results have been used to simulate in vivo activity in isolated muscle preparations using the work loop technique. Preparations from all three locations generated net positive power under in vivo conditions, but the negative power component increased from head to tail. Both kinematically, and in the way its muscle functions to generate hydrodynamic thrust, the rainbow trout appears to be intermediate between anguilliform swimmers such as the eel, which generate thrust along their entire body length, and carangiform fish (e.g. saithe Pollachius virens), which generate thrust primarily at the tail blade.

Hedgehog is required for activation of engrailed during regeneration of fragmented Drosophila imaginal discs

Development ◽  
1999 ◽  
Vol 126 (8) ◽  
pp. 1591-1599 ◽  
Author(s):  
M.C. Gibson ◽  
G. Schubiger
Keyword(s):  
Normal Growth ◽  
Imaginal Discs ◽  
Ideal Model ◽  
Posterior Compartment ◽  
Anterior Compartment ◽  
In Vivo Culture ◽  
Pattern Regulation ◽  
Regulative Capacity ◽  
Anterior Posterior

Surgically fragmented Drosophila appendage primordia (imaginal discs) engage in wound healing and pattern regulation during short periods of in vivo culture. Prothoracic leg disc fragments possess exceptional regulative capacity, highlighted by the ability of anterior cells to convert to posterior identity and establish a novel posterior compartment. This anterior/posterior conversion violates developmental lineage restrictions essential for normal growth and patterning of the disc, and thus provides an ideal model for understanding how cells change fate during epimorphic pattern regulation. Here we present evidence that the secreted signal encoded by hedgehog directs anterior/posterior conversion by activating the posterior-specific transcription factor engrailed in regulating anterior cells. In the absence of hedgehog activity, prothoracic leg disc fragments fail to undergo anterior/posterior conversion, but can still regenerate missing anterior pattern elements. We suggest that hedgehog-independent regeneration within the anterior compartment (termed integration) is mediated by the positional cues encoded by wingless and decapentaplegic. Taken together, our results provide a novel mechanistic interpretation of imaginal disc pattern regulation and permit speculation that similar mechanisms could govern appendage regeneration in other organisms.

In vitro culture of cynomolgus monkey embryos beyond early gastrulation

Science ◽  
2019 ◽  
Vol 366 (6467) ◽  
pp. eaax7890 ◽  
Author(s):  
Huaixiao Ma ◽  
Jinglei Zhai ◽  
Haifeng Wan ◽  
Xiangxiang Jiang ◽  
Xiaoxiao Wang ◽  
...  
Keyword(s):  
In Vitro Culture ◽  
Cynomolgus Monkey ◽  
Primordial Germ Cells ◽  
Lineage Specification ◽  
Single Cell Rna Sequencing ◽  
Human Embryogenesis ◽  
Key Events ◽  
Anterior Posterior

Gastrulation is a key event in embryonic development when the germ layers are specified and the basic animal body plan is established. The complexities of primate gastrulation remain a mystery because of the difficulties in accessing primate embryos at this stage. Here, we report the establishment of an in vitro culture (IVC) system that supports the continuous development of cynomolgus monkey blastocysts beyond early gastrulation up to 20 days after fertilization. The IVC embryos highly recapitulated the key events of in vivo early postimplantation development, including segregation of the epiblast and hypoblast, formation of the amniotic and yolk sac cavities, appearance of the primordial germ cells, and establishment of the anterior-posterior axis. Single-cell RNA-sequencing analyses of the IVC embryos provide information about lineage specification during primate early postimplantation development. This system provides a platform with which to explore the characteristics and mechanisms of early postimplantation embryogenesis in primates with possible conservation of cell movements and lineages in human embryogenesis.

scholarly journals Concurrent Prediction of Muscle and Tibiofemoral Contact Forces During Treadmill Gait

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Trent M. Guess ◽  
Antonis P. Stylianou ◽  
Mohammad Kia
Keyword(s):  
Femoral Component ◽  
Gait Cycle ◽  
Musculoskeletal Model ◽  
Contact Forces ◽  
Grand Challenge ◽  
Subject Specific ◽  
The Right ◽  
Anterior Posterior ◽  
Rms Errors

Detailed knowledge of knee kinematics and dynamic loading is essential for improving the design and outcomes of surgical procedures, tissue engineering applications, prosthetics design, and rehabilitation. This study used publicly available data provided by the “Grand Challenge Competition to Predict in-vivo Knee Loads” for the 2013 American Society of Mechanical Engineers Summer Bioengineering Conference (Fregly et al., 2012, “Grand Challenge Competition to Predict in vivo Knee Loads,” J. Orthop. Res., 30, pp. 503–513) to develop a full body, musculoskeletal model with subject specific right leg geometries that can concurrently predict muscle forces, ligament forces, and knee and ground contact forces. The model includes representation of foot/floor interactions and predicted tibiofemoral joint loads were compared to measured tibial loads for two different cycles of treadmill gait. The model used anthropometric data (height and weight) to scale the joint center locations and mass properties of a generic model and then used subject bone geometries to more accurately position the hip and ankle. The musculoskeletal model included 44 muscles on the right leg, and subject specific geometries were used to create a 12 degrees-of-freedom anatomical right knee that included both patellofemoral and tibiofemoral articulations. Tibiofemoral motion was constrained by deformable contacts defined between the tibial insert and femoral component geometries and by ligaments. Patellofemoral motion was constrained by contact between the patellar button and femoral component geometries and the patellar tendon. Shoe geometries were added to the feet, and shoe motion was constrained by contact between three shoe segments per foot and the treadmill surface. Six-axis springs constrained motion between the feet and shoe segments. Experimental motion capture data provided input to an inverse kinematics stage, and the final forward dynamics simulations tracked joint angle errors for the left leg and upper body and tracked muscle length errors for the right leg. The one cycle RMS errors between the predicted and measured tibia contact were 178 N and 168 N for the medial and lateral sides for the first gait cycle and 209 N and 228 N for the medial and lateral sides for the faster second gait cycle. One cycle RMS errors between predicted and measured ground reaction forces were 12 N, 13 N, and 65 N in the anterior-posterior, medial-lateral, and vertical directions for the first gait cycle and 43 N, 15 N, and 96 N in the anterior-posterior, medial-lateral, and vertical directions for the second gait cycle.

scholarly journals Effects of DCM Leaf Extract of Gnidia glauca (Fresen) on Locomotor Activity, Anxiety, and Exploration-Like Behaviors in High-Fat Diet-Induced Obese Rats

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Wycliffe Makori Arika ◽  
Cromwell Mwiti Kibiti ◽  
Joan Murugi Njagi ◽  
Mathew Piero Ngugi
Keyword(s):  
Locomotor Activity ◽  
High Fat Diet ◽  
Leaf Extract ◽  
Belief Systems ◽  
Activity Patterns ◽  
Phytochemical Analysis ◽  
High Fat ◽  
Neurologic Disorders ◽  
Obese Rats

Obesity is the main component of metabolic syndromes involving distinct etiologies that target different underlying behavioral and physiological functions within the brain structures and neuronal circuits. An alteration in the neuronal circuitry stemming from abdominal or central obesity stimulates a cascade of changes in neurochemical signaling that directly or indirectly mediate spontaneously emitted behaviors such as locomotor activity patterns, anxiety, and exploration. Pharmacological agents available for the treatment of neurologic disorders have been associated with limited potency and intolerable adverse effects. These have necessitated the upsurge in the utilization of herbal prescriptions due to their affordability and easy accessibility and are firmly embedded within wider belief systems of many people. Gnidia glauca has been used in the management of many ailments including obesity and associated symptomatic complications. However, its upsurge in use has not been accompanied by empirical determination of these folkloric claims. The present study, therefore, is aimed at determining the modulatory effects of dichloromethane leaf extract of Gnidia glauca on locomotor activity, exploration, and anxiety-like behaviors in high-fat diet-induced obese rats in an open-field arena. Obesity was experimentally induced by feeding the rats with prepared high-fat diet and water ad libitum for 6 weeks. The in vivo antiobesity effects were determined by oral administration of G. glauca at dosage levels of 200, 250, and 300 mg/kg body weight in high-fat diet-induced obese rats from the 6th to 12th week. Phytochemical analysis was done using gas chromatography linked to mass spectroscopy. Results indicated that Gnidia glauca showed anxiolytic effects and significantly increased spontaneous locomotor activity and exploration-like behaviors in HFD-induced obese rats. The plant extract also contained phytocompounds that have been associated with amelioration of the main neurodegenerative mediators, viz., inflammation and oxidative stress. These findings provide “qualified leads” for the synthesis of new alternative therapeutic agents for the management of neurologic disorders. However, there is a need to conduct toxicity studies of Gnidia glauca to establish its safety profiles.

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