Introduction: Although deep brain stimulation often improves levodopa-responsive gait symptoms, robust therapies for gait dysfunction from Parkinson's disease remain a major unmet need. Walking speed could represent a simple, integrated tool to assess DBS efficacy but is often not examined systematically or quantitatively during DBS programming. Here we investigate the reliability and functional significance of changes in gait by directional DBS in the subthalamic nucleus.Methods: Nineteen patients underwent unilateral subthalamic nucleus DBS surgery with an eight-contact directional lead in the most (...) severely affected hemisphere. They arrived off dopaminergic medications >12 h preoperatively and for device activation 1 month after surgery. We measured a comfortable walking speed using an instrumented walkway with DBS off and at each of 10 stimulation configurations at the midpoint of the therapeutic window. Repeated measures of ANOVA contrasted preoperative vs. maximum and minimum walking speeds across DBS configurations during device activation. Intraclass correlation coefficients examined walking speed reliability across the four trials within each DBS configuration. We also investigated whether changes in walking speed related to modification of step length vs. cadence with a one-sample t-test.Results: Mean comfortable walking speed improved significantly with DBS on vs. both DBS off and minimum speeds with DBS on. Pairwise comparisons showed no significant difference between DBS off and minimum comfortable walking speed with DBS on. Intraclass correlations were ≥0.949 within each condition. Changes in comfortable walk speed were conferred primarily by changes in step length.Conclusion: Acute assessment of walking speed is a reliable, clinically meaningful measure of gait function during DBS activation. Directional and circular unilateral subthalamic DBS in appropriate configurations elicit acute and clinically significant improvements in gait dysfunction related to PD. Next-generation directional DBS technologies have significant potential to enhance gait by individually tailoring stimulation parameters to optimize efficacy. (shrink)

The Cambridge Edition of the Works of Immanuel Kant: Vol. I, Theoretical Philosophy, 1755?1770. Ed. and tr. by D. Walford in collaboration with R. Meerbote, Cambridge University Press, 1992. lxxxi + 543 pp. £50.00 The Cambridge Edition of the Works of Immanuel Kant: Vol. DC, Lectures on Logic. Ed. and tr. by J. Michael Young, Cambridge University Press, 1992. xxxii + 695 pp. £50.00 The Genesis of Kant's Critique of Judgment by John H. Zammito, University of Chicago Press, 1992.490 pp. (...) £51.95 hb; £15.25 pb. (shrink)

The central theme of this book concerns the structure of narratives and the analysis of a special class of narrative sentences. This seemingly specialized technical job has surprisingly broad and fruitful application. In the course of a single connected argument the author manages to throw light on a wide range of problems that have puzzled philosophical students of history including the relation between speculative philosophy of history and history proper, the verification of statements about the past, the alleged relativism of (...) historical interpretation, the distinction between "history" and "chronicle," the nature of historical explanation, and the debate about methodological individualism. The argument also draws upon and contributes to discussions dealing with some broader issues generally carried on outside the context of the philosophy of history such as the logic of temporal language and the problem of future contingencies. The approach is fresh and exciting, the style both clear and lively.—R. C. S. (shrink)

The aim of this study was to test red - green dichromats' ability to discriminate between illuminant and surface-reflectance changes in natural scenes. Stimuli were simulations of natural scenes presented on a colour monitor with 10-bit resolution per gun. The natural scenes were obtained with a fast hyperspectral imaging system. Six different scenes (including rocks, foliage, and buildings) were tested. In each trial, two images were presented in sequence, each for 1 s, with no interval. The images differed in the (...) phase of daylight on the scene: first with correlated colour temperature 25 000 K, then 6 700 K. The spectral reflectance of a region in the second image was changed randomly, consistent with a local change in daylight. The observer's task was to decide whether a particular surface in the successive images was the same (pure illuminant change) or different (illuminant change with a surface-reflectance change). The performance of four deuteranopes and five protanopes varied considerably across the scenes tested, with mean colour constancy indices (± 1 SEM) of 0.48 (± 0.13) and 0.19 (± 0.10), respectively (1.0 representing ideal performance). Deuteranopes seemed less disadvantaged than protanopes, performing close to normal with some scenes. (shrink)

This is a daring and unusual book. It presents a selection of Wittgenstein’s texts without engaging in commentary or criticism, and yet it openly interprets. Guided by the conviction that Wittgenstein is a phenomenologist of the life-world, Brand intersperses textual citations with close paraphrase. While managing to preserve the resolutely unsystematic and evocative style of Wittgenstein’s texts, the paraphrases give a phenomenological tone to many familiar passages and gradually succeed in unfolding a tacit inner unity to his work. The book’s (...) organization is thematic rather than chronological: texts from different periods complement and confront one another in a succession of chapters which focus on such core themes as certainty, world, temporality, meaning, rule, understanding, and givenness. Brand does not attempt to dissipate the tensions between earlier and later works, although he does not include those earlier conceptions that Wittgenstein unequivocally rejected. However, the interpretative paraphrases do tend to soften the conflicts by suggesting the different perspectives from which apparently contradictory statements have been made. Brand attributes the "destructive" and therapeutic style of much of the late work to the phenomenological insight, that authentic comprehension lies hidden beneath the distortions generated by inappropriate theories and by the confusion of language games. (shrink)

A study of the influences which helped to shape the language and the logic of Charles Darwin from 1837 to 1844, the period in which he composed the first drafts of the theory of natural selection. The textual basis of this book is provided by two sets of notebooks which deal with the "transmutation of species" and "metaphysics... morals and speculations on expression." That Darwin preferred metaphors borrowed from ordinary language to the technical idiom of other scientific theories Manier attributes (...) to the influence of both Dugald Stewart’s philosophy of natural language and William Wordsworth’s conviction that nature is of itself expressive. The theme that nature has its own language suggested a continuity between the processes of the inanimate world and the spiritual capacities of man and hence provided a congenial philosophic context for the elaboration of Darwin’s theory of natural selection. Darwin’s rhetorical style thus reinforces his own theory, because the highest human activities are explainable in images taken from nature. These metaphors had both a cognitive and an affective dimension, since they enabled his readers to see the evidence of natural history in a new light, and served to soften the shocking theological implications of this new perspective. The idea of nature as an outcome of struggle among random variants obviously clashed with the contemporary religious view of nature as God’s handiwork, but the metaphor of selection personifies nature and suggests the possibility of a divinity immanent in nature. In this regard, it is interesting to note that Darwin was quite impressed by Wordsworth’s version of natural religion. William Paley’s theodicy also intrigued the young Darwin. Paley argued that chance was compatible with divine design, since God’s moral purposes could be represented through the metaphor of a fair lottery where the chances are evenly distributed but the results unforeseeable. Darwin took this concept of chance out of its apologetical context and employed it in the construction of his scientific theory. (shrink)

This invaluable resource is the first one-volume, in-depth, comprehensive history of modern science ever published.