What is it about?
This study shows that signals from the heart and lungs, specifically from baroreceptors (BRs), can influence how we become aware of visual stimuli. These bodily signals affect brain activity differently depending on the phase of the cardiac (systole/diastole) and the respiratory (exhalation /inhalation) cycle. These signals affect both the timing and brain areas recruited when subjects become aware of visual stimuli. Key findings: 1. When the BRs are silent (diastole/inhalation), the earliest marker of awareness occurs during the sensory processing stage and subsequently recruits prefrontal cortex. 2. When the BRs are active (systole/exhalation), the earliest marker of awareness occurs during the perceptual processing stage and subsequently recruits parietal cortex.
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Why is it important?
Neuroscience primarily studies brain activity and dismisses signals from the body as noise. We show that awareness-related brain activity is crucially shaped by signals from the body which suggests that they should no longer be considered as noise but as modulators of brain activity. This opens up a new view of brain function that considers its intricate connection to the body.
Perspectives
The cardiac and respiratory cycle are important pacemakers of the body: the cardiac rhythm is the first pacemaker of the mammalian organism and develops before the neural tube; breathing is a similarly constant pacemaker – from our first to our last breath. Awareness can fluctuate across the cardiac and the respiratory cycle and with the state of the brain, and we here closed this gap by linking all three measures in simultaneous recordings. This idea is so simple yet fundamental that it is surprising it has not been done previously.
Juliane Britz
Universite de Fribourg
Read the Original
This page is a summary of: Interoceptive signals shape the earliest markers and neural pathway to awareness at the visual threshold, Proceedings of the National Academy of Sciences, September 2024, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2311953121.
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