Pós-Graduação em Física oferta colóquio nesta sexta-feira (17)
O coloquialista do evento é Sergio Neuenschwander
O Programa de Pós-Graduação em Física (PPGF) da UFPE promove nesta sexta-feira (17) o colóquio “Mind the map! How cortical layout may account for gamma oscillations”. O evento contará com a presença do professor Sergio Neuenschwander, do Instituto do Cérebro (UFRN). O colóquio ocorrerá no auditório do Departamento de Física, localizado no CCEN, às 16h.
Gamma rhythms have been implicated in visual binding and attention. So far, most of the evidence in support of this hypothesis was based on simplified stimuli such as gratings and bars. Here we use a paradigm in capuchin monkeys that allows for direct comparisons between fixation vs. free-view conditions and gratings vs. natural stimuli. In V1, gamma is characteristically strong for optimally oriented stimuli regardless of the viewing condition. Gamma is surprisingly absent, however, during free viewing of natural images and movies. In a recent study, in collaboration with Martin Vinck (ESI, Frankfurt), we found a distinct class of bursting excitatory cells in monkey V1 for which gamma is highly predictive of its orientation preferences. Notably, these cells are not present in the mouse. Primates, carnivores, and rodents exhibit profound differences in their cortical arrangement. Monkeys and cats show a well-organized layout; similar orientation domains are preferentially connected. Rodents, on the other hand, have a dispersed arrangement (salt-and-pepper). It is possible that the particular robust gamma synchronization commonly observed in cats and monkeys arises from the distinct cortical organization they have. Complex stimuli, such natural scenes, induce fundamentally different patterns of interactions in the cortex, as compared to moving bars or gratings. Thus, gamma oscillations may reflect different activation dynamics without any particular significance for visual processing.
Secretaria da Pós-Graduação