Biology subjects

Huviyetli, M.

Publications and source records attributed to Huviyetli, M..

3 recordsLinked to original sources

bioRxiv2026

Characterizing the effect of aging on resting and event-evoked ocular response dynamics

Ocular measures are increasingly used as non-invasive proxies of cognitive processes such as attention and listening effort. However, their interpretation in aging populations is complicated by concurrent changes in ocular physiology and oculomotor control, raising a critical question: to what extent do age-related differences in these measures reflect cognitive rather than other physiological factors? Here, we dissociate these contributions by characterizing ocular dynamics (resting and event-evoked) during passive fixation in younger (N = 98, 18-35 years) and older adults (N = 71, 60+ years). Aging is associated with pronounced alterations in pupil dynamics, including reduced baseline variability and slower, attenuated responses to both auditory and visual events. In contrast, microsaccade dynamics did not correlate with aging. Across measures, ocular responses showed moderate-to-high within-subject stability across blocks, and factor analysis in the older cohort revealed separable components reflecting instantaneous pupil responsivity, sustained pupil responsivity, and microsaccade dynamics, with additional variance associated with sensory decline and age-related changes in pupil dynamics. Together, these findings demonstrate a clear dissociation: pupil-based metrics are strongly influenced by aging, whereas microsaccades remain comparatively stable across age groups. This dissociation provides a principled basis for interpreting ocular indices in aging research and highlights the need to account for baseline physiological differences when inferring cognitive processes from eye-based measures.

neuroscience↗

bioRxiv2026

Reduced Pupil-Linked Arousal Marks Implicit Memory for Complex Auditory Sequences

Observers rapidly form long-lasting implicit memories for recurring sensory patterns, supporting adaptive behaviour through learning of environmental contingencies. Here we tested how such memories interact with neuromodulatory systems that regulate arousal--whether implicit familiarity increases arousal through retrieval-related processes or instead decreases arousal via more efficient sensory processing. We examined these competing accounts using complex auditory tone-pip sequences in which a subset of patterns recurred approximately every three minutes. One group of participants (N=30) actively detected transitions from random to regular structure, whereas a second group (N=40) heard the same sequences while performing a decoy task. Consistent with prior work, recurring regular sequences elicited faster reaction times in the active group, confirming the formation of implicit memory. Subsequently, both groups listened to previously encountered regular patterns (REGr) and matched novel regular patterns (REGn) while pupil diameter was recorded. Across groups, REGr sequences evoked significantly smaller pupil dilations than REGn sequences, indicating attenuated arousal for familiar patterns. This reduction was sustained until sequence offset in the active group but was transient in the exposure group, suggesting that task demands during exposure shape the stability of pupil-linked memory expression. Importantly, the REGr-REGn pupil difference did not correlate with explicit post-session recognition, demonstrating that the effect was not driven by conscious awareness. Together, these findings identify pupil dynamics as a robust physiological marker of learned auditory structure and show that implicit auditory sequence memory attenuates arousal. The results support predictive processing accounts in which familiarity reduces uncertainty and, consequently, neuromodulatory drive. Significance StatementHumans rapidly acquire implicit memories for recurring sounds, yet how such memories influence arousal during subsequent exposure remains poorly understood. Using pupillometry, we show that implicitly remembered auditory sequences evoke reduced pupil-linked arousal relative to matched novel sequences, even when listeners are unaware that the patterns have been previously experienced. This effect dissociates from explicit recognition, which typically yields the opposite "old/new" pattern of larger pupil responses to familiar items. Together, these findings establish pupil dynamics as a sensitive, non-invasive marker of implicit auditory memory and support predictive processing accounts in which familiarity reduces uncertainty and, consequently, neuromodulatory drive.

neuroscience↗

bioRxiv2025

The Interplay of Bottom-Up Arousal and Attentional Capture during Auditory Scene Analysis: Evidence from Ocular Dynamics

The auditory system plays a crucial role as the brains early warning system. Previous work has shown that the brain automatically monitors unfolding auditory scenes and rapidly detects new events. Here, we focus on understanding how automatic change detection interfaces with the networks that regulate arousal and attention, measuring pupil diameter (PD) as an indicator of listener arousal and microsaccades (MS) as an index of attentional sampling. Naive participants (N=36; both sexes) were exposed to artificial scenes comprised of multiple concurrent streams of pure tones while their ocular activity was monitored. The scenes were categorized as REG or RND, featuring isochronous (regular) or random temporal structures in the tone streams, respectively. Previous work showed that listeners are sensitive to predictable scene structure and use this information to facilitate change processing. Scene changes were introduced by either adding or removing a single tone stream. Results revealed distinct patterns in the recruitment of arousal and attention during auditory scene analysis. PD was greater in REG scenes compared to RND, indicating heightened arousal in unpredictable contexts. However, no differences in overall MS activity were observed between scene types, suggesting no differences in attentional engagement. Scene changes--though unattended-- elicited both PD and MS suppression, consistent with automatic attentional capture and increased arousal. Notably, only MS responses were modulated by scene regularity. This suggests that changes within predictable environments more effectively recruit attentional resources. Together, these findings offer novel insights into how automatic auditory scene analysis interacts with neural systems governing arousal and attention. Significance StatementEven without active listening, our brains automatically respond to changes in complex sound environments--like noticing a new sound on a busy street. These responses involve shifts in arousal and attention, helping us decide how to react, often without conscious awareness. Understanding this process is key to studying how we perceive sound scenes and how it may be disrupted in individuals with attention or arousal difficulties. In this study, participants passively listened to artificial soundscapes while we tracked eye activity: pupil dilation (a sign of arousal) and microsaccades (tiny eye movements linked to attention). We found that sudden scene changes triggered both responses, but they were differently influenced by scene predictability--suggesting they reflect separate aspects of automatic auditory processing.

neuroscience↗