Does freediving lead to hippocampal adaptability to hypoxia and maintenance of episodic memory?
Poster No:
2288
Submission Type:
Abstract Submission
Authors:
Julia Micaux1, Clément Poiret1, Fawzi Boumezbeur1, Jingwen Zhao1, Franck Mauconduit1, Catherine Chiron1, Marion Noulhiane1
Institutions:
1CEA, Gif sur Yvette, France
First Author:
Co-Author(s):
Introduction:
Hypoxia has detrimental effects on the brain, especially on the hippocampus crucial for episodic memory. However, the performance of freedivers (F) suggests an adaptive mechanisms to low oxygen supply. Freediving sports provide a natural model for studying the effects of repeated voluntary hypoxic exposure on brain function in healthy individuals. Our project aims to compare the anatomical hippocampal subfields (HS) and memory performance of "freediving" athletes versus "non-freediving athletes" as controls (C) to study the adaptive mechanisms in the HS after prolonged and repeated exposure to controlled hypoxia during training. This will shed light on the neural plasticity mechanisms underlying this adaptation and pave the way for therapeutic strategies for various neurological conditions that damage hippocampal formation, such as perinatal hypoxia, stroke, or amnesic ictus.
Methods:
To this day, 9 F have been included and completed the 9 months of uniform hypoxia training (ANR-2021, PI-MN). Data collection was carried out before (F0) and after (F1) training. Cerebral MRI was performed at 3T (Magnetom Prisma, Siemens Healthineers) including acquisition of high-resolution T2-weighted images of the HS. The automatic segmentation of the HS was obtained using the HSF software (Poiret et al, 2023). The episodic memory was studied thanks to two tasks of pattern completion (PC) and pattern separation (PS) (Zhao et al, In Prep). The PC task is composed of an encoding phase (images representing a location associated with a gesture) followed by a test phase, with random presentation of items (gesture to associate with a location or the other way around). The PS task is presented next and composed of a test phase with random presentation of items: (i) identical, (ii) similar or (iii) new to the encoding phase. Meanwhile, 16 age- and sex-matched controls (C) were explored similarly, but once and without freediving activities. HS volumes and memory scores were compared before (F0) and after training (F1) in F (within contrasts) and with C (between contrasts).
Results:
The comparison of the HS volumes showed a significant difference for F at the level of the dentate gyrus (Student t-test with Bonferroni correction α= 0,008 F1>F0 p=0,007) and the total volume of the hippocampus (F1>F0 p=0,006) before and after training (F0 – F1). PC scores were significantly different concerning the percentage of correct answers between the two groups "F1 – C" (Student t-test, F1>C p=0,010). PS scores were significantly different between the groups "F1 – C" (Student t-test, F1>C p=0,010), and "F0 – F1" (Student t-test, F1>F0 p=0,028) for the percentage of correct answers concerning the (i) identical items only.
Conclusions:
Although the recruitment of freedivers is still underway, we show that HS are sensitive to freediving training regimen since the dentate gyrus and hence the total volume of the hippocampus has increased in those 9 months. This finding could reflect the anatomical adaptability of hippocampal structure, in particular the potential influence of the neurogenesis in response to controlled hypoxia in the dentate gyrus (Khuu et al, 2019; Lev-Vachnish et al, 2019). Remarkably, not only a maintenance but a significant improvement after training was found in PC and PS, two tasks which imply episodic memory involving the HS.
These results are additional arguments in favour of the positive influence of sport practices, in our case, freediving training on cognitive function; our hypothesis being that such exercise could encourage neurogenesis (Lev-Vachnish et al, 2019).
To conclude, we already highlight significant changes after 9 months of training both in terms of anatomy and episodic memory. The next step will be to link these results to functional and metabolic MR data acquired on the same subjects, to explore further the mechanisms involved in such adaptation at different neurobiological levels.
These results are additional arguments in favour of the positive influence of sport practices, in our case, freediving training on cognitive function; our hypothesis being that such exercise could encourage neurogenesis (Lev-Vachnish et al, 2019).
To conclude, we already highlight significant changes after 9 months of training both in terms of anatomy and episodic memory. The next step will be to link these results to functional and metabolic MR data acquired on the same subjects, to explore further the mechanisms involved in such adaptation at different neurobiological levels.
Learning and Memory:
Long-Term Memory (Episodic and Semantic) 2
Novel Imaging Acquisition Methods:
Anatomical MRI 1
Keywords:
Memory
Segmentation
STRUCTURAL MRI
Other - Hippocampus, hypoxia
1|2Indicates the priority used for review
Provide references using author date format
Lev-Vachnish, Y., et al, 2019. L-Lactate Promotes Adult Hippocampal Neurogenesis. Front Neurosci 13, 403.
Poiret, C., et al, 2023. A fast and robust hippocampal subfields segmentation: HSF revealing lifespan volumetric dynamics. Front Neuroinform 17, 1130845.
Zhao, J., et al, In Prep. An ecological tool evaluating episodic memory patterns (Pattern Separation and Pattern Completion).