Page 36 - JCBP-2-2

Journal of Clinical and
Basic Psychosomatics Cognitive modulation of baroreceptor afferents

A B

C D

Figure 2. Effects of working memory (WM) and cardiac timing on behavioral performance. (A and B) indicate the results of mean reaction time and
response accuracy, respectively, while (C and D) indicate the results of the ex-Gaussian parameters mu and tau, respectively.
Notes: *P < 0.05; **P < 0.01.
Abbreviations: M: Mean; SE: Standard error.
For example, intersensory facilitation (faster RTs) occurs longer during cardiac systole compared to diastole, a
when a concurrent stimulus is in a different sensory finding consistent with previous studies. 16-19,31,35 Both the
modality, 55,56 demonstrating a dissociation between WM ex-Gaussian parameter μ and the traditional mean RT
and perceptual processing. According to the load theory of are measures of response speed, indicating the efficiency
attention, a high-load secondary task (e.g., the Sternberg of sensorimotor processing. The processing of sensory
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WM task) tasks up limited attentional resources and thus stimuli was less efficient in the early cardiac cycle phase
impairs the performance in the primary task, whereas a and faster in the late phase, 14,15 with RTs linearly shortened
low-load secondary task (e.g., intersensory stimuli) utilizes over a portion of the cardiac cycle. 16,17
minimal cognitive resources and does not interfere with It is important to consider the specific temporal location
RT performance. of the stimulus in relation to a cardiac cycle phase. In
Furthermore, WM load also increased the ex-Gaussian studies examining cardiac timing effects, 14-19,24,25,31,35 stimuli
parameter τ, suggesting that more attentional lapses were commonly time-locked with R-waves. Although
occurred with a higher mental workload. Our findings the timing of stimulus presentation might be arbitrary in
echo the notion that the parameter τ inversely indicates the those studies, those cardiac timing manipulations were
component of responses demanding top-down resources sufficient to elicit cardiac timing effects on behavioral
and is associated with the function of the prefrontal cortex performance. 14-19,24-25,31,35 In our study, the selection
(PFC). 29,30 For example, compared to healthy individuals, of stimulus timing (i.e., R + 300 ms and R + 550 ms)
τ is increased in attention deficit hyperactivity disorder, matched the time course of the systolic blood pressure
and τ has been inversely correlated with performance in pulse following the R-wave and of reflexive baroreceptor
activation. At around R + 300 ms, reflex responsiveness,
16
executive function tasks. 40-42
for instance, the nociceptive flexion reflex and the startle
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Our second hypothesis about the modulation of cardiac reflex, is maximally attenuated by baroreceptor firing. 58,59
19
timing effects by concurrent WM load was supported In contrast, at approximately R+550 ms, baroreceptor
by the results. Specifically, in the absence of concurrent afferent transmission is inhibited. Moreover, individual
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WM load, both mean RTs and the parameter μ were differences in the length of IBIs may also influence the
Volume 2 Issue 2 (2024) 6 https://doi.org/10.36922/jcbp.2248