Dynamic fluctuations in ascending heart-to-brain communication under mental stress

Dynamical information exchange between central and autonomic nervous systems, as referred to functional brain-heart interplay, occurs during emotional and physical arousal. It is well documented that physical and mental stress lead to sympathetic activation. Nevertheless, the role of autonomic inputs in nervous system-wise communication under mental stress is yet unknown. In this study, we estimated the causal and bidirectional neural modulations between electroencephalogram (EEG) oscillations and peripheral sympathetic and parasympathetic activities using a recently proposed computational framework for a functional brain-heart interplay assessment, namely the sympathovagal synthetic data generation model. Mental stress was elicited in 37 healthy volunteers by increasing their cognitive demands throughout three tasks associated with increased stress levels. Stress elicitation induced an increased variability in sympathovagal markers, as well as increased variability in the directional brain-heart interplay. The observed heart-to-brain interplay was primarily from sympathetic activity targeting a wide range of EEG oscillations, whereas variability in the efferent direction seemed mainly related to EEG oscillations in the γ band. These findings extend current knowledge on stress physiology, which mainly referred to top-down neural dynamics. Our results suggest that mental stress may not cause an increase in sympathetic activity exclusively as it initiates a dynamic fluctuation within brain-body networks including bidirectional interactions at a brain-heart level. We conclude that directional brain-heart interplay measurements may provide suitable biomarkers for a quantitative stress assessment and bodily feedback may modulate the perceived stress caused by increased cognitive demand.

Multidimensional components of (state) mathematics anxiety: Behavioral, cognitive, emotional, and psychophysiological consequences

The present study aimed to analyze the different components of state mathematics anxiety that students experienced while solving calculation problems by manipulating their stress levels. A computerized mathematical task was administered to 165 fifth-graders randomly assigned to three different groups: positive, negative, and control conditions, in which positive, negative, or no feedback during the task was given, respectively. Behavioral (task performance), emotional (negative feelings), cognitive (worrisome thoughts and perceived competence), and psychophysiological responses (skin conductance and vagal withdrawal) were analyzed. Behavioral responses did not differ in the positive and negative conditions, while the latter was associated with children's reportedly negative emotional states, worries, and perceived lack of competence. The stress induced in the negative condition led to an increase in skin conductance and cardiac vagal withdrawal in children. Our data suggest the importance of considering students' interpretation of mathematics-related experiences, which might affect their emotional, cognitive, and psychophysiological responses.

Coordination between motor and cognitive tasks in dual task gait

BACKGROUND

Dual Task (DT) paradigms are frequently used by researchers and clinicians to examine the integrity of motor processes in many movement disorders. However, the mechanism of this interaction is not fully understood. Therefore, the aim of this study was to examine the within-stride interactions between cognitive and motor processes during dual task gait (DT).

RESEARCH QUESTION

Do healthy young adults coordinate gait with secondary task processing? If so, is cognitive task processing capability associated with the coordination observed?

METHODS

Nineteen healthy young adults walked for two minutes on a motorized treadmill whilst counting backwards in sevens from three-digit numbers. The coordination of calculation verbalizations with gait parameters were assessed across six phases of the gait cycle. Mid verbalization time points (VER_Mid) were used as points of high cognitive processing of the dual task and compared with the end of the verbalizations (VER_End) as points of low cognitive processing.

RESULTS

VER_Mid and VER_End did not systematically occur in any phase of the gait cycle. However, 10/19 and 9/19 participants showed non-random distributions of verbalizations for VER_Mid and VER_End time points respectively (p < 0.01), indicating that these walkers coordinated gait with the cognitive task. Analysis of subgroups of Verbalization Coordinators and Non-Coordinators showed slower verbalization response durations (VRD) for VER_Mid Coordinators compared to VER_Mid Non-Coordinators, indicating that VER_Mid Coordinators found the cognitive tasks more demanding. No differences were found in VRD for VER_End Coordinators and VER_End Non-Coordinators.

SIGNIFICANCE

It was found that cognitive processing is coordinated with gait phases in some but not all healthy young adults during DT gait. When demands on cognitive processes are high, healthy young adults coordinate cognitive processing with phases of gait. Analysis of within-stride coordination may be of use for studying clinical conditions where gait and attentional cognition performance breaks down.

Phasic Electrodermal Activity During the Standardized Assessment of Concussion (SAC)

CONTEXT

The long-term effects of concussion on brain function during cognitive tasks are not fully understood and neuroimaging findings are equivocal. Some images show hyperactivation of prefrontal brain regions in previously concussed individuals relative to controls, suggesting increased cognitive resource allocation. Others show prefrontal hypoactivation and hyperactivation in other regions as a presumed compensatory mechanism. Given the relationship between sympathetic arousal and neural activation, physiologic measures of arousal, such as electrodermal activity, may provide additional insight into the brain's functional changes in those with a history of concussion.

OBJECTIVE

To quantify differences in electrodermal activity during a commonly used standardized neurocognitive assessment between individuals with or without a history of concussion.

DESIGN

Descriptive laboratory study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Seven asymptomatic individuals with a self-reported history of physician-diagnosed, sport-related concussion (number of previous concussions = 1.43 ± 0.53; time since most recent concussion = 0.75 to 6 years, median = 3 years) and 10 individuals without a history of concussion participated in this study.

MAIN OUTCOME MEASURE(S)

All participants wore bilateral wrist electrodermal activity sensors during the Standardized Assessment of Concussion. We measured normalized phasic (reactive) electrodermal activity during each test element (orientation, immediate recall, concentration, delayed recall).

RESULTS

A significant group-by-test element interaction was present (P = .003). Individuals with a history of concussion had greater phasic activity during delayed recall (P < .001). Delayed-recall phasic activity was greater in both groups relative to the other elements.

CONCLUSIONS

Delayed recall resulted in greater physiologic arousal in previously concussed individuals relative to healthy control participants, supporting previous neuroimaging findings of increased prefrontal cortex activity during memory tasks after concussion. Given similar task performance and arousal patterns across the test, our results suggest that previously concussed individuals incur additional cognitive demands in a short-delay recall task.