Banca de QUALIFICAÇÃO: SERGIO ANDRÉS CONDE OCAZIONEZ

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE: SERGIO ANDRÉS CONDE OCAZIONEZ
DATA: 10/02/2014
HORA: 13:00
LOCAL: Instituto do Cérebro
TÍTULO:

Contribution of lateral connections on multiunit and population activity evoked by composite stimuli in early visual areas

PALAVRAS-CHAVES:

Visual Cortex, Assemblies, Context stimuli

PÁGINAS: 96
GRANDE ÁREA: Ciências Biológicas
ÁREA: Fisiologia
RESUMO:

Since Hubel and Wiesel’s pioneer finding a vast body of literature has accumulated describing neuronal responses in the primary visual cortex (V1) to different visual stimuli. These stimuli mainly consisted of moving bars, dots or gratings which served to explore the response variation to basic features of a visual scene such as orientation, direction of motion or contrast among many others within a classical receptive field (RF). However, in the last two decades it became increasingly evident that the activity of V1 neurons can be modulated by stimulating areas outside their classical RF. V1 is thus probably involved already in more complex visual processes like for example, figure-ground segregation. One key circuit likely to be involved in this kind of processing are long-range lateral connections which can integrate responses of cells with distant receptive fields. Here, we recorded spikes and local field potentials from up to 48 parallel electrodes in the primary visual cortex of anesthetized cats while stimulating with composite grating and natural scene stimuli. In order to examine the influence of lateral connections we removed the inter-hemispheric input of the isotopic contralateral visual areas by means of reversible cooling deactivation. Our results demonstrate that "lateral" interhemispheric connections modulate spike rates and LFP power within the RF dependent on the stimulation of the extra-classical RF surround. Further, we observe an influence of this lateral circuit on the local field’s phase-relationship to spike patterns produced by the population and on spike-field coherences between remote recording sites. In conclusion, our findings are compatible with the hypothesis that long-range lateral connections contribute to the center-surround segregation of composite figures.

MEMBROS DA BANCA:
Interno - 1721223 - ADRIANO BRETANHA LOPES TORT
Presidente - 1871878 - KERSTIN ERIKA SCHMIDT
Interno - 1842426 - SERGIO TULIO NEUENSCHWANDER MACIEL