IJS KOLOKVIJ, sreda, 29. 01. 2014; ob 13. uri; prof. dr. Alessandro Treves

[Tanja Debevec]

Vabimo vas na 9. predavanje iz sklopa "Kolokviji na IJS" v letu 2013/14, ki bo v sredo, 29. januarja 2014, ob 13. uri v Veliki predavalnici Instituta »Jožef Stefan«  na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na http://videolectures.net/kolokviji_ijs. 

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prof. dr. Alessandro Treves 

Cognitive Neuroscience, SISSA, Trst, Italija

 

Samo-organizirajoče neevklidske upodobitve v možganih

L. 2005 so v možganih glodalcev odkrili t.i. mrežne celice, katerih dejavnost izraža presenetljivo pravilno metrično delitev ravnega prostora – trikotno mrežo. Te celice se aktivirajo, ko je žival na vozlih imaginarne mreže, ki se razlikuje od nevrona do nevrona. Gradnike mreže so kasneje odkrili tudi pri netopirjih  med plazenjem. Ni jasno, ali ti gradniki tvorijo pravilno 3D mrežo, kot je ploskovno centrirana kubična mreža ali heksagonalni tesni sklad, tudi pri netopirjih med letom.  Večina računalniških modelov tega pojava sloni na neki obliki pravil za povezavo, mi pa smo raziskali model, ki kaže, da se gradniki mreže lahko spontano samoorganizirajo med razvojem živali. Naš model napoveduje, da bodo pri podganah, vzgojenih v kletki z neravno geometrijo, npr. v krogli ali na hiperbolični ploskvi z negativno ukrivljenostjo, gradniki mreže tvorili neevklidsko pravilno pokritje, pri katerem je frekvenca proženja največja pri gradnikih s 5 ali 7 sosedi in ne s evklidskih 6 sosedih kot pri podganah, vzgojenih v ravni kletki. To napoved skušajo preveriti eksperimentalno. 

Predavanje bo v angleščini.

Lepo vabljeni!

 

 

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We invite you to the 9th Institute colloquium in the academic year 2013/14. The colloquium will be held on Wednesday January 29, 2014 at 1 PM in the main Institute lecture hall, Jamova 39, Ljubljana. To read the abstract click  http://www.ijs.si/ijsw/Koledar_prireditev. Past colloquia are posted on  http://videolectures.net/kolokviji_ijs.

 

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prof. dr. Alessandro Treves 

Cognitive Neuroscience, SISSA, Trieste, Italy

 

Self-organizing non-Euclidean representations in the brain

 

In 2005, so-called grid cells have been discovered in the rodent brain. With their activity, grid cells express a remarkably regular metric tessellation of a flat surface - a triangular grid. Their spiking activity is concentrated when the animal is at the nodes of an imaginary grid, different from neuron to neuron. Later found also in crawling bats, it is not clear yet whether in flying bats grid units will provide a regular 3D tiling - such as a face-cubic-centered or hexagonal-close-packed arrangement. Most computational models of this phenomenon are based on various forms of wiring instructions, whereas we have been analyzing a model that demonstrates how grid units can spontaneously self-organize during animal development. Our model predicts that if rats are raised in a cage with non-flat geometry, such as a ball or a hyperbolic surface of negative curvature, grid units will express a non-Euclidean regular tiling, with firing rate peaks that have e.g. 5 or 7 nearest neighbors instead of the Euclidean 6 so far observed with flat cages. Experiments are underway to test this prediction.

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