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At least 559 records · Page 31Linked to original sources
PubMed1986

Influences on blink reflex induced by IA afferents in human subjects.

The effects induced by IA volleys, evoked with H reflex, on the blink reflex elicited upon electric activation of supraorbital nerves were investigated in 14 healthy subjects as well as in 4 cerebrovascular patients. In both groups a significant increase in amplitude of the early component (R1) of ipsilateral blink reflex has been observed. A brief discussion of possible neural systems which might be involved in these effects is given.

Blinking↗
PubMed1989

Effects of anticholinergic agents on the excitability of the blink reflex in Meige syndrome.

Blink reflex recovery cycle, before and after acute administration of orphenadrine chlorhydrate, was tested in Meige syndrome. Data here reported show, after the drug, a decrease of the unconditioned polysynaptic responses, without a significant modification of the blink reflex recovery curves. This fact rules out a specific effect of anticholinergic drugs on the pathological reduction of the inhibitory process, at an interneuronal level of these polysynaptic pathways, in Meige syndrome.

Aged↗
PubMed1996

Blink reflex in cerebral palsy: evaluation of late components in patients with normal auditory brainstem responses.

The electrically elicited blink reflex was examined and evaluated quantitatively in 60 controls and seven patients with cerebral palsy due to perinatal asphyxia who exhibited normal auditory brainstem responses. In the controls, the early component (R1) latency changed slightly from infancy to adulthood, and the late component (R2 and R2') latencies decreased to adult values by 4 to 6 years of age. The electromyographic activity of R2 and R2' increased later and became mature in the young adolescent period. Prolonged R2 latency and decreased R2 amplitude were observed more frequently than R1 abnormalities in the patients. The electromyographic activity of R2 in the patients was lower than that in control subjects more than 13 years old. Almost all patients showed bilateral cerebral atrophy and dilated lateral ventricles, but only one patient exhibited distinct pontine atrophy on cranial computed tomographic scan. These electrophysiologic abnormalities suggest that decreased excitability of interneurons of the reflex arc was present in the patients, particularly in older ones. The blink reflex test seems to be more sensitive than the auditory brainstem response for detecting brainstem dysfunction in patients with cerebral palsy due to neonatal asphyxia.

Adolescent↗
PubMed1990

Psychiatric correlates of repetitive rhythmic blinking on a routine EEG.

Our findings suggest that EEG tracings dominated by repetitive rhythmic blinking (RRB) may be indicative of a functional rather than an organic brain disorder. Evaluation of organicity in psychiatric patients is the most common reason for obtaining an EEG. As a normal EEG does not totally rule out organic involvement, such findings as the presence of RRB on the record may strengthen the value of EEG in such evaluations. More research is necessary to further delineate the relation between increased blinking and functional psychiatric disorders.

Blinking↗
PubMed1982

Haloperidol-induced changes in blink rates correlate with changes in BPRS score.

Spontaneous eye blink rates, psychiatric symptoms and response to neuroleptic medication may all be mediated by dopamine. Fixed doses of haloperidol, a dopamine blocking agent, were administered for six weeks to 17 chronic schizophrenic patients who had been previously withdrawn from all medications. The change in blink rates caused by haloperidol corresponded to a change in the thought disturbance syndrome which measures positive symptoms (r = .48, P less than .05). The relationship was particularly clear in patients with normal cerebral ventricles (r = .74, P less than .01).

Adult↗
PubMed1983

An inverse correlation between spontaneous eye-blink rate and platelet monoamine oxidase activity.

An inverse correlation between platelet monoamine oxidase activity and spontaneous eye-blink rate, a putative measure of central dopaminergic activity, was found in medication-free chronic schizophrenic patients without tardive dyskinesia (n = 20, rs = -.47, P less than .025). A similar correlation was found when patients with tardive dyskinesia were included but was weaker (n = 27, rs = -.35, P less than .05). Normal controls and patients with tardive dyskinesia did not demonstrate this relationship. This report confirms a previous finding of a significant platelet monoamine oxidase-blink rate correlation in chronic schizophrenic patients. Insofar as this relationship is mediated by dopamine, it suggests that dopaminergic relations are more readily demonstrated in schizophrenic subjects than normals. Moreover, tardive dyskinesia appears to obscure this dopaminergic relationship.

Adult↗
PubMed1981

Multimodality evoked potentials and blink reflex in multiple sclerosis.

Thirty patients with definite multiple sclerosis and 50 patients in whom the diagnosis was suspected but not proved (indefinite multiple sclerosis) were studied with visual evoked potentials from each eye, somatosensory evoked potentials from each limb, brainstem auditory evoked potentials from each ear, and the blink reflex. The purpose was to organize a battery of clinically practical tests. The battery found 100% abnormality in the definite patients and 82% in the indefinite patients. Of the individual tests, somatosensory evoked potentials were most often abnormal: 86% in definite patients, 58% in indefinite patients, and 77% in asymptomatic definite patients. Visual evoked potentials were abnormal in 76%, 55%, and 40% of the same three categories. Brainstem auditory evoked potentials and the blink reflex were abnormal less often but contributed to the efficacy of the battery.

Adult↗
PubMed1989

Blink reflex excitability cycle in hemifacial spasm.

We studied electrically elicited blink reflex responses in patients with hemifacial spasm (HFS) by applying single isolated, as well as paired (conditioning and test), stimuli at both sides of the face. Responses after single stimuli were of larger size on the side of the spasm compared with the uninvolved side and controls. With paired stimuli, the inhibitory effect of the conditioning stimuli upon the test stimuli late response (R2), which was always observed in normals, was significantly less pronounced at short interstimuli intervals. This resulted in an enhanced recovery curve of R2, which was observed on the side of the spasm and the contralateral, clinically normal side. Patients with longer disease duration showed more striking abnormalities of the recovery curve. We suggest that there is enhanced excitability of facial motoneurons and of those brainstem interneurons that mediate the blink reflex pathway in patients with HFS.

Action Potentials↗
PubMed1995

Blink- and saccade-induced seesaw nystagmus.

A 29-year-old woman with bitemporal hemianopia persisting after a suprasellar germinoma was resected twelve years previously had brief periods of pendular seesaw nystagmus after blinks and horizontal or vertical saccades. Nystagmus may have been suppressed during fixation, and escaped only when fixation was interrupted by blinks or saccades.

Adult↗
PubMed2001

Human breathing and eye blink rate responses to airborne chemicals.

Increased levels of air pollution have been linked with morbidity and mortality, but mechanisms linking physiologic responses to quality of life and productivity issues remain largely unknown. Individuals often report irritation of the nose and/or eyes upon exposures to environmental contaminants. Evaluation of these self-reports would be greatly aided by the development of valid physiological markers. Chamber studies (unencumbered exposures) of nonsmoker responses to environmental tobacco smoke offer two candidate end points: (a) Tidal volume increases and breathing frequency declines with stimuli that elicit only moderate irritation. (b) Eye blink rate increases only with a concentration sufficiently high to cause progressive worsening of eye irritation with prolonged exposure. Experiments with very brief nasal-only presentations also suggest the value of breathing changes as sensitive markers of irritation: (a) Tidal volume is inversely related to perceived nasal irritation (NI) intensity in both normal and anosmic (lacking olfactory input) individuals, although normals exhibit greater NI sensitivity. (b) Inhalation duration, in both groups, declines only with trigeminal activation sufficient to cause readily perceptible NI in anosmics. Changes in eye blink rate and breathing may be useful in the investigation of irritation and other effects of air pollution, and could be quite useful in investigations of mixtures of volatile organic compounds.

Air Pollutants↗
PubMed1982

Reactivated response of blink reflex in the cat.

Three reflex responses in the orbicularis oculi muscles were observed by electrical stimulation of the trigeminal nerve in lightly anesthetized or conscious cats. The third response, following the first and second responses, was concluded as being a "reactivated response" of the blink reflex as it was set up by the trigeminal afferent input evoked by the palpebral movement of the preceding blink. The reasons for this were as follows: 1) the third response disappeared on administration of muscle relaxants and 2) was enhanced by touching the palpebral hair; 3) the palpebral movement activated the afferent discharges of the trigeminal exteroceptors which were strong enough to yield the reflex responses and 4) the latency of the first reflex response by the palpebral movement corresponded to the time lag between the preceding large reflex response and the third response; 5) the third response was hardly suppressed at all until the first response disappeared over a period of maximum reflex suppression following the conditioned stimulation of the trigeminal nerve.

Action Potentials↗
PubMed2005

The effect of target contrast on the attentional blink.

In this set of five rapid serial visual presentation experiments, observers identified one or two target letters that were embedded in a stream of distractors. Target contrasts were varied, and their effects on the attentional blink (AB) were examined. Target identification improved when its contrast was increased. But whereas an increase in the first target's (T1) contrast facilitated its identification, the recovery of the second target (T2) was paradoxically hampered (Experiments 2 and 5). Similarly, identification of the target suffered when the preceding singleton's contrast was increased (Experiment 1). The AB was eliminated by inserting a blank after a low-contrast, but not a high-contrast, T1 (Experiment 5). Increasing T2's contrast attenuated the blink (Experiment 3) and compensated the larger AB caused by a high-contrast T1 (Experiment 4). In all, these results showed that attention continued to be engaged as long as the target's contrast prolonged its perceptibility. When the high-contrast target was T1, a larger AB was produced; when it was T2, there was protection from substitution masking.

Attention↗
PubMed2004

Different effects of eyelid blinks and target blanking on saccadic suppression of displacement.

Displacements of visual stimuli during saccadic eye movements are often not noticed. We have demonstrated that saccadic suppression of image displacement can be eliminated by blanking the stimulus for a short period during and after the saccade (Deubel, Schneider, & Bridgeman, 1996). Here we report an experiment in which target visibility was interrupted after the saccade, either by distal target blanking or by voluntary eyeblink. The data show that the effect of blinking is different from blanking; interruption of vision due to a blink did not enable subjects to detect target displacements any better than they had done in the no-blank condition. The results provide evidence for an extraretinal signal that distinguishes between endogenous and exogenous sources of temporary object disappearance after the saccade.

Adult↗
PubMed2003

Automatic recognition of eye blinking in spontaneously occurring behavior.

Previous research in automatic facial expression recognition has been limited to recognition of gross expression categories (e.g., joy or anger) in posed facial behavior under well-controlled conditions (e.g., frontal pose and minimal out-of-plane head motion). We have developed a system that detects a discrete and important facial action (e.g., eye blinking) in spontaneously occurring facial behavior that has been measured with a nonfrontal pose, moderate out-of-plane head motion, and occlusion. The system recovers three-dimensional motion parameters, stabilizes facial regions, extracts motion and appearance information, and recognizes discrete facial actions in spontaneous facial behavior. We tested the system in video data from a two-person interview. The 10 subjects were ethnically diverse, action units occurred during speech, and out-of-plane motion and occlusion from head motion and glasses were common. The video data were originally collected to answer substantive questions in psychology and represent a substantial challenge to automated action unit recognition. In analysis of blinks, the system achieved 98% accuracy.

Adult↗
PubMed1999

Visual masking plays two roles in the attentional blink.

When two targets are displayed in rapid visual sequence and masked by trailing patterns, identification accuracy is nearly perfect for the first target but follows a U-shaped pattern over temporal lag for the second target. Three experiments examined the role of visual masking in this attentional blink. Experiment 1 compared integration and interruption masks for both targets. Although either mask was effective in producing the blink when applied to the first target, only the interruption mask was effective when applied to the second target. Experiment 2 showed that integration masking of the second target was ineffective over a wide range of accuracy levels. Combining the two forms of masking in Experiment 3 confirmed the dissociation: A combined mask and only a main effect on accuracy for the first target, whereas it produced a qualitatively different pattern over temporal lag for the second target. These results suggest that representations of the target are substituted in consciousness by that of the interruption mask when visual attention is preoccupied.

Adolescent↗
PubMed1989

Temporal integration of acoustic and cutaneous stimuli shown in the blink reflex.

Temporal integration of pairs of brief blink-eliciting acoustic and cutaneous stimuli was investigated to determine if there was integration of stimuli from different modalities. Reflexes elicited by a tone burst or by a brief electrical shock to the supraorbital nerve followed by a second tone burst or shock at short stimulus onset asynchronies (SOAs) were larger and faster than control reflexes elicited by a single stimulus identical to the lead stimulus of the stimulus pairs. Reflex amplitude was augmented at longer SOAs where there was no effect on latency. Temporal integration was evident for all stimulus pairs, showing that it is due, at least in part, to processes that occur outside specific sensory pathways. Heterogeneous stimulus pairs produced greater reflex enhancement than did homogeneous stimulus pairs. This finding was examined further in Experiment 2, which showed that reflex enhancement with pairs of acoustic pulses was unaffected by the frequency of the second stimulus, suggesting that sensory masking was not acting to suppress reflex expression with acoustic pulse pairs. Integration of reflexogenic acoustic stimuli shown in the blink reflex is restricted to shorter intervals than is integration of acoustic stimuli shown by psychophysical procedures, suggesting that the two methods reflect different aspects of stimulus processing. Integration of reflexogenic stimuli may result from summation of activity associated more directly with reflex expression than with perceptual awareness.

Acoustic Stimulation↗
PubMed2000

Selective influence of second target exposure duration and task-1 load effects in the attentional blink phenomenon.

The purpose of the experiments was to constrain the locus of interference in the attentional blink (AB) paradigm. Two visual stimuli, T1 and T2, were shown 300 msec apart, and each was followed by a mask. T1 was an "H," an "S," an "&," or a blank field; T2 consisted of five letters. In Task1, blank fields and & characters could be ignored, whereas Hs and Ss had to be identified and reported. Task2 was always to report as many letters as possible from T2. Task2 performance was lower when T1 had to be reported, as expected from the attentional blink phenomenon (AB). The exposure duration of T2 was also manipulated. More letters could be reported as exposure duration was increased. However, this effect was additive with manipulations of Task1 processing load that produced the AB effect. Log-linear analyses assuming that effects of T2 exposure duration and Task1 load effects occur at functionally distinct stages of processing provided satisfactory fits to the results, suggesting that none of the AB effect occurs as early as those of T2 exposure duration. The results suggest that the locus of the AB effect is later than the stage(s) of processing affected by exposure duration.

Adult↗