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PubMed1986

Dependence of visual suppression on the amplitudes of saccades and blinks.

Visual suppression accompanying voluntary saccades and eyeblinks was measured for a range of amplitudes of both. Saccade amplitudes varied from 2 to 32 degrees and blink amplitudes varied from a slight movement to a full closure of the eye. In every case, thresholds for detecting full-field luminance decrements were determined with the method of constant stimuli and a two alternative forced choice procedure. Results from three subjects show a monotonic increase in the amount of suppression produced by saccades and blinks of increasing amplitude. Data are discussed with respect to theories about the origin of visual suppression.

Adult↗
PubMed1995

Modulation of electrically elicited blink reflex components by visual and acoustic prestimuli in man.

The effects of a prestimulus on the electrically elicited blink reflex components were investigated in 20 healthy subjects. In the first group of 10 subjects (warned group), electric shocks were delivered in isolation or preceded, at an interstimulus interval (ISI) of 0.1 s, 1 s, or 10 s, by a visual or acoustic warning stimulus. In the second group of 10 subjects (unwarned group), the electric shocks were delivered either in isolation or preceded, at the same ISI, by visual or acoustic stimuli having no warning value. The modulation of the three blink reflex components was then analysed. Compared to the baseline condition, the R1 oligosynaptic component was enhanced at 0.1 s and 1 s ISI, in the warned group with the visual prestimulus, but only at 0.1 s after a visual and acoustic prestimulus in the unwarned group. On the contrary, the polysynaptic responses showed a different course: R2 was significantly reduced at the 0.1 s interval in the warned group with both the prestimuli, and only with the visual prestimulus in the unwarned group. The R3 was inhibited at all three intervals with the visual prestimulus, and at the 0.1 s and 1 s with the acoustic one in the warned group, and only at 0.1 s in the unwarned group, both after visual and acoustic prestimuli. The decrement in R2 and R3 observed with the shortest interval was probably related to the prepulse inhibition of startle reflex. Furthermore, only R3 was still inhibited at longer intervals, when the sustained processes of attention may have influenced this component. Perhaps this combination of events represents, in the warned group, the best preparation for voluntary reflex reaction.

Acoustic Stimulation↗
PubMed1985

Blink reflex modification by selective attention: evidence for the modulation of 'automatic' processing.

Probe stimuli which elicit activity reflexly provide a means of assessing 'top-down' effects of attentional manipulations while minimizing the perhaps insolvable problem of determining whether effects are due to post-perceptual selection or to changes in the input pathway. Parallel experiments on adults and infants presented acoustic and visual probes unpredictably while subjects attended to acoustic and visual foregrounds: Attention was indexed by heart rate deceleration. When probe and foreground modality matched, probe-elicited reflex blinks were significantly facilitated in magnitude (infants) or latency (adults) relative to reflexes elicited when probe and foreground modality mismatched. Further, facilitation was greater when modality-matching probes were presented over foregrounds judged a priori to be more 'interesting' than 'dull' foregrounds. Because acoustic and visual blink reflexes have a common efferent path, modulating effects must have occurred earlier, in modality-specific paths. As such, the results suggest that attention can influence 'automatic' sensory-perceptual analysis.

Adolescent↗
PubMed1995

Elderly men and women are less responsive to startling noises: N1, P3 and blink evidence.

Previously we observed that the P3 component of the event-related brain potential (ERP) elicited by startling noises, and to a lesser extent P3 to target tones, is reduced in the elderly (Ford & Pfefferbaum, 1991). In the current experiment, we tried to eliminate possible effects of age-related hearing deficits on the responses to noises by filtering them to include only frequencies heard best by the elderly (0-1000 Hz) and by setting noise intensity relative to each subject's threshold (sensation level, SL). Twelve younger (mean 22 years) and 12 older (mean 69 years) men and women listened to three sequences of tones (80%, 500 Hz, 70 dB SPL) and noises (20%). One type of noise occurred in each sequence (wide band noise set to 107 dB SPL, narrow band noise set to 107 dB SPL, or narrow band noise set to approximately 65 dB SL). The order of the three sequences was counterbalanced across age and sex. Younger subjects blinked to the noise 4-5 times more often than older subjects and had N1 and P3 amplitudes that were 2-3 times larger, regardless of the noise type. N1 amplitude to the background frequent tones and non-startle blinks did not differ between groups. Thus, even when noises were narrow band and set relative to each subject's threshold, older subjects were less responsive to startling auditory stimuli than were younger.

Acoustic Stimulation↗
PubMed1989

An electrophysiologically defined trigemino-reticulo-facial pathway related to the blink reflex in the cat.

This study examines the direct projection of neurons in the pontomedullary reticular formation (RF) to the dorsal division of the facial nucleus (FN), where the orbicularis oculi motoneuron pool is located, and the nature of synaptic inputs to the RF neurons from the supraorbital branch of the trigeminal nerve (SON), using electrophysiological techniques in anesthetized cats. A large number of the RF neurons directly projected to the ipsilateral FN dorsal division, and some of these neurons issued axon branches probably terminating on motoneurons in the division. Many of the RF neurons projecting to the dorsal division were synaptically activated by ipsilateral SON stimulation. Most latencies of their activation were between the latencies of the early and late blink reflex responses, and the remaining latencies were shorter than those of the early response. These results suggest that the RF neurons mediate both the early and the late blink reflex responses, but mainly the late response, as premotor relay neurons.

Action Potentials↗
PubMed1982

Comparative effects of electroacupuncture and transcutaneous nerve stimulation on the human blink reflex.

The effects of low frequency (2 Hz) high intensity (10-12 mA) (electroacupuncture, EA) and of high frequency (100 Hz) low intensity (2 mA) (transcutaneous nerve stimulation, TNS) conditioning stimuli were studied on the nociceptive component (R2) of the blink reflex in normal volunteers. EA induced a progressive and moderate partially naloxone-reversible depression in the R2 response. In contrast, TNS induced a rapid and major depression in this reflex. In this latter case, naloxone failed to produce any reversal effect. These two patterns of data are discussed and further electrophysiological studies provide some evidence for two different mechanisms in the depressive effects of EA and TNS upon the nociceptive component of the blink reflex in man.

Acupuncture Therapy↗
PubMed1996

Changes in eye blink responses following hypoglossal-facial anastomosis in the cat: evidence of adult mammal motoneuron unadaptability to new motor tasks.

Hypoglossal-facial anastomosis is used in humans to restore the activity of the mimic musculature following irrecoverable facial nerve lesions. As eyelid movement kinetics is very well known, we have used this experimental model in cats to follow the evolution of blink responses and the adaptability of hypoglossal motor pools to new motor tasks. Although the electromyographic activity of the orbicularis oculi muscle in response to corneal air puffs, flashes of light or electrical stimulation of the supraorbital nerve was not recovered in the seven months following this crossed anastomosis, reflex blinks were got back by the increased activity of the retractor bulbi and extraocular recti muscles. The lid of the anastomosed side oscillated in perfect synchronization with tongue movements during licking, while it was severely affected in its motor function during optokinetic stimulation because of the spontaneous appearance of tongue-related hypoglossal activity. Present results suggest that adult mammal motoneurons are unable to readapt their motor programs to the kinetic needs of new motor targets and that most of the functional recovery observed in the cat was achieved by the compensatory hyperactivity of motor systems not directly affected by the surgery.

Adaptation, Physiological↗
PubMed2005

A neurodynamic model of the attentional blink.

A brain-based neural model of attention is used to simulate results for the 'attentional blink', observed when a subject is exposed to a rapid stream of stimuli and required to monitor for two successive targets in the stream. The 'blink' occurs when the time between the first and second targets is 200-500 ms, when there is reduced accuracy for report of the second target. The model gives a qualitative explanation of the phenomenon, especially of how attention is bolstered, during the processing to report of a given stimulus, in order to defend reportable information from attack by distracters.

Attention↗
PubMed2005

Concurrent measurement of the detectability of tone bursts and their effect on the excitability of the human blink reflex using a probe-signal method.

The probe-signal method has shown that auditory signals that are either presented more often in a series of trials or that are immediately preceded by cues of the same frequency on a single trial are detected more readily than signals of other frequencies. The frequency range in which detection is favored defines an attentional band, which is thought to result from an effective attenuation of deviant frequencies in the cochlea, possibly by activation of the olivocochlear bundle. In a 2IFC procedure in which the first observation interval was preceded by a 1300-Hz cue, subjects detected cued probe tones (at 1300 Hz) but not uncued probe tones (at 1000 Hz or 1600 Hz) at better than chance levels. Concurrent elicitation of a blink reflex by presentation of an air puff in the first observation interval on a random half of the trials showed that cued probes, but not uncued probes, inhibited the size of the blink reflex. These data show that uncued probes do not enter into the low-level sensory processing in the brainstem which is responsible for reflex modification. This finding is consistent with the view that stimuli whose frequency falls outside an attentional band are excluded at the auditory periphery.

Acoustic Stimulation↗
PubMed2006

Prepulse inhibition of the startle blink reflex is modulated during a memory task requiring prepulses to be encoded for later report.

Prepulse inhibition (PPI) of the startle blink reflex in humans can be modulated by selective attention to the prepulse. The present experiment used a memory task to determine whether the encoding of information for later report can modulate PPI. Participants were briefly presented with a display of one or three letters followed by a pattern mask and asked to make a delayed report of the letter(s) shown. Memory recall was better in the 1-letter condition than in the 3-letter condition. Prepulse inhibition was greater in the 3-letter condition than in the 1-letter condition at lead intervals of 120 and 240 ms following the onset of the letter display. Blink modulation did not differ between the letter conditions at lead intervals of 120, 240, 360, or 2600 ms following the mask, ruling out other explanations (e.g., rehearsal) for the earlier difference in PPI. The results suggest that the short-term consolidation of memory, and possibly any cognitive process that requires access to a theoretical limited capacity central processing mechanism modulates PPI.

Adolescent↗
PubMed2005

Attentional blink in adolescents with varying levels of impulsivity.

We explore the temporal attention function in a non-clinical sample of adolescents varying in impulsivity, as assessed with the Barratt Impulsiveness Scale. In a Rapid Serial Visual Presentation task, in which two targets (T(1) and T(2)) were presented in close temporal proximity among distractors, participants tried to identify T(1) and detect T(2) in one (dual-task) experiment and only to detect T(2) in a second, control (single-task) experiment. The sensitivity of T(2) detection was analyzed using signal detection theory. The attentional blink -- the impairment in T(2) detection following the identification of T(1) -- was increased in magnitude and protracted in adolescents with high impulsivity, compared with those with low impulsivity. Moreover, a few more participants with high impulsivity appeared to have a blink temporally weighing toward a later time, an observation also made in children with attention deficit hyperactivity disorder (ADHD) in an earlier study. Taken together, these findings suggest impairment in temporal attention in adolescents with high impulsivity. As in ADHD children, a gating deficit may play a central role in this attention impairment.

Adolescent↗
PubMed2005

The effect on human eye blink frequency of exposure to limonene oxidation products and methacrolein.

Oxidation products of terpenes (e.g. limonene) contain unidentified irritants, which may be responsible for a fraction of the reported eye and airway complaints in indoor environments. Here we report exposure to parts per billion (ppb) levels of limonene oxidation products (LOPs) and the terpene oxidation product methacrolein using blink frequency (BF) as a measure of trigeminal stimulation of the human eye. Ten male subjects averaging 43 (standard deviation 10.5) years were exposed for 20 min to LOPs, methacrolein, and clean air, respectively. A baseline BF was measured prior to and following each exposure (8 min and 4 min, respectively). The subjects were exposed locally in the non-dominant eye and single blind at 20% relative humidity (RH), while viewing an educational film. Blinking was video recorded and evaluated for full sessions of 36 min. Mean BF increased significantly during exposure to LOPs and methacrolein compared to the baseline of clean air, and the findings coincided with weak eye irritation symptoms. Lowest observed effect levels were 286 ppb methacrolein and a 10-min-old LOPs mixture of initially 92 ppb limonene and 101 ppb ozone (O3), which increased the BF comparably by 18% (p=0.001) and 17% (p=0.003), respectively. The increase in BF was smaller, although not significantly different, during exposure to LOPs at 50% RH to 20% RH in mixtures prepared from ca. 350 ppb limonene and 300 ppb O3. LOPs may cause trigeminal stimulation and possibly eye irritation at O3 and limonene concentrations, which are close to high-end values measured in indoor settings. The effects may be exacerbated by low RH.

Acrolein↗
PubMed2005

The role of (micro)saccades and blinks in perceptual bi-stability from slant rivalry.

We exposed the visual system to an ambiguous 3D slant rivalry stimulus consisting of a grid for which monocular (perspective) and binocular (disparity) cues independently specified a slant about a horizontal axis. When those cues specified similar slants, observers perceived a single slant. When the difference between the specified slants was large, observers alternatively perceived a perspective- or a disparity-dominated slant. Eye movement measurements revealed that there was no positive correlation between a perceptual flip and both saccades (microsaccades as well as larger saccades) and blinks that occurred prior to a perceptual flip. We also found that changes in horizontal vergence were not responsible for perceptual flips. Thus, eye movements were not essential to flip from one percept to the other. After the moment of a perceptual flip the occurrence probabilities of both saccades and blinks were reduced. The reduced probability of saccades mainly occurred for larger voluntary saccades, rather than for involuntary microsaccades. We suggest that the reduced probability of voluntary saccades reflects a reset of saccade planning.

Blinking↗
PubMed2002

Visual protective sheet can increase blink rate while playing a hand-held video game.

PURPOSE: To evaluate the effectiveness of a protective sheet in reducing eye strain caused by unnecessary light reflection on portable liquid crystal display panels while playing Game Boy (Nintendo, Kyoto, Japan). DESIGN: Nonrandomized clinical trial. METHODS: The blink rates of 24 normal volunteers were measured under relaxed conditions while viewing a portable liquid crystal display panel and playing Game Boy with and without the protective sheet of polyethylene terephthalate with antiglare coating for a total of 10 minutes each. RESULTS: The results showed a dramatic increase (from 5.6 +/- 3 to 9.1 +/- 4.9 [P <.0001]) in blinks/minute with use of the protective sheet. CONCLUSION: The protective sheet has shown the possibility of increasing the blink rate by making the screen easier to see.

Adult↗
PubMed1997

Lack of visual suppression in the rabbit lateral geniculate nucleus during blink reflex.

Stimulation of the supraorbital branch of the trigeminal nerve (SO) elicited eye blinks in the rabbit, but did not decrease the amplitude of visual cortical evoked potential from stimulation of the optic chiasm (OX). In addition, the SO stimulation neither induced an inhibitory postsynaptic potential (IPSP) in LGN cells, nor activated inhibitory interneurons in the thalamic reticular nucleus (TRN), which proved to mediate both recurrent inhibition and saccadic suppression in the dorsal lateral geniculate nucleus (LGN). All these indicate that there is no visual suppression in the rabbit LGN during blink reflex.

Animals↗
PubMed1996

Postpulse effects on blink reflex responses.

The technique of paired stimulation is routinely used in many laboratories in the assessment of the excitability recovery curve of the blink reflex. Other effects, such as prepulse inhibition or classical conditioning, can also be investigated with repeated presentation of pairs of time-locked stimuli. Regularly repeated presentations of an unpleasant stimulus may give rise to a transient excitability enhancement in neural structures in the reflex circuit. We have investigated whether such a transient shift in excitability can be demonstrated before the actual stimulus is applied. In 10 normal volunteers, we regularly alternated series of 5 trials containing an auditory tone of mild intensity with series of the same auditory tone followed by a relatively strong supraorbital nerve electrical stimulus. We calculated the habituation percentage of the orbicularis oculi responses to the auditory stimulus within a series and compared the results obtained in series containing the auditory tone alone with those from series containing the auditory tone followed by the electrical stimulus. Habituation was significantly less with paired stimulation than with the auditory tone alone, the mean area of the response to the 3rd trial in percentage of that to the first trial being 34.0 +/- 16.4% for paired stimuli, and 20.3 +/- 14.1% for auditory stimulus alone (P = 0.008). This effect, induced by the presence of an impending electrical stimulus on the response to a preceding stimulus, is defined as a postpulse effect in contradistinction to the prepulse effects induced by a weak stimulus on the response to a subsequent startle-eliciting stimulus. When a paradigm with a stimulus pair is used in human subjects, the possibility of effects occurring in both temporal directions should be taken into account. Blink reflex responses to a given stimulus may exhibit excitability changes induced by a preceding or by an impending stimulus.

Acoustic Stimulation↗
PubMed2002

Blinks, blanks and saccades: how blind we really are for relevant visual events.

We report on a study in which subjects viewed color video stills of natural traffic situations while eye movements were recorded. A display change could occur randomly during three different occlusion modes--blinks, blanks and saccades--or during a fixation. These changes could be either relevant or irrelevant with respect to the traffic safety situation. Furthermore we contrasted insertions and deletions. All occlusion modes appeared equivalent concerning detection rate and detection time, and only differed from the fixation condition. The results also show that the detection of relevant changes was more likely and faster than that of irrelevant ones. However, even relevant insertions, which were almost always detected, were around 180 ms longer to report when they occurred during an occlusion. Furthermore, the detection of relevant changes was fairly stable across a wide range of the visual field, whereas irrelevant changes were less well detected, the further away from the fovea they occurred. We close with an outlook on a follow-up study where only relevant insertions and the blank occlusion were used in a driving simulator environment. Surprisingly, we found an advantage in change detection rate and time with blanks compared to the control condition. Change detection was also good during blinks, but not in saccades.

Adult↗
PubMed1999

Abnormal blinking of newscasters.

When compared with a control group, blink rates of Japanese TV newscasters were increased, suggesting a possible reaction to reading the news under stressful studio conditions. Frequent blinking may be distractive to the viewing audience.

Adult↗