Page 35 - JCBP-2-2

Journal of Clinical and
Basic Psychosomatics Cognitive modulation of baroreceptor afferents

Table 1. Descriptive statistics of task performance (N = 47)
Variable No load WM load
Systole Diastole Systole Diastole
Mean RT (M [ms], SD) 590.10 (145.32) 580.21 (136.06) 695.69 (183.36) 713.13 (188.96)
μ (M [ms], SD) 454.14 (101.65) 440.60 (95.22) 492.57 (115.36) 501.01 (127.13)
σ (M [ms], SD) 72.42 (34.06) 64.03 (32.32) 74.94 (25.86) 72.29 (33.39)
τ (M [ms], SD) 150.66 (101.90) 152.92 (87.67) 223.09 (114.74) 231.44 (101.09)
Accuracy (M %, SD) 96.32 (9.67) 95.76 (10.68) 98.34 (2.14) 98.64 (2.05)
Notes: Parameters μ, σ, and τ were derived from the ex-Gaussian model for the RT distribution for each condition; response accuracy was assessed as
the percentage of correct responses in total trials of each condition.
Abbreviations: M: Mean; RT: Reaction time; SD: Standard deviation; WM: Working memory.

3.2. Effects of cardiac timing and WM load on mean RT concurrent WM load. The RT stimuli were time-locked
The results of the ANOVA revealed a significant main effect with cardiac systole (R + 300 ms) or diastole (R + 550 ms).
of WM load on mean RTs: F (1, 46) = 46.35, P < 0.001, The Sternberg WM task was used to manipulate concurrent
and η p = 0.502, but not cardiac timing (F [1, 46] = 1.04; mental workload. In addition, we utilized ex-Gaussian
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P = 0.312). Notably, there was an interaction between WM modeling to differentiate between top-down attentional
load and cardiac timing: F (1, 46) = 15.08; P < 0.001; and processes and lower-order perceptual processing. While
η p = 0.247. Planned contrasts further indicated that, in the no difference in the ex-Gaussian parameter τ was observed
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absence of WM load, cardiac systole prolonged mean RT, between cardiac phases, WM load was found to increase
t (46) = 2.32, P = 0.025, and d = 0.07, compared to cardiac τ, suggesting increased attentional lapses in the choice
diastole. Conversely, under concurrent WM load, the of RT performance during dual-task conditions. As
cardiac systole speeded mean RT: t (46) = −3.00; P = 0.004; predicted, concurrent WM load slowed down response
and d = 0.10 (Figure 2). speed, as indicated by both mean RTs and the ex-Gaussian
parameter μ. Moreover, cardiac timing effects on RTs
3.3. Effects of cardiac timing and WM load on (both μ and traditional mean RT metrics) were evident
ex-Gaussian parameters in the absence of WM load, indicating that cardiac systole
The ANOVA results for the ex-Gaussian parameter prolonged RTs. Notably, in the presence of concurrent WM
μ indicated similar results to mean RTs. Specifically, load, mean RTs were faster during cardiac systole than
a main effect of WM load on mean RTs was observed: diastole. However, contrary to our predictions, neither
F (1, 46) = 10.61, P = 0.002, and η = 0.187, but not in WM load nor cardiac timing influenced response accuracy.
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p
cardiac timing (F [1, 46] = 0.29; P = 0.590). In addition, Our hypothesis regarding the effect of concurrent
there was an interaction between WM load and cardiac WM load on RT performance (Hypothesis 1) was
timing: F (1, 46) = 4.77; P = 0.034; and η p = 0.094. partially supported. Compared to the absence of the
2
Further analyses revealed that, in the absence of WM WM load condition, the ex-Gaussian parameter μ and
load, cardiac systole increased μ, t (46) = 2.22, p = 0.032, traditional mean RTs were prolonged by the concurrent
and d = 0.14, whereas no cardiac timing effect on μ mental workload. These results indicate an impairment
was evident in the WM load condition (t [46] = -1.12; in sensorimotor processing resulting from decreased
p = 0.272) (Figure 2).
cognitive resources during the dual-task condition. These
As for the ex-Gaussian parameter σ, the results did not findings are consistent with prior reports. 30,31,48 According
show main effects or interaction, ps > 0.198. The results to Sander’s model of sensorimotor responses, processing
of the ex-Gaussian parameter τ indicated a main effect occurs in serial stages, including preprocessing, feature
2
of WM load: F (1, 46) = 30.52, P <0.001, and η = 0.399, extraction, identification, response choice, response
p
indicating that WM load induced more attentional lapses. programming, and motor adjustment. Further, non-
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However, there was no main effect of cardiac timing or motor stages (preprocessing, feature extraction, and
interaction (ps > 0.391) (Figure 2). identification) are distinct from motor stages (response
choice, response programming, and motor adjustment).
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4. Discussion In our study, WM loading reduced cognitive resources for
This study investigated the impact of cardiac cycle time these stages. It is noteworthy that a concurrent secondary
effects on choice RT responses and their modulation by task may not always reduce sensorimotor performance.

Volume 2 Issue 2 (2024) 5 https://doi.org/10.36922/jcbp.2248