Blinking in patients with clinically probable multiple system atrophy

In order to measure blinking, we developed a dynamic device consisting of a CCD camera connected to a videonystagmography machine. We developed an artificial pupil that allowed the camera to track movements of the upper eyelid. Blinking parameters were measured in eight healthy volunteers, studying spontaneous blinking (SB) and voluntary blinking (VB) responses. Closing time, opening time, closing speed, vertical amplitude, horizontal amplitude and frequency of spontaneous blinking were recorded. In SB, opening time (0.21 +/- 0.04 s) was significantly longer than closing time (0.10 +/- 0.02 s) (p < 0.0001). Mean closing speed was 87 +/- 26 m/s in SB and 168 +/- 59 m/s in VB. Mean vertical amplitude was 9.1 +/- 2.2 mm. Mean vertical amplitude was lower in SB (9.1 +/- 2.2 mm) than in VB (12.3 +/- 1.9 mm) (p < 0.001). Mean horizontal amplitude was also lower in SB (2.7 +/- 0.9 mm) than in VB (3.8 +/- 0.9 mm) (p < 0.05). Frequency of SB was 18.4 +/- 3.4 per minute. Computer-assisted video acquisition provides real-time measurement of eyeblink dynamics. On healthy volunteers, this method enables accurate measurement of opening and closing responses as well as associated horizontal movement, and enables differentiating spontaneous and voluntary blinking.

A New Perspective on Spontaneous Blinks

To examine the recovery process of blinking in a longitudinal study of nine patients severely affected by Bell's palsy. Kinematics of bilateral eyelid and eye movements and concomitant orbicularis oculi activity during voluntary blinking and air-puff- and acoustic-click-induced reflex blinking were determined by using the magnetic search coil technique and electromyographic recording of the orbicularis oculi muscle (OO-EMG). In the first 3 months of absence of OO-EMG activity, reduced eyelid and eye movement of the palsied eyelid were observed during all types of blinking. First OO-EMG activity was determined 3 months after onset of the affliction. After 1 year, OO-EMG activity was normalized and showed values similar to those on the nonpalsied side. Clinically, eyelid movements were normal after 1 year, although corresponding maximum amplitudes and corresponding velocities were two times smaller, expressed in reduced eyelid motility. Directions of eye movement during reflex blinking were normal after 1 year, although maximum amplitudes were smaller on the palsied side. Eye movements during voluntary blinking remained impaired. A simultaneous horizontal upward shift of both eyes in the same direction was recorded throughout the study. Although OO-EMG activity on the palsied side was normalized 1 year after onset of the affliction, the accompanying eyelid movements and their maximum amplitudes and velocities remained smaller throughout the study. The consistent impairment of eye movements in voluntary blinking during the study and reduced motility of eyelid movements indicates that higher brain structures, which modify eyelid and eye movement control during blinking, may be altered by the affliction.

Multiple system atrophy(MSA) is a rare adult-onset synucleinopathy that can be divided in two subtypes depending on whether the prevalence of its symptoms is more parkinsonian or cerebellar (MSA-P and MSA-C, respectively). The aim of this work is to investigate the structural MRI changes able to discriminate MSA phenotypes. The sample includes 31 MSA patients (15 MSA-C and 16 MSA-P) and 39 healthy controls. Participants underwent a comprehensive motor and neuropsychological battery. MRI data wereacquired with a 3T scanner (MAGNETOM Trio, Siemens, Germany). FreeSurfer was used to obtain volumetric and cortical thickness measures. A Support Vector Machine (SVM) algorithm was used to assess the classification between patients' group using cortical and subcortical structural data. After correction for multiple comparisons, MSA-C patients had greater atrophy than MSA-P in the left cerebellum, whereas MSA-P showed reduced volume bilaterally in the pallidum and putamen. Using deep gray matter volume ratios and mean cortical thickness as features, the SVM algorithm provided a consistent classification between MSA-C and MSA-P patients (balanced accuracy 74.2%, specificity 75.0%, and sensitivity 73.3%). The cerebellum, putamen, thalamus, ventral diencephalon, pallidum, and caudate were the most contributing features to the classification decision (z>3.28; p<.05 [false discovery rate]). MSA-C and MSA-P with similar disease severity and duration have a differential distribution of gray matter atrophy. Although cerebellar atrophy is a clear differentiator between groups, thalamic and basal ganglia structures are also relevant contributors to distinguishing MSA subtypes.

Development and validation of a non-invasive imaging system to capture spontaneous blinking and characterise blink dynamics using a custom image analysis algorithm. A pilot study investigated the influence of illumination type on blink dynamics. Spontaneous blinking was recorded in eight subjects using a high-speed camera under two illumination conditions: white light and infrared. Custom semi-automated software assessed palpebral aperture height (PAH), blink rate, blink speed, blink completeness and blink duration. The main clinical study compared two different image analysis techniques. Spontaneous blinking was recorded in 20 subjects using a high-speed infrared camera. Blink speed and duration were determined using two techniques: manual tracking and semi-automated tracking. Agreement between the two techniques was assessed using Bland-Altman analysis. Coefficients of repeatability (COR) were calculated for the semi-automated technique. There were significant differences between white light and infrared illumination for PAH (p<0.0001), blink rate (p=0.04), closing speed (p=0.009), opening speed (p<0.0001) and blink duration (p=0.0003). The mean differences (95% limits of agreement) between the two techniques were 0.6mms-1 (-15.9 to 17.0) closing speed, 1.5mms-1 (-6.8 to 9.8) opening speed, 2.4ms (-6.8 to 11.5) closed phase duration and 5.0ms (-19.4 to 29.3) total blink duration. COR values were 10.1mms-1 closing speed, 3.7mms-1 opening speed, 6.7ms closed phase duration and 11.2ms total blink duration. This study has shown that spontaneous blinking can be characterised using a non-invasive imaging system. The semi-automated analysis provides a rapid characterisation of blink dynamics, allowing its application in large-scale trials in a number of clinical areas.

Introduction: The normal blink rate for humans is between 12 and 15 blinks per minute (bpm). Screen use has been associated with decreased blink rate and increased percentage of incomplete blinks, however, little is known about the effects of videogaming on blink rate. The purpose of this study was to assess the blink rate of online livestream video game players. Methods: A total of 30 livestream video gamers across YouTube, Twitch, and Facebook Gaming were selected for this study. Video gamers were characterized by gender and whether or not they were wearing glasses. Blink rate was observed for 5 minutes and defined as a complete closure of the ocular surface. Descriptive statistics and linear regression were used to determine significance (p&lt;0.05) between variables. All analyses were conducted using RStudio (version 1.3.1056; RStudio, Inc). Results: The study population comprised of 30 video game players (50% men). The mean (standard deviation [SD]) blink rate of the total study population was 14.79 (8.79) bpm. Compared to male gamers, female gamers had a higher mean blink rate, however this was not statistically significant (17.07 vs. 12.51, p=0.16). A total of 3 (10%) video game players wore glasses. The difference in blink rate between video game players wearing and not wearing glasses was not statistically significant (14.07 vs 14.87, p=0.88). Conclusions: The average blink rate of select livestream video game players was observed to be within the range of normal spontaneous blink rates. The observed blink rate between male and female gamers did not differ. More research in controlled environments would help to elucidate the blink rate and patterns of video game players

To evaluate physical methods for inducing death during the slaughter of American alligators (Alligator mississippiensis). 24 captive hatched-and-reared American alligators. Baseline electroencephalograms (EEGs) were obtained for awake and anesthetized alligators. Corneal reflex, spontaneous blinking, and EEGs were evaluated after severance of the spinal cord, severance of the spinal cord followed by pithing of the brain, application of a penetrating captive bolt, or application of a nonpenetrating captive bolt (6 alligators/group). Overall, alligators subjected to spinal cord severance alone differed from those subjected to the other techniques. Spinal cord severance alone resulted in postprocedure EEG power values greater than those in anesthetized alligators, whereas the postprocedure EEG power values were isoelectric for the other 3 techniques. Corneal reflex and spontaneous blinking were absent in all alligators immediately after application of a penetrating or nonpenetrating captive bolt. One of 6 alligators had a corneal reflex up to 1 minute after pithing, but all others within that group had immediate cessation of reflexes after pithing. Mean time to loss of spontaneous blinking and corneal reflex for alligators subjected to spinal cord severance alone was 18 minutes (range, 2 to 37 minutes) and 54 minutes (range, 34 to 99 minutes), respectively. Spinal cord severance followed by pithing of the brain and application of a penetrating or nonpenetrating captive bolt appeared to be humane and effective techniques for inducing death in American alligators, whereas spinal cord severance alone was not found to be an appropriate method.

Parkinson's disease (PD) patients and the 6-hydroxydopamine (6-OHDA) lesioned rat model share blink abnormalities. In view of the evolutionarily conserved organization of blinking, characterization of blink reflex circuits in rodents may elucidate the neural mechanisms of PD reflex abnormalities. We examine the extent of this shared pattern of blink abnormalities by measuring blink reflex excitability, blink reflex plasticity, and spontaneous blinking in 6-OHDA lesioned rats. We also investigate whether 130-Hz subthalamic nucleus deep brain stimulation (STN DBS) affects blink abnormalities, as it does in PD patients. Like PD patients, 6-OHDA-lesioned rats exhibit reflex blink hyperexcitability, impaired blink plasticity, and a reduced spontaneous blink rate. At 130 Hz, but not 16 Hz, STN DBS eliminates reflex blink hyperexcitability and restores both short- and long-term blink plasticity. Replicating its lack of effect in PD patients, 130-Hz STN DBS does not reinstate a normal temporal pattern or rate to spontaneous blinking in 6-OHDA lesioned rats. These data show that the 6-OHDA lesioned rat is an ideal model system for investigating the neural bases of reflex abnormalities in PD and highlight the complexity of PD's effects on motor control, by showing that dopamine depletion does not affect all blink systems via the same neural mechanisms.

A growing body of research suggests that spontaneous eye blinks have a cognitive role in addition to their biological functions. Blinking has been associated with cognitive effort and with processes related to the dynamic nature of incoming sensory information, such as the release of attention. However, there is limited evidence supporting the cognitive role of spontaneous blinks, specifically during reading. This study provides the first systematic investigation of blinking patterns in eye-tracking data of naturalistic silent text reading. We hypothesized that blinks would be more likely to occur (1) around punctuation marks signaling a breakpoint in the text and (2) following fixations on lower-frequency and less predictable words. To test these hypotheses, we utilized data from the large Ghent Eye Tracking Corpus (GECO), which contains eye movement data from 15 participants who read an entire novel in silence. The results indicate higher blinking proportions at punctuation marks compared to other positions in the text. Additionally, blink rates were modulated by word frequency and predictability, with higher word frequencies and predictabilities significantly reducing the probability of blinking. Extending previous research, our findings suggest substantial cognitive regulation of blinking during reading.

Spontaneous Eyeblink Activity

Increased spontaneous eye blink rate following prolonged wakefulness

The paralytic lagophthalmos following palpebral nerve neurotmesis and consequent peripheral denervation of the orbicularis oculi muscle is often associated with harmful effects on the exposed cornea. This study investigated how daily electrical stimulation affects the blink reflex recovery of this muscle after its reinnervation. Six dogs underwent unilateral facial nerve neurotmesis with immediate epineurial repair of the palpebral nerve. Three dogs were randomly chosen to receive electrical stimulation of the reinnervated orbicularis oculi muscles for 75 days. The remaining 3 dogs were controls (nonstimulated muscles). During the study, the reinnervated orbicularis oculi muscle electrophysiology and blink reflex recovery were investigated. The Student's t test was used for statistical analysis. The results can be summarized as follows: (1) between 30 and 50 days, the minimum mean stimulus intensities evoking complete up-per palpebral closure of the stimulated muscles were significantly lower than those of the nonstimulated muscles (p less than 0.01) and (2) the stimulated muscles recovered complete closure of the interpalpebral fissure (blink reflex) at 49.6 days, significantly earlier (p less than 0.01) than the nonstimulated muscles (72.6 days). It is concluded that daily electrical stimulation of the orbicularis oculi muscles, if started immediately after epineurial repair of the palpebral nerve neurotmesis, promotes a faster blink reflex recovery in the dog model.

BS19. Reorganization of sensory input in brainstem after peripheral facial paralysis

Differential patterns of central synucleinopathy and catecholaminergic abnormalities in Lewy body diseases and multiple system atrophy.

Objective To investigate the resting-state functional connectivity of the two hemispheres between multiple system atrophy (Parkinsonian type, MSA-P) and Parkinson′s disease (PD). Methods A total of 25 MSA-P, 29 PD patients and 29 well-matched healthy controls recruited in the Nanjing Brain Hospital Affiliated to Nanjing Medical University from June 2013 to December 2015 were scanned with resting-state functional magnetic resonance imaging for voxel mirrored homotopic correlation (VMHC) analysis. The Mini Mental State Examination, Montreal Cognitive Assessment, Frontal Assessment Battery and Unified Parkinson′s Disease Rating Scale-Ⅲ (UPDRS-Ⅲ) were used to assess the clinical symptom. Then the relationship between the change of VMHC values and severity of clinical symptoms was investigated. Results Compared with healthy controls, MSA-P and PD patients both showed decreased VMHC in bilateral cerebellum posterior lobe, precuneus gyrus, middle temporal gyrus, and postcentral gyrus. Compared with PD or healthy controls, MSA-P patients exhibited lower VMHC in bilateral putamen. Significant negative correlation between VMHC values of putamen and UPDRS-Ⅲ scores was found in MSA-P patients (r=-0.607, P=0.001). Conclusion These functional changes suggest that the abnormal interhemispheric synchrony probably plays an important role in pathophysiology of both MSA-P and PD, and abnormal VMHC values in putamen of MSA-P may be helpful in differentiating MSA-P from PD. Key words: Multiple system atrophy; Parkinson disease; Magnetic resonance imaging; Voxel mirrored homotopic correlation