Perception: In sync with the heart
Sit back and relax. Close your eyes. Can you feel your heart beating in your chest? What you are experiencing is your heart working in a cyclic manner. During the systolic phase, the heart contracts, ejecting blood into the vessels that lead out of it, and increasing the activity of pressure sensors called baroreceptors. During the diastolic phase, the heart expands, allowing blood to flow into it, while the baroreceptors remain quiescent.
Even though the whole cycle usually takes just under a second, a lot is happening during that time. With every heartbeat, the brain receives input about the strength and precise timing of each cardiac contraction – information that needs to be promptly processed and acted upon if necessary. In recent years, a lot of studies have focused on the internal state of our body and the way we process its subtle signals; and in how physiological fluctuations in our bodies (such as the cardiac cycle) can impact our cognition and behaviour.
Certain behaviours have been shown to occur in sync with internal bodily oscillations (Kunzendorf et al., 2019; Ohl et al., 2016). For example, when we look for something, we fixate our eyes more (i.e., sample new information) during diastole, and move our eyes more (to search new areas) during systole (Galvez-Pol et al., 2020). Moreover, the sensitivity of touch also varies between the two phases: people are less perceptive to touch during systole than during diastole (Al et al., 2020; Motyka et al., 2019). So far, it was unclear what behavioural benefits such synchronicity brings (Herman and Tsakiris, 2021). Now, in eLife, Alejandro Galvez-Pol, Pavandeep Virdee, Javier Villacampa and James Kilner of University College London and the University of the Balearic Islands report new insights on this matter (Galvez-Pol et al., 2022).
In a cleverly designed experiment, Galvez-Pol et al. used electrocardiography to record the cardiac activity of participants while they performed a simple tactile discrimination task. Without looking, the participants had to figure out whether the objects they touched had vertical or horizontal grooves. They found that touches initiated during systole were held for longer than touches initiated during diastole (Figure 1). This was particularly pronounced when it was difficult to discriminate the objects, indicating that people use prolonged touch to compensate for the reduced sensitivity during systole.

Schematic representation of the interplay between cardiac cycles and perception.
The heart beats in a cyclic manner. It contracts to actively push blood around the body (systolic phase, red, top centre) and relaxes to refill again (diastolic phase, blue, bottom centre). Using a tactile discrimination task, Galvez-Pol et al. show that the sensitivity of touch decreases during systole: therefore, to compensate, people hold their fingers longer over an object (red clock), especially when the task was more difficult. Conversely, people will hold their fingers on an object for a shorter time if they start touching it during diastole (blue clock).
Moreover, Galvez-Pol et al. found that the timing of touch also affected the duration of a cardiac cycle. When touch was initiated during systole, it increased the proportion of the cycle in diastole, which had previously been associated with the greatest tactile sensitivity. Thus, people adapt their behaviour in line with their perceptual needs; but their internal bodily cycles also adjust according to external demands to ensure a stable perception of the world around us.
Our bodies work in a rhythmic fashion – a fact that we typically pay little attention to in our daily lives. However, these internal rhythms have a much greater influence on our cognition than previously thought and can modulate how we perceive the environment around us. But there is still a lot to discover. Bodily signals may impact our perception in a relatively simple tactile discrimination task, but do they also affect more complex cognitive processes, such as decision-making? And are individuals, who are more attuned to subtle changes in their physiology, better able to adjust their behaviours to overcome cardiac-related effects? Answering these questions will allow us to better understand the complex interplay between the brain and the rest of the body and, ultimately, better understand ourselves.
References
-
The impact of cardiac afferent signaling and interoceptive abilities on passive information samplingInternational Journal of Psychophysiology 162:104–111.https://doi.org/10.1016/j.ijpsycho.2021.02.010
-
Active information sampling varies across the cardiac cyclePsychophysiology 56:e13322.https://doi.org/10.1111/psyp.13322
-
Microsaccades are coupled to heartbeatThe Journal of Neuroscience 36:1237–1241.https://doi.org/10.1523/JNEUROSCI.2211-15.2016
Article and author information
Author details
Publication history
- Version of Record published: November 17, 2022 (version 1)
Copyright
© 2022, Herman
This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 672
- Page views
-
- 66
- Downloads
-
- 1
- Citations
Article citation count generated by polling the highest count across the following sources: Crossref, PubMed Central, Scopus.
Download links
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Further reading
-
- Genetics and Genomics
- Neuroscience
A hexanucleotide repeat expansion in C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A hallmark of ALS/FTD pathology is the presence of dipeptide repeat (DPR) proteins, produced from both sense GGGGCC (poly-GA, poly-GP, poly-GR) and antisense CCCCGG (poly-PR, poly-PG, poly-PA) transcripts. Translation of sense DPRs, such as poly-GA and poly-GR, depends on non-canonical (non-AUG) initiation codons. Here, we provide evidence for canonical AUG-dependent translation of two antisense DPRs, poly-PR and poly-PG. A single AUG is required for synthesis of poly-PR, one of the most toxic DPRs. Unexpectedly, we found redundancy between three AUG codons necessary for poly-PG translation. Further, the eukaryotic translation initiation factor 2D (EIF2D), which was previously implicated in sense DPR synthesis, is not required for AUG-dependent poly-PR or poly-PG translation, suggesting that distinct translation initiation factors control DPR synthesis from sense and antisense transcripts. Our findings on DPR synthesis from the C9ORF72 locus may be broadly applicable to many other nucleotide repeat expansion disorders.
-
- Cell Biology
- Neuroscience
The amyloid beta (Aβ) plaques found in Alzheimer’s disease (AD) patients’ brains contain collagens and are embedded extracellularly. Several collagens have been proposed to influence Aβ aggregate formation, yet their role in clearance is unknown. To investigate the potential role of collagens in forming and clearance of extracellular aggregates in vivo, we created a transgenic Caenorhabditis elegans strain that expresses and secretes human Aβ1-42. This secreted Aβ forms aggregates in two distinct places within the extracellular matrix. In a screen for extracellular human Aβ aggregation regulators, we identified different collagens to ameliorate or potentiate Aβ aggregation. We show that a disintegrin and metalloprotease a disintegrin and metalloprotease 2 (ADM-2), an ortholog of ADAM9, reduces the load of extracellular Aβ aggregates. ADM-2 is required and sufficient to remove the extracellular Aβ aggregates. Thus, we provide in vivo evidence of collagens essential for aggregate formation and metalloprotease participating in extracellular Aβ aggregate removal.