January 20, 2014 § 1 Comment
In the late 1880s, Italian scientist Angelo Mosso built an intricate full-body balance and reported that mental activity tips the scales. Now, a modern-day version of Mosso’s “human circulation balance” backs him up…
Right after a two-second blip of either audio or audio and video, blood leaves the brain, as measured by a drop in force, Field and Inman found. This quick dip in blood volume, a phenomenon that’s also seen in functional MRI, may represent the brain preparing for work by shunting waste-ridden blood out via the jugular vein. Seconds after that, a surge of new blood enters the brain, increasing the force measured by the scale.
These changes in force were very small — about 0.005 newtons — and most prominent in the people who both listened to music and watched a video, Field says. It’s hard to calculate how much blood rushes into the brain with each mental task. To know that value, scientists would need to know the distance of the head from the lever’s fulcrum, which could be easily measured, and exactly where the blood came from, which is nearly impossible to know.
In his original experiments, Mosso found that tasks that required more mental energy made the brain heavier. Reading a page from a mathematics manual seemed to tip the balance more than reading a page from a newspaper. Strong emotions also tipped the scales: When a subject read a letter from an angry creditor, Mosso wrote, “the balance fell at once.” read more
PHOTOGRAPH: Mike Hollingshead
December 10, 2013 § Leave a comment
During the past decade or two, there’s been a growing body of work arguing for a special connection between endogenous brain rhythms and timing patterns in speech. Thus Anne-Lise Giraud & David Poeppel, “Cortical oscillations and speech processing: emerging computational principles and operations”, Nature Neuroscience 2012:
Neuronal oscillations are ubiquitous in the brain and may contribute to cognition in several ways: for example, by segregating information and organizing spike timing. Recent data show that delta, theta and gamma oscillations are specifically engaged by the multi-timescale, quasi-rhythmic properties of speech and can track its dynamics. We argue that they are foundational in speech and language processing, ‘packaging’ incoming information into units of the appropriate temporal granularity. Such stimulus-brain alignment arguably results from auditory and motor tuning throughout the evolution of speech and language and constitutes a natural model system allowing auditory research to make a unique contribution to the issue of how neural oscillatory activity affects human cognition…
A possible weakness of Luo and Poeppel 2007 (a fascinating and deservedly influential study) was that the same phase analysis that they found to identify the brain responses to different sentences also worked in exactly the same way when applied to the amplitude envelope of the original audio. This suggests that simple modulation of auditory-cortex response by input signal amplitude might be the main mechanism, rather than any more elaborate process of phase-locking of endogenous brain rhythms. read more
MAP: Environmental Agency