First and foremost, we breathe to absorb oxygen – but this vital rhythm could have other functions as well. In recent years, a number of studies have shown that breathing affects neural processes, including stimulus processing and memory processes. LMU researchers led by Dr. Thomas Schreiner, head of an Emmy Noether junior research group in the Department of Psychology, in collaboration with colleagues from the Max Planck Institute for Human Development in Berlin and the University of Oxford, analyzed how breathing affects the retrieval of previously learned material and recorded what happens in the brain during this process.
For the experiment, 18 participants learned to associate 120 pictures with specific words. Participants were then asked to recall these associations and then asked to recall them again after a two-hour afternoon nap. While this was happening, the researchers recorded their breathing as well as their brain activity via EEG.
Breathing rhythm aids in the multi-stage recall process
Now published on The Journal of Neurosciencethe study results show that participants were better able to recall the words and corresponding pictures when the reminders were presented during or shortly before inhalation. “In the EEG, it becomes apparent, however, that the actual memory retrieval tends to occur during the next exhalation,” Schreiner reports. “Our data thus indicate a kind of functional bifurcation: inhalation is a favorable time to receive the recall cue, while exhalation is a favorable time to actually reconstruct the memory in the brain.” This indicates that respiratory rate modulates the temporal interaction of perception and working memory.
In the EEG recordings, the researchers found two signatures of successful memory, which offer insight into the underlying neural patterns: One was the weakening of certain brain waves—specifically, alpha and beta activity. This suggests that the brain can activate a memory and focus more intensely on retrieval. The second signature consisted of so-called memory reactivations. In successful memory, the same neural patterns that were active during learning reappeared here.
In the experiment, the participants focused entirely on the memory task while maintaining their natural breathing rhythm. “To find out whether useful daily strategies can emerge from our findings, we would need studies with targeted respiratory manipulation,” says first author Esteban Bullón Tarrasó. He also notes the need for more research into older memories. “However, the underlying mechanisms suggest that respiration also plays a role there.”
There may be individual variations in the degree to which memory-related brain processes are synchronized with breathing. The researchers found differences in the degree between participants, from which they conclude that breathing is more effectively linked to neural processes in some people than in others. And if the brain and breath interact better, then memory probably works better accordingly: “Breath is a natural pacemaker for memory processes, underscoring how closely our body and brain interact.”
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