Banca de DEFESA: JOSÉ HENRIQUE TARGINO DIAS GÓIS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE: JOSÉ HENRIQUE TARGINO DIAS GÓIS
DATA: 24/02/2015
HORA: 10:00
LOCAL: INSTITUTO DO CÉREBRO
TÍTULO:

EFEITOS DA NICOTINA NO COMPLEXO DO SEPTO MEDIAL NA VIA SEPTO HIPOCAMPAL EM CAMUNDONGOS ANESTESIADOS POR KETAMINA

PALAVRAS-CHAVES:

Electrophysiology, MS/DBB, Hippocampus, Nicotine, Gamma, Theta.

PÁGINAS: 80
GRANDE ÁREA: Ciências Biológicas
ÁREA: Fisiologia
RESUMO:

The hippocampus is known to be crucial to mammals to create new memories; the MS/DBB is the major hippocampal cholinergic input. Early electrophysiological studies proposed MS/DBB as the key structure to theta rhythmogenesis. It has been demonstrated in the literature that nicotine can induce theta rhythm in vitro on both structures. This work investigates the role of nicotine in the MS/DBB on the septo-hippocampal pathway rhythmogenesis in ketamine-anaesthetised mice. My in vivo experiments showed that, although microinfusions of nicotine in the MS/DBB didn’t elicit theta rhythm in either structure, it induced gamma rhythm on both. This increase of gamma can be an electrophysiological substrate to the enhancement on attention reported in psychophysical experiments.

The literature reports that nicotine on MS/DBB depolarizes local glutamatergic neurons to excite both local and projection GABAergic neurons; and that the generation of gamma can be a result of a local network and modulated by conductance of GABA receptors. My experiments corroborates with the current hypothesis of gamma oscillation genesis. Although not present, nicotine-induced theta rhythm couldn’t be observed because of the ketamine-induced delta rhythm. A realistic model implementing known currents – with Hodgkin-Huxley formalism – of the three major neuron types of MS/DBB replicated the gamma oscillation seen in the experiments, higher excitability on glutamatergic neurons would elicit a higher power within gamma rhythm frequency band. In my in vitro experiments, I couldn’t find a neuron that would fire on these findings, supposedly because the lack of afferents that leads the network to a less excited state.

MEMBROS DA BANCA:
Interno - 1764910 - GEORGE CARLOS DO NASCIMENTO
Presidente - 1824636 - RICHARDSON NAVES LEAO
Externo à Instituição - WILFREDO BLANCO FIGUEROLA - UERN