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At least 199 records · Page 11Linked to original sources
PubMed1993

Effect of diltiazem on lid tension during light-flash-induced eye blinks in the rabbit.

PURPOSE: The purpose of this study was to examine the effect of the Ca blocker diltiazem in combination with the Ca chelator EGTA (ethyleneglycol-bis-ta-amino-ethyl ether]N,N'-tetraacetic acid) on eyelid tension generated during the light-induced eyeblink reflex in the adult rabbit. The goal is to develop nontoxic, nonsurgical therapies for blepharospasm. METHODS: Blinks were triggered in the alert rabbit, and tension was measured with a strain gauge attached to the eyelid. Strain gauge output was amplified, digitized, and stored on computer for later analysis. Experiments consisted of a set of trials in which identical light stimuli were delivered at 0.1 Hz for 5 min. RESULTS: In control trials, blink tensions decreased dramatically for the first seven to nine blinks and then levelled off, indicating that with respect to muscle tension output, blinks contained both rapidly habituating and nonhabituating components. After diltiazem and EGTA were injected in the lid, blinks were reduced 30% to 90% over those in control trials. Reductions could not be explained by injection trauma or irritation due to fluid volume, because injections of saline alone did not produce such tension depression. CONCLUSIONS: Diltiazem-EGTA produces a transient reduction in blink tension. A clinical application will depend on developing methods for the sustained release of these drugs in the eyelid.

Animals↗
PubMed1987

Blink-related eye movements.

Eye movements that accompany a blink have been measured in human subjects by the use of a visual-persistence method. With straight-ahead binocular viewing, each eye typically rotates nasalward and downward 1-2 deg during the closing phase of a blink. These eye movements are more rapid than the lid movements as recorded by high-speed photography. In fact, the eyes have already completed their initial rotation and started back again before the lids are fully closed. With off-center viewing, a blink causes each eye to rotate toward its primary position of regard. Indeed, if the eye is already in that position when the blink starts, the eye moves very little. With eyelids taped open, an eye tracker can be used, and records confirming the visual persistence tracings are obtained. Sequential photography of the cornea in profile reveals that the eye moves inward and back out again during a blink. The amplitude of this retraction is typically less than 1 mm; and its time course, slower than that of the rotational eye movements, parallels the closure and opening of the lids. In normal conditions of viewing there is no evidence of conjugate saccades, or of any large, upward rotation of the eyes (Bell's phenomenon) that was once believed to take place during a blink.

Blinking↗
PubMed2001

Modulation of the attentional blink by differential resource allocation.

When one masked target (T2) follows another (T1) in close temporal proximity, identification accuracy of the second target is reduced for a period referred to as the attentional blink. Analysis of the attentional blink literature suggests that increasing the difficulty of T1 processing increases the magnitude of the blink. In a previous study that eliminated several untoward features of the typical attentional blink design (e.g., task switching, location switching, and stream contribution), we found no effect on blink magnitude when three levels of T1 difficulty (manipulated in a data-limited manner) were randomly intermixed. Here, when we repeated the previous study using a blocked manipulation of T1 difficulty, which is characteristic of the literature, a significant positive relation between T1 difficulty and blink magnitude was found. Resource allocation put in place to encode T1 in advance of a dual-target trial thus seems to be the critical factor in mediating this relation.

Attention↗
PubMed1997

Beyond similarity: masking of the target is sufficient to cause the attentional blink.

When subjects are asked to identify a letter target embedded in a rapid serial visual presentation stream, the detection of a subsequent letter probe is briefly impaired. This transient deficit in probe detection, termed the "attentional blink," depends on the type of item that immediately follows the letter target (Raymond, Shapiro, & Arnell, 1995). Two models have been proposed to account for this effect. The interference model of the attentional blink predicts that visual similarity between the probe and item immediately following the target (+1 item) causes the attentional blink, whereas the two-stage model is based on the notion that increased time needed to process the target letter causes the attentional blink. In order to test between these two possibilities, the masking properties of the +1 item and its similarity to the probe were varied. We found the attentional blink when the +1 item acted as a mask of the target, even though the +1 item and the probe were visually dissimilar. This pattern of results supports the two-stage model of the attentional blink.

Adult↗
PubMed2000

Developmental changes in eye-blink conditioning and neuronal activity in the inferior olive.

Neuronal activity was recorded in the dorsal accessory inferior olive in infant rats during classical conditioning of the eye-blink response. The percentage and amplitude of eye-blink conditioned responses (CRs) increased as a function of age. The magnitude of the neuronal response to the unconditioned stimulus (US) decreased with age. There were also age-specific modifications of US-elicited inferior olive neuronal activity during paired trials in which a conditioned eye-blink response was performed. The results indicate that the development of the conditioned eye-blink response may depend on dynamic interactions between multiple developmental processes within the eye-blink circuitry. Differences in the functional maturity of olivo-cerebellar pathways may limit the induction of plasticity in the cerebellum and thereby limit the development of eye-blink conditioned responses.

Aging↗
PubMedDate not supplied

[Electrologic syndromes of alteration of elicited blink reflex in multiple sclerosis. Study of a group of 33 patients (author's transl)].

The study of the blink reflex, performed in a group of 33 patients with multiple sclerosis show, as Kimura (1970) and Namerow (1973) had established, the high frequency of its alterations in this disease (almost half of the cases). The alterations of blink reflex don't depend on duration of illness; if it is true that the alterations of blink reflex are more often observed in patients with clinical symptoms of involvement of brain-stem (and particularly of pons), in some cases, only the alteration of the blink reflex suggests a brain-stem's lesion and helps to establish the diagnosis. The diversity of sites of lesions induced by multiple sclerosis in the brain-stem explains the diversity of blink reflex alteration's syndromes since they correspond to the (almost) totality of the semiology of blink reflex.

Electrophysiology↗
PubMed2004

Spontaneous eye blinking in human infants: a review.

Spontaneous eye blinking has been studied in clinical and neuropharmacological research in adult humans and nonhuman primates as a putative index of central dopamine system activity. One purpose of this review is to provide a general overview of the research on spontaneous eye blinking with an emphasis on the relationship between spontaneous eye blinking and central dopamine systems. We suggest that the body of research from human (adults, children, and infants) and nonhuman primates supports the continued empirical investigation of spontaneous eye blinking in human infants. A second purpose is to present approaches for empirical work to further investigate the development, correlates, and mechanisms of spontaneous eye blinking in human infants. The results of further investigation may reveal new insights into relationships between the central nervous system activity and behavior in early human development.

Blinking↗
PubMedDate not supplied

Blink reflex abnormalities in diabetes mellitus.

BACKGROUND: Damage of the peripheral nervous system is particularly frequent in diabetes mellitus (DM), but somatic cranial neuropathies usually presenting as mononeuropathies are rare. Oculomotor and facial nerves are among the most commonly affected, whereas the Vth, IXth and Xth cranial nerves are less often affected. While existing neurophysiological tests in the subclinical diagnosis of damage to the peripheral nerve in diabetic patients have advanced, the same does not hold true for the subclinical diagnosis of the central nervous system (CNS). Electrophysiological studies such as the blink reflex was shown to be an effective method for revealing subclinical involvement of cranial nerves in generalised neuropathies. The aim of the present study was to evaluate the efficacy of blink reflex as a method for obtaining early diagnosis of cranial nerve involvement in diabetic patients frequently affected with peripheral neuropathy. METHODS: Twenty diabetic patients with electrophysiologically confirmed neuropathy were included in the present study for the evaluation of blink reflex. Patients with earlier cranial nerve involvement were excluded. RESULTS: Abnormal blink reflex responses were found in 55% of patients studied. R2Y and R2C latencies in diabetic patients were prolonged relative to controls (p<0.001 and p<0.001, respectively). However R1 values in diabetic patients did not differ significantly from those of normal controls (p<0.5). R2Y and R2C prolongation showed a positive correlation with the duration of disease (p=0.015 and p=0.009, respectively). However the same correlation could not be found with R1 values. No correlations were found between R1, R2Y, R2C values and HbA(1c) nor between R1, R2Y, R2C values and patients' age. CONCLUSION: We suggest that blink reflex testing is a useful method for obtaining early diagnosis of cranial nerve compromise in diabetic patients who do not show any clinical symptoms or signs of CNS involvement.

Aged↗
PubMed1992

Blink reflex measurement of effects of trichloroethylene exposure on the trigeminal nerve.

Trichloroethylene (TCE) exposure is known to have specific toxic effects on cranial nerves, the trigeminal nerve (V) in particular. The electrophysiological measurement of the blink reflex (BR) can quantify latency changes in the Vth and VIIth cranial nerve reflex arc. Prior study looked at the blink reflex measurement in a community group exposed to TCE in their drinking water. This study evaluated the use of the electrophysiologic blink reflex as an indicator of neurotoxic effects of TCE in occupationally exposed workers. The BR was tested in individual cases with documented histories of exposure to known chemical neurotoxins including TCE (n = 18). When compared with the nonexposed laboratory control values (n = 30), the subjects with a significant history of TCE exposure demonstrated the most prolonged latencies (greater than or equal to 3.0 SD above the nonexposed group mean) in the R1 component of the blink reflex measurement. The electrophysiological study of the blink reflex has application in assessing TCE exposure and in documenting the neurotoxic effects of that exposure on trigeminal nerve functions in humans.

Adult↗
PubMed1995

The trigeminally evoked blink reflex. I. Neuronal circuits.

In this study, we characterized the pathways that generate the trigeminal blink reflex in the guinea pig. Blinks were evoked by stimulation of the supraorbital branch of the trigeminal nerve and measured by recording electromyographic activity in the lid-closing orbicularis oculi muscle (OOemg) and, in one case, lid position. Blinks evoked by stimulation of the supraorbital nerve consisted of two bursts of muscle activity ipsilateral to the side of stimulation. The first, R1, had a latency of 6.9 ms and the second, R2, had a latency of 17.25 ms. Increasing stimulus intensity to 3 times threshold for evoking an ipsilateral blink elicited an R1 and R2 response contralaterally, with latencies of 9.2 ms and 19.25 ms, respectively. We investigated the causes for this bipartite response that is seen in the guinea pig, as well as other mammals including humans. The two-component response could arise from different populations of afferents, or from different central circuits, or a combination of these two causes. Multiunit recording in the trigeminal ganglion and simultaneous measurement of the OOemg showed that activation of A beta afferents alone was sufficient to elicit both the R1 and the R2 responses, but that activation of A delta afferents could enhance both responses. Different neural circuits, however, produce the R1 and R2 responses. Transganglionic tracing with wheatgerm agglutin or choleragenoid subunit of cholera toxin bound to HRP revealed that primary afferents from the supraorbital branch of the trigeminal nerve terminated densely in the dorsal horn of spinal cord segment C1 and in the caudalis-interpolaris border region of the spinal trigeminal nucleus. Injections of HRP into the orbicularis oculi motoneuron region of the facial nucleus showed that both of these regions projected to the facial nucleus. Hemisections at the level of C1 eliminated the R2 blink response, but not the R1 response, evoked by stimulation of the supraorbital branch of the trigeminal nerve. Subsequent hemisections at the level of the obex eliminated the R1 response. Microinjections of the GABAB agonist baclofen into the spinal trigeminal nucleus at the level of the obex abolished the R1 but not the R2 response. Thus, the spinal trigeminal nucleus produces the R1 component, whereas the R2 component originates in the C1 region of the spinal cord.

Action Potentials↗
PubMed1991

Brain-stem auditory evoked potentials and blink reflex in Friedreich's ataxia.

The brain-stem involvement in Friedreich's ataxia (FA) was studied by using brain-stem auditory evoked potentials (BAEPs) and the blink reflex. Ten out of 18 patients had abnormal BAEPs, the main abnormality being complete absence of responses and disappearance of wave V. Combined degeneration of the peripheral and central acoustic pathways probably accounts for these findings. The blink reflex was abnormal in 50% of the cases. The outstanding abnormality was bilateral delay of late responses with normal early response, which could be correlated with the known pallor of the descending trigeminal tracts. In contrast with BAEP findings, blink reflex abnormalities did not correlate with either the age of patients or the severity and duration of the disease. These data suggest a difference in susceptibility to degeneration between the auditory system and neuronal system subserving the blink reflex. We conclude that systematic BAEP and blink reflex recording is useful in the electrophysiological evaluation of FA patients.

Adolescent↗
PubMed2003

Attentional blink in adults with attention-deficit hyperactivity disorder. Influence of eye movements.

The attentional blink paradigm tests attention by overloading it: a list of stimuli is presented very rapidly one after another at the same location on a computer screen, each item overwriting the last, and participants monitor the list using two criteria [e.g. detect the target (red letter) and identify the probe (letter p)]. If the interval between the target and the probe is greater than about 500 ms, both are usually reported correctly, but, when the interval between the target and the probe is within 200-500 ms, report of the probe declines. This decline is the attentional blink, an interval of time when attention is supposedly switching from the first criterion to the second. The attentional blink paradigm should be difficult to perform correctly without vigilantly attending to the rapidly presented list. Vigilance tasks are often used to assess attention-deficit hyperactivity disorder (ADHD). Symptoms of the disorder include hyperactivity and attentional dysfunction; however, some people with ADHD also have difficulty maintaining gaze at a fixed location. We tested 15 adults with ADHD and their age- and sex-matched controls, measuring accuracy and gaze stability during the attentional blink task. ADHD participants reported fewer targets and probes, took longer to recover from the attentional blink, made more eye movements, and made identification errors consistent with non-perception of the letter list. In contrast, errors made by control participants were consistent with guessing (i.e., report of a letter immediately preceding or succeeding the correct letter). Excessive eye movements result in poorer performance for all participants; however, error patterns confirm that the weak performance of ADHD participants may be related to gaze instability as well as to attentional dysfunction.

Adult↗
PubMed2006

Eye blink frequency during different computer tasks quantified by electrooculography.

The purpose of the study was to evaluate electrooculography (EOG) as an automatic method to measure the human eye blink frequency (BF) during passive and interactive computer tasks performed at two screen heights. Ten healthy subjects (5 males and 5 females) participated in the study in a 23 degrees C temperature and 30-35% relative humidity controlled simulated office environment. Each test subject completed a 2 x 10 min active task of computer work and a 3 x 10 min passive task of watching a film on a video display unit (VDU). Both tasks included two viewing angles: standard (the monitors' upper edge was in the same height as the subjects' eyes) and low (lowered by 25 degrees). EOG signals were recorded with two Ag/AgCl surface electrodes positioned above and below the right eye, and a reference electrode was placed behind the ear. The experiments were video filmed, and eye blinks were counted manually from the video recordings and compared to the EOG measurements. The method showed a high validity to detect blinks during computer work: 95.4% of the blinks were retrieved by the EOG method and very few artefacts from eye movements were erroneously classified as eye blinks (2.4%). By use of the EOG method, the computer task was found to significantly decrease the BF by 69% compared to the passive task (P < 0.001), and a small decrease (12-14%) was found by lowering the viewing angle by 25 degrees.

Adult↗
PubMed1990

Increased blink rate in drug-naive acute schizophrenic patients.

Eye blinks were investigated during a standardized visuomotor task in 15 drug-naive schizophrenic inpatients (8 men and 7 women) and 15 age- and gender-matched healthy volunteers. Whereas the schizophrenics demonstrated the same precision as normal controls in executing the visuomotor task, their mean blink rate was markedly increased (16.2 +/- 10.8 versus 9.3 +/- 6.4, p less than 0.05). Following neuroleptic treatment, the blink rate decreased, and was no longer statistically distinct from controls. The changes in blink rate correlated significantly with changes in several Brief Psychiatric Rating Scale (BPRS) items: "anxiety" (tau = 0.75; p less than 0.02), "hostility" (tau = 0.78; p less than 0.02), and "unusual thought content" (tau = 0.59, p less than or equal to 0.05), but not with the neuroleptic dose given between the first and second testing. These results underscore the influence of psychopathology on blink rates in schizophrenics.

Adult↗
PubMed1996

Blink rate in childhood-onset schizophrenia: comparison with normal and attention-deficit hyperactivity disorder controls.

Several lines of evidence have implicated central dopaminergic pathways in the modulation of blink rate. In the present study, blink rate during smooth pursuit was examined in 17 children with childhood-onset schizophrenia, on and off of clozapine, and compared to that of age-matched normal children and unmedicated children with attention-deficit hyperactivity disorder (ADHD). As has been observed in adolescent and adult schizophrenics, blink rate was significantly higher in schizophrenic children relative to normal and ADHD controls. Within the schizophrenic group, blink rate did not significantly change with the introduction of clozapine and was not related to clinical variables. Blink rate was positively correlated with deterioration in smooth pursuit in normal subjects.

Adolescent↗
PubMed1981

Speaking, thinking, and blinking.

The effect of several mental tasks on the spontaneous eye blink rate in 36 normals was examined. The blink rate during silence was 19.0 blinks/minute. This was significantly lower than the mean blink rate during speech (24.7 blinks/minute) and while listening to a paragraph to be memorized (27.6 blinks/minute). Reading reduced the blink rate to 12.3 blinks/minute. Men were more able to suppress and speed up blinking than women.

Adult↗
PubMed1993

Auditory effects on the electrically elicited blink reflex in patients with Parkinson's disease.

The effects of sound on the electrically elicited blink reflex were examined in 11 PD patients and 8 control subjects. The blink reflex was conditioned by sound stimulation which did not produce the blink response by itself. Latencies of onset, durations and amplitudes of the R1 and R2 components of the blink reflex produced by single electrical stimulation in PD patients were not different from those in control subjects. In control subjects, sound stimulation produced the facilitation of the R1 component at intervals between 50 and 100 msec, the facilitation of the R2 component at intervals between -20 and 10 msec and the suppression of the R2 component at intervals between 100 and 1000 msec. In PD patients, the facilitation of the R1 and R2 components increased and the suppression of the R2 component decreased. The hyperfunction of the facilitatory interneurones and the hypofunction of the inhibitory interneurones, relating with the blink reflex, might play a role in the abnormal motor control system in the faces of PD patients. These abnormalities might be related to the disturbed function of the reticular formation and the basal ganglia.

Analysis of Variance↗
PubMed1994

Salience of fear/threat in the affective modulation of the human startle blink.

Affective valence modulates the magnitude of the human startle blink such that blinks are reduced by positive affect and enhanced by negative affect. Do different negative contents similarly potentiate startle? Our first study compared the effects of slides selected to depict positive, neutral, frightening, or disgusting scenes. Blink magnitude was significantly facilitated during frightening pictures and attenuated during positive pictures, but blinks during disgusting pictures did not differ from the neutral condition. Replicating previous work, skin conductance magnitude and baseline EMG activity were greater during affective than neutral scenes. In an additional group of 12 subjects, both reaction times for whether slide content was positive or negative and subsequent picture recall were similar for frightening and disgusting pictures. A follow-up study replicated the blink results for subjects who viewed the same picture set and for subjects who viewed only positive, neutral, and disgusting pictures. These results suggest that scenes depicting fear or threat may be especially salient in the affective augmentation of human startle.

Acoustic Stimulation↗