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Time perception in the brain

By on May 22, 2017 in Temporal processing | 0 comments

In our previous two entries, we discussed how painters and writers reflected on the passage of time, and we also learned what philosophers and physicists had to say about this issue. Now it’s the time of neurobiology! How does our brain perceive time? What are the neural bases and possible mechanisms underlying time perception? Is there any internal clock or pacemaker? Is timekeeping distributed among different brain areas? Temporal processing is a daunting task. A rich gamut of behaviors depends on our capacity to calibrate and align incoming signals timely. We sample these inputs at various channels, in distant brain areas, and with different processing speeds. However, our brain does an excellent job in generating a coherent picture of the world around us, updating this report to match the fluctuation of external signals. From prestissimo to largo We can compute timing differences...

The time of philosophers

By on Apr 26, 2017 in Philosophy | 0 comments

In the novel A l’ombre des jeunes filles en fleurs (Within a budding grove), written by Marcel Proust in 1919, Madame Swann says: ¨The soldier is convinced that a certain interval of time, capable of being indefinitely prolonged, will be allowed him before the bullet finds him, the thief before he is taken, men in general before they have to die.¨ Such a high hope also pervades Jorge Luis Borges’ tale El Milagro secreto (The secret miracle), included in the collection Ficciones (Fictions). Jorge Luis Borges In this narration, we learn that a writer is going to be executed at 9 am. As he stands in front of the firing squad, thanks to an unexpected intercession, his death is momentarily suspended. First surprised, then grateful, he realises that the world around him came to a timely pause. The bullets froze halfway during their trip, and the curls of smoke from his last cigar have not...

Time in Art

By on Apr 1, 2017 in Painting | 0 comments

In his poem “Time, Real and Imaginary” the English writer Samuel Taylor Coleridge (1772-1834) tells us about an endless race between two kids: a little girl and her blind brother. The girl is taking the lead, but at some point, she looks over her shoulders just to find her brother struggling to catch up. This poem suggests that our imagination flies ahead, transporting us to the realm where everything is possible. On the contrary, our senses anchor us to the present, binding us to the immediate circumstances. This work introduces two substantially different ways of perceiving time. The blind boy symbolizes the metric time that marks the beat of our everyday lives while being unaware of the future and what it will bring to us. But we also have the imaginary time represented by the girl, the time of our expectations, dreams, and plans that defy any measuring system. Unfortunately,...

Miracle in Cremona? The science behind Stradivarius

By on Mar 22, 2017 in Music | 2 comments

An aura of unattainable perfection surrounds the violins created by Cremonese luthiers, particularly those made by Antonio Stradivari and Giuseppe Guarneri ‘del Gesù.’ For many, the Golden Age of violin making (1550-1750) represents an unsurpassed pinnacle. Almost all of the most acclaimed soloists have played on these historical instruments, and still, no objective study permits to establish their supposed tonal superiority over modern ones. Authentication of old Italian violins does not take the quality of their sound into account, relying instead on other parameters (visual inspection, historical research of the instrument, the dating of the wood, etc.). Correlating their performance with specific attributes is not only important for historical reasons but also to guide further improvements in the construction of violins. Recently, Fritz and collaborators decided to test...

Baroque music in France and Italy

By on Mar 22, 2017 in Music | 0 comments

“Antonius Stradivarius Cremonensis faciebat anno 1666”, reads the signature on the first of a famous series of string instruments that would become legendary. Between the “Sunrise” violin from 1677 and his last work, the aptly named “Chant du cygne” (Swansong) from 1737, Stradivari produced around one thousand and one hundred instruments. From this rich legacy, about six hundred have survived to the present day in the hands of musicians and collectors or locked in the safety vaults of investors. Many more could be merely slumbering in their cases, unbothered by the passing of time. Forgotten in taxicabs, stolen, resurfaced in night-clubs or confiscated by the Nazis, these instruments secured for themselves a leading role in a long and outlandish saga. The changing hands through which they passed, recorded in the evocative names with which they conquer auctions (for instance, the “Lady...

Seeing the movement: our visual brain at work

By on Feb 18, 2017 in Vision | 2 comments

Having discussed how painters tackled the problem of representing motion in art, we can, therefore, ask ourselves the following question: how is this type of information processed in our brain? On a different occasion, we will describe the stream of visual information from the retina via the lateral geniculate nucleus (LGN) to the posterior pole of the occipital lobe, which contains the primary visual cortex (V1). From V1, information flows along two channels: a ventral pathway extending towards the temporal lobe and a more dorsal pathway, that projects towards the parietal lobe (see figure below). The ventral stream of information is mainly concerned with establishing identities and building categories of visual objects. Running in an anterior direction from the occipital lobe, neurons lying along this pathway are selectively activated by increasingly more complex visual stimuli....

Motion seen through a painter’s palette

By on Feb 17, 2017 in Painting | 0 comments

The illusion of movement The motion has always fascinated us. In pre-Socratic Greece, Zeno of Elea distrusted its credentials, arguing that “it is impossible to move because what moves must reach the half-way point earlier than the end.” Since the number of half-points between two end-points of a journey is infinite, he concluded that it is impossible to traverse an infinite number of states in a limited time. He was inadvertently sowing the seeds of calculus, which would remain dormant for a while. At the beginning of the XXth century, poets and painters were adamant in proclaiming the virtues of motion and speed. In his Manifesto del futurismo (1909), Marinetti wrote: Up to now, literature has glorified contemplation, ecstasy, and reverie. We want to exalt the aggressive movement, feverish insomnia, the racing step, the deadly leap, the slap and the punch. We declare that the world’s...

Light music for the masses: a story of LEDs

By on Jan 28, 2017 in Vision | 0 comments

Optics: fast and furious imaging With optics coming of age and its widespread use in biomedical sciences, scientists invest substantial efforts in new imaging technologies. The aim is to reconcile versatility, performance and cost issues. Developments take place in the design of new molecules with expanded capabilities (e.g., increased resistance to photodamage, exquisite sensitivity to excitation frequency, chemical stability). But they also pursue the engineering of more flexible sensors and stimulators with improved performance (e.g. higher quantum efficiency detectors, higher signal-to-noise ratios and the choice of selectable wavelengths of excitation with narrower bandwidths). Being able to quickly switch across different stimulation wavelengths while keeping them as narrow as possible is of great value for the experimenter. The optical properties of most materials largely depend...