Jimmy Hernandez

Undergraduate Student
Univ of Montreal
Email author

Age-related changes in phase-amplitude coupling between frontal cortex and the hippocampus

Hernandez, J., Dubé, J., Aumont, T., Lina, J.-M., Carrier, J.


Hi and welcome to my presentation!

I completed my B.Sc. in Cognitive Neuroscience at the University of Montreal and I'm joining the M.Sc. Neuroscience program this fall. During the last years at the Center for Advanced Research in Sleep Medicine, I have become familiar with different EEG analytical methods and my interests have focused on functional connectivity. I believe that sleep is a state of consciousness which offers the opportunity to study the intrinsic activity of the brain and the literature relating sleep to different pathological condition has grown exponentially during the last decades.

This summer, my project has focused on phase-amplitude coupling analysis during NREM sleep and whether there is an age-related change in the coupling of different oscillations that have been associated with memory consolidation between hippocampal and cortical sites.

Click on the Presentation button to view my abstract and poster.

I look forward to tell you more about my project on Tuesday, August 10 from 3:10-4:30 PM.


Age-related changes in phase-amplitude coupling between frontal cortex and the hippocampus

Hernandez, J., Dubé, J., Aumont, T., Lina, J.-M., Carrier, J.

Non-Rapid Eye Movement (NREM) sleep is characterized by three cardinal oscillations within distinct frequency bands (i.e. slow-waves (SW; 0.25-4 Hz), sleep-spindles (SS; 10-16 Hz) and hippocampal sharp-wave ripples (SWR; 150-200 Hz)). Several studies have proposed a fine temporal tuning between these oscillations which could reflect a physiological mechanism of memory consolidation during NREM sleep (Staresina et al., 2015; Maingret et al., 2016). On the other hand, it is well known that aging is related to a qualitative and quantitative diminution of sleep quality as well as an impaired ability to form new hippocampal-dependent memories (Mader et al., 2017). It has been shown that aging leads to desynchronization and uncoupling of SW and SS, which predict an impaired overnight memory consolidation (Helfrich et al., 2018). No animal or human aging study has assessed whether there is an age-related uncoupling of cortical SW with hippocampal SWR.

Here, we aim to study the coupling between hippocampal SWR and frontal SW and SS between young and older healthy mice. We hypothesize that the coupling strength linking these frequency bands will be diminished in older mice compared to younger mice.

To assess this research question, 10 young (mean age : 7.5 months) and 10 older (mean age : 15.5 months) C57BL\6 mice underwent a week-long continuous recording from 5 cortical local-field potential (LFP) electrodes as well as one hippocampal LFP. Vigilance states were determined by a semi-automated algorithm and NREM sleep was segmented in 4s epochs for coupling analyzes. To estimate the degree of phase-amplitude coupling (PAC), we used a data-driven approach based on the Modulation Index (Tort et al., 2008) to compute PAC values between a large range of frequencies. Significance was assessed with permutation testing using 500 iterations at each coupling computation. Group differences were examined using a mixed-model ANOVA.