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At least 577 records · Page 32Linked to original sources
PubMed1999

Excitability recovery curves of blink reflexes in patients with athetotic cerebral palsy.

We evaluated the brainstem function or its excitability by the blink reflex evoked with the electrical stimulation to the supraorbital nerve in 10 patients with athetotic cerebral palsy compared with 10 normal subjects and 7 spastic type patients. There were no differences in stimulus intensity, latency of R1 and R2 components, and duration and area of EMG activity of the R2 component of the blink reflex elicited by single stimulation among the two patients' groups and normal subjects. R1 recovery cycle to paired stimuli in the athetotic group showed a facilitation of the test responses by the conditioning stimuli at 100 and 200 ms intervals, but were not significantly different from those in the normals. On the other hand, the R2 recovery curve in the athetotic group showed a significant hyperexcitability at all intervals from 100 to 600 ms compared to the normals. Our results from the R2 hyperexcitable recovery to paired stimuli are indicative of increased brainstem interneuronal excitability in athetotic patients and similar to the results reported in the disorders of the basal ganglia, i.e. Parkinson's disease, dystonia and blepharospasm. We suggest that this hyperexcitability might be caused by abnormal input possibly from the basal ganglia upon these brainstem interneurons.

Adolescent↗
PubMedDate not supplied

Impaired eye-blink conditioning in waggler, a mutant mouse with cerebellar BDNF deficiency.

In addition to their trophic functions, neurotrophins are also implicated in synaptic modulation and learning and memory. Although gene knockout techniques have been used widely in studying the roles of neurotrophins at molecular and cellular levels, behavioral studies using neurotrophin knockouts are limited by the early-onset lethality and various sensory deficits associated with the gene knockout mice. In the present study, we found that in a spontaneous mutant mouse, waggler, the expression of brain-derived neurotrophic factor (BDNF) was selectively absent in the cerebellar granule cells. The cytoarchitecture of the waggler cerebellum appeared to be normal at the light microscope level. The mutant mice exhibited no sensory deficits to auditory stimuli or heat-induced pain. However, they were massively impaired in classic eye-blink conditioning. These results suggest that BDNF may have a role in normal cerebellar neuronal function, which, in turn, is essential for classic eye-blink conditioning.

Animals↗
PubMed1999

[The blink reflex in the electrophysiologic exploration of Bell's palsy and its prognostic value].

Conventional electrophysiology of the facial nerve gives only information about the functional condition of its extracranial segment. The blink-reflex triggered for the electric stimulation of supraorbital nerve allows the study of the whole nerve path, even the intraosteal, where the great majority of its pathology settles. We have realized this tests in 43 Bell's palsy cases (at the beginning of the paralysis and three weeks later) and correlated the results with the clinic course, in order to set up the pronostic value of the procedure. The cases with shorter tendency of blink reflex along the three first week have a better outcome.

Adolescent↗
PubMed1999

The effects of threat and nonthreat word lead stimuli on blink modification.

Two experiments examined the effects of visually presented threat and nonthreat word lead stimuli on blink modification among unselected young adults (Experiment 1, N = 35) and participants selected for low and high trait anxiety (Experiment 2, N = 60). The blink reflex was elicited by a white noise probe of 105 dB. Lead stimulus intervals of 60, 120, 240, and 2000 ms were used in both experiments. Prepulse inhibition was observed at the 240-ms interval and prepulse facilitation was observed at the 60-ms interval in both experiments. Also, greater facilitation was found in both experiments during threat words at the 60-ms interval and greater inhibition during threat words at the 240-ms interval. Experiment 2 provided some evidence that the greater facilitation during threat words than during nonthreat words at the 60-ms probe interval may be found in high trait anxious participants, but not in low trait anxious participants. The results are discussed in relation to contemporary information processing theories of anxiety.

Acoustic Stimulation↗
PubMed2000

[Feeding function, blink reflex and MRI in the severely handicapped].

Blink reflexes were studied in 41 patients with severe handicaps, and were correlated with feeding problems and other lower brainstem symptoms such as drooling, an absent gag reflex and stridor. Ventrodorsal diameters of the pons and medulla oblongata on sagittal MRI were also studied in 29 of the cases. The patients were divided into three groups: tube feeding (25 cases), oral feeding (13 cases) and mixed feeding (3 cases). In the tube feeding group, all but three cases showed a prolonged or absent R1 component, and all cases showed prolonged or absent R2 and R2' components. These abnormalities were significantly more frequent in the tube than in the oral feeding group. The patients with drooling, stridor or an absent gag reflex more frequently showed prolonged or absent components than the patients without these symptoms. The brainstem size on MRI was not different between the tube and oral feeding group. These results suggest that the blink reflex, particularly its late components, is a useful indicator for evaluating feeding function and other lower brainstem functions.

Adolescent↗
PubMed2001

In vitro eye-blink classical conditioning is NMDA receptor dependent and involves redistribution of AMPA receptor subunit GluR4.

The classically conditioned vertebrate eye-blink response is a model in which to study neuronal mechanisms of learning and memory. A neural correlate of this response recorded in the abducens nerve can be conditioned entirely in vitro using an isolated brainstem-cerebellum preparation from the turtle by pairing trigeminal and auditory nerve stimulation. Here it is reported that conditioning requires that the paired stimuli occur within a narrow temporal window of <100 msec and that it is blocked by the NMDA receptor antagonist d,l-2-amino-5-phosphonovaleric acid. Moreover, there is a significant positive correlation between the levels of conditioning and greater immunoreactivity with the glutamate receptor 4 (GluR4) AMPA receptor subunit in the abducens motor nuclei, but not with NMDAR1 or GluR1. It is concluded that in vitro classical conditioning of an abducens nerve eye-blink response is generated by NMDA receptor-mediated mechanisms that may act to modify the AMPA receptor by increasing GluR4 subunits in auditory nerve synapses.

Abducens Nerve↗
PubMed2001

Missed prime words within the attentional blink evoke an N400 semantic priming effect.

When subjects identified a target among distractors in a rapid serial visual presentation task, the detection of a subsequent target is impaired (attentional blink). By measuring event-related potentials (ERPs) we investigated if the processing of an unidentified prime word elicits the N400 semantic priming effect. Subjects (N = 12) had to identify three target words among distractors in a rapid serial visual presentation task. We varied the association strength between a prime (second target) and a probe (third target). The detection of the prime was impaired. Missed primes did not elicit a P300, indicating that they were not explicitly recognized. Despite this difference between recognized and missed primes, the N400 effect was present in both cases. This result suggests that automatic spread of activation (ASA) can be evoked by missed primes within the attentional blink. It furthermore demonstrates that ASA is sufficient to evoke the N400 effect.

Adult↗
PubMed2001

Effects of phonological length on the attentional blink for words.

The authors tested whether the attentional blink (AB), a deficit in the ability to report a second target appearing within half a second of a first target, may reflect limitations for consolidating visual stimuli into working memory and awareness. Previous research has shown that people are severely limited in the rate that they can identify and report visual events presented in rapid succession. Word length was examined, a variable known to affect verbal working memory. Experiment 1 showed that the AB was modulated by the phonological length of the first target. Phonologically longer pseudowords triggered larger blink deficits. Experiment 2 also demonstrated the word-length effect on the AB using real-world stimuli, anagrams, that controlled for low-level visual differences between conditions. These data support proposals that the AB reflects a difficulty in consolidating information into working memory.

Attention↗
PubMed1998

[The normal value and clinical applications of the blink reflex].

OBJECTIVE: To study the normal value and clinical applications of blink reflex. METHODS: Using the clinical electrodiagnostic techniques, the orbital nerve was stimulated to elicit the blink reflex. RESULTS: In 20(40 sides) normal subjects, two components (R1 and R2) had been documented. The latencies were about 10.1 ms for R1, 30.4 ms and 30.7 ms separately for R2 and R2'. In 30 patients with trigeminal and facial nerve diseases and acoustic neuromas, the latencies on the affected sides were apparently longer or the reflex disappeared (P < 0.01). CONCLUSION: This study indicates that the simple, harmless electrodiagnostic measurements are of value in the initial investigation of trigeminal and facial nerve diseases and acoustic neuroma.

Adolescent↗
PubMed2002

Blink reflex: comparison of latency measurements in different human races.

The blink reflex latencies and cephalometric indexes were analysed in 30 male volunteers from three different races, 10 white, 10 black, and 10 Oriental. Ages ranged from 15 to 59 years, height from 1,60 to 1,80 m, and weight from 60 to 80 kg. Blink reflexes were obtained after unilateral electric stimulation of the supraorbital nerve for quantitative analysis of 3 responses, early ipsilateral (R1), late ipsilateral (R2i) and late contralateral (R2c), obtained from the orbicularis oculi muscle. Cephalometric indexes were calculated by multiplying the ratio between the longer transverse and the longer saggital head diameters by 100. The R1, R2i and R2c latencies were consistent with other published papers revealing no differences between the different racial groups. The mean of the cephalometric indexes of each group were consistent with respective racial characteristics. This study revealed that there are no differences between R1, R2i and R2c latencies in the 3 different studied races.

Adolescent↗
PubMed2005

Somatosensory evoked blink response in hemifacial spasm and peripheral facial palsy.

Somatosensory blink response (SBR) is produced by electrical stimulation of peripheral nerves or skin areas remote from the face. We investigated the presence of SBR in cases with hemifacial spasm (HFS) and peripheral facial palsy (PFP). Fifty-seven cases of HFS, 54 cases of PFP and 39 normal subjects were included in the study. A routine blink reflex study was performed in all subjects. Supramaximal stimulation of the median nerve was given ipsilateral to the either spasm or paralytic side for SBR. Recordings were made at the orbicularis oculi (o.oc) bilaterally and ipsilaterally at the orbicularis oris (o.or) muscles. SBR was elicited in 12 of 39 control subject. Twenty four of 48 HFS cases were SBR positive. Twelve of them had o.or response. An SBR was elicited at the ipsilateral o.oc in 35 of 46 patients with PFP with synkinesia. Twenty-six patients had an SBR at the ipsilateral o.or. In the 13 patients with PFP without synkinesia only 3 people had an SBR. SBR positivity was seen more often in PFP with synkinesia than in cases with HFS. SBR if positive spreads to the lower part of the face in most of cases with HFS and PFP with synkinesia.

Adolescent↗
PubMedDate not supplied

Blink reflex in motor neuron disease.

The aim of the study was to analyse the diagnostic value of blink reflex (BR) in motor neuron disease (MND). We studied 25 patients with MND including amyotrophic lateral sclerosis (ALS) in 18 patients, primary muscular atrophy (PMA) in 4 patients, and primary lateral sclerosis (PLS) in 3 patients and 12 healthy volunteers. The blink reflex was obtained in typical way. In ALS group, statistically significant increase in latency and decreased amplitude of R2 responses were found compared to the control group (p < 0.05), whereas BR in patients with PLS and PMA was within normal limits. The presence of low amplitude of R2 responses in patients with ALS may suggest loss of lower brainstem neurons connecting trigeminal and facial system, and probably also decreased facilitator effect of central nervous system on reticular formation in the brainstem.

Adolescent↗
PubMed2006

Median sep and blink reflex in thyroid diseases.

Pathological disturbances of thyroid hormones is associated with central and peripheral nervous system disturbances. The aim of this study is to evaluate median nerve stimulated somatosensory evoked potential (SEP) and blink reflex of thyroid patients (hypo and hyperthyroidism). Median SEP was performed in 40 patients (21 with hyperthyroidism and 19 with hypothyroidism). We evaluated the latencies of N9, N11, N13, P9, P11, P14, N20 and P25 waves and the N9-N20, N9-N13, N13-N20 and P14-N20 interpeak latencies. We compared the results of patients with the control group (26 persons). We found that the N20 latency was longer in patients with hyperthyroidism than in the control group and the difference was statistically significant. There was not any statistically significant difference regarding the N9, N11, N13, P9, P11, P14, N20 and P25 latencies and the N9-N20, N9-N13, N13-N20 and P14-N20 interpeak latencies between hypothyroid patients and controls. We performed the blink reflex study in 28 of 40 patients (14 patients with hyperthyroidism and 14 patients with hypothyroidism). Comparing the R1, R2, CR2 (contralateral R2) latencies and durations of the patients and controls, we found that R2 and CR2 duration was shorter in patients with hyperthyroidism. This difference was statistically significant.

Adult↗
PubMed1991

The use of cardiac and eye blink measures to determine flight segment in F4 crews.

Discriminant analysis techniques were used to classify 8 flight segments for 19 F4 crewmembers and to classify pilots from Weapons Systems Officers (WSOs). Heart rate and eye blink data were used as variables. Pilots and WSOs were correctly classified 84% of the time, while 92% of the flight segments were correctly classified for pilots and 89% for WSOs. The percent correct classifications of flight segments using the jackknife procedure were 69% and 68%, respectively. The advantage of collecting multiple physiological signals was demonstrated. Combined cardiac and eye blink data produced better classifications than when each was used alone. Application of this technique to the flight environment is discussed.

Aerospace Medicine↗
PubMed1991

Changes in photically evoked blink reflex during sleep and wakefulness.

The effects of the state of arousal on photically evoked blink reflex were studied. Eyelid potential (ELP), the averaged electromyographic activity of the orbicularis oculi muscle, was used to define the onset latency and intensity of the reflex. ELP was maximum with the shortest latency when the subjects were awake and doing mental arithmetic. ELP amplitude gradually decreased and the latency lengthened with the advance in non-rapid eye movement (non-REM) sleep stages. In the REM stage, ELP was augmented and resembled that when awake. ELP is useful as an objective sign of the photically evoked blink reflex, which closely reflects cortical activities and brain stem function.

Adult↗
PubMed1991

[Changes in the blink reflex in patients with essential blepharospasm and hemifacial spasm].

Electrophysiological investigations have been carried out in 46 patients with essential blepharospasm and 41 with hemifacial spasm. In both diseases reproducible pathologic alterations in the blink reflex were found. In essential blepharospasm a direct R1/R2 transition and a contralateral early component with and without direct transition into the R2C component were recorded. In patients with hemifacial spasm there was a loss of the R1 component in addition. In repeated treatments with botulinum toxin the amplitude (R1,R2) of the blink reflex was reduced in some cases, although in some cases the intensity of spasm was as high as before treatment once the effect had faded.

Blepharospasm↗
PubMed1991

Reappearance of the visual percept after intentional blinking in a patient with Balint's syndrome.

We present a patient with Balint's syndrome who complained of fading of the scenes under visual fixation. When he intentionally blinked, the faded visual percept reappeared. The disappearance of the visual percept may be explained as the result of either unstable visual fixation or of saturation of the visual pathways. The role of blinking in reviving the visual percept may be explained accordingly as causing a refixation of the target under visual fixation or as resetting the visual pathways for visual processing.

Aged↗
PubMed1990

[Modification of the blink reflex in hemidystonia].

With the aim of evaluating the excitability of the brain stem reflex centers, we studied the side-to-side differences in the EMG activity of the early and late components of the blink reflex, in subjects with unilateral dystonia without demonstrable brain lesions. We observed that both early and late responses of direct blink reflex were significantly higher in the affected side than in the contralateral one.

Blinking↗