Maintaining balance comes naturally to healthy people. In subjects with vestibulopathy, even when compensated, and especially if it is bilateral, maintaining balance requires cognitive effort. Pupillometry is an established method of quantifying cognitive effort. Background/Objectives: We hypothesized that pupillometry would be able to capture the increased effort required to maintain posture in subjects with bilateral vestibulopathy in increasingly difficult conditions. Additionally, we hypothesized that the cognitive workload during balance tasks, indexed by pupil size, would decrease with the activation of the BionicVEST cochleo-vestibular implants. Methods: Subjects with a cochleo-vestibular implant as of March 2023 were recruited, excluding those with ophthalmological issues that precluded pupillometry. Pupillometry was performed using a validated modified videonystagmography system. Computed dynamic posturography and a Modified Clinical Test of Sensory Integration on Balance were performed while the pupil was recorded. Tests were first performed after 24 h of deactivating the vestibular component of the implant. Thereafter, it was reactivated, and after 1 h of rest, the tests were repeated. The pupil recording was processed using custom software and the mean relative pupil diameter (MRPD) was calculated. Results: There was an average of 10.7% to 24.2% reduction in MRPD when the vestibular implant was active, with a greater effect seen in tasks of moderate difficulty, and lesser effect when the task was easy or of great difficulty. Conclusions: Despite technical challenges, pupillometry appears to be a promising method of quantifying the cognitive effort required for maintaining posture in subjects with bilateral vestibulopathy before and after vestibular implantation.

BACKGROUND: Pupillary unrest in ambient light (PUAL) describes the fluctuation of pupil diameter observed in normal, awake subjects under typical levels of indoor light. PUAL becomes low to absent in young healthy subjects during opioid intoxication. We sought to determine the age-related distribution of PUAL values in a random sample of ambulatory participants.
METHODS: Subjects ≥18 years of age were recruited. All were identified by age range (18-29, 30-49, 50-69, and ≥70), and surveyed for diabetes, beta-blocker use, and prior 24-hour opioid use. Relationship between mean PUAL, age group, comorbidity and opioid use were examined by Kruskal Wallis test, and PUAL and was modeled using stepwise multilevel linear regression, including diabetes, beta blocker use, prior 24-hour opioid use, autonomic dysfunction, and pupil diameter as fixed effects and subject as random effect.
RESULTS: Among 150 subjects, 17 reported diabetes, 12 reported beta-blocker use, 14 reported prior 24-hour opioid use, and 120 reported no comorbid conditions. PUAL declined in higher age categories (by 0.0307, P < 0.001), with diabetes (by 0.0481, P = 0.025), and with beta-blocker use (by 0.0616, P = 0.005). Opioid related PUAL decline was observed, but statistical significance varied by model. Among healthy subjects, no PUAL value fell within range indicating high likelihood of opioid toxicity based on previous data from healthy subjects undergoing opioid infusion.
CONCLUSIONS: PUAL declined in higher age groups, diabetes and beta-blocker use, conditions associated with impaired autonomic function, and with opioid use but significance varied depending on the chosen model.

Our actions shape our everyday experience: what we experience, how we perceive, and remember it are deeply affected by how we interact with the world. Performing an action to deliver a stimulus engages neurophysiological processes which are reflected in the modulation of sensory and pupil responses. We hypothesized that these processes shape memory encoding, parsing the experience by grouping self- and externally generated stimuli into differentiated events. Participants encoded sound sequences, in which either the first or last few sounds were self-generated and the rest externally generated. We tested recall of the sequential order of sounds that had originated from the same (within event) or different sources (across events). Memory performance was not higher for within-event sounds, suggesting that actions did not structure the memory representation. However, during encoding, we observed the expected electrophysiological response attenuation for self-generated sounds, together with increased pupil dilation triggered by actions. Moreover, at the boundary between events, physiological responses to the first sound from the new source were influenced by the direction of the source switch. Our results suggest that introducing actions creates a stronger contextual shift than removing them, even though actions do not directly contribute to memory performance. This study contributes to our understanding of how interacting with sensory input shapes experiences by exploring the relationships between action effects on sensory responses, pupil dilation, and memory encoding. Importantly, it challenges the notion of a meaningful contribution from low-level neurophysiological mechanisms associated with action execution in the modulation of the self-generation effect.

Oculomotor palsy with cyclic spasms is an extremely rare condition whose exact pathophysiology remains a mystery. We followed a boy from the onset of symptoms at the age of ten months until 15 years and documented the case with video oculography. In addition, he was diagnosed with hereditary motor and sensory neuropathy (Charcot-Marie-Tooth disease type 1). Although a pure coincidence cannot be ruled out, it is conceivable that the underlying demyelinating neuropathy of this patient rendered the oculomotor nerve more susceptible to damage.

In prosopagnosia, brain lesions impair overt face recognition, but not face detection, and may coexist with residual covert recognition of familiar faces. Previous studies that simulated covert recognition in healthy individuals have impaired face detection as well as recognition, thus not fully mirroring the deficits in prosopagnosia. We evaluated a model of covert recognition based on continuous flash suppression (CFS). Familiar and unfamiliar faces and houses were masked while participants performed two discrimination tasks. With increased suppression, face/house discrimination remained largely intact, but face familiarity discrimination deteriorated. Covert recognition was present across all masking levels, evinced by higher pupil dilation to familiar than unfamiliar faces. Pupil dilation was uncorrelated with overt performance across subjects. Thus, CFS can impede overt face recognition without disrupting covert recognition and face detection, mirroring critical features of prosopagnosia. CFS could be used to uncover shared neural mechanisms of covert recognition in prosopagnosic patients and neurotypicals.

Visual working memory (VWM) can selectively filter task-irrelevant information from incoming visual stimuli. However, whether a similar filtering process applies to task-irrelevant information retrieved from visual long-term memory (VLTM) remains elusive. We assume a \"resource-limited retrieval mechanism\" in VWM in charge of the retrieval of irrelevant VLTM information. To make a comprehensive understanding of this mechanism, we conducted three experiments using both a VLTM learning task and a VWM task combined with pupillometry. The presence of a significant pupil light response (PLR) served as empirical evidence that VLTM information can indeed make its way into VWM. Notably, task-relevant VLTM information induced a sustained PLR, contrasting with the transient PLR observed for task-irrelevant VLTM information. Importantly, the transience of the PLR occurred under conditions of low VWM load, but this effect was absent under conditions of high load. Collectively, these results show that task-irrelevant VLTM information can enter VWM and then fade away only under conditions of low VWM load. This dynamic underscores the resource-limited retrieval mechanism within VWM, exerting control over the entry of VLTM information.

Witnessing emotional expressions in others triggers physiological arousal in humans. The current study focused on pupil responses to emotional expressions in a community sample as a physiological index of arousal and attention. We explored the associations between parents\' and offspring\'s responses to dynamic facial expressions of emotion, as well as the links between pupil responses and anxiety/depression. Children (N = 90, MAge = 10.13, range = 7.21-12.94, 47 girls) participated in this lab study with one of their parents (47 mothers). Pupil responses were assessed in a computer task with dynamic happy, angry, fearful, and sad expressions, while participants verbally labeled the emotion displayed on the screen as quickly as possible. Parents and children reported anxiety and depression symptoms in questionnaires. Both parents and children showed stronger pupillary responses to negative versus positive expressions, and children\'s responses were overall stronger than those of parents. We also found links between the pupil responses of parents and children to negative, especially to angry faces. Child pupil responses were related to their own and their parents\' anxiety levels and to their parents\' (but not their own) depression. We conclude that child pupils are sensitive to individual differences in parents\' pupils and emotional dispositions in community samples.

UNASSIGNED: Incentive salience processes are important for the development and maintenance of addiction. Eye characteristics such as gaze fixation time, pupil diameter, and spontaneous eyeblink rate (EBR) are theorized to reflect incentive salience and may serve as useful biomarkers. However, conventional cue exposure paradigms have limitations that may impede accurate assessment of these markers.
UNASSIGNED: This study sought to evaluate the validity of these eye-tracking metrics as indicators of incentive salience within a virtual reality (VR) environment replicating real-world situations of nicotine and tobacco product (NTP) use.
UNASSIGNED: NTP users from the community were recruited and grouped by NTP use patterns: nondaily (n=33) and daily (n=75) use. Participants underwent the NTP cue VR paradigm and completed measures of nicotine craving, NTP use history, and VR-related assessments. Eye-gaze fixation time (attentional bias) and pupillometry in response to NTP versus control cues and EBR during the active and neutral VR scenes were recorded and analyzed using ANOVA and analysis of covariance models.
UNASSIGNED: Greater subjective craving, as measured by the Tobacco Craving Questionnaire-Short Form, following active versus neutral scenes was observed (F1,106=47.95; P<.001). Greater mean eye-gaze fixation time (F1,106=48.34; P<.001) and pupil diameter (F1,102=5.99; P=.02) in response to NTP versus control cues were also detected. Evidence of NTP use group effects was observed in fixation time and pupillometry analyses, as well as correlations between these metrics, NTP use history, and nicotine craving. No significant associations were observed with EBR.
UNASSIGNED: This study provides additional evidence for attentional bias, as measured via eye-gaze fixation time, and pupillometry as useful biomarkers of incentive salience, and partially supports theories suggesting that incentive salience diminishes as nicotine dependence severity increases.

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BACKGROUND: Late-life depression (LLD) is a prevalent neuropsychiatric disorder in the older population. While LLD exhibits high mortality rates, depressive symptoms in older adults are often masked by physical health conditions. In younger adults, depression is associated with deficits in pupil light reflex and eye blink rate, suggesting the potential use of these responses as biomarkers for LLD.
METHODS: We conducted a study using video-based eye-tracking to investigate pupil and blink responses in LLD patients (n = 25), older (OLD) healthy controls (n = 29), and younger (YOUNG) healthy controls (n = 25). The aim was to determine whether there were alterations in pupil and blink responses in LLD compared to both OLD and YOUNG groups.
RESULTS: LLD patients displayed significantly higher blink rates and dampened pupil constriction responses compared to OLD and YOUNG controls. While tonic pupil size in YOUNG differed from that of OLD, LLD patients did not exhibit a significant difference compared to OLD and YOUNG controls. GDS-15 scores in older adults correlated with light and darkness reflex response variability and blink rates. PHQ-15 scores showed a correlation with blink rates, while MoCA scores correlated with tonic pupil sizes.
CONCLUSIONS: The findings demonstrate that LLD patients display altered pupil and blink behavior compared to OLD and YOUNG controls. These altered responses correlated differently with the severity of depressive, somatic, and cognitive symptoms, indicating their potential as objective biomarkers for LLD.