Biology subjects

Petro, N. M.

Publications and source records attributed to Petro, N. M..

4 recordsLinked to original sources

bioRxiv2025

Isolating the Contribution of the Koniocellular Visual Pathway in Aversive Learning in Human Visual Cortex

The present study examined the contribution of the koniocellular retino-geniculate visual pathway to the electrocortical amplification of threat cues in human visual cortex using an aversive conditioning task. The task involved tritan stimuli, which are thought to convey visual information through S-cone signals that project to regions along the koniocellular pathway (tritan condition) and achromatic stimuli that preferentially activate luminance channels (luminance condition). Steady-state visual evoked potential (ssVEPs) responses to the conditioned threat (CS+) and safety cues (CS-) in each condition were analyzed using a non-parametric Bayesian bootstrapped approach. Results showed that the tritan and luminance conditions exhibited greater ssVEP responses to the CS+ compared to the CS-stimuli in occipital sensors early into the trial (0 ms - 1000 ms; logBF10 > 2, decisive support). In addition to these early conditioning effects, a late conditioning effect was observed (1500 ms - 2500 ms) in the tritan condition that emerged in bilateral anterior sensors (logBF10 > 2). To further examine the tritan contribution to aversive learning, transitive Bayes factors were computed to compare the magnitude of the conditioning effects across conditions. Transitive Bayes factors showed that the early conditioning effect was larger in the luminance condition compared to the tritan condition (logBF10 > 2). Furthermore, the late conditioning effect remained larger in the tritan condition compared to the luminance condition (logBF10 > 2). Our findings suggest that both the koniocellular visual pathway and luminance channels play a role in the electrocortical amplification of threat signals in human visual cortex.

neuroscience↗

bioRxiv2024

Anterior pituitary gland volume mediates associations between pubertal hormones and changes in transdiagnostic symptoms in youth

The pituitary gland (PG) plays a central role in the production and secretion of pubertal hormones, with documented links to the emergence and increase in mental health symptoms known to occur during adolescence. Although much of the literature has focused on examining whole PG volume, recent findings suggest that there are associations among pubertal hormone levels, including dehydroepiandrosterone (DHEA), subregions of the PG, and elevated mental health symptoms (e.g., internalizing symptoms) during adolescence. Surprisingly, studies have not yet examined associations among these factors and increasing transdiagnostic symptomology, despite DHEA being a primary output of the anterior PG. Therefore, the current study sought to fill this gap by examining whether anterior PG volume specifically mediates associations between DHEA levels and changes in dysregulation symptoms in an adolescent sample (N = 114, 9 - 17 years, Mage = 12.87, SD = 1.88). Following manual tracing of the anterior and posterior PG, structural equation modeling revealed that greater anterior, not posterior, PG volume mediated the association between greater DHEA levels and increasing dysregulation symptoms across time, controlling for baseline dysregulation symptom levels. These results suggest specificity in the role of the anterior PG in adrenarcheal processes that may confer risk for psychopathology during adolescence. This work not only highlights the importance of separately tracing the anterior and posterior PG, but also suggests that transdiagnostic factors like dysregulation are useful in parsing hormone-related increases in mental health symptoms in youth.

neuroscience↗

bioRxiv2023

Specialized cingulo-opercular network activation in judging ambiguity of facial expressions in a slow reveal fMRI paradigm

Cortical task control networks, including the cingulo-opercular (CO) network play a key role in decision-making across a variety of functional domains. In particular, the CO network functions in a performance reporting capacity that supports successful task performance, especially in response to errors and ambiguity. In two studies testing the contribution of the CO network to ambiguity processing, we presented a valence bias task in which masked clearly and ambiguously valenced emotional expressions were slowly revealed over several seconds. This slow reveal task design provides a window into the decision-making mechanisms as they unfold over the course of a trial. In the main study, the slow reveal task was administered to 32 young adults in the fMRI environment and BOLD time courses were extracted from regions of interest in three control networks. In a follow-up study, the task was administered to a larger, online sample (n = 81) using a more extended slow reveal design with additional unmasking frames. Positive judgments of surprised faces were uniquely accompanied by slower response times and strong, late activation in the CO network. These results support the initial negativity hypothesis, which posits that the default response to ambiguity is negative and positive judgments are associated with a more effortful controlled process, and additionally suggests that this controlled process is mediated by the CO network. Moreover, ambiguous trials were characterized by a second CO response at the end of the trial, firmly placing CO function late in the decision-making process.

neuroscience↗

bioRxiv2020

Positivity effect in aging: Evidence for the primacy of positive responses to emotional ambiguity

Older compared to younger adults show greater amygdala activity to positive emotions, and are more likely to interpret emotionally ambiguous stimuli (e.g., surprised faces) as positive. While some evidence suggests this positivity effect results from a relatively slow, top-down mechanism, others suggest it emerges from early, bottom-up processing. The amygdala is a key node in rapid, bottom-up processing and patterns of amygdala activity over time (e.g., habituation) can shed light on the mechanisms underlying the positivity effect. Younger and older adults passively viewed neutral and surprised faces in an MRI. Only in older adults, we found that amygdala habituation was associated with the tendency to interpret surprised faces as positive or negative (valence bias), where a more positive bias was associated with greater habituation. Interestingly, although a positive bias in younger adults was associated with slower reaction times, consistent with an initial negativity hypothesis in younger adults, older adults showed faster ratings of positivity. Together, we propose that there may be a switch to a primacy of positivity in aging.

neuroscience↗