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Comment
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- By Robert G. Shulman, Yale University Department of Molecular Biophysics and Biochemistry, Ian Shapiro, Yale University Department of Political Science
- Edited by C. Mantzavinos, Witten/Herdecke University
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- Book:
- Philosophy of the Social Sciences
- Published online:
- 05 June 2012
- Print publication:
- 10 September 2009, pp 124-129
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Summary
David Papineau contends that the possibility of science depends on there being uniformly realized phenomena that are reducible to physical laws, not merely the variably realized selection mechanisms that are characteristic of much social science. Some who share Papineau's view regard it as fatal to the possibility of social science on the grounds that their subject matter lacks the uniformly realized phenomena that he regards as necessary for science.
Papineau disagrees with this pessimism, asserting that, like “pain mechanisms,” many cognitive abilities are uniformly realized across humans. As a result, there can be a “rich nexus of laws” about them – though he says nothing about what these laws might be. Not everything social scientists study exhibits what Papineau regards as the necessary reductive feature, but although he sidesteps any attempt to demarcate what he takes to be the scientific zone of the social sciences, he is confident that enough falls within its ambit to make the game worth the candle.
To the extent that human categories are uniformly physically realized, they will function as scientific kinds in a full sense. There will be a wide range of projectible general truths about various facets of human pain, human vision, and human learning. Moreover, to the extent that subjects such as economics and sociology formulate generalizations that depend only on the basic structure of human reasoning, rather than on variably realized learned states, we can expect them to deal with complexes of interrelated generalizations too. It is plausible that many of the principles of economics, political science, and social choice theory will fit this bill.
Papineau, this book, p. 120
NMR of glycogen in exercise
- Thomas B. Price, Douglas L. Rothman, Robert G. Shulman
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- Journal:
- Proceedings of the Nutrition Society / Volume 58 / Issue 4 / November 1999
- Published online by Cambridge University Press:
- 12 June 2007, pp. 851-859
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- Article
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Natural-abundance 13CNMR spectroscopy is a non-invasive technique that enables in vivo assessments of muscle and/or liver glycogen concentrations. Over the last several years, 13C NMR has been developed and used to obtain information about human glycogen metabolism with diet and exercise. Since NMR is non-invasive, more data points are available over a specified time course, dramatically improving the time resolution. This improved time resolution has enabled the documentation of subtleties of muscle glycogen re-synthesis following severe glycogen depletion that were not previously observed. Muscle and liver glycogen concentrations have been tracked in several different human populations under conditions that include: (1) muscle glycogen recovery from intense localized exercise with normal insulin and with insulin suppressed; (2) muscle glycogen recovery in an insulin-resistant population; (3) muscle glycogen depletion during prolonged low-intensity exercise; (4) effect of a mixed meal on postprandial muscle and liver glycogen synthesis. The present review focuses on basic 13C NMR and gives results from selected studies.
Biophysical basis of brain activity: implications for neuroimaging
- Robert G. Shulman, Fahmeed Hyder, Douglas L. Rothman
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- Journal:
- Quarterly Reviews of Biophysics / Volume 35 / Issue 3 / August 2002
- Published online by Cambridge University Press:
- 21 January 2003, pp. 287-325
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1. Summary 288
2. Introduction 288
3. Relationship between neuroenergetics and neurotransmitter flux 294
4. A model of coupling between neuroenergetics and neurotransmission 296
5. Relationship between neuroenergetics and neural spiking frequency 297
6. Comparison with previous electrophysiological and fMRI measurements 298
7. Contributions of non-oxidative energetics to a primarily oxidative brain 299
8. Possible explanation for non-oxidative energetics contributions 300
9. A model of total neuronal activity to support cerebral function 302
10. Implications for interpretation of fMRI studies 305
11. The restless brain 306
12. Acknowledgements 310
13. Appendix A. CMRO2by13C-MRS 310
14. Appendix B.Vcycand test of model 313
15. Appendix C. CMRO2by calibrated BOLD 316
16. Appendix D. Comparison of spiking activity of a neuronal ensemble with CMRO2318
17. References 320
In vivo13C magnetic resonance spectroscopy (MRS) studies of the brain have quantitatively assessed rates of glutamate–glutamine cycle (Vcyc) and glucose oxidation (CMRGlc(ox)) by detecting 13C label turnover from glucose to glutamate and glutamine. Contrary to expectations from in vitro and ex vivo studies, the in vivo13C-MRS results demonstrate that glutamate recycling is a major metabolic pathway, inseparable from its actions of neurotransmission. Furthermore, both in the awake human and in the anesthetized rat brain, Vcyc and CMRGlc(ox) are stoichiometrically related, where more than two thirds of the energy from glucose oxidation supports events associated with glutamate neurotransmission. The high energy consumption of the brain measured at rest and its quantitative relation to neurotransmission reflects a sizeable activity level for the resting brain. The high activity of the non-stimulated brain, as measured by cerebral metabolic rate of oxygen use (CMRO2), establishes a new neurophysiological basis of cerebral function that leads to reinterpreting functional imaging data because the large baseline signal is commonly discarded in cognitive neuroscience paradigms. Changes in energy consumption (ΔCMRO2%) can also be obtained from magnetic resonance imaging (MRI) experiments, using the blood oxygen level- dependent (BOLD) image contrast, provided that all the separate parameters contributing to the functional MRI (fMRI) signal are measured. The BOLD-derived ΔCMRO2% when compared with alterations in neuronal spiking rate (Δν%) during sensory stimulation in the rat reveals a stoichiometric relationship, in good agreement with 13C-MRS results. Hence fMRI when calibrated so as to provide ΔCMRO2% can provide high spatial resolution evaluation of neuronal activity. Our studies of quantitative measurements of changes in neuroenergetics and neurotransmission reveal that a stimulus does not provoke an arbitrary amount of activity in a localized region, rather a total level of activity is required where the increment is inversely related to the level of activity in the non-stimulated condition. These biophysical experiments have established relationships between energy consumption and neuronal activity that provide novel insights into the nature of brain function and the interpretation of fMRI data.