Directional deep brain stimulation contacts provide greater spatial flexibility for therapy than traditional ring-shaped electrodes, but little is known about longitudinal changes of impedance and orientation. We measured monopolar and bipolar impedance of DBS contacts in 31 patients who underwent unilateral subthalamic nucleus deep brain stimulation as part of a randomized study. At different follow-up visits, patients were assigned new stimulation configurations and impedance was measured. Additionally, we measured the orientation of the directional lead during surgery, immediately after surgery, and (...) 1 year later. Here we contrast impedances in directional versus ring contacts with respect to local anatomy, active stimulation contact, and over time. Directional contacts display larger impedances than ring contacts. Impedances generally increase slightly over the first year of therapy, save for a transient decrease immediately post-surgery under general anesthesia during pulse generator placement. Local impedances decrease at active stimulation sites, and contacts in closest proximity to internal capsule display higher impedances than other anatomic sites. DBS leads rotate slightly in the immediate postoperative period but otherwise remain stable over the following year. These data provide useful information for setting clinical stimulation parameters over time. (shrink)

A publication by Professor Margenau is always of interest to persons concerned with philosophy of science. This is especially true, however, of his recently published book, The Nature of Physical Reality; for this book, dealing with basic epistemological problems arising from the development of modern quantum mechanics, is the most comprehensive and most systematic formulation of its author's philosophical position and is at the same time conceived as a “challenge” to “uncritical realism, unadorned operationalism, and radical empiricism”—to points of view, (...) that is, which Professor Margenau regards as “outmoded and in disharmony with the successful phases of contemporary physics”. (shrink)

Philosophy of science and, more specifically, philosophy of quantum physics can be but special fields of a general philosophy of knowledge; and the problems arising in these fields can be evaluated properly only when they are seen under the perspective of the whole range of human knowledge. This paper deals with problems of quantum physics and, in particular, with the problem of scientific objects in quantum physics from the epistemological point of view previously defined in the author's books, A Philosophy (...) of Science and The Basis and Structure of Knowledge. The argument of the paper, however, has not been stated before in the direct and concise manner here attempted and may therefore contain elements of novelty even for those readers who are familiar with the books just mentioned. (shrink)

Historians generally see ideas as the product of circumstances, looking beyond the idea to the external factor which influenced its acceptance. Behind an idea there are acknowledged or, more commonly, unacknowledged clusters of assumptions shared by a social group. Although these clusters influence thoughts, they cannot be traced as direct causal agents. In the connection between situations and ideas, how the situation is perceived is more important than what is objectively true. Rough causal laws can be outlined by correlating types (...) of social conditions with types of states of mind. Sets of ideas point beyond themselves to the background against which they were framed. (shrink)