Pupil Diameter Research Articles

Effect of cognitive load on time spent offline during wakefulness.

Humans continuously alternate between online attention to the current environment and offline attention to internally generated thought and imagery. This may be a fundamental feature of the waking brain, but remains poorly understood. Here, we took a data-driven approach to defining online and offline states of wakefulness, using machine learning methods applied to measures of sensory responsiveness, subjective report, electroencephalogram (EEG), and pupil diameter. We tested the effect of cognitive load on the structure and prevalence of online and offline states, hypothesizing that time spent offline would increase as cognitive load of an ongoing task decreased. We also expected that alternation between online and offline states would persist even in the absence of a cognitive task. As in prior studies, we arrived at a three-state model comprised of one online state and two offline states. As predicted, when cognitive load was high, more time was spent online. Also as predicted, the same three states were present even when participants were not performing a task. These observations confirm our method is successful at isolating seconds-long periods of offline time. Varying cognitive load may be a useful way to manipulate time spent in at least one of these offline states in future experimental studies.

Enteric Dysbiosis in Children With Autism Spectrum Disorder and Associated Response to Stress.

Background Microbiome studies in humans, though limited, have facilitated the evaluation of the potential connection between the microbiome and brain function. Children with autism spectrum disorder (ASD) have several behavioral challenges and avoidant/restrictive food intake disorder, which may contribute to gut microbiome dysbiosis. Aim The aim of this study is to examine the extent to which the gut microbiome of children with ASD differs in comparison to children with neurotypical development (CWND) and to assess whether a probiotic intervention has the potential to influence the gut microbiome in mediating positive behavior change and stress regulation. Methods This pilot study collected data from three children with ASD and four CWND before and after a four-week probiotic intervention. Data collection included microbiome diversity screening from stool samples as well as the following biophysiological measures: salivary alpha-amylase (sAA) levels, response to simulated stressor and calming stimulus (behavior), including pulse rate, galvanic skin response, and pupil diameter (PD). In addition, telomere length was assessed. All measures, except for telomere length, were repeated after the four-week intervention on the ASD and CWND groups for pre-/post-comparison. Data analysis consisted of multivariate analyses, including ANOVA. Results While greater heterogeneity in the ASD group was evident in all measures, the gut microbiome of participants who received probiotic intervention differed from pretreatment results within and across the groups investigated. Further, the biophysiological parameter sAA displayed a significant increase between baseline and exposure to stress in both groups, whereas PD increased in both groups from baseline,F(11, 26615) = 123.43, p = 0.00. Conclusion Though gut microbiome diversity is diminished in children with ASD compared to CWND, the gap is narrowed following a brief probiotic intervention. The results suggest that probiotic interventions have the potential to rescue microbiome diversity and abundance, potentially supporting stress regulation in pediatric populations.

Eye Tracking in MEG.

Magnetoencephalography (MEG) can measure brain activity in ms-level temporal resolution. MEG sensors are super sensitive devices for magnetic signals of the brain but are also prone to electromagnetic interferences. The MEG device is located inside the magnetically shielded room (MSR), and any monitoring device used inside the MSR requires special shielding and its location must be carefully selected to suppress electromagnetic interference. Eye-tracker measures eye movements, providing spatial location of the gaze, pupil diameters, and eye blinks. Eye tracking in MEG enables, for example, categorization of the MEG data based on gaze position and interactive stimulus using gaze position. Combining the methods together will require considering the electromagnetic interference for the MEG-that is, additional shielding, positioning of the eye tracker, and subject-specific issues related to make-up and eye-corrective lenses.

Measuring Efficiency and Accuracy in Locating Symbols on Mobile Maps Using Eye Tracking

This study investigated the impact of smartphone usage frequency on the effectiveness and accuracy of symbol location in a variety of spatial contexts on mobile maps using eye-tracking technology while utilizing the example of Mapy.cz. The scanning speed and symbol detection were also considered. The use of mobile applications for navigation is discussed, emphasizing their popularity and convenience of use. The importance of eye tracking as a valuable tool for testing the usability of cartographic products, enabling the assessment of users’ visual strategies and their ability to memorize information, was highlighted. The frequency of smartphone use has been shown to be an important factor in users’ ability to locate symbols in different spatial contexts. Everyday smartphone users have shown higher accuracy and efficiency in image processing, suggesting a potential link between habitual smartphone use and increased efficiency in mapping tasks. Participants who were dissatisfied with the legibility of a map looked longer at the symbols, suggesting that they put extra cognitive effort into decoding the symbols. In the present study, gender differences in pupil size were also observed during the study. Women consistently showed a larger pupil diameter, potentially indicating greater cognitive load on the participants.

Quantitative analysis of dynamic iris changes in primary angle-closure disease with long axial lengths: the Handan Eye Study.

To investigate dynamic iris changes in patients with primary angle-closure disease (PACD) with long axial length (AL) compared to those with short and medium AL. This observational cross-sectional study enrolled participants aged 35 years or older from the Handan Eye Study follow-up examination who were diagnosed with PACD and underwent Visante anterior segment optical coherence tomography (ASOCT) imaging under light and dark conditions. The right eye of each participant was included in the analysis. AL was categorized as short (<22.0 mm), medium (≥22.0 to ≤23.5 mm), or long (>23.5 mm). Anterior segment parameters, including iris dynamic changes, were compared among the three groups with different ALs. Data from 448 patients with PACD were analyzed. We found that 10.9% of included eyes had a long AL with a flatter cornea; larger central anterior chamber depth, angle opening distance, anterior chamber width, anterior chamber area, and volume; and smaller lens thickness and lens vault (LV) (P < 0.05) than those with short AL. No significant difference existed between the three groups in iris thickness, iris cross-sectional area (IA), iris curvature, or pupil diameter (PD) change between light and dark (P > 0.05). The significant associated factors for IA changes were area recess area (ARA) in the dark, LV in the dark, and PD change from light to dark (P < 0.05). Dynamic and static iris parameters were consistent across patients with PACD with short, medium, or long AL and may contribute to the pathogenesis of angle closure in atypical PACD.

Effects of Screen Color Mode and Color Temperature on Visual Fatigue under Different Ambient Illuminations

Viewing electronic screens for a long time can cause visual fatigue, even induce eye problems such as refractive errors, dry eyes, etc. The relationship between screen display and visual fatigue has received much attention. This article aims to study the optimal display color temperature and color mode under two common ambient illuminations—normal office lighting (450 lux) and dark environment (3 lux). In a 2 × 2×3 experimental design, 36 participants evaluated the effects of two display color modes (light mode and dark mode) and three screen color temperatures (2800 K, 4500 K, and 6500 K) on visual fatigue under two ambient illuminations. We used eye movement tracking technology to collect blink rate and pupil diameters as objective indicators and used the Richter scale to collect subjective visual fatigue and preference score as subjective indicators. Results showed that at 450 lux, lower visual fatigue was found in the dark mode, 4500 K and 6500 K. At 3 lux, the visual fatigue was lower in the dark mode and 4500 K color temperature. Whether at daytime or night, the 2800 K color temperature resulted in the highest visual fatigue. Our findings complement the research on screen display and visual fatigue. They have practical implications for reducing visual fatigue caused by prolonged viewing of electronic screens.

Ray-tracing model of a perfect lens compliant with Fermat's principle: the Cardinal Lens.

When using ray tracing for optical system design, it is often the case that the designer would like to implement simplified versions of one or more compound lens groups. This could be the case during initial layout when idealized versions of such compound lenses are needed or, perhaps alternatively, to mimic a well-corrected commercially available lens for which the prescription details are unavailable. One option is to use a paraxial thin lens as a proxy for the actual lens group, but doing so will yield a layout that is not consistent with Fermat's principle or the Abbe sine condition. For example, a paraxial lens version of a compound microscope objective typically produces the wrong numerical aperture for a given entrance pupil diameter, and vice versa. A better option is to use a lens model that provides perfect imaging for a specified paraxial magnification and obeys Fermat's principle. A variant of the model can yield a perfect Fourier transform lens. In addition, it is desirable to implement an idealized thick lens in which the principal planes are separated by a user-specified distance. This paper presents such a model, referred to as the Cardinal Lens, with implementation in Zemax OpticStudio via a user-defined surface.

Sutureless intrascleral intraocular lens fixation and modified iris cerclage pupilloplasty for aphakia and traumatic mydriasis.

To evaluate the safety and efficacy of sutureless intrascleral intraocular lens (IOL) fixation combined with modified iris cerclage pupilloplasty for treating aphakia and traumatic mydriasis. Five patients with aphakia and traumatic mydriasis were operated on by the same surgeon. All patients underwent sutureless intrascleral IOL fixation combined with modified iris cerclage pupilloplasty and were followed up for ≥6 months. Best-corrected visual acuity (BCVA) was measured using the logarithm of the minimum angle of resolution (logMAR). BCVA, intraocular pressure (IOP), pupil diameter, and corneal endothelial cell count (CECC) preoperatively and postoperatively were statistically analyzed. The pupil shape, photophobia, IOL position, and surgical complications were evaluated. The mean BCVA was significantly improved 6 months postoperatively (0.26 ± 0.17 logMAR, P = 0.042) than preoperatively (0.50 ± 0.30 logMAR). No significant difference was observed between the preoperative and postoperative IOP (P = 0.138). The mean pupil diameter significantly reduced postoperatively than preoperatively (3.44 ± 0.35 mm vs. 7.28 ± 0.35 mm, P = 0.043). There was no significant decrease in CECC postoperatively (P = 0.225). The pupil shape was round-like, and photophobia disappeared in all patients. No intraoperative or postoperative complications occurred. Sutureless intrascleral IOL fixation combined with modified iris cerclage pupilloplasty is a safe and efficient procedure for treating aphakia traumatic mydriasis patients without sufficient capsular support.

Long-Term Visual Quality and Pupil Changes after Small-Incision Lenticule Extraction for Eyes without Preoperative Cylinder Refraction.

To investigate the long-term changes in visual quality and pupil size after small incision lenticule extraction (SMILE) for eyes without preoperative cylinder refraction. Thirty-three myopic eyes (33 patients) without preoperative cylinder refraction were corrected using SMILE. Refractive outcomes, corneal curvature, aberrations, contrast sensitivity (CS), and pupil diameter were evaluated preoperatively, and 30 months postoperatively. The 30-month postoperative uncorrected and corrected distance visual acuity (UDVA and CDVA, LogMAR) were -0.10 ± 0.09 and -0.14 ± 0.06, respectively, whereas the preoperative CDVA (LogMAR) was -0.07 ± 0.05. Cylinder refraction of -0.11 ± 0.21 D (ranging from -0.50 to 0.00) was observed at 30 months postoperatively, increasing from the preoperative cylinder refraction of 0.00 ± 0.00 D (P=0.004). Moreover, the centroid coordinates x, y of corneal anterior astigmatic vectors were -0.19 ± 0.22, 0.81 ± 0.33 at 30 months postoperatively, and 0.02 ± 0.28, 0.76 ± 0.51 preoperatively (Px < 0.001 and Py=0.810, respectively). Furthermore, a 15° axis change in the mean anterior corneal astigmatic vector was observed at 30 months postoperatively from the preoperative state, as measured by Pentacam. At 30 months postoperatively, the photopic Log CS reduced significantly with glare at three and six cycles/degrees (P < 0.001 and P=0.015, respectively), a decreased photopic pupil diameter (3.27 ± 0.55 mm vs. 3.10 ± 0.66 mm, P=0.030), and an increased Coma (Z31) and Trefoil (Z3-3) at 4 mm diameter area analysis. However, a significant linear regression relationship was only observed between changes in photopic pupil diameter and changes in photopic Log CS with glare at 12 cycles/degree (P=0.038 and β = 0.282). Slight cylinder regression was observed with thicker corneal lenticular extraction after SMILE correction of nonastigmatic eyes 30 months postoperatively. This regression was mainly because of the axis changes in anterior corneal astigmatism power. Therefore, a cylinder nomogram modification of 0.25 to 0.50 D is considerable for correcting nonastigmatic myopic eyes with a predicted spherical lenticular thickness over 100 µm.

Development of performance and learning rate evaluation models in robot-assisted surgery using electroencephalography and eye-tracking

The existing performance evaluation methods in robot-assisted surgery (RAS) are mainly subjective, costly, and affected by shortcomings such as the inconsistency of results and dependency on the raters’ opinions. The aim of this study was to develop models for an objective evaluation of performance and rate of learning RAS skills while practicing surgical simulator tasks. The electroencephalogram (EEG) and eye-tracking data were recorded from 26 subjects while performing Tubes, Suture Sponge, and Dots and Needles tasks. Performance scores were generated by the simulator program. The functional brain networks were extracted using EEG data and coherence analysis. Then these networks, along with community detection analysis, facilitated the extraction of average search information and average temporal flexibility features at 21 Brodmann areas (BA) and four band frequencies. Twelve eye-tracking features were extracted and used to develop linear random intercept models for performance evaluation and multivariate linear regression models for the evaluation of the learning rate. Results showed that subject-wise standardization of features improved the R2 of the models. Average pupil diameter and rate of saccade were associated with performance in the Tubes task (multivariate analysis; p-value = 0.01 and p-value = 0.04, respectively). Entropy of pupil diameter was associated with performance in Dots and Needles task (multivariate analysis; p-value = 0.01). Average temporal flexibility and search information in several BAs and band frequencies were associated with performance and rate of learning. The models may be used to objectify performance and learning rate evaluation in RAS once validated with a broader sample size and tasks.

Cortical Zinc Signaling Is Necessary for Changes in Mouse Pupil Diameter That Are Evoked by Background Sounds with Different Contrasts.

Luminance-independent changes in pupil diameter (PD) during wakefulness influence and are influenced by neuromodulatory, neuronal, and behavioral responses. However, it is unclear whether changes in neuromodulatory activity in a specific brain area are necessary for the associated changes in PD or whether some different mechanisms cause parallel fluctuations in both PD and neuromodulation. To answer this question, we simultaneously recorded PD and cortical neuronal activity in male and female mice. Namely, we measured PD and neuronal activity during adaptation to sound contrast, which is a well-described adaptation conserved in many species and brain areas. In the primary auditory cortex (A1), increases in the variability of sound level (contrast) induce a decrease in the slope of the neuronal input-output relationship, neuronal gain, which depends on cortical neuromodulatory zinc signaling. We found a previously unknown modulation of PD by changes in background sensory context: high stimulus contrast sounds evoke larger increases in evoked PD compared with low-contrast sounds. To explore whether these changes in evoked PD are controlled by cortical neuromodulatory zinc signaling, we imaged single-cell neural activity in A1, manipulated zinc signaling in the cortex, and assessed PD in the same awake mouse. We found that cortical synaptic zinc signaling is necessary for increases in PD during high-contrast background sounds compared with low-contrast sounds. This finding advances our knowledge about how cortical neuromodulatory activity affects PD changes and thus advances our understanding of the brain states, circuits, and neuromodulatory mechanisms that can be inferred from pupil size fluctuations.

The long-term effects of topical latanoprost 0.005% treatment on pupillary functions: A 2-year longitudinal study.

To investigate the long-term effects of topical latanoprost 0.005% treatment on pupillary functions in early-stage primary open-angle glaucoma (POAG) eyes using automated pupillometry. This prospective study involved 20 eyes of 20 treatment-naive subjects with early-stage POAG. After comprehensive ophthalmic examination, static and dynamic pupillometry measurements were performedbefore treatment, at the 1st follow-up visit (1.10 ± 0.30 months) and the 2nd follow-up visit (25.85 ± 10.26 months) after treatment initiation. Dynamic parameters included resting diameter (mm), amplitude (mm), latency (ms), duration (ms), and velocity (mm/s) of pupil contraction and dilation. Static pupillometry parameters were pupil diameter (PD, mm) in high-photopic, low-photopic, mesopic and scotopic conditions. The velocity of pupil dilation significantly decreased during the 1st visit (p = 0.008) and the 2nd visit (p = 0.0003) of treatment compared to the pre-treatment visit. The resting PD was also significantly higher after the 1st visit (p = 0.003) and the 2nd visit (p = 0.001) compared to the pre-treatment visit. However, the difference in resting PD measured between the 1st and 2nd visits did not reach statistical significance (p = 0.065). There were no significant changes in other dynamic parameters (p > 0.05 for all). Additionally, a mild, but not significant, mydriatic effect was observed in PD measurements under scotopic, mesopic and low photopic lighting conditions after follow-up. None of the static and dynamic parameters correlate with age, changes in intraocular pressure (IOP) or mean deviation (MD) values of visual field tests. The long-term topical latanoprost 0.005% treatment in early-stage POAG has a slight mydriatic effect on the pupil. Further longitudinal clinical studies with larger patient cohorts are necessary to better understand the effects of latanoprost on pupillary functions.

Understanding distracted pedestrians’ risky behaviour: The role of walking and visual characteristics through a field study

Use of mobile phones while crossing the road has become a growing safety concern among pedestrians. Though recently, some studies have attempted to understand risky behaviour of distracted pedestrians by analyzing impacts of distraction on pedestrians’ walking and visual characteristics, the impacts were measured individually. Moreover, most of the existing findings are based on lab-based experiments, whereas the real-world conditions are quite dynamic in nature. Hence, to overcome these gaps, the current study aims to understand to what extent different potential factors (such as distraction, walking characteristics, visual behaviour, etc.) affect the risk of unsafe pedestrian-vehicle interactions in real-world settings. For this purpose, a field experiment was designed to understand the impact of distraction on pedestrians’ risky behaviour using an eye-tracker at an unsignalized intersection in Delhi. The risk assessment was done using Post-Encroachment Time (PET) measure. The results indicate that the use of mobile phone while crossing the road increased the chances of unsafe (PET < 1.5 s) pedestrian-vehicle interactions by approximately eight folds. Surprisingly, pedestrians who crossed the intersection at high speed had higher chances of unsafe interactions, whereas their increased crossing initiation time reduced the probability of unsafe interactions. Moreover, increased pupil diameter and fixating more on vehicles approaching from the right side resulted in a reduced probability of unsafe interactions. However, the high frequency of saccades and higher fixations on the crosswalk's right side negatively affected unsafe interactions. This study highlights that it is important to consider visual characteristics along with demographic and walking and traffic characteristics as they can provide in-depth insights into pedestrians’ road crossing behaviour that are required to design and implement effective countermeasures and policies.

Effects of music on the preoperative and intraoperative anxiety through the assessment of pupil size and vital signs (blood pressure, respiratory, and pulse rates) among cataract surgery patients at UNTH-Enugu.

To examine how music can impact preoperative and intraoperative anxiety via assessment of physiological markers such as pupil size, blood pressure, pulse rate, and respiratory rate. This is a randomized interventional study of individuals aged 50 years and above who were scheduled for and undergoing cataract surgery under regional anesthesia, with music (test group) randomly matched with similar individuals undergoing the same procedure but without music (control group). The surgeries were performed in the operating theater of the Department of Ophthalmology, University of Nigeria Teaching Hospital (UNTH), Ituku-Ozalla, Enugu. Using a systematic random sampling method, a total of 98 patients were grouped into two. Both groups completed the State-Trait Anxiety Inventory (STAI) questionnaire at baseline, immediately upon entrance into the preoperative room and 5 min after intervention. Relevant study indices (blood pressure, pulse, respiratory rate, and pupil diameter) were measured and recorded, and these served as baseline parameters. The STAI questionnaire was then administered. Results were analyzed using the SPSS version 20 and analysis of variance was used to compare means of variables measured at baseline, preoperative before intervention, and preoperative after intervention. Categorical variables were compared using the Chi-square test. Student's t-test was used to analyze the continuous variables. Our analysis, using the multiple linear regression, showed that music has an effect on preoperative anxiety and intraoperative anxiety by positively affecting the blood pressure, pulse rate, respiratory rate, and pupil diameter (P ≤ 0.001). Music reduces preoperative and intraoperative anxiety evidenced by its effect on the physiological biomarkers.

Evaluation of Quantitative Pupillometry in Acute Postinjury Pediatric Concussion

BackgroundAlthough millions of children sustain concussions each year, a rapid and objective test for concussion has remained elusive. The aim of this study was to investigate quantitative pupillometry in pediatric patients in the acute, postinjury setting. MethodsThis was a prospective case-control study of concussed patients presenting to the emergency department within 72 hours of injury. Pupillary measurements were gathered using NeurOptics’ PLR 3000; evaluation included a symptom checklist and neurocognitive assessment. Data were analyzed using descriptive statistics and regression models. ResultsA total of 126 participants were enrolled. One significant difference in pupillometry between concussed and control participants was found: left minimum pupil diameter in 12- to 18 year-olds (P = 0.02). Models demonstrating odds of a concussion revealed significant associations for time to 75% recovery (T75) of the left pupil in five- to 11-year-olds and average dilation velocity of the left pupil in 12- to 18-year-olds (P = 0.03 and 0.02 respectively). Models predicting symptom improvement showed one significant association: percent change of the right pupil in five-to-11-year-olds (P = 0.02). Models predicting neurocognitive improvement in 12- to 18-year-olds demonstrated significant association in T75 in the left pupil for visual memory, visual motor processing speed, and reaction time (P = 0.002, P = 0.04, P = 0.04). ConclusionsThe limited statistically significant associations found in this study suggest that pupillometry may not be useful in pediatrics in the acute postinjury setting for either the diagnosis of concussion or to stratify risk for prolonged recovery.

An empirical investigation of driver’s eye-catching effect in the entrance zone of freeway tunnels: A naturalistic driving experiment

This study aims to evaluate the impact of different visual attraction environments at the entrance zone of freeway tunnels on drivers' visual performance and subjective mental workload. Through a naturalistic driving experiment conducted on actual roads, participants experienced various visual attraction environments at the entrance zones of freeway tunnels. The selected visual environments included baseline, landscape-style architecture, tip slogan, and billboard scenarios. Objective visual performance was assessed using eye-tracking devices to collect participants' eye movement data, while subjective mental workload was evaluated through the NASA-TLX measurement reports administered after the driving experiment. The results indicate that the visual attraction environments at the entrance zone of freeway tunnels have significant impacts on drivers’ visual attention level, cognitive workload, and subjective mental workload. Under the billboard condition, participants exhibited the longest first fixation duration (FFD) and paid the earliest attention to visual attraction (reflected by participants positioned their initial fixation at the visual attraction farthest from the tunnel entrance zone (DFT)). Additionally, the tip slogan condition resulted in the highest mean fixation duration (MFD), the largest percentage of total fixation duration on the visual attraction (PTFD), and the highest cognitive workload (reflected in maximum pupil diameter (PD)). Billboard at the entrance zone of freeway tunnel had the greatest effect on attracting drivers’ visual attention, while tip slogan resulted in the highest cognitive workload on drivers. The results of the subjective mental workload evaluation (NASA-TLX) also indicated that tip slogan had the greatest impact on drivers’ subjective mental workload. This study provides valuable insights into the potential impact of different visual attraction environments at the entrance zone of freeway tunnels on drivers' eye-catching effect. The results contribute to both theoretical knowledge and practical applications in the field of transportation safety.

On-eye centration of soft contact lenses.

To evaluate the relative positions of modern soft contact lenses (SCLs) relative to the limbus/cornea and the pupil. Sixty images of the anterior eyes of 101 subjects were acquired over 10 s while participants fixated the centre of the camera lens located 33 cm in front of the eye in a well-lit (300 lux) clinic. Custom validated image analysis software was used to locate the boundaries of the contact lenses, pupils and corneas (limbus). Horizontal and vertical relative positions of the contact lens, pupil and limbus were calculated from the fitted boundaries. The mean (standard deviation) pupil and corneal diameters for all subjects were 3.84 mm, (0.83) and 11.97 mm (0.48), respectively. The mean [95% confidence interval] pupil centre was located 0.28 mm [0.26, 0.30] nasally and 0.07 mm [0.05, 0.10] superiorly to the corneal centre. Consistent with clinical observations, the contact lenses centred accurately relative to the corneal centre both nasally 0.04 mm [0.01, 0.07] and inferiorly -0.01 mm [-0.06, 0.03]. However, regardless of the eye, the contact lens was significantly (p < 0.001) decentred relative to the pupil centre both temporally -0.23 mm [-0.26, -0.20] and inferiorly -0.08 mm [-0.12, -0.04]. Decentration magnitudes were significantly correlated between the right and left eyes. Spherical SCLs centred well on the cornea but temporally and inferiorly from the primary line of sight (pupil centre), due to the differences in the location of the pupil and corneal centres. Contrary to some previous reports, there was no evidence that lens optics or material affected lens centration significantly.

Neurobiological Underpinnings of Hyperarousal in Depression: A Comprehensive Review.

Patients with major depressive disorder (MDD) exhibit an abnormal physiological arousal pattern known as hyperarousal, which may contribute to their depressive symptoms. However, the neurobiological mechanisms linking this abnormal arousal to depressive symptoms are not yet fully understood. In this review, we summarize the physiological and neural features of arousal, and review the literature indicating abnormal arousal in depressed patients. Evidence suggests that a hyperarousal state in depression is characterized by abnormalities in sleep behavior, physiological (e.g., heart rate, skin conductance, pupil diameter) and electroencephalography (EEG) features, and altered activity in subcortical (e.g., hypothalamus and locus coeruleus) and cortical regions. While recent studies highlight the importance of subcortical-cortical interactions in arousal, few have explored the relationship between subcortical-cortical interactions and hyperarousal in depressed patients. This gap limits our understanding of the neural mechanism through which hyperarousal affects depressive symptoms, which involves various cognitive processes and the cerebral cortex. Based on the current literature, we propose that the hyperconnectivity in the thalamocortical circuit may contribute to both the hyperarousal pattern and depressive symptoms. Future research should investigate the relationship between thalamocortical connections and abnormal arousal in depression, and explore its implications for non-invasive treatments for depression.

Responses to a "Typical" Morning Dose of Kratom in People Who Use Kratom Regularly: A Direct-Observation Study.

Use of kratom has outpaced systematic study of its effects, with most studies reliant on retrospective self-report. We aimed to assess acute effects following kratom use in adults who use regularly, and quantify alkaloids in the products, urine, and plasma. Between July and November 2022, 10 adults came to our clinic and orally self-administered their typical kratom dose; blinding procedures were not used. Physiological measures included blood pressure, respiratory rate, heart rate, pulse oximetry, temperature, and pupil diameter. Subjective outcomes included Subjective Opioid Withdrawal Scale, Addiction Research Center Inventory, and Drug Effects Questionnaire. Psychomotor performance was also assessed. Participants were 6 men and 4 women, mean age 41.2 years. Nine were non-Hispanic White; 1 was biracial. They had used kratom for 6.6 years (SD, 3.8 years) on average (2.0-14.1). Sessions were 190.89 minutes on average (SD, 15.10 minutes). Mean session dose was 5.16 g (median, 4.38 g; range, 1.1-10.9 g) leaf powder. Relative to baseline, physiological changes were minor. However, pupil diameter decreased (right, b = -0.70, P < 0.01; left, b = -0.73, P < 0.01) 40-80 minutes postdose and remained below baseline >160 minutes. Subjective Opioid Withdrawal Scale pre-dosing was mild (5.5 ± 3.3) and decreased postdose (b = [-4.0, -2.9], P < 0.01). Drug Effects Questionnaire "feeling effects" increased to 40/100 (SD, 30.5) within 40 minutes and remained above baseline 80 to 120 minutes (b = 19.0, P = 0.04), peaking at 72.7/100; 6 participants rated euphoria as mild on the Addiction Research Center Inventory Morphine-Benzedrine-scale. Psychomotor performance did not reliably improve or deteriorate postdosing. Among regular consumers, we found few clinically significant differences pre- and post-kratom dosing. Alkaloidal contents in products were within expected ranges.

Investigating pupillometry to detect preoperative anxiety: a pilot study.

Guidelines from the European Society of Anesthesia (ESA) insist on the importance of preoperative anxiety management. However, its assessment currently relies on questionnaires that are long to submit and sometimes difficult to interpret. Exploring the balance between sympathetic and parasympathetic neural systems through the use of pupillometry is a promising path to identify anxiety and thus provides an objective and reproducible assessment tool. A single-center prospective observational study was conducted in a population of ambulatory ophthalmological surgery patients. Preoperative anxiety was assessed using the Surgical Fear Questionnaire (SFQ). Measurements were taken using an Algiscan® (IDMed) type pupillometer before, during, and after insertion of the peripheral IV catheter. A statistical correlation test was carried out between the different evaluations of anxiety and the coefficient of variation of the pupillary diameter (VCPD). A total of 71 patients were included in the study between July 2020 and February 2021, with a median SFQ score of 23 [IQR 11-34]. No significant statistical correlation was found between the baseline pupillary diameter, or VCPD, and preoperative anxiety levels. Similarly, the pupillometric variables did not differ significantly when adjusting for the level of anxiety during and after painful stimulation due to canulation. More studies are necessary to explore the potential correlation between preoperative anxiety and pupillometry.