title: Microsaccades Are Coupled to Heartbeat.
abstract: During visual fixation, the eye generates microsaccades and slower components of fixational eye movements that are part of the visual processing strategy in humans. Here, we show that ongoing heartbeat is coupled to temporal rate variations in the generation of microsaccades. Using coregistration of eye recording and ECG in humans, we tested the hypothesis that microsaccade onsets are coupled to the relative phase of the R-R intervals in heartbeats. We observed significantly more microsaccades during the early phase after the R peak in the ECG. This form of coupling between heartbeat and eye movements was substantiated by the additional finding of a coupling between heart phase and motion activity in slow fixational eye movements; i.e., retinal image slip caused by physiological drift. Our findings therefore demonstrate a coupling of the oculomotor system and ongoing heartbeat, which provides further evidence for bodily influences on visuomotor functioning.
  
  
  CONCLUSIONS
  In the present study, we show that microsaccades are coupled to heartbeat. Moreover, we revealed a strong modulation of slow eye movements around the R peak in the ECG. These results suggest that heartbeat as a basic physiological signal is related to statistical modulations of fixational eye movements, in particular, the generation of microsaccades. Therefore, our findings add a new perspective on the principles underlying the generation of fixational eye movements. Importantly, our study highlights the need to record eye movements when studying the influence of heartbeat in neuroscience to avoid misinterpretation of eye-movement-related artifacts as heart-evoked modulations of neural processing.
authors.affiliation: Bernstein Center for Computational Neuroscience Berlin, 10115 Berlin, Germany, Department of Psychology, Humboldt Universität zu Berlin, 12489 Berlin, Germany, sven.ohl@bccn-berlin.de.
authors.forename: Sven
authors.initials: S
authors.lastname: Ohl
authors.affiliation: Department of Psychology, Universität Potsdam, 14476 Potsdam, Germany, and.
authors.forename: Christian
authors.initials: C
authors.lastname: Wohltat
authors.affiliation: Department of Psychology, Universität Potsdam, 14476 Potsdam, Germany, and.
authors.forename: Reinhold
authors.identifier: http://orcid.org/0000-0002-0180-8488
authors.initials: R
authors.lastname: Kliegl
authors.affiliation: Institute of Psychology and Education, Universität Ulm, 89069 Ulm, Germany.
authors.forename: Olga
authors.identifier: http://orcid.org/0000-0002-0512-565X
authors.initials: O
authors.lastname: Pollatos
authors.affiliation: Department of Psychology, Universität Potsdam, 14476 Potsdam, Germany, and.
authors.forename: Ralf
authors.identifier: http://orcid.org/0000-0002-2909-5811
authors.initials: R
authors.lastname: Engbert
mesh_terms: D000293:Adolescent; D000328:Adult; D004562:Electrocardiography; D005260:Female; D005403:Fixation, Ocular; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: eye movements; heartbeat; microsaccades
references.citation: Biol Psychol. 2001 Jul-Aug;57(1-3):179-201
references.pmid: 11454439
references.citation: Vision Res. 2002 Oct;42(22):2533-45
references.pmid: 12445847
references.citation: Vision Res. 2003 Apr;43(9):1035-45
references.pmid: 12676246
references.citation: J Physiol. 1959 Jan 28;145(1):98-107
references.pmid: 13621424
references.citation: J Neurophysiol. 2004 Jun;91(6):2429-36
references.pmid: 14736865
references.citation: Neuron. 2006 Jan 19;49(2):297-305
references.pmid: 16423702
references.citation: Proc Natl Acad Sci U S A. 2006 May 2;103(18):7192-7
references.pmid: 16632611
references.citation: Brain Res. 2007 Apr 13;1141:178-87
references.pmid: 17296169
references.citation: Proc Natl Acad Sci U S A. 2007 Apr 17;104(16):6818-23
references.pmid: 17420478
references.citation: Nature. 2007 Jun 14;447(7146):851-4
references.pmid: 17568745
references.citation: Neuron. 2008 May 8;58(3):429-41
references.pmid: 18466752
references.citation: Front Neuroinform. 2008 Nov 04;2:4
references.pmid: 19050754
references.citation: Science. 2009 Feb 13;323(5916):940-3
references.pmid: 19213919
references.citation: Vision Res. 2009 Oct;49(20):2415-41
references.pmid: 19683016
references.citation: J Neurosci. 2009 Sep 30;29(39):12321-31
references.pmid: 19793991
references.citation: J Vis. 2010 Mar 24;10(3):6.1-18
references.pmid: 20377283
references.citation: Nat Neurosci. 2010 Dec;13(12):1549-53
references.pmid: 21037583
references.citation: Nat Neurosci. 2010 Dec;13(12):1443-4
references.pmid: 21102565
references.citation: Eur J Neurosci. 2011 Jun;33(11):2101-13
references.pmid: 21645104
references.citation: Proc Natl Acad Sci U S A. 2011 Sep 27;108(39):E765-70
references.pmid: 21873243
references.citation: Curr Biol. 2012 Mar 20;22(6):510-4
references.pmid: 22342751
references.citation: Curr Biol. 2012 Mar 20;22(6):R186-8
references.pmid: 22440800
references.citation: J Neurosci. 2012 Jun 6;32(23):8035-9
references.pmid: 22674278
references.citation: J Neurosci. 2012 Jul 4;32(27):9194-204
references.pmid: 22764228
references.citation: J Neurosci. 2012 Aug 1;32(31):10627-36
references.pmid: 22855812
references.citation: Nat Rev Neurosci. 2013 Feb;14(2):83-96
references.pmid: 23329159
references.citation: Eur J Neurosci. 2013 Apr;37(7):1169-81
references.pmid: 23331638
references.citation: J Neurosci. 2013 Mar 20;33(12):5375-86
references.pmid: 23516303
references.citation: Neuroimage. 2013 Nov 1;81:178-190
references.pmid: 23684883
references.citation: Curr Biol. 2013 Sep 9;23(17):1691-5
references.pmid: 23954428
references.citation: J Neurosci. 2014 Feb 19;34(8):2956-66
references.pmid: 24553936
references.citation: Nat Neurosci. 2014 Apr;17(4):612-8
references.pmid: 24609466
references.citation: Nat Neurosci. 2014 Apr;17(4):482-3
references.pmid: 24671060
references.citation: J Physiol. 2014 Oct 1;592(19):4381-94
references.pmid: 25128571
references.citation: Trends Neurosci. 2015 Apr;38(4):195-206
references.pmid: 25698649
references.citation: Science. 1973 Aug 31;181(4102):810-9
references.pmid: 4198903
references.citation: Biol Psychol. 1996 Jan 5;42(1-2):75-85
references.pmid: 8770371
references.citation: Nature. 1998 Mar 19;392(6673):239-40
references.pmid: 9521318