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|Title:||Hippocampal Theta Oscillations and Cross-Frequency Coupling during Spatial Decision-Making|
Santos, Vítor Lopes dos
Ribeiro, Sidarta T. G.
Tort, Adriano B. L.
|Keywords:||Oscillations;Local field potential;Spatial choice;Speed;Radial maze|
|Portuguese Abstract:||Introdução The processing of spatial and mnemonic information is believed to depend on hippocampal theta oscillations (512 Hz). However, in rats both the power and frequency of the theta rhythm are modulated by locomotor activity, which is a major confounding factor when estimating its cognitive correlates. Previous studies have suggested that hippocampal theta oscillations and its modulation of higher frequency rhythms support decisionmaking processes. Objetivos In the present study, we investigated to what extent spatial decisionmaking modulates hippocampal theta oscillations when controlling for variations in locomotion speed. In addition, we measured how the amplitude of lowgamma (2550 Hz), high-gamma (6090 Hz), and highfrequency oscillations (>100 Hz) is modulated by the phase of theta oscillations (crossfrequency coupling). Métodos We recorded local field potentials from the CA1 region of 5 male Wistar rats while animals had to choose one arm to enter for reward (goal) in a fourarm radial maze. The animals were previously trained to achieve 70% of correct choices and four sessions were used to the analyses. We then analyzed intervals of intertrial period (DELAY), decisionmaking (DM), and running to reward (RUN). Trials with similar locomotion speed were used to compare theta power across intervals. We measured crossfrequency coupling within each interval and temporally triggered to the end of DM. Resultados e Conclusões We observed prominent theta oscillations and strong phase modulation of gamma amplitude during DM interval of the task, which occurred in the center of the maze before animals deliberately ran through an arm towards goal location. In speed-controlled analyses, theta power and frequency were higher during the decision period when compared to either an intertrial delay period (also at the maze center), or to the period of running towards goal location (p<0.05, twoway ANOVA followed by Tukey's post hoc test). Moreover, theta activity was higher during decision intervals preceding correct choices than during decision intervals preceding incorrect choices (p<0.05, Student's ttest). Altogether, our data support a cognitive function for the hippocampal theta rhythm in spatial decisionmaking.|
|Appears in Collections:||ICe - Trabalhos apresentados em eventos|
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