Biology subjects

Garfinkel, S.

Publications and source records attributed to Garfinkel, S..

4 recordsLinked to original sources

bioRxiv2024

Methodological approaches to derive the heartbeat-evoked potential: pastpractices and future recommendations

The heartbeat-evoked potential (HEP) is an implicit, electrophysiological marker of cortical heartbeat processing and interoception, with increasing clinical relevance. However, on the scalp, HEP are low-amplitude signals mixed with cardiac field artefacts (CFA), requiring signal processing pipelines to separate HEP from CFA. This review evaluates current analytical approaches, addresses methodological gaps in HEP pipelines, and examines the impact of key parameter choices. HEP processing methods/parameters used in EEG (N=101) and MEG (N=10) studies were investigated, focusing on the effects of HEP window, electrodes, filters, independent component analysis (ICA) and artefact subspace reconstruction (ASR), on HEP extraction, using Temple Universitys normal scalp EEG data. EEG and MEG studies revealed clear inconsistencies in HEP parameter use and reporting. ASR-20 (ASR threshold for artifact identification) performed comparably to ICA for artefact removal, supporting its potential real-time EEG applicability. Epoch rejection, a HEP quality metric, appeared equivalent between ICA and ASR-20 after artefact removal. Linear Mixed Model analysis identified significant effects of RR interval, maximum epoch amplitude, HEP window and baseline correction start time on measured HEP amplitude. Publications should report critical values for reliable HEP extraction, emphasising the need for standardised methods to enhance study comparability and reproducibility.

neuroscience↗

bioRxiv2023

The entropic heart: Tracking the psychedelic state via heart rate dynamics

A growing body of work shows that autonomic signals provide a privileged evidence-stream to capture various aspects of subjective and neural states. This work investigates the potential for autonomic markers to track the effects of psychedelics -- potent psychoactive drugs with important scientific and clinical value. For this purpose, we introduce a novel Bayesian framework to estimate the entropy of heart rate dynamics under psychedelics. We also calculate Bayesian estimates of mean heart rate and heart rate variability, and investigate how these measures relate to subjective reports and neural effects. Results on datasets covering four drugs -- lysergic acid diethylamide (LSD), dimethyltryptamine (DMT), psilocybin, and sub-anaesthetic doses of the dissociative agent ketamine -- show consistent increases in mean heart rate, high-frequency heart rate variability, and heart rate entropy during the psychedelic experience. Moreover, these effects have predictive power over various dimensions of the psychedelic experience. Changes in heart rate entropy were found to be correlated with increases in brain entropy, while other autonomic markers were not. Overall, our results show that a cost-efficient autonomic measure has the potential to reveal surprising detail about subjective and brain states, opening up a range of new research avenues to explore in both basic and clinical neuroscience.

physiology↗

bioRxiv2020

Serotonergic Effects on Interoception

Interoception is the signalling, perception, and interpretation of internal physiological states. Much of the psychopharmacology of interoception is still undiscovered. However, psychiatric disorders associated with changes of interoception, including depressive, anxiety, and eating disorders are often treated with selective serotonin reuptake inhibitors (SSRIs). The causal effect of acute changes of serotonin transmission on interoceptive cognition was tested by a within-participant, crossover, placebo-controlled study. Forty-seven healthy human volunteers (31 female, 16 male) were tested both on and off a 20mg oral dose of the commonly prescribed SSRI citalopram. For each randomly ordered session, participants made judgments on the synchrony of their heartbeat to auditory tones and expressed confidence in each of these judgments. Citalopram enhanced insight into the likelihood that ones interoceptive judgment had been correct, driven primarily by enhanced confidence for correct responses. This effect was independent of measured cardiac and subjective effects of the drug. This novel result is evidence that acute serotonin changes can alter metacognitive insight into the reliability of inferences based on interoceptive information, which is a foundation for considering effects of serotonin on cognition and emotion in terms of effective top-down regulation of interoceptive influence on mental states.

neuroscience↗

bioRxiv2020

Feeling the beat: Temporal and spatial perception of heartbeat sensations

The majority of interoceptive tasks (i.e. measuring the sensitivity to bodily signals) are based upon the heartbeat sensations perception. However, temporal perception of heartbeats varies among individuals and confidence and spatial perception of heartbeats in relation to temporal judgements have not yet been systematically investigated. This study examined the perception of heartbeat sensations in both time and spatial domains, using a multi-interval heartbeat discrimination task. The relationship between these domains was investigated, as well as the contribution of mental health conditions and cardiovascular parameters. Heartbeat sensations occurred on average ~250ms after the ECG R-wave and were more frequently sampled from the left part of the chest. Participants confidence in their experience of heartbeat sensations was maximal for the 0 ms interval. Interestingly, higher confidence was related to reduced dispersion of sampling locations but we found evidence toward the absence of relationship between temporal and spatial heartbeat sensations perception, using Bayesian statistics. Finally, we found evidence toward a relationship between spatial precision of heartbeat sensations and state anxiety score, which seems independent from the cardiovascular parameters. This systematic investigation of heartbeat sensations perception provides important fresh insights, informing the mechanistic understanding of the interoceptive signaling contribution to emotion, cognition and behaviour.

neuroscience↗