PubMed · 9802637
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
A A Loveys. 1998. Measuring temperatures.. https://doi.org/10.1097/00006454-199810000-00015
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
A fundamental discovery of modern human brain imaging with positron-emission tomography that the blood flow to activated regions of the normal human brain increases substantially more than the oxygen consumption has led to a broad discussion in the literature concerning possible mechanisms responsible for this phenomenon. Presently no consensus exists. It is well known that oxygen delivery is not the only function of systemic circulation. Additional roles include delivery of nutrients and other required substances to the tissue, waste removal, and temperature regulation. Among these other functions, the role of regional cerebral blood flow in local brain temperature regulation has received scant attention. Here we present a theoretical analysis supported by empirical data obtained with functional magnetic resonance suggesting that increase in regional cerebral blood flow during functional stimulation can cause local changes in the brain temperature and subsequent local changes in the oxygen metabolism. On average, temperature decreases by 0.2 degrees C, but individual variations up to +/-1 degrees C were also observed. Major factors contributing to temperature regulation during functional stimulation are changes in the oxygen consumption, changes in the temperature of incoming arterial blood, and extensive heat exchange between activated and surrounding brain tissue.
The first electrophysiological recordings from animal and human taste nerves gave clear evidence of thermal sensitivity, and studies have shown that as many as half of the neurons in mammalian taste pathways respond to temperature. Because temperature has never been shown to induce sensations of taste, it has been assumed that thermal stimulation in the gustatory system is somehow nulled. Here we show that heating or cooling small areas of the tongue can in fact cause sensations of taste: warming the anterior edge of the tongue (chorda tympani nerve) from a cold temperature can evoke sweetness, whereas cooling can evoke sourness and/or saltiness. Thermal taste also occurs on the rear of the tongue (glossopharyngeal nerve), but the relationship between temperature and taste is different there than on the front of the tongue. These observations indicate the human gustatory system contains several different types of thermally sensitive neurons that normally contribute to the sensory code for taste.
Explore the source record for details and available documents.