Banca de QUALIFICAÇÃO: TIAGO SIEBERT ALTAVINI

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE: TIAGO SIEBERT ALTAVINI
DATA: 24/04/2015
HORA: 10:50
LOCAL: INSTITUTO DO CÉREBRO
TÍTULO:

Patchy interhemispheric circuits account for a cardinal bias in ongoing activity within early central visual areas.

PALAVRAS-CHAVES:

electrophysiology,circuits, central visual areas, neural ensembles

PÁGINAS: 30
GRANDE ÁREA: Ciências Biológicas
ÁREA: Fisiologia
RESUMO:

Ongoing brain activity has spatial features resembling neural ensembles co-activated by stimulation or task performance (Kenet et al., 2003; Smith et al.,2009). These ongoing maps are likely linked to the functional architecture of the brain, i.e. to the patchy network of long-range intra and corticocortical intrinsic and/or feedback connections. In the present work we aim to causally investigate the contribution of patchy connections to intrinsically generated modular orientation maps. We reversibly deactivated parts of contralateral areas 17 and 18 while imaging the corresponding areas in the ipsilateral hemisphere using voltage-sensitive dyes (VSD). Eight adult cats received a craniotomy on both hemispheres partially covering areas 17 and 18. Over the left craniotomy, a recording chamber was implanted for intrinsic signal and VSD imaging. Over the right hemisphere, a surface cryoloop (Lomber et al., 1999) was placed. We also recorded spiking activity with tungsten microelectrode arrays. We recorded evoked activity (through presentation of gratings) and ongoing activity with the cryoloop off (baseline), on (cooling), and 30 minutes after we turned it off again (recover). We confirmed an existing bias for cardinal orientations during baseline (Kenet et al., 2003). The bias disappeared for ongoing but not for evoked activity during deactivation of VIC. Our finding indicates that synapses conveyed by VIC – which can be interpreted as a prolongation of the patchy intracortical network (Schmidt et al. 1997; Rochefort et al. 2009; Schmidt 2013) - are more numerous or stronger between neurons preferring horizontal and/or cardinal contours. 

MEMBROS DA BANCA:
Presidente - 1871878 - KERSTIN ERIKA SCHMIDT
Interno - 1674643 - MARCOS ROMUALDO COSTA
Interno - 1842426 - SERGIO TULIO NEUENSCHWANDER MACIEL