Habituation of parasympathetic-mediated heart rate responses to recurring acoustic startle

Autonomic activity, posttraumatic and nontraumatic nightmares, and PTSD after trauma exposure

BACKGROUND

Nightmares are a hallmark symptom of posttraumatic stress disorder (PTSD). This strong association may reflect a shared pathophysiology in the form of altered autonomic activity and increased reactivity. Using an acoustic startle paradigm, we investigated the interrelationships of psychophysiological measures during wakefulness and PTSD diagnosis, posttraumatic nightmares, and nontraumatic nightmares.

METHODS

A community sample of 122 trauma survivors were presented with a series of brief loud tones, while heart rate (HRR), skin conductance (SCR), and orbicularis oculi electromyogram (EMGR) responses were measured. Prior to the tone presentations, resting heart rate variability (HRV) was assessed. Nightmares were measured using nightmare logs. Three dichotomous groupings of participants were compared: (1) current PTSD diagnosis (n = 59), no PTSD diagnosis (n = 63), (2) those with (n = 26) or without (n = 96) frequent posttraumatic nightmares, and (3) those with (n = 22) or without (n = 100) frequent nontraumatic nightmares.

RESULTS

PTSD diagnosis was associated with posttraumatic but not with nontraumatic nightmares. Both PTSD and posttraumatic nightmares were associated with a larger mean HRR to loud tones, whereas nontraumatic nightmare frequency was associated with a larger SCR. EMGR and resting HRV were not associated with PTSD diagnosis or nightmares.

CONCLUSIONS

Our findings suggest a shared pathophysiology between PTSD and posttraumatic nightmares in the form of increased HR reactivity to startling tones, which might reflect reduced parasympathetic tone. This shared pathophysiology could explain why PTSD is more strongly related to posttraumatic than nontraumatic nightmares, which could have important clinical implications.

Diminished preparatory physiological responses in frontotemporal lobar degeneration syndromes

Researchers typically study physiological responses either after stimulus onset or when the emotional valence of an upcoming stimulus is revealed. Yet, participants may also respond when they are told that an emotional stimulus is about to be presented even without knowing its valence. Increased physiological responding during this time may reflect a 'preparation for action'. The generation of such physiological responses may be supported by frontotemporal regions of the brain that are vulnerable to damage in frontotemporal lobar degeneration. We examined preparatory physiological responses and their structural and functional neural correlate in five frontotemporal lobar degeneration clinical subtypes (behavioural variant frontotemporal dementia, n = 67; semantic variant primary progressive aphasia, n = 35; non-fluent variant primary progressive aphasia, n = 30; corticobasal syndrome, n = 32; progressive supranuclear palsy, n = 30). Comparison groups included patients with Alzheimer's disease (n = 56) and healthy controls (n = 35). Preparatory responses were quantified as cardiac interbeat interval decreases (i.e. heart rate increases) from baseline to an 'instruction period', during which participants were told to watch the upcoming emotional film but not provided the film's valence. Patients' behavioural symptoms (apathy and disinhibition) were also evaluated via a caregiver-reported measure. Compared to healthy controls and Alzheimer's disease, the frontotemporal lobar degeneration group showed significantly smaller preparatory responses. When comparing each frontotemporal lobar degeneration clinical subtype with healthy controls and Alzheimer's disease, significant group differences emerged for behavioural variant frontotemporal dementia and progressive supranuclear palsy. Behavioural analyses revealed that frontotemporal lobar degeneration patients showed greater disinhibition and apathy compared to Alzheimer's disease patients. Further, these group differences in disinhibition (but not apathy) were mediated by patients' smaller preparatory responses. Voxel-based morphometry and resting-state functional MRI analyses revealed that across patients and healthy controls, smaller preparatory responses were associated with smaller volume and lower functional connectivity in a circuit that included the ventromedial prefrontal cortex and cortical and subcortical regions of the salience network. Diminished preparatory physiological responding in frontotemporal lobar degeneration may reflect a lack of preparation for actions that are appropriate for an upcoming situation, such as approaching or withdrawing from emotional stimuli. The ventromedial prefrontal cortex and salience network are critical for evaluating stimuli, thinking about the future, triggering peripheral physiological responses, and processing and interpreting interoceptive signals. Damage to these circuits in frontotemporal lobar degeneration may impair preparatory responses and help explain often-observed clinical symptoms such as disinhibition in these patients.

Childhood adversity modulation of central autonomic network components during cognitive regulation of emotion in major depressive disorder and borderline personality disorder

Adverse childhood experiences (ACEs) have lifelong effects on emotional behavior and are frequent in Borderline Personality Disorder (BPD) and Major Depressive Disorder (MDD). The Central Autonomic Network (CAN), which modulates heart rate variability (HRV), comprises brain regions that mediate emotion regulation processes. However, it remains unclear the effect of ACEs on CAN dynamics and its relationship with HRV in these disorders. We studied the effects of ACEs on the brain and HRV simultaneously, during regulation of psychological stress in 19 BPD, 20 MDD and 20 healthy controls (HC). Participants underwent a cognitive reappraisal task during fMRI with simultaneous ECG acquisition. ACEs exposure was associated with increased activity of CAN and salience network components in patients with MDD compared to BPD during cognitive reappraisal. A brain-autonomic coupling was found in BPD relative to HC during emotion regulation, whereby greater activity of left anterior cingulate and medial superior frontal gyrus areas was coupled with increased HRV. Results suggest that ACEs exposure is associated with a distinct activation of the CAN and salience network regions governing responses to psychological stress in MDD compared to BPD. These alterations may constitute a distinctive neurobiological mechanism for abnormal emotion processing and regulation related to ACEs in MDD.

Physiological linkage during shared positive and shared negative emotion

Physiological linkage refers to the degree to which peoples' physiological responses change in coordinated ways. Here, we examine whether and how physiological linkage relates to incidents of shared emotion, distinguished by valence. Past research has used an "overall average" approach and characterized how physiological linkage over relatively long time periods (e.g., 10-15 min) reflects psychological and social processes (e.g., marital satisfaction, empathy). Here, we used a "momentary" approach and characterized whether physiological linkage over relatively short time periods (i.e., 15 s) reflects shared positive emotion, shared negative emotion, or both, and whether linkage during shared emotions relates to relational functioning. Married couples (156 dyads) had a 15-min conflict conversation in the laboratory. Using behavioral coding, each second of conversation was classified into 1 of 4 emotion categories: shared positive emotion, shared negative emotion, shared neutral emotion, or unshared emotion. Using a composite of 3 peripheral physiological measures (i.e., heart rate, skin conductance, finger pulse amplitude), we computed momentary in-phase and antiphase linkage to represent coordinated changes in the same or opposite direction, respectively. We found that shared positive emotion was associated with higher in-phase and lower antiphase linkage, relative to the other 3 emotion categories. Greater in-phase physiological linkage during shared positive emotion was also consistently associated with higher-quality interactions and relationships, both concurrently and longitudinally (i.e., 5 to 6 years later). These findings advance our understanding of the nature of physiological linkage, the emotional conditions under which it occurs, and its possible associations with relational functioning. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Notification alert! Effects of auditory text alerts on attention and heart rate variability across three developmental periods

In a modern world saturated with cellphone-related stimuli, surprisingly little is known about their psychological effects. A small number of previous studies have found global distracting effects of cellphone rings on cognitive performance in undergraduate students. However, moment-to-moment reactions to cellphone sounds have not been investigated, nor have physiological changes that might accompany the cognitive effects. Developmental variations also remain unexamined. Thus, two experiments were conducted to examine the effects of cellphone notification sounds on cognitive performance (i.e., reaction time and accuracy on math problems) and heart rate variability in three age groups: adolescents (mean age: 15 years); young adults (mean age: 20 years); and mid-life adults (mean age: 48 years). Effects were most pronounced in the adolescent group, whose math problem accuracy and reaction time was compromised in response to notification sounds. These compromises were accompanied by increases in heart rate variability.

The short-term association between exposure to noise and heart rate variability in daily locations and mobility contexts

BACKGROUND

Personal exposure to noise has been shown to be associated with concomitant increases and lagged decreases of short-term heart rate variability (HRV). It is however unknown whether this association differs between contexts defined by visited places or mobility as both exposure sources and expectations may be different between these contexts.

METHOD

Between July 2014 and June 2015, the RECORD MultiSensor Study collected sound level and heart rate data for 75 participants, aged 34-74 years, in their living environments for 7 days using a personal dosimeter and electrocardiography sensor on the chest. Their whereabouts were collected using a GPS receiver and a mobility survey. Short-term concomitant and lagged associations between sound level and HRV parameters were assessed within types of visited places and transport modes using mixed effects models with a random intercept for participants.

RESULTS

Increases in sound level were associated with a concomitant increase in all HR/HRV parameters, and delayed decreases in the overall HRV. Interactions between the sound level and the visited place/mobility context were documented. Compared with home, the concomitant association of sound level with HR and rMSSD was doubled within active and private-motorized transport modes, respectively.

CONCLUSIONS

The association of sound level with HR/HRV varies between visited places/mobility contexts. Future studies investigating these context-dependent associations in ambulatory settings will need to assess additional acoustical factors relating to the visited environments as well as non-acoustical factors impacting the perception of noise.

Characterizing autonomic response to arousing visual-auditory multi-modal task in Autism Spectrum Disorder (ASD)

Sensory abnormalities are widespread in Autism Spectrum Disorder (ASD). However, their definition is still quite subjective and vague. Here we propose a novel approach for characterization of Autonomic Nervous System responses to sensory stimulation based on electrocardiogram (ECG) assessment. In particular, we develop a preliminary study where autonomic responses of both autistic (ASD = 5) and neurotypical (NT = 5) participants have been evaluated in terms of changes in responsiveness to repeated stimuli. Autonomic control has been estimated via high-frequency heart rate variability (HF-HRV) and low-frequency HRV (LF-HRV). Results show significant differences among groups for the HRV measures (p value = 0.0158), supported by expected changes of HF (p value = 0.0079) and LF (p value = 0.0079) trends over stimulations. We thus conclude that an overall decrease in autonomic arousal can give important insights for devising new habituation metrics in NT and ASD individuals.

Role of the prefrontal lobe in young normotensives with a family history of hypertension and hypertensives

Accumulating evidence has demonstrated a significant relationship between prefrontal lobe and hypertension. Elevated blood pressure is usually associated with a prefrontal hemodynamic abnormality. However, the detailed process is still unclear. In this study, we designed a startle protocol and tested the response of the cerebral cortex and cardiovascular system in young normotensive subjects with a family history of hypertension (FH+). Additionally, the cold forehead test (CFT) was performed in hypertensive subjects. In total, 40 young normotensive subjects (21 with FH+ and 19 without a family history of hypertension (FH-)) and 49 middle-aged subjects (21 normotensives (NT) and 28 hypertensives (HT)) were recruited. Our results showed that the magnitude of startle-evoked alpha oscillation at the parasympathetic-related prefrontal cortex (FP1 and FP2) in the FH+ group was significantly smaller than in the FH- group. Acute bradycardia (RRI increase) was observed in FH- subjects but disappeared in the FH+ group. The coupling between instant cardiac acute response (increased RRI) and prefrontal arousal (magnitude of evoked oscillation) was significantly weakened in the FH+ group compared with the FH- group. Furthermore, the decrease in HR induced by parasympathetic outflow during CFT was absent in HT subjects. Hence, we concluded that the impairment of parasympathetic outflow derived from the prefrontal lobe occurs in both healthy young offspring of hypertensive and hypertensive patients.

A Little Goes a Long Way: Low Working Memory Load Is Associated with Optimal Distractor Inhibition and Increased Vagal Control under Anxiety

Anxiety impairs both inhibition of distraction and attentional focus. It is unclear whether these impairments are reduced or exacerbated when loading working memory with non-affective information. Cardiac vagal control has been related to top-down regulation of anxiety; therefore, vagal control may reflect load-related inhibition of distraction under anxiety. The present study examined whether: (1) the enhancing and impairing effects of load on inhibition exist together in a non-linear function, (2) there is a similar association between inhibition and concurrent vagal control under anxiety. During anxiogenic threat-of-noise, 116 subjects maintained a digit series of varying lengths (0, 2, 4, and 6 digits) while completing a visual flanker task. The task was broken into four blocks, with a baseline period preceding each. Electrocardiography was acquired throughout to quantify vagal control as high-frequency heart rate variability (HRV). There were significant quadratic relations of working memory load to flanker performance and to HRV, but no associations between HRV and performance. Results indicate that low load was associated with relatively better inhibition and increased HRV. These findings suggest that attentional performance under anxiety depends on the availability of working memory resources, which might be reflected by vagal control. These results have implications for treating anxiety disorders, in which regulation of anxiety can be optimized for attentional focus.

Startle Habituation and Midfrontal Theta Activity in Parkinson Disease

The ability to adapt to aversive stimuli is critical for mental health. Here, we investigate the relationship between habituation to startling stimuli and startle-related activity in medial frontal cortex as measured by EEG in both healthy control participants and patients with Parkinson disease (PD). We report three findings. First, patients with PD exhibited normal initial startle responses but reduced startle habituation relative to demographically matched controls. Second, control participants had midfrontal EEG theta activity in response to startling stimuli, and this activity was attenuated in patients with PD. Finally, startle-related midfrontal theta activity was correlated with the rate of startle habituation. These data indicate that impaired startle habituation in PD is a result of attenuated midfrontal cognitive control signals. Our findings could provide insight into the frontal regulation of startle habituation.