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Previous issue date: 2011-12-02 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Brain oscillation are not completely independent, but able to interact with each other
through cross-frequency coupling (CFC) in at least four different ways: power-to-power,
phase-to-phase, phase-to-frequency and phase-to-power. Recent evidence suggests that not
only the rhythms per se, but also their interactions are involved in the execution of cognitive
tasks, mainly those requiring selective attention, information flow and memory consolidation.
It was recently proposed that fast gamma oscillations (60 150 Hz) convey spatial
information from the medial entorhinal cortex to the CA1 region of the hippocampus by
means of theta (4-12 Hz) phase coupling. Despite these findings, however, little is known
about general characteristics of CFCs in several brain regions. In this work we recorded local
field potentials using multielectrode arrays aimed at the CA1 region of the dorsal
hippocampus for chronic recording. Cross-frequency coupling was evaluated by using
comodulogram analysis, a CFC tool recently developted (Tort et al. 2008, Tort et al. 2010).
All data analyses were performed using MATLAB (MathWorks Inc). Here we describe two
functionally distinct oscillations within the fast gamma frequency range, both coupled to the
theta rhythm during active exploration and REM sleep: an oscillation with peak activity at
~80 Hz, and a faster oscillation centered at ~140 Hz. The two oscillations are differentially
modulated by the phase of theta depending on the CA1 layer; theta-80 Hz coupling is
strongest at stratum lacunosum-moleculare, while theta-140 Hz coupling is strongest at
stratum oriens-alveus. This laminar profile suggests that the ~80 Hz oscillation originates
from entorhinal cortex inputs to deeper CA1 layers, while the ~140 Hz oscillation reflects
CA1 activity in superficial layers. We further show that the ~140 Hz oscillation differs from
sharp-wave associated ripple oscillations in several key characteristics. Our results
demonstrate the existence of novel theta-associated high-frequency oscillations, and suggest a
redefinition of fast gamma oscillations / As oscila??es cerebrais n?o s?o completamente independentes, mas capazes de
interagir umas com as outras atrav?s de acoplamentos entre frequ?ncias (cross-frequency
coupling, doravante CFC) em pelo menos quatro diferentes modalidades: amplitudeamplitude,
fase-fase (coer?ncia), fase-frequ?ncia e fase-amplitude. Evid?ncias recentes
sugerem que n?o somente os ritmos per se, mas tamb?m as intera??es entre eles est?o
envolvidas na execu??o de tarefas cognitivas, principalmente aquelas que requerem aten??o
seletiva, transmiss?o de informa??es e consolida??o de mem?rias. Estudos recentes prop?em
que oscila??es gama alto (60 150 Hz) transferem informa??es espaciais do c?rtex entorrinal
medial para a regi?o CA1 do hipocampo atrav?s do acoplamento com a fase de teta (4 12
Hz). Apesar destas descobertas, entretanto, pouco se sabe sobre as caracter?sticas gerais dos
CFCs em diversas regi?es cerebrais. Neste trabalho, registramos potenciais de campo local
usando matrizes de multieletrodos implantadas no hipocampo dorsal para registro neural
cr?nico. O acoplamento fase-amplitude foi avaliado por meio da an?lise de comodulogramas,
uma ferramenta de CFC desenvolvida recentemente (Tort et al. 2008, Tort et al. 2010). Todas
as an?lises de dados foram realizadas em MATLAB (MathWorks Inc). Descrevemos duas
oscila??es funcionalmente distintas dentro da faixa de frequ?ncia de gama, ambas acopladas
ao ritmo teta durante explora??o ativa e sono REM: uma oscila??o com um pico de atividade
em ~80 Hz e uma mais r?pida centrada em ~140 Hz. As duas oscila??es s?o diferencialmente
moduladas pela fase de teta conforme a camada de CA1; o acoplamento teta-80 Hz ? mais
forte no stratum lacunosum-moleculare, enquanto que o acoplamento teta-140 Hz ? mais forte
no stratum oriens-alveus. Este perfil laminar sugere que a oscila??o de 80 Hz origina-se das
entradas do c?rtex entorrinal para as camadas profundas de CA1, e que a oscila??o de 140 Hz
reflete a atividade de CA1 em camadas superficiais. Ademais, n?s mostramos que a oscila??o
de 140 Hz difere-se das oscila??es ripples associadas com sharp-waves em diversos aspectos
chave. Nossos resultados demonstram a exist?ncia de novas oscila??es de alta frequ?ncia
associadas ? teta e sugerem uma redefini??o das oscila??es gama alto
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17019 |
| Date | 02 December 2011 |
| Creators | Teixeira, Robson Scheffer |
| Contributors | CPF:96602767020, http://lattes.cnpq.br/3181888189086405, Ara?jo, Dr?ulio Barros de, CPF:50554310163, http://lattes.cnpq.br/7818012155694188, Amaral, Olavo Bohrer, CPF:95668128091, http://lattes.cnpq.br/4987439782337345, Ribeiro, Sidarta Tollendal Gomes, Tort, Adriano Bretanha Lopes |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Neurociencias, UFRN, BR, Neurobiologia Celular e Molecular; Neurobiologia de Sistemas e Cogni??o; Neurocomputa??o Neuroengen |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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