Weighing brain activity with the balance: a contemporary replication of Angelo Mosso’s historical experiment

Sir, Sandrone et al. (2012, 2013) rediscovered, translated, and commented on the manuscripts of Angelo Mosso (1882, 1884), in which Mosso described his ‘human circulation balance’; James (1890) described this as a ‘delicately balanced table which could tip downwards either at the head or the foot if the weight of either end were increased’. Mosso claimed that the balance allowed him to observe changes in cerebral blood volume associated with mental effort and emotional responses, and consequently the balance is regarded as the direct forerunner of modern non-invasive functional neuroimaging techniques. However, Sandroneet al. (2012, 2013) stated that ‘we have no direct evidence that the balance was really able, as stated, to measure changes in cerebral blood flow during acts of cognition … despite its proven ability to measure blood volume changes in various organs (e.g. lungs, feet, hands)’

Brain 2014