Biology subjects

Kaduk, K.

Publications and source records attributed to Kaduk, K..

5 recordsLinked to original sources

bioRxiv2025

Higher glucose levels buffer against everyday stress load

Adaptive stress responses are dependent on the availability of energy and the bodys effectiveness in metabolizing glucose as fuel. However, it is not well understood if glucose levels contribute to the functional regulation of daily stress in healthy individuals. Here, we used 4,307 ratings of stress during a four-week period of ecological momentary assessment (EMA) with concurrent recordings from continuous glucose monitoring (CGM) in 91 participants (47 women). In accordance with the hypothesized metabolic link, we found that higher glucose levels were associated with lower self-reported stress (b = -.038, p = .035, controlling for mood). Crucially, dynamic changes in glucose levels also precipitated subsequent increases in stress levels (0-2h before EMA: p = .013; incremental effect 10-12h before: p < .001), with lower glucose levels associated with subsequent stress increases and elevated glucose with stress relief, highlighting the potential of monitoring physiological biosensor data to improve adaptive stress regulation. We conclude that metabolic signals, such as glucose, play an important role in channeling stress responsiveness in healthy adults, pointing to a pivotal avenue for improved interventions to avoid excessive stress experiences.

neuroscience↗

bioRxiv2025

Glucose levels are associated with mood, but the association is mediated by ratings of metabolic state

Hunger is commonly linked to negative mood and mood shifts are thought to arise from sensing the bodys internal state. However, it is unclear whether circulating glucose levels affect mood subconsciously or via subjectively sensed metabolic states. Here, we continuously monitored the interstitial glucose levels of 90 healthy adults for four weeks while they completed ecological momentary assessments (EMA; M=47 runs per participant) to rate their mood and metabolic states. As expected, hungry participants reported lower mood, and metabolic state ratings were associated with glucose levels. Although glucose levels were associated with mood, the metabolic state ratings fully mediated this association. Individual differences reflecting metabolic health (i.e., BMI and insulin resistance) did not affect the interaction between glucose and metabolic state ratings on mood. Notably, individuals with higher interoceptive accuracy had fewer fluctuations in mood ratings. We conclude that hunger-related mood shifts depend on conscious sensing of the bodys internal state instead of acting subconsciously. Our study highlights the relevance of considering the self-report of bodily signals in understanding mood shifts, offering new fundamental insights into mood regulation mechanisms. Key messagesO_ST_ABSWhat is already known on this topicC_ST_ABSO_LIAlthough glucose is linked to satiety and hunger to negative mood, it is not known if this is due to the conscious perception of metabolic states. C_LI What this study addsO_LIThe longitudinal study design leveraging continuous glucose monitoring (CGM) and ecological momentary assessment (EMA) over four weeks, offers a unique perspective on glucose-mood interactions in naturalistic settings. C_LIO_LIWe found that the link between mood and glucose levels is fully mediated by consciously sensed metabolic states, clarifying the interoceptive link between glucose and mood. C_LI How this study might affect research, practice or policyO_LIMood is shaped by perceived metabolic states highlighting the relevance of metabolic health for mental health. C_LIO_LIThese insights improve our understanding of the association between metabolic and mental disorders. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/645871v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@7b1981org.highwire.dtl.DTLVardef@1c7a1f2org.highwire.dtl.DTLVardef@15944eaorg.highwire.dtl.DTLVardef@1bb802a_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

Non-invasive vagus nerve stimulation decreases vagally mediated heart rate variability

The vagus nerve plays a critical role in balancing the bodys physiological functions, including the cardiovascular system. Measures of heart rate (HR) and its variability (HRV) may provide non-invasive proxies of vagal activity in humans, but transcutaneous auricular vagus nerve stimulation (taVNS) has produced mixed effects so far--limited by a lack of studies stimulating the right branch. Here, we used a randomized cross-over design to study the effects of taVNS on HR and HRV. To estimate how the side of the stimulation (left vs. right ear) affects cardiovascular function, we recorded an electrocardiogram in four sessions per person (factors: Stimulation x Side). To evaluate potential interactions with physiological states, we investigated three phases per session: baseline, during stimulation (taVNS vs. sham), and after consuming a milkshake ([~]400 kcal) with concurrent stimulation. First, we found moderate evidence against an effect of taVNS on HR (BF10=0.21). Second, taVNS decreased HRV (multivariate p =.004) independent of physiological state with strong evidence for RMSSD (BF10=15.11) and HF-HRV (BF10=11.80). Third, taVNS-induced changes were comparable across sides and more strongly correlated (vs. sham), indicating similar cardiovascular effects independent of the stimulation side. We conclude that taVNS reduces HRV without altering HR, contradicting the common assumption that increased HRV indexes a heightened vagal tone. Instead, our results support a putative role of vagal afferent activation in arousal. Crucially, modulatory effects on the cardiovascular system can be safely elicited by taVNS on both sides, opening new options for treatment. Graphical AbstractCreated with BioRender.com O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/542695v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@1b6a615org.highwire.dtl.DTLVardef@51bcf7org.highwire.dtl.DTLVardef@4d047forg.highwire.dtl.DTLVardef@626251_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

Dorsal pulvinar inactivation leads to spatial selection bias without perceptual deficit

The dorsal pulvinar has been implicated in visuospatial attentional and perceptual confidence processing. Pulvinar lesions in humans and monkeys lead to spatial neglect symptoms, including an overt spatial saccade bias during free choices. But it remains unclear whether disrupting the dorsal pulvinar during target selection that relies on a perceptual decision leads to a perceptual impairment or a more general spatial orienting and choice deficit. To address this question, we reversibly inactivated the unilateral dorsal pulvinar by injecting GABA-A agonist THIP while two macaque monkeys performed a color discrimination saccade task with varying perceptual difficulty. We used Signal Detection Theory and simulations to dissociate perceptual sensitivity (d-prime) and spatial selection bias (response criterion) effects. We expected a decrease in d-prime if dorsal pulvinar affects perceptual discrimination and a shift in response criterion if dorsal pulvinar is mainly involved in spatial orienting. After the inactivation, we observed response criterion shifts away from contralesional stimuli, especially when two competing stimuli in opposite hemifields were present. Notably, the d-prime and overall accuracy remained largely unaffected. Our results underline the critical contribution of the dorsal pulvinar to spatial orienting and action selection while showing it to be less important for visual perceptual discrimination.

neuroscience↗

bioRxiv2018

Post-decision wagering after perceptual judgments reveals bi-directional certainty readouts

Humans and other animals constantly evaluate their decisions in order to learn and behave adaptively. Experimentally, such evaluation processes are accessed using metacognitive reports made after decisions, typically using verbally formulated confidence scales. When subjects report high confidence, it reflects a high certainty of being correct, but a low confidence might signify either low certainty about the outcome, or a high certainty of being incorrect. Hence, metacognitive reports might reflect not only different levels of decision certainty, but also two certainty directions (certainty of being correct and certainty of being incorrect). It is important to test if such bi-directional processing can be measured because, for decision-making under uncertainty, information about being incorrect is as important as information about being correct for guidance of subsequent behavior. We were able to capture implicit bi-directional certainty readouts by asking subjects to bet money on their perceptual decision accuracy using a six-grade wager scale (post-decision wagering, PDW). To isolate trial-specific aspects of metacognitive judgments, we used pre-decision wagering (wagering before the perceptual decision) to subtract, from PDW trials, influences resulting from non-trial-specific assessment of expected difficulty and psychological biases. This novel design allowed independent quantification of certainty of being correct and certainty of being incorrect, showing that subjects were able to read out certainty in a bi-directional manner. Certainty readouts about being incorrect were particularly associated with metacognitive sensitivity exceeding perceptual sensitivity (i.e. meta-d' > d'), suggesting that such enhanced metacognitive efficiency is driven by information about incorrect decisions. Readouts of certainty in both directions increased on easier trials, and both certainty directions were also associated with faster metacognitive reaction times, indicating that certainty of being incorrect was not confounded with low certainty. Finally, both readouts influenced the amount of money subjects earned through PDW, suggesting that bi-directional readouts are important for planning future actions when feedback about previous decisions is unavailable.

neuroscience↗