Banca de DEFESA: NATÁLIA CASTELO BRANCO MATOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : NATÁLIA CASTELO BRANCO MATOS
DATE: 26/11/2020
TIME: 14:00
LOCAL: VÍDEO CONFERÊNCIA
TITLE:

Quantitative analysis of retinogeniculate gamma oscillations in the cat

KEY WORDS:

Retinogeniculate system, gamma oscillations, synchronization, entrainment

PAGES: 50
BIG AREA: Ciências Biológicas
AREA: Fisiologia
SUMMARY:

Retinal gamma oscillations have been observed in a variety of vertebrates. Recent and former evidence points to their involvement in encoding stimulus properties such as size and continuity. To investigate these claims, we started by revisiting already established relationships between oscillation characteristics and different visual stimuli in the anesthetized animal. We analyzed single and multi-unit activity recorded from the retina and LGN of cats while they observed complex (short videos) and simple (light circles) stimuli. In follow-up experiments, the LGN of awake cats was also recorded. The animals were subsequently anesthetized with ketamine and later on, halothane. We observed that under natural stimuli and halothane anesthesia, the oscillatory response elicited by video stimuli was unreliable. It occurred in brief periods, which seemed to mainly reflect image contrast. Large circles presented to anesthetized cats, on the other hand, robustly generated gamma-band oscillations, with its strength modulated by luminance and stimulus size. Interestingly, in the awake or ketamine only anesthetized animals, no oscillations could be detected, although entrainment to the monitor refresh rate was observed up to 120 Hz. Furthermore, gamma oscillation in the cat's retina was dependent on halothane concentration. Gamma activity was drastically reduced as levels of halothane were decreased. Taken together, our results do not support a cognitive role for gamma oscillations in the retinogeniculate system.

BANKING MEMBERS:
Externo à Instituição - JEROME PAUL ARMAND LAURENT BARON - UFMG
Interna - 1871878 - KERSTIN ERIKA SCHMIDT
Presidente - 1842426 - SERGIO TULIO NEUENSCHWANDER MACIEL