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PubMed1982

Measurements of visual suppression during opening, closing and blinking of the eyes.

We have previously shown that the sensitivity of human vision, as measured with a stimulus that bypasses the eyelids, is briefly impaired at the time of an eyeblink. We now find that the visual loss is almost equally extensive during eye closure if the eyes then remained closed. But little impairment occurs during eye opening when the eyes then remain open. We have previously concluded that, in blinking, visual suppression is associated with an inhibitory signal sent out by the brain. We now conclude that this signal arises primarily as a corollary to the efferent discharge that closes the eyelids.

Adult↗
PubMedDate not supplied

Habituation of P300 and reflex motor (startle blink) responses to repetitive startling stimuli in children.

Positive EEG deflections with the latency and scalp distribution of the P300 accompany startle in response to loud auditory stimuli in a non-task context. The purpose of this investigation is to determine if habituation would have effects on the P300 similar to those on the startle blink. Thirty-four normal 7 to 11-year-old boys from a startle habituation study had EEG recordings of sufficient quality to provide data for the current study. Startle was measured both as orbicularis oculi EMG and vertical EOG and P300 was recorded at Pz in response to 40,104 dB bursts of white noise presented at 23-s intervals. Both the startle response and the P300 habituated toward asymptotic levels after the first 28 trials, suggesting that both startle and the subsequent cognitive evaluation of the startling stimulus, reflected in the P300 response, are modulated by a common neurophysiological mechanism extrinsic to the direct startle pathway. A modest significant correlation between the P300 and the vertical EOG peak latencies for the initial trials suggests that the cognitive evaluation of the startling stimulus may also include evaluation of the reflex response to that stimulus. Analyses of the within-subject associations between startle and P300 initial amplitudes and rates of habituation showed that these parameters varied independently within the individual subject, suggesting that the P300 is not a component of the startle response. Rather, it reflects an evaluation of the startling stimulus, decreasing in amplitude as the surprising value of the startling stimulus decreases with habituation.

Aging↗
PubMed1985

Neural pathways mediating the corneal blink reflex and Bell's phenomenon in the cat.

Two central projections from the corneal representation of the sensory trigeminal complex in the cat were demonstrated with horseradish peroxidase, autoradiographic and Golgi methods: (1) to the dorsal subdivision of the ipsilateral facial nucleus that innervates the orbicularis oculi muscle; and (2) to the bordering area between the contralateral central gray matter and the oculomotor nucleus, which receives dendrites of the oculomotor cells innervating the contralateral superior rectus muscle. These two routes probably mediate early responses of the corneal blink reflex and Bell's phenomenon, respectively.

Animals↗
PubMed1982

Recruitment of single motor units in the human blink reflex.

The recruitment of single motor units (MU) in the early (R1) and late (R2) components of the electrically evoked human blink reflex (BR) was studied using bipolar needle electrodes with a limited take-off area. It could be shown that the same MUs can discharge in R1 and R2 of a BR as well as during voluntary eyelid contraction. At repetitive stimulation (1 Hz), facilitation of MU discharges in R1 and habituation in R2 became apparent. The visible reflex eyelid contraction may mainly be due to repetitive MU discharges in R2. The discharges of the same MUs in R1, however, contribute to it and shorten the latency between stimulus and reflex response.

Adult↗
PubMed1988

Effects of heterotopic ischemic pain on muscular pain threshold and blink reflex in humans.

Ischemic pain was induced in the left arm of 6 healthy volunteers using a modification of the submaximal effort tourniquet test. Its effects on both muscular pain threshold (determined in the vastus medialis muscle by means of electrical stimulation) and on the 2nd component of the blink reflex (R2) were investigated in the contralateral body side. Muscular pain threshold increased (peak value during ischemic pain) and maintained significantly higher values for 60 min. R2 response decreased while its latency increased; these variations appeared during ischemic pain and reached a maximum soon after the end of ischemia, still remaining significant for 15 min. The results support the suggestion that the analgesic effects of heterotopic noxious stimulation in humans are subserved by supraspinal inhibitory mechanisms.

Adult↗
PubMed1996

The R3 component of the blink reflex: normative data and application in spinal lesions.

The clinical value of the R3 component (R3) of the blink reflex (BR) for differentiating between lesions at the medulla oblongata and cervical spinal cord level is still unclear. In 50 healthy volunteers (25 women, 25 men, aged 20-75 years) reproducible ipsi- and contralateral R3 responses could be evoked showing a mean onset latency of 84 ms, a duration of 32 ms and a side-to-side difference of almost 3 ms. The latency increased with age. Eleven patients with lesions of the cervical spinal cord (segments C1-C6) showed normal R3 latencies. In 4 patients with pathology of the brain-stem, however, R3 was abnormal, showing identical changes as observed with the R2 component. Our results suggest that the reflex arc of R3 does not descend to the cervical spinal cord but within the brain-stem possibly takes the same connections as the R2 component.

Adult↗
PubMed2006

An investigation into the temporal dimension of the Mozart effect: evidence from the attentional blink task.

In the present study, we examined whether the 'Mozart effect' would influence participants' temporal attention using a visual attentional blink (AB) task that provides a reliable measure of the temporal dynamics of visual attention. The 'Mozart effect' refers to the specific claim that listening to Mozart's Sonata for Two Pianos in D Major, K.448 can improve the performance in spatio-temporal tasks. Participants had to try and identify two target digits (in their correct order of presentation) presented amongst a stream of distractor letters in three different conditions (presented in separate blocks of trials): while listening to the Mozart sonata played normally, while listening to the same Mozart sonata played in reverse, and while in silence. The results showed that the participants were able to detect the second target (T2) significantly more accurately (given the correct detection of the first target, T1) in the AB stream when the Mozart sonata was played normally than in either of the other two conditions. Possible explanations for the differential effects of Mozart's music being played normally and in reverse and potential confounds in previous studies reporting a facilitatory 'Mozart effect' are discussed. Our results therefore provide the first empirical demonstration supporting the existence of a purely temporal component to the 'Mozart effect' using a non-spatial visual AB task.

Acoustic Stimulation↗
PubMed2005

Background noise decreases both prepulse elicitation and inhibition of acoustic startle blink responding.

Prepulse inhibition of startle (PPI) has proved to be useful in distinguishing between schizophrenia patients and normal controls, although not all studies in this area find such group differences. One reason for this inconsistency may be the fact that some research labs present the startle eliciting and inhibiting stimuli over a steady background noise (70 dB), whereas others present stimuli in ambient noise conditions (30-56 dB). The present study tested the impact of background noise (30, 50, and 70 dB) on PPI in normal college adults, with prepulses at intensities of 75, 80, and 85 dB, and with prepulse rise times of 1 or 10 ms. Background noise decreased the amount of PPI caused by the prepulses, and also decreased the ability of the prepulses to themselves elicit blink responses. We conclude that background noise interferes with the processing of the prepulse, attenuating its effect as both an elicitor and inhibitor of the startle reflex. By elevating the difficulty of prepulse processing, this attenuation may be a necessary condition for observing differences in PPI between patient and control groups.

Acoustics↗
PubMed2004

Blink reflex discloses CNS dysfunction in neurologically asymptomatic patients with systemic sclerosis.

OBJECTIVE: To investigate trigeminal-nerve, brain-stem, and brain function, in order to disclose a possible nervous system involvement in neurologically asymptomatic systemic sclerosis (SSc) patients. METHODS: Using a standard electromyographic (EMG) technique, we recorded the early (R1) and late (R2) components of the blink reflex in 35 SSc patients with no history or signs of cranial-nerve impairment and 20 control subjects. SSc patients were classified as limited or diffuse SSc and also evaluated for disease duration, autoantibody pattern (ANA, ACA, Scl70) and skin score (by Rodnan modified method). RESULTS: Whereas no SSc patients had an abnormal R1, six (18%) had delayed R2 responses. We found no correlation between R2 latency and clinical or laboratory data. CONCLUSIONS: Whereas previous studies reported both R1 and R2 abnormalities (reasonably due to trigeminal neuropathy) in symptomatic SSc patients, we found selective abnormalities of the R2 components in asymptomatic patients. The selective R2 abnormality is secondary to a central dysfunction, either because of a direct impairment of the polysynaptic circuits in the medulla, or because of a decreased cortico-reticular drive on these circuits. The lack of overt trigeminal symptoms in our patients favours a suprasegmental dysfunction, possibly due to microvascular lesions disseminated in the subcortical white matter.

Adult↗
PubMed2006

Viewpoint costs occur during consolidation: evidence from the attentional blink.

Do the viewpoint costs incurred when naming rotated familiar objects arise during initial identification or during consolidation? To answer this question we employed an attentional blink (AB) task where two target objects appeared amongst a rapid stream of distractor objects. Our assumption was that while both targets and distractors undergo initial identification only targets are consolidated in a form that allows overt report. We presented line drawings of objects with a usual upright canonical orientation, and separately manipulated the orientation of targets and distractors. In two experiments, targets were defined by colour, whereas in a third experiment they were defined by semantic category. Target 1 orientation influenced the AB, with objects rotated by 90 degrees causing a larger second target deficit than upright and upside-down objects. However, distractor orientation did not affect the magnitude of the second target deficit, regardless of whether targets were defined by colour or semantic category. Taken together, these findings suggest that the visual representations involved in the preliminary recognition of familiar objects are viewpoint-invariant and that viewpoint costs are incurred when these objects are consolidated for report.

Attention↗
PubMed2026

HoT auto-blinking probes enable real-time, super-resolution chromatin imaging in live cells and tissues.

Single-molecule localization microscopy (SMLM) enables visualization of chromatin architecture at nanoscale resolution. However, high-performance DNA probes suitable for SMLM in both live cells and tissues remain limited. We developed Hoechst-6-Carboxytetramethylrhodamine (6-TAMRA) derivative (HoT) probes-rhodamine-based derivatives conjugated to a Hoechst moiety-through structural fine-tuning of rhodamine spirocyclization. HoTs are self-assembling, auto-blinking probes with excellent photostability and high temporal resolution. They permeate live cells, enabling long-term, real-time nanoscopic chromatin imaging in live and fixed cells and in tissue sections. In live cells, we identified nanoscale features in the 3D organization of chromatin and quantified DNA fiber kinetics at high resolution. We quantified DNA compaction in single cells within retinal and colon cancer sections. OligoSTORM (stochastic optical reconstruction microscopy)-labeled gene loci can be visualized and measured within their HoT-labeled chromatin footprints. Our work provides powerful tools for investigating chromatin structure and functions in living cells and tissues, with applications ranging from cancer diagnosis to retinal regeneration.

Chromatin↗
PubMed2000

Influence of stimulus control on the excitability of the electrically elicited blink reflex in patients with schizophrenia.

BACKGROUND: In humans, the excitability of the electrically evoked blink reflex is influenced by the subject's attention to the stimulus. The early reflex component R1 has been found to be facilitated in conditions of increased selective attention, whereas the late components R2 and R3 exhibited a marked suppression. Distraction from the stimulus leads to enhanced R2 and R3 magnitudes. METHODS: We investigated the excitability of the distinct reflex components in 19 patients with schizophrenia and 19 healthy control subjects. In the control condition (EE), stimulation was elicited by the experimenter; in a second condition (SE), subjects released a key to evoke the reflex themselves. RESULTS: The SE patients with schizophrenia exhibited an abnormally increased R1 facilitation and an impaired R2 inhibition in comparison with normal control subjects. An R3 component could be registered in EE in 13 of 19 patients but only in one control subject; SE resulted in a complete suppression of this component in all but two patients with schizophrenia. CONCLUSIONS: The abnormal R1 facilitation and the impaired R2 inhibition may be regarded as neurophysiological markers of defective information processing in a condition of increased selective attention to a self-controlled stimulus in patients with schizophrenia. The enhanced excitability of the R3 component under standard conditions indicates defective attentional mechanisms in patients with schizophrenia in an uninstructed passive condition attending a stimulus triggered by the experimenter.

Adult↗
PubMed2004

Evidence against a central bottleneck during the attentional blink: multiple channels for configural and featural processing.

When a visual target is identified, there is a period of several hundred milliseconds when the processing of subsequent targets is impaired, a phenomenon labeled the attentional blink (AB). The emerging consensus is that the identification of a visual target temporarily occupies a limited attentional resource that is essential for all visual perception. The present results challenge this view. With the same digit discrimination task that impaired subsequent letter discrimination for several hundred milliseconds, we found no disruption of subsequent face discrimination. These results suggest that all stimuli do not compete for access to a single resource for visual perception. We propose a multi-channel account of interference in the AB paradigm.

Attention↗
PubMed2003

Four-dot masking produces the attentional blink.

When two target stimuli (T1 and T2) are presented sequentially within half a second of each other, identification accuracy is often poor for T2. This phenomenon, known as attentional blink (AB), can be observed generally only if the stimulus terminating the presentation of T2 acts as an interruption mask. Recent evidence suggests that even four small dots surrounding a target item can exert masking effects, provided the target onset occurs at an unattended spatial location. In order to test whether an AB could be observed under conditions of four-dot masking of T2, five rapid serial visual presentation streams of letters were synchronously displayed on each trial of the present experiment. T1 and T2 were digits presented at unpredictable locations and unpredictable temporal intervals. T2 was followed by either a blank field, a letter, or four-dots. No AB was observed when T2 was not masked, but robust and equally sized ABs were observed when T2 was followed by both the letter mask and the four-dots.

Adult↗
PubMed1997

Very short-term visual memory via reverberation: a role for the cortico-thalamic excitatory circuit in temporal filling-in during blinks and saccades?

There is a large projection of neurons from Layer VI of V1 that makes excitatory connections on LGN relay cells. It has been proposed that this circuit is involved in signal processing and thalamic sensitivity regulation. Alternatively, Crick has suggested that the circuit could be a reverberatory loop-a site for very short-term (iconic) visual memory. This hypothesis is shown to be plausible if the reverberation is keyed to the onset of neurally initiated visual disruptions such as blinks and saccades. Neural mechanisms suppress perception during these events but little is known about temporal filling-in processes analogous to the mechanisms that fill-in spatial scotomas. Crick's reverberatory loop could provide a process for filling-in temporal scotomas with information acquired just before the disruption, thus maintaining the continuity of visual experience.

Blinking↗
PubMed1991

Effect of blinking on tear elimination as evaluated by dacryoscintigraphy.

To document the change in drainage of tears that occurs with blinking, the authors evaluated 17 lacrimal systems of 12 individuals with dacryoscintigraphy. A significant difference in tear drainage was found by keeping the eyelids closed during the first 2 minutes after drop placement (P less than 0.03), but not from 2 to 5 minutes (P greater than 0.4). Retardation of tear drainage after droplet placement can be achieved by simple eyelid closure for 2 minutes.

Adult↗
PubMed2003

Prepulse inhibition of the human startle eye blink response by visual food cues.

We present a new paradigm to investigate cognitive processing of food cues. The study assessed if pictures of food induce prepulse inhibition (PPI) of startle eye blink, and if any such effect is sensitive to food deprivation. In a balanced cross-over design, 16 healthy male volunteers (mean age: 29 years) were tested on 2 days 1 week apart, either after a period of normal food intake (NFI) or after a 24 h period of food restriction (RFI). On each experimental day, 80 control and 20 food pictures (slides) were displayed. Noise stimuli were presented 250 ms after slide onset. Startle responses were assessed by EMG recordings of the right M. orbicularis oculi. Startle elicited during dark inter-slide periods served as control responses to calculate PPI effects. The arousing content of each picture was rated by all subjects at the end of the session. The perceived arousal effect of control slides was strongly related to their PPI effect; no impact of food access status on this association was detectable. After NFI, food slides significantly induced PPI of startle (mean: -14.5%). After RFI, arousal ratings for food pictures increased but PPI did not. These results are evidence for a pre-attentive mechanism operative in the processing of visual food cues.

Adult↗
PubMed2003

The validity of eye blink rate in Chinese adults for the diagnosis of Parkinson's disease.

We evaluated the eye blink rate (EBR) in healthy Chinese adults and Parkinson's disease (PD) patients. In healthy subjects, the EBR declined with age, was lower in women than men younger than 50 years of age, and did not differ from male PD patients older than 60 years or female PD patients older than 50 years. Accordingly, EBR is not a good indicator for bradykinesia in Chinese individual older than 50 years that is prevalent for PD onset also.

Adult↗