Efficiency: an underlying principle of learning?

2018 ◽  
Vol 29 (2) ◽  
pp. 183-197 ◽  
Author(s):  
Sean Commins
Keyword(s):  
Multiple Solutions ◽  
Metabolic Cost ◽  
Descriptive Term ◽  
Underlying Principle ◽  
All Solutions ◽  
Metabolic Costs ◽  
Cost Reductions ◽  
The Brain

AbstractLearning is essential. It allows animals to change circumstances, deal with new situations and adapt to environments. Here, we argue that learning, at behavioral and neural levels, involves efficiency, reflected in metabolic cost reductions. Behaviourally, although multiple solutions to a novel problem may be available, all solutions are not learnt – it is too costly. Furthermore, once a strategy has been selected, it is reinforced producing an efficiency that leads to a maximisation of performance and metabolic cost reductions. Learning can be represented in the brain through many mechanisms; however, if learning is truly efficient, then, all such mechanisms should also be accompanied by a reduction in measurable metabolic costs. By thinking about learning in terms of efficiency, not simply as a descriptive term but rather in terms of metabolic costs, it allows learning to be examined more carefully and provides predictions that can be easily tested (and indeed refuted).

scholarly journals Limitations of Foot-Worn Sensors for Assessing Running Power

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 4952
Author(s):  
Tobias Baumgartner ◽  
Steffen Held ◽  
Stefanie Klatt ◽  
Lars Donath
Keyword(s):  
Time Use ◽  
Stride Length ◽  
Metabolic Cost ◽  
Running Economy ◽  
Accelerometer Data ◽  
Gait Characteristics ◽  
Significant Difference ◽  
Metabolic Costs ◽  
Ground Contact Time ◽  
Training Signal

Running power as measured by foot-worn sensors is considered to be associated with the metabolic cost of running. In this study, we show that running economy needs to be taken into account when deriving metabolic cost from accelerometer data. We administered an experiment in which 32 experienced participants (age = 28 ± 7 years, weekly running distance = 51 ± 24 km) ran at a constant speed with modified spatiotemporal gait characteristics (stride length, ground contact time, use of arms). We recorded both their metabolic costs of transportation, as well as running power, as measured by a Stryd sensor. Purposely varying the running style impacts the running economy and leads to significant differences in the metabolic cost of running (p < 0.01). At the same time, the expected rise in running power does not follow this change, and there is a significant difference in the relation between metabolic cost and power (p < 0.001). These results stand in contrast to the previously reported link between metabolic and mechanical running characteristics estimated by foot-worn sensors. This casts doubt on the feasibility of measuring running power in the field, as well as using it as a training signal.

scholarly journals Muscle Metabolic Energy Costs While Modifying Propulsive Force Generation During Walking

2020 ◽  
Author(s):  
Richard E. Pimentel ◽  
Noah L. Pieper ◽  
William H. Clark ◽  
Jason R. Franz
Keyword(s):  
Young Adults ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Energy Costs ◽  
Joint Power ◽  
Lower Limb Muscles ◽  
Age Related ◽  
Musculoskeletal Models ◽  
Metabolic Costs ◽  
Related Increase

AbstractWe pose that an age-related increase in the metabolic cost of walking arises in part from a redistribution of joint power where muscles spanning the hip compensate for insufficient ankle push-off and smaller peak propulsive forces (FP). Young adults elicit a similar redistribution when walking with smaller FP via biofeedback. We used targeted FP biofeedback and musculoskeletal models to estimate the metabolic costs of operating lower limb muscles in young adults walking across a range of FP. Our simulations support the theory of distal-to-proximal redistribution of joint power as a determinant of increased metabolic cost in older adults during walking.

Reduced prosthetic stiffness lowers the metabolic cost of running for athletes with bilateral transtibial amputations

2017 ◽  
Vol 122 (4) ◽  
pp. 976-984 ◽  
Author(s):  
Owen N. Beck ◽  
Paolo Taboga ◽  
Alena M. Grabowski
Keyword(s):  
Lower Limb ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Metabolic Rates ◽  
Distance Running ◽  
Cost Of Transport ◽  
Leg Stiffness ◽  
Metabolic Costs ◽  
In Series ◽  
Reaction Forces

Inspired by the springlike action of biological legs, running-specific prostheses are designed to enable athletes with lower-limb amputations to run. However, manufacturer’s recommendations for prosthetic stiffness and height may not optimize running performance. Therefore, we investigated the effects of using different prosthetic configurations on the metabolic cost and biomechanics of running. Five athletes with bilateral transtibial amputations each performed 15 trials on a force-measuring treadmill at 2.5 or 3.0 m/s. Athletes ran using each of 3 different prosthetic models (Freedom Innovations Catapult FX6, Össur Flex-Run, and Ottobock 1E90 Sprinter) with 5 combinations of stiffness categories (manufacturer’s recommended and ± 1) and heights (International Paralympic Committee’s maximum competition height and ± 2 cm) while we measured metabolic rates and ground reaction forces. Overall, prosthetic stiffness [fixed effect (β) = 0.036; P = 0.008] but not height ( P ≥ 0.089) affected the net metabolic cost of transport; less stiff prostheses reduced metabolic cost. While controlling for prosthetic stiffness (in kilonewtons per meter), using the Flex-Run (β = −0.139; P = 0.044) and 1E90 Sprinter prostheses (β = −0.176; P = 0.009) reduced net metabolic costs by 4.3–4.9% compared with using the Catapult prostheses. The metabolic cost of running improved when athletes used prosthetic configurations that decreased peak horizontal braking ground reaction forces (β = 2.786; P = 0.001), stride frequencies (β = 0.911; P < 0.001), and leg stiffness values (β = 0.053; P = 0.009). Remarkably, athletes did not maintain overall leg stiffness across prosthetic stiffness conditions. Rather, the in-series prosthetic stiffness governed overall leg stiffness. The metabolic cost of running in athletes with bilateral transtibial amputations is influenced by prosthetic model and stiffness but not height. NEW & NOTEWORTHY We measured the metabolic rates and biomechanics of five athletes with bilateral transtibial amputations while running with different prosthetic configurations. The metabolic cost of running for these athletes is minimized by using an optimal prosthetic model and reducing prosthetic stiffness. The metabolic cost of running was independent of prosthetic height, suggesting that longer legs are not advantageous for distance running. Moreover, the in-series prosthetic stiffness governs the leg stiffness of athletes with bilateral leg amputations.

THE ENERGETIC COSTS OF CALLING IN THE BUSHCRICKET REQUENA VERTICALIS (ORTHOPTERA: TETTIGONIIDAE: LISTROSCELIDINAE)

1993 ◽  
Vol 178 (1) ◽  
pp. 21-37 ◽  
Author(s):  
W. J. Bailey ◽  
P. C. Withers ◽  
M. Endersby ◽  
K. Gaull
Keyword(s):  
Body Mass ◽  
Sound Pressure ◽  
Metabolic Cost ◽  
Acoustic Power ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Metabolic Efficiency ◽  
Metabolic Costs ◽  
Sound Pressure Levels ◽  
The Relationship

1. The metabolic costs of calling for male Requena verticalis Walker (Tettigoniidae: Listroscelidinae) were measured by direct recordings of oxygen consumption. The acoustic power output was measured by sound pressure levels around the calling bushcricket. 2. The average metabolic cost of calling was 0.143 ml g-1 h-1 but depended on calling rate. The net metabolic cost of calling per unit call, the syllable, was calculated to be 4.34×10-6+/−8.3×10-7 ml O2 syllable-1 g-1 body mass (s.e.) from the slope of the relationship between total V(dot)O2 and rate of syllable production. The resting V(dot)O2, calculated as the intercept of the relationship, was 0.248 ml O2 g-1 body mass h-1. 3. The energetic cost of calling for R. verticalis (average mass 0.37 g) was estimated at 31.85×10-6 J syllable-1. 4. Sound pressure levels were measured around calling insects. The surface area of a sphere of uniform sound pressure level [83 dB SPL root mean square (RMS) acoustic power] obtained by these measurements was used to calculate acoustic power. This was 0.20 mW. 5. The metabolic efficiency of calling, based on total metabolic energy utilisation, was 6.4 %. However, we propose that the mechanical efficiency for acoustic transmission is closer to 57 %, since only about 10 % of muscle metabolic energy is apparently available for sound production. 6. R. verticalis emits chirps formed of several syllables within which are discrete sound pulses. Wing stroke rates, when the insect is calling at its maximal rate, were approximately 583 min-1. This is slow compared to the rates observed in conehead tettigoniids, the only other group of bushcrickets where metabolic costs have been measured. The thoracic temperatures of males that had been calling for 5 min were not significantly different from those of non-calling males. 7. For R. verticalis, calling with relatively slow syllable rates may reduce the total cost of calling, and this may be a compensatory mechanism for their other high energetic cost of mating (a large spermatophylax).

Metabolic costs of isometric force generation and maintenance of human skeletal muscle

2002 ◽  
Vol 282 (2) ◽  
pp. E448-E457 ◽  
Author(s):  
David W. Russ ◽  
Mark A. Elliott ◽  
Krista Vandenborne ◽  
Glenn A. Walter ◽  
Stuart A. Binder-Macleod
Keyword(s):  
Isometric Force ◽  
Maintenance Phase ◽  
Metabolic Cost ◽  
Force Generation ◽  
Medial Gastrocnemius ◽  
Single Frequency ◽  
Atp Turnover ◽  
Metabolic Costs ◽  
Force Maintenance ◽  
The Cost

During isometric contractions, no true work is performed, so the force-time integral (FTI) is often used to approximate isometric work. However, the relationship between FTI and metabolic cost is not as linear. We tested the hypothesis that this nonlinearity was due to the cost of attaining a given force being greater than that of maintaining it. The ATP consumed per contraction in the human medial gastrocnemius muscle ( n = 6) was determined by use of 31P-NMR spectroscopy during eight different electrical stimulation protocols. Each protocol consisted of 8 trains of a single frequency (20 or 80 Hz) and duration (300, 600, 1,200, or 1,800 ms) performed under ischemic conditions. The cost of force generation was determined from the ATP turnover during the short-duration trains that did not attain a steady force level. Estimates of the cost of force maintenance at each frequency were determined by subtracting the ATP turnover during the shorter-duration trains from the turnover during the long-duration trains. The force generation phase of an isometric contraction was indeed more metabolically costly than the force maintenance phase during both 20- and 80-Hz stimulation. Thus the mean rate of ATP hydrolysis appeared to decline as contraction duration increased. Interestingly, the metabolic costs of maintaining force during 20-Hz and 80-Hz stimulation were comparable, although different levels of force were produced.

Effects of Prosthetic Mass Distribution on Metabolic Costs and Walking Symmetry

2013 ◽  
Vol 29 (3) ◽  
pp. 317-328 ◽  
Author(s):  
Jeremy D. Smith ◽  
Philip E. Martin
Keyword(s):  
Angular Velocity ◽  
Mass Distribution ◽  
Mass Difference ◽  
Center Of Mass ◽  
Metabolic Cost ◽  
Energy Costs ◽  
Swing Time ◽  
Metabolic Costs ◽  
Transtibial Amputees ◽  
Temporal Symmetry

Unilateral, transtibial amputees exhibit walking asymmetries and higher metabolic costs of walking than nonamputees walking at similar speeds. Using lightweight prostheses has previously been suggested as a contributing factor to walking asymmetries. The purpose was to investigate the effects of prosthesis mass and mass distribution on metabolic costs and walking asymmetries among six unilateral, transtibial amputees. Kinematic and temporal symmetry did not improve when mass was added at different locations on the limb. Stance and swing time asymmetries increased by 3.4% and 7.2%, respectively, with loads positioned distally on the limb. Maximum knee angular velocity asymmetries increased by 6% with mass added to the thigh, whereas maximum thigh angular velocity asymmetries increased by approximately 10% with mass positioned near the prosthetic ankle. Adding 100% of the estimated mass difference between intact and prosthetic legs to the ankle of the prosthesis increased energy costs of walking by 12%; adding the same mass to the prosthesis center of mass or thigh center of mass increased metabolic cost by approximately 7% and 5%, respectively. Unless other benefits are gained by increasing prosthesis mass, this should not be considered as a possible alternative to current lightweight prosthesis designs currently being prescribed to unilateral amputees.

scholarly journals External mechanical work in the galloping racehorse

2019 ◽  
Vol 15 (2) ◽  
pp. 20180709 ◽  
Author(s):  
Z. T. Self Davies ◽  
A. J. Spence ◽  
A. M. Wilson
Keyword(s):  
Mechanical Energy ◽  
Metabolic Cost ◽  
Mechanical Work ◽  
External Work ◽  
Thoroughbred Horses ◽  
Metabolic Costs ◽  
The Mean ◽  
And Performance ◽  
Force Data ◽  
Insight Into

Horse locomotion is remarkably economical. Here, we measure external mechanical work of the galloping horse and relate it to published measurements of metabolic cost. Seven Thoroughbred horses were galloped (ridden) over force plates, under a racing surface. Twenty-six full strides of force data were recorded and used to calculate the external mechanical work of galloping. The mean sum of decrements of mechanical energy was −876 J (±280 J) per stride and increments were 2163 J (±538 J) per stride as horses were accelerating. Combination with published values for internal work and metabolic costs for galloping yields an apparent muscular efficiency of 37–46% for galloping, which would be reduced by energy storage in leg tendons. Knowledge about external work of galloping provides further insight into the mechanics of galloping from both an evolutionary and performance standpoint.

scholarly journals The sense of should: A biologically-based framework for modeling social pressure

2019 ◽  
Author(s):  
Jordan E. Theriault ◽  
Liane Young ◽  
Lisa Feldman Barrett
Keyword(s):  
Subjective Experience ◽  
Formal Model ◽  
Metabolic Cost ◽  
Social Pressure ◽  
Developmental Trajectory ◽  
Altruistic Behavior ◽  
Social Environments ◽  
Motivated Cognition ◽  
Social Sanctions ◽  
Metabolic Costs

What is social pressure, and how could it be adaptive to conform to others’ expectations? Existing accounts highlight the importance of reputation and social sanctions. Yet, conformist behavior is multiply determined: sometimes, a person desires social regard, but at other times she feels obligated to behave a certain way, regardless of any reputational benefit—i.e. she feels a sense of should. We develop a formal model of this sense of should, beginning from a minimal set of biological premises: that the brain is predictive, that prediction error has a metabolic cost, and that metabolic costs are prospectively avoided. It follows that unpredictable environments impose metabolic costs, and in social environments these costs can be reduced by conforming to others’ expectations. We elaborate on a sense of should’s benefits and subjective experience, its likely developmental trajectory, and its relation to embodied mental inference. From this individualistic metabolic strategy, the emergent dynamics unify social phenomenon ranging from status quo biases, to communication and motivated cognition. We offer new solutions to long-studied problems (e.g. altruistic behavior), and show how compliance with arbitrary social practices is compelled without explicit sanctions. Social pressure may provide a foundation in individuals on which societies can be built.

A Case of Sturge-Weber Syndrome

1963 ◽  
Vol 109 (459) ◽  
pp. 211-212 ◽  
Author(s):  
J. K. W. Morrice ◽  
Winifred M. Small
Keyword(s):  
Similar Case ◽  
The Self ◽  
The Other ◽  
Pathological Features ◽  
Neurological Condition ◽  
Descriptive Term ◽  
Weber Syndrome ◽  
Original Case ◽  
Sturge Weber Syndrome ◽  
The Brain

In 1879 Sturge described a patient with hemiparesis, epilepsy and a facial naevus. He ascribed the neurological condition to a naevus of the brain similar to that on the patient's face. Weber gained the distinction of providing the other half of the eponym by describing the radiological appearances of a similar case. In 1955, however, he advanced the self-effacing descriptive term “encephalofacial angiomatosis”. The essential pathological features of the disorder are facial naevus and leptomeningeal angiomatosis. It is generally agreed that buphthalmos (present in Sturge's original case) is not a necessary component.

The Brain-Scrambling, Fit-Inducing, Mind-Numbing Technicolor Laser Show

2014 ◽  
Author(s):  
Michael Tansey
Keyword(s):  
Common Sense ◽  
Cell Phones ◽  
Common Reason ◽  
Underlying Principle ◽  
Different Types ◽  
Training Courses ◽  
The Brain ◽  
And Training ◽  
Made In

The main objective is to make presentations less painful and more presentable. Presentations are made in order to provide information to an audience in such a way as to achieve a desired objective, whatever that may be. The objective is unlikely to be achieved unless the audience • wants to listen; • remains interested; • understands; • is convinced. A natural talent for presenting material effortlessly in an informative, entertaining, and engrossing way is shared by few, so most of us put disproportionate reliance on props. The most commonly used props are slides and pointers. Unfortunately, the use of slides and pointers has almost become an end in itself, often obscuring the message. As with all the processes described in this book, the aim here is to apply a core of common sense. This will not address every aspect of the use of slides and pointers or result in the perfect presentation every time (something even the most comprehensive manuals and training courses rarely achieve). What should result with consistency is more clarity and comprehensibility, and less frustration and confusion, all of which should serve to keep an audience from losing interest and fiddling with their cell phones after five minutes. Why use slides? After all, the greatest orators of all time managed to keep audiences spellbound with long recitations (just think of Homer and the Iliad) without using any props or prompts. Okay, so their audiences didn’t have TV or many other alternatives for entertainment, but that does not detract from the underlying principle, namely that audiences are generally primarily interested in what the speaker has to say, not in the props. After all, why else go to a presentation when information is so widely available today in many forms, especially electronically? The question may be answered by thinking about the good reasons for using slides. This is a common reason for most presenters, especially in situations when there is new, lengthy, detailed, or complicated information. Just as presenters have difficulty remembering detailed information, so audiences need time and different types of input (visual, as well as auditory) in order to assimilate new details.

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