Heart-brain interactions shape somatosensory perception and evoked potentials

Be still my heart: Cardiac regulation as a mode of uncertainty reduction

Decreased heart rate (HR) and variability (HRV) are well-established correlates of attention; however, the functional significance of these dynamics remains unclear. Here, we investigate whether attention-related cardiac modulation is sensitive to different varieties of uncertainty. Thirty-nine adults performed a binocular rivalry-replay task in which changes in visual perception were driven either internally (in response to constant, conflicting stimuli; rivalry) or externally (in response to physically alternating stimuli; replay). Tonic HR and high-frequency HRV linearly decreased as participants progressed from resting-state baseline (minimal visual uncertainty) through replay (temporal uncertainty) to rivalry (temporal uncertainty and ambiguity). Time-resolved frequency estimates revealed that cardiac deceleration was sustained throughout the trial period and modulated by ambiguity, novelty, and switch rate. These findings suggest cardiac regulation during active attention may play an instrumental role in uncertainty reduction.

[Premature complexes, anxiety and quality of life]

Premature complexes can be indicative of an increased cardiac risk or can contribute to the initiation or deterioration of heart failure in particular in the presence of organic heart disease. Most premature complexes are benign. The postextrasystolic pause or the augmented postextrasystolic premature beat may cause the following symptoms: feeling of a skipped beat or the sensation of a pounding heart beat causing the feeling "that something is seriously wrong". It is mentioned that premature beats cause an unconscious reaction of the autonomic nervous system. Symptoms related to premature complexes may cause uneasiness or franc anxiety which may itself intensify the symptoms. This may cause a panic reaction which may be associated with shortness of breath or angina of the chest mimicking dyspnea of heart failure of an acute coronary syndrome. Along the "vicious cycle of anxiety" it is demonstrated how patients may be comforted. In addition, the panic disorder itself should be treated by cognitive behavioral or psychodynamic therapy.

The impact of cardiac afferent signaling and interoceptive abilities on passive information sampling

A growing body of research suggests that perception and cognition are affected by fluctuating bodily states. For example, the rate of information sampling is coupled with cardiac phases. However, the benefits of such spontaneous coupling between bodily oscillations and decision-making remains unclear. Here, we studied the role of the cardiac cycle in information sampling by testing whether sequential information sampling phase-locked to systolic or diastolic parts of the cardiac cycle impacts the rate of information gathering and processing. To this aim, we employed a modified Information Sampling Task, a standard measure of the rate of information gathering before reaching a decision, in which the onset of new information delivery in each trial was coupled either to cardiac systole or diastole. Information presented within cardiac systole did not significantly modulate the information processing in a manner that would produce clear behavioral changes. However, we found evidence suggesting that higher interoceptive awareness increased accuracy, especially in the costly version of the task, when new information was sequentially presented at systole. Overall, our results add to a growing body of research on body-brain interactions and suggest that our internal bodily rhythms (i.e., heartbeats) and our awareness of them can interact with the way we process the noisy world around us.

Desflurane and sevoflurane differentially affect activity of the subthalamic nucleus in Parkinson's disease

BACKGROUND

Desflurane and sevoflurane are commonly used during inhalational anaesthesia, but few studies have investigated their effects on deep cerebral neuronal activity. In addition, the association between subthalamic nucleus (STN) neurophysiology and general anaesthesia induced by volatile anaesthetics are not yet identified. This study aimed to identify differences in neurophysiological characteristics of the STN during comparable minimal alveolar concentration (MAC) desflurane and sevoflurane anaesthesia for deep brain stimulation (DBS) in patients with Parkinson's disease.

METHODS

Twelve patients with similar Parkinson's disease severity received desflurane (n=6) or sevoflurane (n=6) during DBS surgery. We obtained STN spike firing using microelectrode recording at 0.5-0.6 MAC and compared firing rate, power spectral density, and coherence.

RESULTS

Neuronal firing rate was lower with desflurane (47.4 [26.7] Hz) than with sevoflurane (63.9 [36.5] Hz) anaesthesia (P<0.001). Sevoflurane entrained greater gamma oscillation power than desflurane (62.9% [0.9%] vs 57.0% [1.5%], respectively; P=0.002). There was greater coherence in the theta band of the desflurane group compared with the sevoflurane group (13% vs 6%, respectively). Anaesthetic choice did not differentially influence STN mapping accuracy or the clinical outcome of DBS electrode implantation.

CONCLUSIONS

Desflurane and sevoflurane produced distinct neurophysiological profiles in humans that may be associated with their analgesic and hypnotic actions.

Feeling in Control: The Role of Cardiac Timing in the Sense of Agency

The sense of agency describes the experience of controlling one’s body to cause desired effects in the world. We explored whether this is influenced by interoceptive processes. Specifically, we investigated whether the sense of agency changes depending on where, in the cardiac cycle (systole or diastole), the action was executed and where the outcome of the action occurred. In two experiments, participants completed decision-making task to win/lose money. Explicit (ratings of control) and implicit (temporal judgement) measures of agency were differentially affected by cardiovascular state. Implicit agency scores were affected by the cardiac phase at the point of action execution. Explicit ratings of control were affected by the type of (free vs. instructed) and by outcome valence (win vs. lose). The time of the action was uniformly distributed across the cardiac cycle. These results show interoceptive impact on agency, but that cardiac cycle may affect explicit and implicit agency differently.

Spontaneous Brain Oscillations and Perceptual Decision-Making

Making rapid decisions on the basis of sensory information is essential to everyday behaviors. Why, then, are perceptual decisions so variable despite unchanging inputs? Spontaneous neural oscillations have emerged as a key predictor of trial-to-trial perceptual variability. New work casting these effects in the framework of models of perceptual decision-making has driven novel insight into how the amplitude of spontaneous oscillations impact decision-making. This synthesis reveals that the amplitude of ongoing low-frequency oscillations (<30 Hz), particularly in the alpha-band (8-13 Hz), bias sensory responses and change conscious perception but not, surprisingly, the underlying sensitivity of perception. A key model-based insight is that various decision thresholds do not adapt to alpha-related changes in sensory activity, demonstrating a seeming suboptimality of decision mechanisms in tracking endogenous changes in sensory responses.

Altered interoception in patients with borderline personality disorder: a study using heartbeat-evoked potentials

BACKGROUND

Patients with borderline personality disorder (BPD) experience difficulties in emotional awareness (alexithymia), and often develop dissociative symptoms, which may reflect broader deficits in interoceptive awareness. Whether this is associated with alterations in cortical processing of interoception is currently unknown.

METHODS

We utilized an electrophysiological marker of interoception, i.e. heartbeat-evoked potentials (HEP), and examined its relationship with electrocardiographic correlates of autonomic nervous system (ANS) functioning (heart rate variability), and with self-report measures of alexithymia, dissociation and borderline symptom severity in patients with BPD.

RESULTS

Individuals with BPD had higher HEP amplitudes over frontal electrodes compared to healthy controls. Sympathetic ANS activity was greater in BPD patients than in controls. Across groups, HEP amplitudes were associated with parasympathetic activity over central electrodes and correlated with alexithymia over frontal electrodes.

CONCLUSIONS

These findings support the idea that difficulties in emotional awareness in BPD are reflected in altered frontal electrophysiological markers of interception. Therefore, emotional awareness can be understood as failures of modulation between interoceptive and exteroceptive attention. Future research may aim to investigate whether altered interoception and its electrophysiological correlates are malleable by therapeutic intervention.