ABC | Volume 113, Nº4, October 2019

Short Editorial Rivarola & Scanavacca The neurolinguistics of the heart Arq Bras Cardiol. 2019; 113(4):734-736 1. Sanchez-HecharvarriaME, Chiya S, Carrazona-Escalona R, Cortina-Reyna S, Andreu-Heredia A, et al. Introdução da aplicação do coeficiente de Gini ao espectro de variabilidade da frequência cardíaca para avaliação do estresse mental. Arq Bras Cardiol. 2019; 113(4):725-733. 2. Kapa S, VenkatachalamK, Asirvathan S. The Autonomic Nervous System in Cardiac Electrophysiology. An Elegant Interection and Emerging Concepts. Cardiol Ver. 2010;18(6):275-84. 3. Armour J, Murphy D, Yuan B, Macdonald S, Hopkins D. Gross and microscopic anatomy of the human intrinsic cardiac nervous system. Anat Rec. 1997;247(2):289-98. 4. Pauza D, Skripka V, Pauziene N, Stropus R. Morphology, distribution, and variability of the epicardiac neural ganglionated subplexuses in the human heart. Anat Rec. 2000;259(4):353-82. 5. Wake E, Brack K. Characterization of the intrinsic cardiac nervous system. Auton Neurosci. 2016 Aug;199:3-16. 6. Thayer JF, Ahs Fredrik, FredriksonM, Sollers III, JJ,Wager, TD. AMeta-analysis of heart rate variability and neuroimaging studies: Implications for heart rate variability as amarker of stress and health. Neuroscience and Biobehav Rev.2012;36(2):747-56. 7. Thayer JF, Hansen AL, Saus-Rose E, Johnsen BH. Heart rate variability, Prefrontal Neural Function, and Cognitive Performance: The Neurovisceral IntegrationPerspectiveoSelf-regulation,Adaptation,andHealth.AnnBehav Med. 2009;37(2):141-53. 8. Goldman-Ratik, PS. The prefrontal landscape: implications of functional architectureforunderstandinghumanmentationandthecentralexecutive.In Roberts AC, Robbins TW,Weiskrantz L, eds. The prefrontal cortex: executive and cognitive function. Oxford: Oxford University Press; 199.p. 87-102. 9. Hon EH, Lee ST. Electronic evaluations of the fetal heart rate patterns preceding fetal death, further observations. Am J Obstet Gynec. 1965 Nov 15;87:814-26. 10. Aarbaoui TE, Meline J, Brondeel R, Chaix B. Short-termassociation between personal exposure to noise and heart rate variability: The RECORD multisensor Study. Environ Pollut. 2017;231(Pt1):703-11. 11. Aarbaoui TE, Chaix B. The short-termassociation between exposure to noise and heart rate variability in daily locations and mobility contexts. J Expo Sci Environ Epidemiol. 2019 Aug 12. doi: 10.1038/s41370-019-0158-x. [Epub ahead of print]. 12. Wager TD, van Ast VA, Hughes BL, Davidson ML, Lindquist MA, Ochsner KN. Brain mediators of cardiovascular response to social threat. Part I: prefrontal-subcortical pathways and relationshipwith anxiety. Neuroimage 2009;47(3):836-51. 13. Conway ARA, Engle RW, Individual differences inworkingmemorycapacity: More evidence for a general capacity theory. Memory. 1996;4(6):577-90. 14. Hansen AL, Johnsen BH, Thayer JF. Vagal influence in the regulation of attention and working memory. Int J Psycophysiol. 2003;48(3):263-74. 15. Verkuil B, Brosschot JF, Borkovec TD, Thayer JF. Acute autonomic effects of experimental worry and cognitive problemsolving:Whyworry about worry? Int J Clin Health Psycol. 2009;9(3):439-53. 16. JaneRD,McRaeK,ReimanEM,ChenK,AhemGL,ThayerJF.Neuralcorrelates of heart rate variability during emotion. Neuroimage. 2009;44(1):213-22. References Complex tasks requiring cognitive functions, such as arithmetic, online processing and manipulation of information are highly dependent on this reciprocal downregulation between the cortex and the amygdala. 8 The resultant HRV takes so many variables into account that defining specific spectral bands as reliable biomarkers, assuming a mechanistic causality, seems unlikely, especially so when it comes to abstract stressful contexts, such as expectations of future outcomes, emotional conditions and representation of economic values. 7 To illustrate this limitation, in a very simplified way, imagine you are about to take a math test. At first, the challenge may disturb you, being felt as “danger”, and so the amygdala nucleus promptly triggers a vagal withdraw (affecting both high and low frequency spectral powers) and a sympathoexcitatory reflex (modifying low frequency spectra). A few minutes later you realize you can handle it and start feeling confident. It is just going to take a little focus. A more accurate Gestalt representation has now been reached. By activating a GABA pathway, three main different areas of your preFC engage: 1-posterior and dorsal region of the rostral preFC (linked to cognitive functions), 2-dorso medial preFC (reliably related to social cognition) and finally 3- medial-orbitoFC and anterior ventral preFC (associated with autonomic aspects of emotional contexts and to “reward and punishment”). 6,7 Exerting a balanced inhibitory control over the amygdala through an integrated Central Autonomic Network, these anatomic structures guide goal-directed behavior and adaptability and ultimately dictates the amount of acetylcholine and norepinephrine to be released from the post-ganglionic fibers close to the sinus node, reshaping HRV spectra once again. Keep in mind that genetic background and cognitive performance may influence all these processes significantly. 7 What is the value of HRV on assessing stress, then? As of 1965, Hon and Lee 9 had already identified inter-beat interval patterns preceding severe fetal distress even before a perceivable change in fetal heart rate. Undoubtedly, HRV has been proven to be an essential index of adaptability of the organism, and therefore, extensively studied under a wide range of stressful stimuli. Conflicting results, however, suggest distinct reactions to different forms of stress. While some authors demonstrated a global increase in HRV after exposure to noise, 10,11 public speech tasks 12 and sustained attention, 13 others found a global HRV reduction during memory 14 and cognitive tasks. 15 Emotional conditions have been proven to correlate with high-frequency band reduction by some authors, 16 and yet to be neutral by others. 12 We are far from relying on surrogate endpoints to understand the different parts of the link between heart and brain. Even by using much more sophisticated techniques, such as regional cerebral blood flow neuroimaging, we are still scratching the surface of this intricate physiology. HRV could be an interesting tool for detecting general features of the stress response, although unreliable for distinguishing its complex mechanisms. 735