Re: In What types of conditions does the brain work best?

This is an interesting science project in an area that has not be widely researched. I also could not find information about postion or posture on brain chemicals. The changes in blood flow and intracranial pressure associated with the changes in posture you are going to produce in your experiment may not change brain chemicals. That is a good reason to try your experiment.

I did find an article about the perception of gravity in people in different postures, including two postures similar to the ones you will be using. It is difficult to understand, but the article seems to suggest that the perception of gravity may affected by our cardiovascular system as well as our vestibular (inner ear) system. The author goes futher and suggests that the cardiovascular system effects are mediated by the sympatheic nervous system. I found another article that suggests that sympathetic nervous system function is not as good in Alzheimer's Disease patients as in people without Alzheimer's Disease. Memory loss in one of the symptoms of Alzheimer's Disease. These two articles together may be thought of as providing some support to the idea that posture and memory are related. The abstracts of the articles are below. I also found a newspaper article relating cardiovascular function to brain function (http://news.bbc.co.uk/hi/english/sci/tech/newsid_406000/406334.stm). This news article is from a research paper by Arthur F. Kramer, Sowon Hahn, Neal J. Cohen, Marie T. Banich, Edward McAuley, Catherine R. Harrison, Julie Chason, Eli Vakil, Lynn Bardell, Richard A. Boileau, and Angela Colcombe. (Ageing, fitness and neurocognitive function. Nature, July 29 1999, volume 400, pages 418 - 419.

"Somatic versus vestibular gravity reception in man." by H. Mittelstaedt of (Annal of the New York Academy of Science, May 22 1992, volume 656, pages 124-39), Max-Planck-Institut fur Verhaltensphysiologie, Seewiesen, Germany.

In order to assess the effect of extravestibular gravity receptors on perception and control of body position against that of the otoliths, the subject (S) is exposed to gravitoinertial forces along the spinal (Z) axis on a tiltable board and on a sled centrifuge. It turns out that (1) both effects, on average, are equally strong, although with considerable variance between Ss; (2) the centroid of the mass(es) governing the somatic receptors lies near the centroid of the body; and (3) somatic gravity reception contains two distinctly different systems. Both appear unimpaired in paraplegic Ss with total bilateral sensory loss (TSL) from the 5th to the 1st lumbar spinal segment. One, the truncal system, is eliminated with TSL from the 11th thoracic segment upwards. Yet another is still functioning with TSL up to and including the 6th cervical segment, with the same effectiveness throughout this range. Hence it must be mediated by vagal or, less likely, sympathetic afference, that is, probably, by the influence of gravity on the cardiovascular system. That the afference of the truncal system appears to enter the cord at the last two thoracic segments supports earlier conjectures about a supererogatory static function of the kidneys. In fact, on the tiltable board, 7 bilaterally nephrectomized Ss behaved like paraplegics with TSL between T11 and C6, yet differed significantly in the predicted direction from the normal controls.

S. Borson, R. F. Barnes, R. C. Veith, J. B. Halter, and M. A. Raskind MA. I"mpaired sympathetic nervous system response to cognitive effort in early Alzheimer's disease." Journal of Gerontology, January 1989, volume 44 issue 1, pages M8 to M12.

Sympathetic nervous system responses to a cognitive challenge and a physiologic stimulus (upright posture) were compared in 10 patients with early Alzheimer's Disease and a group of healthy older adults. Plasma catecholamine and cardiovascular responses to upright posture were similar in the two groups. However, sympathetic activation during mental effort was impaired in the patient group; this difference did not appear to be attributable to motivational factors. Alzheimer's Disease is associated with a defect in sympathetic nervous system function that is specifically linked to cognitive effort and appears early in the course of the disease.