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PubMedDate not supplied

Blink reflexes and preparation.

Blink reflexes were evoked during a foreperiod of 3 sec between a warning signal (WS) and a reaction signal (RS). In a between group design, two possible reactions following RS were investigated: 20 subjects always reacted with both hands, another group of 20 subjects always reacted with a voluntary blink. A manual response was assumed not to involve the circuit of the blink reflex, whereas a blink as a response was thought to be (at least partly) realized via the same circuit as the blink reflex. Both groups showed a strong increase of the early component (R1) of the blink reflex during the first 300 msec after WS, while the late polysynaptic component (R2) showed a strong inhibition during the same period. R1 did not decrease as a function of presentation order when the demanded reaction was a voluntary blink. No other inhibition or excitation related to the type of reaction after RS was observed during the foreperiod before RS.

Adolescent↗
PubMed2001

Excessive blinking in childhood: a prospective evaluation of 99 children.

OBJECTIVE: To determine the characteristics and causes of excess blinking in children and to determine outcomes after treatment. DESIGN: Prospective, noncomparative, consecutive case series. PARTICIPANTS: Ninety-nine consecutive children who presented for evaluation of excessive blinking over a 2 year period. METHODS: Children less than 16 years of age who had excessive blinking as their sole or major chief complaint underwent detailed history and ophthalmologic examination. Treatment was recommended based on clinical examination findings. Follow-up evaluations were performed at least 2 months after initial examination. MAIN OUTCOME MEASURES: Etiology of excess blinking and patient characteristics in each diagnostic group. RESULTS: The majority (89%) of children presented with bilateral excessive blinking. Boys outnumbered girls at a ratio of almost 2:1. The most common etiologies were anterior segment and/or lid abnormalities (37%), habit tics (23%), uncorrected refractive errors (14%), intermittent exotropia (11%), and psycogenic blepharospasm (10%). A history of neurologic disease was present in 22% of the patients but was not causally related to the excessive blinking in most cases. Vision-threatening disease was noted in 6% and was easily detected on standard clinical examination. Life-threatening disease was the cause in 4% of the children, but the presence of life-threatening disease was already known in all such patients. CONCLUSIONS: Excessive blinking in children can occur because of a large number of potential problems. Most cases are caused by benign and/or self-limiting conditions. The cause can usually be determined after careful history and clinical examination and routine neurologic evaluation and neuroimaging is unnecessary.

Adolescent↗
PubMed2001

Eye blinks: new indices for the detection of deception.

Eyeblink variables were investigated while subjects performed a guilty knowledge test (Experiment 1) and a dual modality attention task (Experiment 2). In both experiments, the temporal distribution of blinks was analyzed using an automatic video based blink analysis system [Matsuo and Fukuda, Jpn. J. Physiol. Psychol. Psychophysiol., 14 (1996), 17]. In experiment 1, the blink rate pattern discriminated between relevant and irrelevant stimuli. In experiment 2, the blink rate peak after the auditory stimulus disappeared during visually attended tasks whereas the blink rate peak after the visual stimulus was significant during auditory attended tasks. It was suggested that eye blinks could be related to the selective attention and that eye blinks could provide an additional index for the detection of deception.

Acoustic Stimulation↗
PubMed1999

Failures of automatic and strategic processing in schizophrenia: comparisons of event-related brain potential and startle blink modification.

Noises elicit startle blinks that are inhibited when immediately (approximately 100 ms) preceded by non-startling prepulses, perhaps reflecting automatic sensory gating. Startle blinks are facilitated when preceded by prepulses at longer lead intervals, perhaps reflecting strategic processes. Event-related brain potentials (ERPs) and startle blinks were used to investigate the well-documented prepulse inhibition failure in schizophrenia. Blinks and ERPs were recorded from 15 schizophrenic men and 20 age-matched controls to noises alone and to noises preceded by prepulses at 120 (PP120), 500 (PP500) and 4000 ms (PP4000) lead intervals. Neither blinks nor any of the ERP components elicited by the noise alone differentiated schizophrenics from controls, although responses to noises were modified by prepulses differently in the two groups. With the N1 component of the ERP, patients showed normal inhibition but lacked facilitation, and with P2, patients lacked inhibition, but showed normal facilitation. With reflex blinks and P300, inhibition was seen in both groups, but no facilitation. These results suggest that different neural circuits are involved in blink and cortical reflections of startle modification in schizophrenics and controls, with both automatic and strategic processes being impaired in schizophrenia.

Acoustic Stimulation↗
PubMed2003

Event-related potential correlates of the attentional blink phenomenon.

The attentional blink phenomenon results from a transitory impairment of attention that can occur during rapid serial stimulus presentation. A previous study on the physiological correlates of the attentional blink employing event-related potentials (ERPs) suggested that the P3 ERP component for target items presented during this impairment is completely suppressed. This has been taken to indicate that the target-related information does not reach working memory. To reevaluate this hypothesis, we compared ERPs evoked by detected and missed targets in the attentional blink paradigm. Eighteen subjects performed a rapid serial visual presentation (RSVP) task in which either one target (control condition) or two targets had to be detected. ERPs elicited by the second target were analyzed separately for trials in which the target had been detected and missed, respectively. As predicted, detected targets did elicit a P3 during and after the attentional blink period. No clear P3 was found for detected targets presented before the attentional blink, that is, at lag 1. In contrast, missed targets generally did not evoke a P3. Our results provide evidence that targets presented during the attentional blink period can reach working memory. Thus, these findings contribute to evaluating theories of the attentional blink phenomenon.

Adult↗
PubMed2003

Functional MRI of brain activation evoked by intentional eye blinking.

Eye blinking is not only a reflexive action to protect the ocular surface from injury and desiccation; it can also be done intentionally. However, only a few studies have investigated the brain mechanism controlling intentional blinking, and there are still inconsistencies among the reported activation patterns in the human brain evoked by intentional blinking. In monkeys, some areas where blinking is evoked by electrical microstimulation have been found in the premotor areas and in the posterior parietal cortex. But there have been no reports about neuronal activity related to blinking in the cerebral cortex. In the present study, the brain activation evoked by intentional blinking was examined in humans by using fMRI, and the activations were found in the middle precentral gyrus, but not in the posterior parietal cortex, suggesting that the premotor areas, rather than the posterior parietal cortex, are important for controlling intentional blinking.

Adult↗
PubMed2005

Blinking and superficial punctate keratopathy in patients with diabetes mellitus.

AIM: To evaluate blinking patterns in patients with diabetes mellitus and whether blinking contributes to the formation of superficial punctate keratopathy in diabetic patients. METHODS: We examined 163 patients with type II diabetes mellitus and 76 without diabetes. Blinks were recorded, analysed using six parameters, and compared between patients with and without diabetes. Multivariate regression analysis was performed to assess the influence of other ocular factors, such as status of tear lipid layer, tear breakup time, corneal sensitivity, the result of cotton thread test, or blinking rate related to superficial punctate keratopathy. RESULTS: In patients with diabetes, the average mean and maximum interblinking times were longer, the average coefficient of variation of interblinking time was higher, and the average blinking rates were lower than those in patients without diabetes. Multivariate regression analysis revealed that the status of tear lipid layer and tear breakup time were significantly relevant to superficial punctate keratopathy (P < 0.01). CONCLUSION: Interblinking time was longer in diabetic patients, resulting in a decreased blinking rate. The prevalence of superficial punctate keratopathy cannot be predicted from blinking patterns in patients with diabetes.

Aged↗
PubMed1997

The Guinea Pig Blinking Test: a comparison with human responses.

The Guinea Pig Blinking Test (2) was presented as a model for the selection and development of comfortable ocular formulations. This study compares human nociceptive responses and the blinking response of the guinea pig to different concentrations of a topically applied ophthalmic drug, sulfacetamide. The number of human subjects noting pain upon instillation of various concentrations of sulfacetamide (3) was compared to the blinking responses of guinea pigs treated with 2.5%-17.5% sulfacetamide. The number of blinks was counted over a period of 5 minutes following (1) saline (0.9% NaCl), and (2) 30-60 minutes later a test solution. A Blinking Index (B.I.) = blinks drug/blinks saline was calculated for each animal. The dose/response curves of both humans and guinea pigs were almost identical, showing a threshold at 5% sulfacetamide, followed by a linear increase, reaching a maximum at 12.5%-15% sulfacetamide. A 2.5% solution that elicited pain in 10% of human subjects yielded a B.I. = 1.04 +/- 0.05, whereas a 12.5% solution that elicited pain in 95% of human subjects yielded a B.I. = 1.61 +/- 0.13 (mean +/- S.E., n = 10, P < 0.05). The strong linear relationship between the guinea pig blinking response and the human perception of pain, following identical treatment with a topical ophthalmic drug, demonstrates that this animal test can be useful in predicting the degree of ocular discomfort of human subjects.

Adrenergic Agonists↗
PubMed2001

The stability of corneal topography in the post-blink interval.

PURPOSE: Videokeratoscopes provide a wealth of information about the topography of the ocular surface. Although there have been numerous studies of the accuracy and precision of videokeratoscopes with inanimate test objects, little information exists on their precision (repeatability) for real eyes. METHODS: To investigate the stability of the ocular surface in the inter-blink period, 10 patients were recruited for videokeratoscopy. Tear break-up time was measured and videokeratographs were acquired immediately post-blink and again at 4, 8, and 12 seconds post-blink. To permit statistical inferences to be drawn from the data, we acquired 24 videokeratographs for each of the four post-blink intervals. The videokeratograph data were interpolated (bilinear) to a common grid, and average and standard deviation (SD) maps were derived for each post-blink condition. t Tests were used to test the significance of changes observed in the topography. RESULTS: The instantaneous power SD maps showed increasing variation toward the periphery, with most maps showing less than +/-0.5 diopters (D) of SD in the central 4 to 5 mm and variation in the periphery often reaching more than +/-1 D SD at the edge of an 8-mm diameter. When the 4-, 8-, and 12-second average maps were subtracted from the average map acquired immediately after blinking, regions of statistically significant ( p < 0.001) change were apparent in the upper and lower regions of the maps. The upper and lower bands of change were found to correlate with the natural position of the patients' lid margins. CONCLUSIONS: For normal eyes, the central regions of videokeratographs show high stability in the inter-blink period. However, the upper and lower edges of 8-mm diameter maps show statistically significant variability, which appears to be related to the effects of eyelid pressure.

Adult↗
PubMed1987

Blinking patterns in soft contact lens wearers can be altered with training.

The blinking patterns of 15 soft contact lens wearers were recorded with a concealed video camera. Each of 20 consecutive blinks were graded, during slow motion replay of the video, as either complete, incomplete, forced, or twitch. Ten of these subjects were instructed to perform blinking exercises for a period of 2 weeks and the remaining 5 subjects acted as controls. After these exercises all the experimental group displayed an increased frequency of complete blinks, whereas the blinking patterns of the control group remained unchanged. Blinking exercises are likely to alleviate many of the signs and symptoms associated with incomplete blinking amongst contact lens wearers.

Blinking↗
PubMed2006

Blinking patterns and corneal staining.

PURPOSE: To investigate the blinking patterns of healthy subjects and soft contact lens wearers and determine whether these blinking characteristics were associated with corneal fluorescein staining. METHODS: Fifteen young soft contact lens wearers and 11 young, healthy subjects participated in the study. The subjects were selected to have no significant eyelid disease. High-speed filming (100 frames per second) was used to capture the natural blinking patterns of the subjects for approximately 3 minutes. Custom written software was used to measure the vertical palpebral aperture at the start and the end of the downward motion of the upper eyelid. The vertical gap between the lids at the lowest point of the upper lid movement during each blink was measured (closed palpebral aperture). Corneal fluorescein staining was quantified on a 0-to-4 scale for each subject. RESULTS: Closed palpebral apertures in the healthy and soft contact lens-wearing subjects showed a wide distribution, with 22% of blinks being incomplete (<2/3 open aperture) in both groups of subjects. In soft contact lens wearers, there was a significant correlation (r = 0.40, P<0.05) between the mean closed palpebral aperture and the grade of corneal staining (primarily located inferiorly). The healthy subjects did not show the same degree of correlation (r = 0.16, P>0.1). However, the distribution of closed palpebral apertures was significantly different between those subjects with corneal staining compared to those without corneal staining (Kolmogorov-Smirnov two-sample test, healthy subjects with P=0.002 and soft lens wearers with P<0.001). CONCLUSIONS: The distribution of closed palpebral apertures of healthy and soft contact lens-wearing subjects showed no clear distinction between complete and incomplete blinks. Both groups of subjects show evidence of an association between the mean closed palpebral aperture size (degree of incomplete blinking) and the grade of corneal fluorescein staining, but the association is stronger in soft contact lens wearers.

Adult↗
PubMed1995

Electrophysiological study of blink reflex in humans: differences in mental and supraorbital nerves.

In order to find an explanation for the discrepancy between previous reports on the consistency of the blink reflex response with stimulation of the mental nerve, the habituation of the blink reflex was studied with stimulation of the supraorbital and mental nerves in 14 healthy adults. A series of eight electrical stimuli was delivered to the distributions of the nerves on each side at frequency rates of 1.0, 0.5, 0.2 and 0.1 Hz. The latencies and peak-to-peak amplitudes of the ipsilateral late blink reflex components (R2i) were measured. The habituation phenomenon was analysed by means of multivariate analysis of the amplitudes, the nerve and frequency effects were determined by means of a repeated measures analysis of variance model. The blink reflex showed more pronounced amplitude attenuation of the consecutive responses with stimulation of the mental than the supraorbital nerve at rates of 0.5 and 0.2 Hz, and marginally so also at 0.1 Hz. For the supraorbital nerve, habituation could be demonstrated with stimulation frequencies of 1.0 and 0.5 Hz, while for the mental nerve a statistically significant habituation phenomenon was found even with the lowest repetition rate of 0.1 Hz. The greater tendency of the mental nerve blink reflex to habituate is obviously one reason why it has previously sometimes been considered too inconsistent to be useful in clinical practice. For the recording of the supraorbital nerve blink reflex, a 10 s interval between stimuli is adequate, whereas longer interstimulus intervals may have to be adopted to obtain consistent blink reflex responses with stimulation of the mental nerve.

Adult↗
PubMed1989

The relationship between eye-winking tics, frequent eye-blinking and blepharospasm.

A family is reported in which three generations were affected with eye-winking tics and/or blepharospasm. The proband developed eye-winking tics in childhood and then developed excessive blinking progressing to blepharospasm by the age of 21 years. His mother presented with Meige's syndrome and spasmodic torticollis at the age of 59 years; his uncle had blinked excessively from his early forties. His eldest son developed an eye-winking tic with facial grimacing at the age of 8 years, and in another son, a self-limiting period of eye-blinking occurred at the age of 4 years. The recovery cycle of the blink reflex was abnormal in all three generations. Three other children with eye-winking tics have a parent or close relative with frequent eye-blinking or blepharospasm. Five patients with adult-onset blepharospasm or Meige's syndrome are also described who had excessive eye-blinking dating back to childhood. It is suggested that eye-winking tics, frequent blinking and blepharospasm may share common pathophysiological mechanisms; the clinical expression may be age-related.

Adolescent↗
PubMed1999

Quantitative study of spontaneous eye blinks and eye tics in Gilles de la Tourette's syndrome.

Spontaneous eye blink rate and frequency of eye tics were studied in nine Tourette patients during periods of rest, conversation, and video watching. In comparison with controls, the Tourette patients showed a significantly higher blink rate during rest and video watching. Conversation induced a significant increase in blink rate in the control group, but not in the Tourette patients, whereas video watching significantly increased blink rate in both groups. The frequency of eye tics showed a significant decrease during conversation and increased significantly during video watching in Tourette patients. In five patients, a significant positive correlation between blink rate and eye tic frequency was found, whereas one patient showed a significant negative correlation. Our results show that, even though some of our patients were on neuroleptic treatment, blink rate was about twofold to threefold increased versus healthy controls, suggesting increased central dopaminergic activity. Furthermore, these first quantitative data illustrate task specific effects on eye tic frequency and the complexity of their relation with eye blinks.

Adult↗
PubMed2000

Activity of primate V1 cortical neurons during blinks.

Every time we blink our eyes, the image on the retina goes almost completely dark. And yet we hardly notice these interruptions, even though an external darkening is startling. Intuitively it would seem that if our perception is continuous, then the neuronal activity on which our perceptions are based should also be continuous. To explore this issue, we compared the responses of 63 supragranular V1 neurons recorded from two awake monkeys for four conditions: 1) constant stimulus, 2) during a reflex blink, 3) during a gap in the visual stimulus, and 4) during an external darkening when an electrooptical shutter occluded the entire scene. We show here that the activity of neurons in visual cortical area V1 is essentially shut off during a blink. In the 100-ms epoch starting 70 ms after the stimulus was interrupted, the firing rate was 27.2 +/- 2.7 spikes/s (SE) for a constant stimulus, 8.2 +/- 0.9 spikes/s for a reflex blink, 17.3 +/- 1.9 spikes/s for a gap, and 12.7 +/- 1.4 spikes/s for an external darkening. The responses during a blink are less than during an external darkening (P < 0.05, t-test). However, many of these neurons responded with a transient burst of activity to the onset of an external darkening and not to a blink, suggesting that it is the suppression of this transient which causes us to ignore blinks. This is consistent with other studies where the presence of transient bursts of activity correlates with the perceived visibility of a stimulus.

Action Potentials↗
PubMed1996

Unilateral blinking: a lateralizing sign in partial seizures.

BACKGROUND: Despite lateralizing signs, clinical lateralization of partial seizures may be difficult. We evaluated the usefulness of ictal unilateral blinking as a new lateralizing sign. METHODS: We retrospectively searched our seizure database over a 30-month period and collected videotapes of patients with ictal unilateral blinking. After initial review, we excluded patients in whom blinking was not clearly unilateral and those in whom it was accompanied by simultaneous facial clonic activity or mouth deviation. All patients underwent prolonged EEG-video monitoring. RESULTS: We identified 14 patients who met the above criteria, for a frequency of 1.5%. Age ranged from 18 months to 50 years (mean, 21.6). There were 11 males and 3 females. Unilateral blinking occurred 0 to 37 seconds (mean, 10) after clinical onset and was visible for 1 to 37 seconds (mean, 17). In 10 patients, other lateralizing signs were present. All patients had partial epilepsy, localized by surface EEG in 10 and by additional invasive EEG in four--nine were left hemisphere (four temporal, four frontal, one not further localized), three right hemisphere (two temporal, one frontal), and two undetermined. Of the 12 patients whose epileptogenic zone was lateralized, blinking was ipsilateral in 10 and contralateral in two. The predictive value of unilateral blinking was 83% against EEG localization. CONCLUSION: Unilateral blinking is a relatively uncommon but reliable lateralizing sign in partial seizures, usually indicating an ipsilateral epileptogenic zone.

Adolescent↗
PubMed2005

Effects of caffeine on the trigeminal blink reflex.

The acoustic startle and trigeminal blink reflexes share the same motor output. Since caffeine has been shown to augment the startle reflex, it was proposed that caffeine would also increase the trigeminal blink reflex. In 6 humans, the effects of caffeine (100 mg) on the trigeminal blink reflex were investigated. Reflex blinks were elicited by stimulation of the supraorbital branch of the trigeminal nerve. Following ingestion of caffeinated coffee, reflex blinks increased in amplitude and duration and occurred at a shorter latency than reflex blinks following ingestion of decaffeinated coffee. Since the blink reflex is a brainstem reflex, these results suggest that the psychomotor effects of caffeine facilitate brainstem processing.

Blinking↗
PubMedDate not supplied

[Decreased blink frequency in myotonic dystrophy].

We counted spontaneous eye blink rate in 11 myotonic dystrophy (MD) patients. Seven healthy subjects as well as 10 Parkinson disease (PD) and 7 facio-scapulo-humeral dystrophy (FSH) patients were used as controls. Blink frequency was significantly decreased in MD and PD patients (7.6 +/- 4.9/min in average and 11.0 +/- 7.5/min, respectively), compared with healthy subjects and FSH patients (17.5 +/- 4.3/min and 17.3 +/- 9.9/min, respectively). Normal blink frequency in FSH suggests that the facial muscle weakness is not responsible for decreased blink frequency in MD. This observation is compatible with prolonged R1 latency in blink reflex in MD, suggesting a dysfunction of central mechanism of blink control system as in the case of PD, although there remains a possibility that the myotonia in levator palpebrae muscles disturbs blinking.

Adolescent↗