Background: Magnetic resonance spectroscopic imaging is a neuroimaging technique that may be useful for non-invasive mapping of brain temperature over a large brain volume. To date, intra-subject reproducibility of MRSI-based brain temperature has not been investigated. The objective of this repeated measures MRSI-t study was to establish intra-subject reproducibility and repeatability of brain temperature, as well as typical brain temperature range.Methods: Healthy participants aged 23–46 years were scanned at two time points ~12-weeks apart. Volumetric MRSI data were processed by reconstructing (...) metabolite and water images using parametric spectral analysis. Brain temperature was derived using the frequency difference between water and creatine for 47 regions of interest delineated by the modified Automated Anatomical Labeling atlas. Reproducibility was measured using the coefficient of variation for repeated measures, and repeatability was determined using the standard error of measurement. For each region, the upper and lower bounds of Minimal Detectable Change were established to characterize the typical range of TCRE values.Results: The mean global brain temperature over all subjects was 37.2°C with spatial variations across ROIs. There was a significant main effect for time [F = 37.0, p < 0.0001] and for brain region [F = 2.66, p < 0.0001]. The time*brain region interaction was not significant [F = 0.80, p = 0.83]. Participants' TCRE was stable for each ROI across both time points, with ROIs' COVrep ranging from 0.81 to 3.08% ; majority of ROIs had a COVrep <2.0%.Conclusions: Brain temperature measurements were highly consistent between both time points, indicating high reproducibility and repeatability of MRSI-t. MRSI-t may be a promising diagnostic, prognostic, and therapeutic tool for non-invasively monitoring brain temperature changes in health and disease. However, further studies of healthy participants with larger sample size and numerous repeated acquisitions are imperative for establishing a reference range of typical brain TCRE, as well as the threshold above which TCRE is likely pathological. (shrink)

There have been many claims that quantum mechanics plays a key role in the origin and/or operation of biological organisms, beyond merely providing the basis for the shapes and sizes of biological molecules and their chemical affinities. These range from Schr¨odinger’s suggestion that quantum fluctuations produce mutations, to Hameroff and Penrose’s conjecture that quantum coherence in microtubules is linked to consciousness. I review some of these claims in this paper, and discuss the serious problem of decoherence. I advance some further (...) conjectures about quantum information processing in bio-systems. Some possible experiments are suggested. © 2004 Elsevier Ireland Ltd. All rights reserved. (shrink)

Institute of Theoretical Astronomy, University of Cambridge, Cambridge, UK 3fS. received 28th August 1970, in final revised form 1st July 1971..

An inquiry into the nature of the universe draws out the implications of the quantum theory and argues that our universe is only one among many possible universes and that other universes may exist.