Acute methamphetamine and alcohol usage alters gaze behaviour during driving: A randomised, double-blind, placebo-controlled study.

BACKGROUND: Methamphetamine is frequently co-consumed with alcohol, yet combined effects on visually guided behaviours have not been experimentally assessed. This study examined whether methamphetamine and alcohol-induced changes in gaze behaviour can be accurately detected and indexed during a simulated driving task to establish characteristic patterns relevant to traffic safety. METHODS: In a randomised, placebo-controlled, cross-over study design, the effects of acute oral methamphetamine (0.42 mg/kg) were assessed with and without low doses of alcohol (target 0.04% blood alcohol content) on gaze behaviour during driving. Twenty healthy adults (mean age 29.5 years (SD ± 4.9), 40% female) completed four, 1-h simulated drives with simultaneous eye monitoring using the SensoMotoric Instruments cap-mounted eye tracker over a 4-week experimental paradigm. Gaze entropy measures were used to quantify visual scanning efficiency, expressed as gaze transition entropy and stationary gaze entropy. Fixations, recorded as duration (milliseconds, ms) and rate (count) per minute, were examined in 10-min bins over the duration of the drive. Driving performance was assessed by the standard deviation of lateral position, standard deviation of speed and steering variability. RESULTS: Methamphetamine increased the rate and duration of fixations and produced a less dispersed but more disorganised pattern of gaze during highway driving while preserving performance. Alcohol alone impaired both oculomotor control and driving performance, even when consumed at levels well below the legal limit stipulated in many international jurisdictions. CONCLUSIONS: Methamphetamine-affected drivers display inefficient exploration in a limited visual range during driving. Eye-tracking metrics thus show potential for indexing intoxication due to psychoactive substance usage.

Effect of topical brinzolamide on visual function and waveform in patients of infantile nystagmus syndrome: A randomized control trial.

PURPOSE: To evaluate the effect of topical carbonic anhydrase inhibitor (brinzolamide) versus placebo on visual function and waveforms in infantile nystagmus syndrome (INS). DESIGN: Prospective, placebo-controlled, double-blind, cross-over study. METHODS: Setting- A tertiary eye care center. Patients- Cases of idiopathic INS with and without abnormal head posture aged ≥10 years who had not received previous treatment for nystagmus. Intervention- Patients were randomized into two groups. Group 1 was given placebo for 3 months, and after a washout period of 7 days started on topical brinzolamide for the next 3 months. In group 2, the order was reversed. The drops were administered topically three times (every 8 hours) in both eyes. Outcome measure- Binocular best corrected visual acuity (BCVA) using the ETDRS chart, eXpanded nystagmus acuity function (NAFX) score and INS waveforms obtained from eye movement recordings, intraocular pressure (IOP) by Goldmann applanation tonometer, near stereopsis by TNO stereo test, and change in abnormal head posture before and after intervention in the null position. RESULTS: A total of 29 cases completed the study (23 with abnormal head posture; 6 without abnormal head posture).A significant improvement was noted in INS waveform characteristics, mean NAFX score (P < 0.001), and mean binocular visual acuity (P < 0.001) with topical brinzolamide in comparison to baseline as well as placebo. No significant change in head position and stereopsis was noted. No side effects were reported with 3 months of brinzolamide therapy. CONCLUSIONS: While brinzolamide shows improvement in visual acuity and NAFX score in idiopathic INS, its clinical significance needs further evidence.

VEGF is an essential retrograde trophic factor for motoneurons.

VEGF was initially discovered due to its angiogenic activity and therefore named "vascular endothelial growth factor." However, its more recently discovered neurotrophic activity may be evolutionarily more ancient. Our previous work showed that all the changes produced by axotomy on the firing activity and synaptic inputs of abducens motoneurons were completely restored after VEGF administration. Therefore, we hypothesized that the lack of VEGF delivered by retrograde transport from the periphery should also affect the physiology of otherwise intact abducens motoneurons. For VEGF retrograde blockade, we chronically applied a neutralizing VEGF antibody to the lateral rectus muscle. Recordings of extracellular single-unit activity and eye movements were made in alert cats before and after the application of the neutralizing antibody. Our data revealed that intact, noninjured abducens motoneurons retrogradely deprived of VEGF exhibited noticeable changes in their firing pattern. There is a general decrease in firing rate and a significant reduction in eye position and eye velocity sensitivity (i.e., a decrease in the tonic and phasic components of their discharge, respectively). Moreover, by means of confocal immunocytochemistry, motoneurons under VEGF blockade showed a marked reduction in the density of afferent synaptic terminals contacting with their cell bodies. Altogether, the present findings demonstrate that the lack of retrogradely delivered VEGF renders abducens motoneurons into an axotomy-like state. This indicates that VEGF is an essential retrograde factor for motoneuronal synaptic drive and discharge activity.

Chemogenetic inactivation reveals the inhibitory control function of the prefronto-striatal pathway in the macaque brain.

The lateral prefrontal cortex (LPFC) has a strong monosynaptic connection with the caudate nucleus (CdN) of the striatum. Previous human MRI studies have suggested that this LPFC-CdN pathway plays an important role in inhibitory control and working memory. We aimed to validate the function of this pathway at a causal level by pathway-selective manipulation of neural activity in non-human primates. To this end, we trained macaque monkeys on a delayed oculomotor response task with reward asymmetry and expressed an inhibitory type of chemogenetic receptors selectively to LPFC neurons that project to the CdN. Ligand administration reduced the inhibitory control of impulsive behavior, as well as the task-related neuronal responses observed in the local field potentials from the LPFC and CdN. These results show that we successfully suppressed pathway-selective neural activity in the macaque brain, and the resulting behavioral changes suggest that the LPFC-CdN pathway is involved in inhibitory control.

Associations of prenatal exposure to phthalates with measures of cognition in 7.5-month-old infants.

BACKGROUND: Phthalates are endocrine disrupting chemicals that have been associated with adverse neurobehavior, but little is known about their influence on infant cognition. METHODS: A visual recognition memory task was used to assess cognition in 244 7-8-month-old infants (121 females; 123 males) from a prospective cohort study. Phthalate metabolites were quantified in maternal urines pooled from across pregnancy. The task included familiarization trials (infant shown 2 identical faces) and test trials (infant shown the now familiar face paired with a novel one). Half of the infants saw one set of faces as familiar (set 1) and half saw the other set as familiar (set 2). During familiarization trials, average run duration (time looking at stimuli before looking away, measure of processing speed), and time to familiarization (time to reach 20 s looking at the stimuli, measure of attention) were assessed. During test trials, novelty preference (proportion of time looking at the novel face, measure of recognition memory) was assessed. Multivariable generalized linear models were used to assess associations of monoethyl phthalate (MEP), sum of di(2-ethylhexyl) phthalate metabolites (ΣDEHP), sum of di(isononyl) phthalate metabolites (ΣDINP), and sum of anti-androgenic phthalate metabolites (ΣAA) with each outcome. RESULTS: Mothers were mostly white and college educated, and urine phthalate concentrations were similar to those in reproductive age women in the U.S. POPULATION: All phthalate exposure biomarkers, except MEP, were associated with increases in average run duration. However, depending on the phthalate, associations were only in males or infants who saw the set 2 stimuli as familiar. Unexpectedly, ΣAA was associated with a shorter time to reach familiarization. Phthalate biomarkers also were associated with modest decrements in novelty preference, but these associations were nonsignificant. CONCLUSION: Prenatal exposure to phthalates may be related to slower information processing and poorer recognition memory in infants.

Quantification of Global Ocular Motility Impairment in Graves' Orbitopathy by Measuring Eye Muscle Ductions.

Background: The overall changes of ocular motility in Graves' orbitopathy (GO) are not easily quantifiable with the methods currently available, especially in clinical studies. The aim of the present study was to calculate parameters that quantify the changes of ocular motility in GO in relation to the Gorman score for diplopia. Methods: We studied 100 GO patients (Group 1) and 100 controls (Group 2). We also included 30 patients treated with intravenous methylprednisolone (iv-MP), assessed at baseline and after 12 and 24 weeks (Group 3), and 66 patients submitted to squint surgery, assessed at baseline and after 12 weeks (Group 4). Ocular ductions were measured in four gaze directions by a perimeter arc and were used to calculate a total motility score (TMS) as the sum of ductions in each direction; a biocular TMS (b-TMS) as the sum of the TMS of two eyes; and an asymmetry ratio (AR) as the sum of the differences of the corresponding ductions between the two fellow eyes divided by the mean difference found in controls. Quality of life was accessed by a specific questionnaire (Graves' orbitopathy quality of life [GO-QoL] questionnaire). Results: TMS and b-TMS were lower, while AR was higher, in Group 1 compared with controls (p < 0.001). In Group 1, TMS and b-TMS were inversely correlated with the Gorman score (p < 0.001) and AR was higher in patients with constant diplopia compared with the others (p < 0.001). In Group 3, TMS and b-TMS increased after treatment in responders to iv-MP (p < 0.001). In Group 4, TMS and b-TMS improved in all patients after surgery (p < 0.01), while AR and GO-QoL score improved only in those without residual constant diplopia (p < 0.001). Conclusion: We describe a quantitative method to assess eye motility dysfunction in any stage of GO to be used as an outcome measure in clinical studies.

Atomoxetine modulates the contribution of low-level signals during free viewing of natural images in rhesus monkeys.

Visuo-spatial attentional orienting is fundamental to selectively process behaviorally relevant information, depending on both low-level visual attributes of stimuli in the environment and higher-level factors, such as goals, expectations and prior knowledge. Growing evidence suggests an impact of the locus-cœruleus-norepinephrine (LC-NE) system in attentional orienting that depends on taskcontext. Nonetheless, most of previous studies used visual displays encompassing a target and various distractors, often preceded by cues to orient the attentional focus. This emphasizes the contribution of goal-driven processes, at the expense of other factors related to the stimulus content. Here, we aimed to determine the impact of NE on attentional orienting in more naturalistic conditions, using complex images and without any explicit task manipulation. We tested the effects of atomoxetine (ATX) injections, a NE reuptake inhibitor, on four monkeys during free viewing of images belonging to three categories: landscapes, monkey faces and scrambled images. Analyses of the gaze exploration patterns revealed, first, that the monkeys spent more time on each fixation under ATX compared to the control condition, regard less of the image content. Second, we found that, depending on the image content, ATX modulated the impact of low-level visual salience on attentional orienting. This effect correlated with the effect of ATX on the number and duration of fixations. Taken together, our results demonstrate that ATX adjusts the contribution of salience on attentional orienting depending on the image content, indicative of its role in balancing the role of stimulus-driven and top-down control during free viewing of complex stimuli.

Attachment anxiety moderates the effect of oxytocin on negative emotion recognition: Evidence from eye-movement data.

Valence-specific effects of oxytocin have been revealed in a selection of preceding studies, while others report that oxytocin could improve facial recognition, regardless of emotion valence. The reported effect was mediated by increased eye gaze during face processing, and attachment style proved to moderate the effect of oxytocin administration on social behavior and cognition. In this study, we used eye tracking to test whether attachment style moderates the effect of oxytocin on negative emotion recognition, which is crucial for social cognition. We employed a placebo-controlled, double-blind, within-participants design. The participants were 73 healthy individuals (41 men) who received a single dose of intranasal oxytocin (24 IU) on one occasion and a placebo dose on another occasion. Visual attention to the eye region was assessed on both occasions, through the completion of an emotion recognition task. Our results showed that oxytocin increased participants' eye gaze towards facial expressions. Among participants who received oxytocin, as opposed to a placebo, only individuals with high attachment anxiety displayed more eye gaze and less mouth gaze towards facial expression, regardless of emotion valence. Our findings confirmed that oxytocin increases gaze to the eye region, thus improving facial recognition, regardless of emotion valence, this relationship was moderated by attachment anxiety. Further, our results highlighted the importance of considering individual differences when evaluating the effects of oxytocin on emotion recognition.

The effect of oxytocin on pupil response to naturalistic dynamic facial expressions.

The neuropeptide oxytocin (OT) has been found to play an important role in a variety of social behaviours and social cognition in particular. The social salience hypothesis of OT suggests that OT shifts attention towards socially relevant stimuli, which offers an explanation for improvements on social cognition measures following OT administration. Pupil dilation occurs with increasing attentional resource allocation and previous research has found that OT administration led to an increase in pupil diameter in response to social stimuli relative to placebo (PL), thereby suggesting increased social attention. The current study aimed to investigate the effects of OT on pupillary responses to more naturalistic social stimuli in a larger sample. Ninety-four male participants took part in the double-blind, placebo controlled, mixed-design study, in which they self-administered either an OT or PL nasal spray before viewing naturalistic dynamic facial expressions of emotion (happy, sad, fear and anger). Contrary to prediction, there was no effect of OT administration on pupil diameter. The results are discussed in light of the social salience hypothesis and with reference to the methodological differences between studies.

Ergogenic Effects of 8 Days of Sceletium Tortuosum Supplementation on Mood, Visual Tracking, and Reaction in Recreationally Trained Men and Women.

Hoffman, JR, Marcus, I, Dubnov-Raz, G, and Gepner, Y. Ergogenic effects of 8 days of Sceletium tortuosum supplementation on mood, visual tracking, and reaction in recreationally trained men and women. J Strength Cond Res 34(9): 2476-2481, 2020-Sceletium tortuosum (ST) is a South African plant that has been reported to promote a sense of well-being in healthy individuals and used in treating people with anxiety, stress, or depression. These studies have been conducted in middle-aged and older adults, but no investigations have been performed in a healthy, young adult population. Thus, the purpose of this study was to examine the effect of 8 days of ST extract (25-mg) supplementation on changes in reactive agility, visual tracking, and mood. Sixty recreationally trained men (n = 48) and women (n = 12), between 20 and 35 years, were randomly assigned to 1 of 2 groups: ST or placebo (PL). Subjects were tested on 2 occasions: before supplementation and 2-hours after supplementation on day 8. Subjects completed a subjective questionnaire to assess alertness and energy using a visual analog scale (VAS). In addition, subjects completed the Profile of Mood States questionnaire and performed reactive agility and visual tracking assessments. Significant improvements were noted for ST in complex reactive performance that required subjects to respond to repeated visual stimuli with a cognitive load compared with PL. However, no significant changes were noted between the groups in either VAS or total mood score. In addition, no differences were observed in simple reaction assessments. The results of this study demonstrate an ergogenic benefit in complex reactive tasks that include a cognitive load. However, in this subject population studied, no benefits in mood were observed.

Reduced attentional capture by reward following an acute dose of alcohol.

RATIONALE: Previous research has shown that physically salient and reward-related distractors can automatically capture attention and eye gaze in a visual search task, even though participants are motivated to ignore these stimuli. OBJECTIVES: To examine whether an acute, low dose of alcohol would influence involuntary attentional capture by stimuli signalling reward. METHODS: Participants were assigned to the alcohol or placebo group before completing a visual search task. Successful identification of the target earned either a low or high monetary reward but this reward was omitted if any eye gaze was registered on the reward-signalling distractor. RESULTS: Participants who had consumed alcohol were significantly less likely than those in the placebo condition to have their attention captured by a distractor stimulus that signalled the availability of high reward. Analysis of saccade latencies suggested that this difference reflected a reduction in the likelihood of impulsive eye movements following alcohol. CONCLUSIONS: Our findings suggest that alcohol intoxication reduces the capacity to attend to information in the environment that is not directly relevant to the task at hand. In the current task, this led to a performance benefit under alcohol, but in situations that require rapid responding to salient events, the effect on behaviour would be deleterious.

Eye tracking correlates of acute alcohol consumption: A systematic and critical review.

Eye tracking has emerged as a reliable neuroscience tool indexing the eye movements' correlates of impairments resulting from alcohol-use disorders, ranging from perceptive abilities to high-level cognitive functions. This systematic review, following PRISMA guidelines, encompasses all human studies using eye tracking in participants presenting acute alcohol consumption. A literature search was conducted in PsycINFO, PubMed and Scopus, and a standardized methodological quality assessment was performed. Eye tracking studies were classified according to the processes measured (perception, attentional bias, memory, executive functions, prevention message processing). Eye tracking data centrally showed a global visuo-motor impairment (related to reduced cerebellar functioning) following alcohol intoxication, together with reduced memory and inhibitory control of eye movements. Conversely, the impact of such intoxication on alcohol-related attentional bias is still debated. The limits of this literature have been identified, leading to the emergence of new research avenues to increase the understanding of eye movements during alcohol intoxication, and to the proposal of guidelines for future research.

Melatonin for rapid eye movement sleep behavior disorder in Parkinson's disease: A randomised controlled trial.

BACKGROUND: Melatonin may reduce REM-sleep behavior disorder (RBD) symptoms in Parkinson's disease (PD), though robust clinical trials are lacking. OBJECTIVE: To assess the efficacy of prolonged-release (PR) melatonin for RBD in PD. METHODS: Randomized, double-blind, placebo-controlled, parallel-group trial with an 8-week intervention and 4-week observation pre- and postintervention (ACTRN12613000648729). Thirty PD patients with rapid eye movement sleep behavior disorder were randomized to 4 mg of prolonged-release melatonin (Circadin) or matched placebo, ingested orally once-daily before bedtime. Primary outcome was the aggregate of rapid eye movement sleep behavior disorder incidents averaged over weeks 5 to 8 of treatment captured by a weekly diary. Data were included in a mixed-model analysis of variance (n = 15 per group). RESULTS: No differences between groups at the primary endpoint (3.4 events/week melatonin vs. 3.6 placebo; difference, 0.2; 95% confidence interval = -3.2 to 3.6; P = 0.92). Adverse events included mild headaches, fatigue, and morning sleepiness (n = 4 melatonin; n = 5 placebo). CONCLUSION: Prolonged-release melatonin 4 mg did not reduce rapid eye movement sleep behavior disorder in PD. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Nicotinic acid promotes sleep through prostaglandin synthesis in mice.

Nicotinic acid has been used for decades for its antiatherogenic properties in humans. Its actions on lipid metabolism intersect with multiple sleep regulatory mechanisms, but its effects on sleep have never been documented. For the first time, we investigated the effects of acute systemic administration of nicotinic acid on sleep in mice. Intraperitoneal and oral gavage administration of nicotinic acid elicited robust increases in non-rapid-eye movement sleep (NREMS) and decreases in body temperature, energy expenditure and food intake. Preventing hypothermia did not affect its sleep-inducing actions suggesting that altered sleep is not secondary to decreased body temperature. Systemic administration of nicotinamide, a conversion product of nicotinic acid, did not affect sleep amounts and body temperature, indicating that it is not nicotinamide that underlies these actions. Systemic administration of monomethyl fumarate, another agonist of the nicotinic acid receptor GPR109A, fully recapitulated the somnogenic and thermoregulatory effects of nicotinic acid suggesting that they are mediated by the GPR109A receptor. The cyclooxygenase inhibitor indomethacin completely abolished the effects of nicotinic acid indicating that prostaglandins play a key role in mediating the sleep and thermoregulatory responses of nicotinic acid.

Role of Botulinum Toxin Type A in Cyclic Esotropia: A Long-Term Follow-up.

PURPOSE: To describe two patients with childhood cyclic esotropia 8 and 9 years after they underwent botulinum toxin type A treatment to report its long-term outcome. METHODS: Two patients with sudden onset cyclic esotropia aged 2 and 4 years were included. Botulinum toxin type A injections were performed on the appropriate muscles. RESULTS: The first patient was a 2-year-old boy with left dominant alternating esotropia on a cyclic basis. His strabismus ranged from 25 to 45 prism diopters (PD) at near and distance. A botulinum toxin type A injection into the left medial rectus muscle revealed orthotropia at near and distance with a stereopsis of 60 seconds of arc (arcsec). During the 9 years of follow-up, he remained stable. The second patient was a 4-year-old girl who complained of double vision and strabismus. Her deviation was 40 PD at near and 35 PD at distance on a cyclic pattern. She became orthotropic with glasses after a bimedial botulinum toxin A injection. During the 8 years of follow-up, she remained stable with a stereo-acuity of 120 arcsec. CONCLUSIONS: Considering the consecutive and recurrent deviations with surgical treatment in previous reports, botulinum toxin type A is an appropriate first-line option for the treatment of cyclic deviations, despite its limitations. The results suggest that botulinum toxin type A is an effective method to break the cycle in cyclic esotropia permanently. [J Pediatr Ophthalmol Strabismus. 2019;56(6):360-364.].

Dexamethasone induces alterations of slow wave oscillation, rapid eye movement sleep and high-voltage spindle in rats.

Glucocorticoids arising from chronic stress and long-term inflammatory treatment with corticosteroids are both associated with neuropathology and cognitive impairments. Many previous studies have focused on changes in brain morphology and deficits in learning behavior. However, effects of long-term exposure to stress hormones on electrical brain signaling and sleep-wake patterns have remained largely unexplored. This study aimed to monitor electroencephalographic (EEG) patterns induced by prolonged dexamethasone exposure. Adult male Wistar rats implanted with electrodes on the skull over the frontal and parietal cortices were intraperitoneally injected with either saline or dexamethasone (0.5 mg/kg) once daily for 21 consecutive days. Longitudinal EEG recording was performed on day 6, 11, 16 and 21. Fast Fourier transform was used for frequency power analysis. One-way ANOVA revealed significant increases in parietal EEG power of slow frequencies (delta, theta and alpha) particularly, with the dominant theta activity seen as early as day 11 of dexamethasone treatment. Sleep-wake analysis on day 21 confirmed a significant reduction of rapid-eye movement (REM) sleep and increased slow frequency oscillations mainly in the parietal cortex during the awake period. The number of high-voltage spindles (HVSs) (6-10 Hz EEG oscillation) was significantly increased during awake and slow wave sleep (SWS) periods following dexamethasone treatment. These findings demonstrated that distinct frequency oscillations, sleep-wakefulness and sleep spindles may be parameters of neuropathology produced by long-term dexamethasone exposure. Early detection of these parameters might be predictive of neuropathology in long-term corticosteroid users.

Gaze entropy measures detect alcohol-induced driver impairment.

Driving under the influence of alcohol is an ongoing cause of road traffic accidents. The biphasic nature of alcohol effects on subjective experience appears to contribute to the prevalence of drink-driving, as people perceive the declining phase of the BAC curve as recovery from intoxication and are more willing to drive despite significant impairments in objectively measured functions. The present study investigates whether alcohol-induced changes in gaze behaviour can be detected during engagement in a simulated driving task. In a repeated-measures and placebo-controlled design, this study examines the biphasic influence of moderate alcohol intake (0.6 g/kg) on measures of gaze behaviour and simulated driving performance. Twenty-two healthy young adults completed three driving sessions (baseline, ascending and descending) under two conditions (placebo, alcohol) while their eye movements were simultaneously recorded. The results revealed that gaze behaviour as measured by gaze transition entropy (GTE) and stationary gaze entropy (SGE) and driving performance measured by the standard deviation of lateral position (SDLP) of the vehicle, were significantly affected by alcohol across the ascending and descending sessions. The alcohol-induced reduction in GTE with an increase in SGE is discussed as alcohol's impact on top-down modulation of gaze resulting in more dispersed and erratic pattern of visual scanning. The observed changes in gaze behaviour also mediated the influence of alcohol upon driving performance. These results have significant implications for the development of driver monitoring systems that can detect alcohol-induced impairment.