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Nature Neuroscience Mar 2016Recent years have seen a growing interest in inhibitory interneurons and their circuits. A striking property of cortical inhibition is how tightly it balances... (Review)
Review
Recent years have seen a growing interest in inhibitory interneurons and their circuits. A striking property of cortical inhibition is how tightly it balances excitation. Inhibitory currents not only match excitatory currents on average, but track them on a millisecond time scale, whether they are caused by external stimuli or spontaneous fluctuations. We review, together with experimental evidence, recent theoretical approaches that investigate the advantages of such tight balance for coding and computation. These studies suggest a possible revision of the dominant view that neurons represent information with firing rates corrupted by Poisson noise. Instead, tight excitatory/inhibitory balance may be a signature of a highly cooperative code, orders of magnitude more precise than a Poisson rate code. Moreover, tight balance may provide a template that allows cortical neurons to construct high-dimensional population codes and learn complex functions of their inputs.
Topics: Animals; Cerebral Cortex; Models, Neurological; Neural Inhibition; Neurons; Poisson Distribution
PubMed: 26906504
DOI: 10.1038/nn.4243 -
Chaos (Woodbury, N.Y.) Jul 2023Mobile intrinsic localized modes (ILMs) in balanced nonlinear capacitive-inductive cyclic transmission lines are studied by experiment, using a spatiotemporal driver...
Mobile intrinsic localized modes (ILMs) in balanced nonlinear capacitive-inductive cyclic transmission lines are studied by experiment, using a spatiotemporal driver under damped steady-state conditions. Without nonlinear balance, the experimentally observed resonance between the traveling ILM and normal modes of the nonlinear transmission line generates lattice drag via the production of a lattice backwave. In our experimental study of a balanced running ILM in a steady state, it is observed that the fundamental resonance can be removed over extended, well-defined driving frequency intervals and strongly suppressed over the complete ILM driving frequency range. Because both of these nonlinear capacitive and inductive elements display hysteresis our observation demonstrates that the experimental system, which is only partially self-dual, is surprisingly tolerant, regarding the precision necessary to eliminate the ILM backwave. It appears that simply balancing the cell dual nonlinearities makes the ILM envelope shape essentially the same at the two locations in the cell, so that the effective lattice discreteness seen by the ILM nearly vanishes.
PubMed: 37486665
DOI: 10.1063/5.0156547 -
Annual Review of Nutrition Aug 2019Writing this biography forced me to look back over my career as a scientist, teacher, wife, and mother. To my surprise, a lifelong theme emerged that I was unaware of,...
Writing this biography forced me to look back over my career as a scientist, teacher, wife, and mother. To my surprise, a lifelong theme emerged that I was unaware of, that is, the role of maintaining balance between work and family, science and teaching, mentorship and administration, and personal values and challenges. My primary mentor, Dr. Doris Calloway, demonstrated the importance of maintaining balance. My interest in nutrition started as a preschooler living on a farm where I learned firsthand the importance of balancing the expense of providing good nutrition to the livestock with potential income. In our small high school, I became acquainted with the fascinating field of chemistry, but found it critical to balance that interest with a politically correct field of study for a woman in the early 1960s. I chose dietetics for its strong roots in chemistry. As a US Army dietitian, I learned firsthand how to conduct metabolic studies and knew, immediately, that I had to balance that interest with future opportunities feasible for a dietitian. I chose the University of California, Berkeley, for my PhD because it needed to train dietitians in research to balance an emerging need to offer undergraduates a practicum in dietetics. My subsequent faculty appointment there enabled me to develop novel isotopic approaches for studying zinc and prenatal nutrition, and balance my research with teaching and administrative responsibilities. During the next 40 years, my work as a Berkeley professor led to appointments at the Western Human Nutrition Research Center and Children's Hospital Oakland Research Institute, while balancing my responsibilities as a wife and a mother to my two sons. Balance is defined as a condition in which different elements are equal or in the correct proportions. It is extremely satisfying to look back and see evidence of successfully balancing the disparate elements of my career.
Topics: History, 20th Century; History, 21st Century; Nutritional Sciences
PubMed: 30986116
DOI: 10.1146/annurev-nutr-082018-124634 -
Sensors (Basel, Switzerland) Jan 2021Total knee arthroplasty (TKA) surgery with manual instruments provides a quantitatively balanced knee in approximately 50% of cases. This study examined the effect of...
Total knee arthroplasty (TKA) surgery with manual instruments provides a quantitatively balanced knee in approximately 50% of cases. This study examined the effect of combining robotics technology with real-time intra-operative sensor feedback on the number of quantitatively balanced cases in a consecutive series of 200 robotic-assisted primary TKAs. The robotics platform was used to plan the implant component position using correctable poses in extension and a manual, centrally pivoting the balancer in flexion, prior to committing to the femoral cuts. During the initial trialing, the quantitative state of balance was assessed using an instrumented tibial tray that measured the intra-articular loads in the medial and lateral compartments. These sensor readings informed a number of surgical corrections, including bone recuts, soft-tissue corrections, and cement adjustments. During initial trialing, a quantitatively balanced knee was achieved in only 65% of cases. After performing the relevant soft-tissue corrections, bone recuts, and cement adjustments, 87% of cases ended balanced through the range of motion. Meanwhile, this resulted in a wide range of coronal alignment conditions, ranging from 6° valgus to 9° varus. It is therefore concluded that gaps derived from robotics navigation are not indicative for a quantitatively balanced knee, which was only consistently achieved when combining the robotics platform with real-time feedback from intra-operative load sensors.
Topics: Aged; Arthroplasty, Replacement, Knee; Female; Humans; Knee; Knee Joint; Male; Osteoarthritis, Knee; Range of Motion, Articular
PubMed: 33451019
DOI: 10.3390/s21020535 -
EFORT Open Reviews Dec 2018For multifactorial reasons an estimated 20% of patients remain unsatisfied after total knee arthroplasty (TKA).Appropriate tension of the soft tissue envelope...
For multifactorial reasons an estimated 20% of patients remain unsatisfied after total knee arthroplasty (TKA).Appropriate tension of the soft tissue envelope encompassing the knee is important in total knee arthroplasty and soft tissue imbalance contributes to several of the foremost reasons for revision TKA, including instability, stiffness and aseptic loosening.There is debate in the literature surrounding the optimum way to achieve balancing of a total knee arthroplasty and there is also a lack of an accepted definition of what a balanced knee replacement is.It may be intuitive to use the native knee as a model for balancing; however, there are many difficulties with translating this into a successful prosthesis.One of the foundations of TKA, as described by Insall, was that although the native knee has more weight transmitted through the medial compartment this was to be avoided in a TKA as it would lead to uneven wear and early failure. There is a focus on achieving symmetrical tension and pressure and subsequent 'balance' in TKA, but the evidence from cadaveric studies is that the native knee is not symmetrically balanced.As we are currently trying to design an implant that is not based on its anatomical counterpart, is it possible to create a truly balanced prosthesis or to even to define what that balance is? The authors have reviewed the current evidence surrounding TKA balancing and its relationship with the native knee. Cite this article: 2018;3:614-619. DOI: 10.1302/2058-5241.3.180008.
PubMed: 30697441
DOI: 10.1302/2058-5241.3.180008 -
Current Opinion in Anaesthesiology Oct 2008A total balanced volume replacement strategy is a new concept for correcting hypovolemia. To fulfill this concept, balanced colloids, for example, balanced hydroxyethyl... (Comparative Study)
Comparative Study Review
PURPOSE OF THE REVIEW
A total balanced volume replacement strategy is a new concept for correcting hypovolemia. To fulfill this concept, balanced colloids, for example, balanced hydroxyethyl starch (HES) solutions, are necessary in addition to balanced crystalloids. Conventional HES solutions consist of saline with abnormally high concentrations of sodium (154 mmol/l) and chloride (154 mmol/l).
RECENT FINDING
In animal as well as in human studies, the use of HES dissolved in a plasma-adapted solution showed beneficial effects on acid-base status compared with conventional HES dissolved in saline. As the base excess is an important surrogate marker for identifying patients with malperfused tissues, infusion of considerable amounts of unbalanced HES solutions producing low base excess would possibly result in inappropriate clinical interventions. Balancing the HES preparation was associated with significantly fewer alterations in coagulation; dilution of blood with balanced HES showed significantly fewer negative effects on thrombelastography and platelet aggregation than conventional HES.
SUMMARY
Although only a few studies using balanced HES solutions are available at present, it is difficult to argue against using HES preparations that are adapted to plasma instead of HES preparations that contain unphysiologic saline solution. First results are very promising - large clinical trials are necessary to assess the value of a total balanced volume replacement strategy including plasma-adapted HES solutions.
Topics: Animals; Humans; Hydroxyethyl Starch Derivatives; Hypovolemia; Plasma Substitutes; Sodium Chloride
PubMed: 18784499
DOI: 10.1097/ACO.0b013e32830dd05b -
Biometrika Sep 2018The seminal work of Morgan & Rubin (2012) considers rerandomization for all the units at one time.In practice, however, experimenters may have to rerandomize units...
The seminal work of Morgan & Rubin (2012) considers rerandomization for all the units at one time.In practice, however, experimenters may have to rerandomize units sequentially. For example, a clinician studying a rare disease may be unable to wait to perform an experiment until all the experimental units are recruited. Our work offers a mathematical framework for sequential rerandomization designs, where the experimental units are enrolled in groups. We formulate an adaptive rerandomization procedure for balancing treatment/control assignments over some continuous or binary covariates, using Mahalanobis distance as the imbalance measure. We prove in our key result that given the same number of rerandomizations, in expected value, under certain mild assumptions, sequential rerandomization achieves better covariate balance than rerandomization at one time.
PubMed: 30174335
DOI: 10.1093/biomet/asy031 -
The Journal of Arthroplasty Aug 2013Rotational alignment of the femoral component is an important factor to achieve beneficial results in total knee arthroplasty. Femoral rotation pre versus post surgery...
Rotational alignment of the femoral component is an important factor to achieve beneficial results in total knee arthroplasty. Femoral rotation pre versus post surgery was prospectively assessed in 40 patients who underwent ligament balanced knee arthroplasty. Computerized tomography of the knee was performed before and after the surgery to determine the femoral rotation. In 36 out of 40 patients the rotation of the femoral implants differed compared to the preoperative femur (P > 0.001). After surgery the rotational alignment of the femoral component ranged from -3° (internal rotation) to 7° (external rotation). Increased external rotation was found in 33 out of 40 patients ranging from 1° to 7°. These results highlight the importance of individually determined femoral rotation in ligament balanced knee arthroplasty.
Topics: Aged; Aged, 80 and over; Arthroplasty, Replacement, Knee; Female; Femur; Humans; Knee Prosthesis; Male; Prospective Studies; Rotation; Statistics, Nonparametric; Tomography, X-Ray Computed; Treatment Outcome
PubMed: 23540534
DOI: 10.1016/j.arth.2013.02.031 -
Neuron Nov 2021Many studies have shown that the excitation and inhibition received by cortical neurons remain roughly balanced across many conditions. A key question for understanding... (Review)
Review
Many studies have shown that the excitation and inhibition received by cortical neurons remain roughly balanced across many conditions. A key question for understanding the dynamical regime of cortex is the nature of this balancing. Theorists have shown that network dynamics can yield systematic cancellation of most of a neuron's excitatory input by inhibition. We review a wide range of evidence pointing to this cancellation occurring in a regime in which the balance is loose, meaning that the net input remaining after cancellation of excitation and inhibition is comparable in size with the factors that cancel, rather than tight, meaning that the net input is very small relative to the canceling factors. This choice of regime has important implications for cortical functional responses, as we describe: loose balance, but not tight balance, can yield many nonlinear population behaviors seen in sensory cortical neurons, allow the presence of correlated variability, and yield decrease of that variability with increasing external stimulus drive as observed across multiple cortical areas.
Topics: Cerebral Cortex; Models, Neurological; Neurons
PubMed: 34464597
DOI: 10.1016/j.neuron.2021.07.031 -
Pharmaceutical Statistics May 2017Response adaptive randomization (RAR) methods for clinical trials are susceptible to imbalance in the distribution of influential covariates across treatment arms. This...
Response adaptive randomization (RAR) methods for clinical trials are susceptible to imbalance in the distribution of influential covariates across treatment arms. This can make the interpretation of trial results difficult, because observed differences between treatment groups may be a function of the covariates and not necessarily because of the treatments themselves. We propose a method for balancing the distribution of covariate strata across treatment arms within RAR. The method uses odds ratios to modify global RAR probabilities to obtain stratum-specific modified RAR probabilities. We provide illustrative examples and a simple simulation study to demonstrate the effectiveness of the strategy for maintaining covariate balance. The proposed method is straightforward to implement and applicable to any type of RAR method or outcome.
Topics: Clinical Protocols; Computer Simulation; Probability; Random Allocation; Randomized Controlled Trials as Topic
PubMed: 28261972
DOI: 10.1002/pst.1803