Investigators use cardiac cycle (systole vs diastole) to evaluate effects of interoceptive afferent signaling on cognitive and emotional processing. Some believe that baroreceptor activity is quiescent during diastole. But, is it?!
Dear Ali,
some papers:
Article Sensory detection thresholds are modulated across the cardia...
Article The relationship between aortic baroreceptor activity and ar...
Article Time related characteristics of cardiac systole, diastole, b...
Article Electrocutaneous pain thresholds are higher during systole t...
Article Influence of Physical Exercise on Baroreceptor Sensitivity d...
Thanks for sharing these articles. As I understand from the literature baroreceptor activity is not quiescent during diastole if the blood pressure is above the threshold pressure.
http://users.atw.hu/blp6/BLP6/HTML/common/M9780323045827-018-f027.jpg
http://www.zuniv.net/physiology/book/images/9-2.jpg
Even with increasing pressure, higher activity at diastolic phase and quiescent state at systolic phase is observed:
http://www.ncbi.nlm.nih.gov/pubmed/26379539
So, it is not that simple that baroreceptor activity is always higher during systole than diastole or quiescent during diastole. It depends on blood pressure dynamics and such dynamics are rarely approached in studies evaluating modulating effects of cardiac afferent signals on cognitive and emotional processing !
It is acceptable to think that in resting condition there is relatively higher baroreceptor activity and therefore higher cardiac afferent signaling during systole than diastole but in a physically active condition it may change as blood pressure dynamic changes.
Dear Ali,
You're getting the hang of things. We must always keep in mind that the baroreceptor activity is just an output of the afferent branch of the whole baroreflex. Peripheral vascular dilation/constriction and direct control of the heart contractibility, all combine with respiratory sinus arrhythmia to make a mess on the efferent branch (at some point, you loose track of what is "efferent" and "afferent"). For that reason, the cardiac cycle paradigm (at rest) tries to take advantage of phasic (systole vs diastole) changes in BP which stimulate baroreceptors in a supposedly "quiet" efferent baroreflex regulation, i.e., without notorious variations in tonic BP. But is it really quiet? Like you neatly pointed out, with rhythmic exercise, everything changes because there is the full demand of the whole baroreflex control. I've also sweated marbles over this issue during my Ph.D...
And a few more papers:
http://www.ncbi.nlm.nih.gov/pubmed/19766395
http://www.ncbi.nlm.nih.gov/pubmed/25308911
Best wishes,
Amadeu
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