Neuroskeptic, over on Discover Blogs, has just posted a review of an article now in press at Brain on nineteenth century Italian physiologist Angelo Mosso’s attempts to measure blood flow to the brain. As Neuroskeptic describes, Mosso’s

…early work included studies of the blood pressure in the brains of individuals with skull defects. His most ambitious project, however, was his balance – or as he sometimes called it, according to his daughter, his ‘metal cradle’ or ‘machine to weigh the soul’….

It was in essence just a large balance. A volunteer lay on a table, their head on one side of the scale’s pivot and their feet on the other. It was carefully adjusted so that the two sides were perfectly balanced.

The theory was that if mental activity caused increased brain blood flow, it ought to increase the weight of the head relative to the rest of the body, so that side of the balance would fall.

Mosso claimed that this, indeed, occurred – starting to read a newspaper caused the brain to get weightier, while a difficult book of philosophy was even more effective, presumably because it required more mental effort to understand.

You can read Neuroskeptic’s review online here. Full article details follow below.

“Weighing brain activity with the balance: Angelo Mosso’s original manuscripts come to light,” by S. Sandrone, M. Bacigaluppi, M. R. Galloni, S. F. Cappa, A. Moro, M. Catani, M. Filippi, M. M. Monti, D. Perani, & G. Martino. The abstract reads,

Neuroimaging techniques, such as positron emission tomography and functional magnetic resonance imaging are essential tools for the analysis of organized neural systems in working and resting states, both in physiological and pathological conditions. They provide evidence of coupled metabolic and cerebral local blood flow changes that strictly depend upon cellular activity. In 1890, Charles Smart Roy and Charles Scott Sherrington suggested a link between brain circulation and metabolism. In the same year William James, in his introduction of the concept of brain blood flow variations during mental activities, briefly reported the studies of the Italian physiologist Angelo Mosso, a multifaceted researcher interested in the human circulatory system. James focused on Mosso’s recordings of brain pulsations in patients with skull breaches, and in the process only briefly referred to another invention of Mosso’s, the ‘human circulation balance’, which could non-invasively measure the redistribution of blood during emotional and intellectual activity. However, the details and precise workings of this instrument and the experiments Mosso performed with it have remained largely unknown. Having found Mosso’s original manuscripts in the archives, we remind the scientific community of his experiments with the ‘human circulation balance’ and of his establishment of the conceptual basis of non-invasive functional neuroimaging techniques. Mosso unearthed and investigated several critical variables that are still relevant in modern neuroimaging such as the ‘signal-to-noise ratio’, the appropriate choice of the experimental paradigm and the need for the simultaneous recording of differing physiological parameters.