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Cross-modality attentional blinks without preparatory task-set switching.

When two masked targets (T1 and T2), both requiring attention, are presented within half a second of each other, report of the second target is poor, demonstrating an attentional blink (AB). Potter, Chun, Banks, and Muckenhoupt (1998) argued that all previous demonstrations of an AB occurring when one or more targets were presented outside the visual modality did not represent true AB but were, instead, artifactual, resulting from switching of task set. In the present experiments, T1 and T2 modalities were independent and varied randomly from trial to trial, allowing no useful preparatory task-set switching from T1 to T2. However, reliable ABs were observed when both targets were visual, when both targets were auditory, and cross-modally when T2s were visual. Furthermore, the ABs observed for cross-modality visual T2s showed the characteristic U-shaped pattern often found in AB experiments in which two visual targets are used--a pattern that should not be observed under task-set switching conditions. These results provide evidence that cross-modality AB can be found under conditions that do not allow useful preparatory task-set switching.

Acoustic Stimulation↗

Modulation of the attentional blink by on-line response selection: evidence from speeded and unspeeded task1 decisions.

Two critical target stimuli (T1 and T2) were embedded in a stream of white letters shown on a black background, using a rapid serial visual presentation paradigm (RSVP, 100 msec/item). T1 was a red H or S; T2 was an X or a Y. Performance in a two-alternative discrimination on T2 was impaired when processing of T1 was required--a result often called an attentional blink (AB). In previous work, the response in Task1 has been an unspeeded and delayed response at the end of the trial. Three experiments compared performances in Task2 that depended on whether Task1 required an unspeeded delayed response or a speeded immediate response. A larger AB was found when a speeded response was required. Furthermore, in the speeded conditions, faster responses in Task1 were associated with a smaller and shorter AB effect than were slower responses. The results show that manipulations affecting a relatively late stage of processing--response selection--affect the magnitude and duration of the AB phenomenon. A new central inhibition theory is proposed to account for these results. According to this theory, the AB is similar to the psychological refractory period effect and is caused by central postponement of short-term consolidation of T2.

Adult↗

The roles of location specificity and masking mechanisms in the attentional blink.

In a series of four experiments using rapid serial visual presentations of two target letters embedded in numeral distractors, with different numbers of display positions and with or without masking, we show that (1) the nonmonotonic, U-shaped attentional blink (AB) function, which occurs when all items are presented at the same display location, is eliminated in favor of a monotonic function when targets and distractors are presented randomly dispersed over four or nine adjacent positions; (2) the AB monotonicity is maintained with the spatially distributed presentation even when backward masks are used in all possible stimulus positions and when the location of the next item in sequence is predictable; and (3) the U-shaped AB is not due to position-specific forward or backward masking effects occurring at early levels of visual processing. We tentatively conclude that the U-shaped AB is primarily a function of the interruption of late visual processing produced when the item following the first target occurs at the same location. In order for the AB to severely disrupt performance, the item following the first target must be presented at the same location as the target so that it can serve both as a distractor and as a mask interrupting of interfering with subsequent visual processing.

Adult↗

Attentional blink and attentional capture: endogenous versus exogenous control over paying attention to two important events in close succession.

Identification of the second of two targets is impaired if it is presented less than about 500 msec after the first This attentional blink (AB) occurs under dual-task conditions in which observers are required to report both targets. AB magnitude has been estimated by subtracting the accuracy scores in the dual task from the corresponding scores in a single task in which observers are instructed to ignore the first target. Experiment 1 showed this procedure to be inappropriate, because the first target cannot be ignored. The remaining three experiments elaborated on this finding andrevealed separate endogenous and exogenous sources of the second-target deficit. A parallel was drawn between the AB deficit and the deficit observed in attentional capture. Both types of deficit can be explained on the basis of a hybrid input-filtering model in which endogenous and exogenous factors are subserved by different pathways.

Attention↗

Blinking-blepharospasm after long-term neuroleptic treatment.

A patient is described who developed frequent blinking and blepharospasm after long-term treatment with trifluoperazine, whose condition improved dramatically after the cessation of the drug. The implications of this for our understanding of the manifestations and natural course of the late-onset side-effects of neuroleptic drugs are discussed. This case further supports the role of dopaminergic mechanisms in the aetiology of Meige's syndrome, which has blepharospasm and oromandibular dystonia as its main manifestations.

Akathisia, Drug-Induced↗

[Assessment of blink reflex in hemiparetic patients after stroke].

Blink reflex (BR) was evaluated in a group of 50 hemiparetic patients after stroke with lesions localized in cerebral hemispheres and in a group of 12 healthy controls. The response was examined and compared, after stimulation of the supraorbital nerve, on both paretic and "healthy" side in affected patients. Abnormalities of BR were observed in late response only. The damage of one hemisphere affects the BR bilaterally. We found prolongation of latency and decrease of amplitude of late responses bilaterally when stimulating the supraorbital nerve of the paretic side. On the contrary, stimulation of the "healthy" side evoked similar abnormalities mainly contralaterally.

Adult↗

Corneal reflex and blink reflex changes in thalamic hemorrhage.

We studied the corneal reflex (CR) with air-puff and direct touch by using a standardized method in patients with thalamic hemorrhage (TH) (n: 15) and in normal control subjects (n: 21). The conventional blink reflex (BR) was also studied. In the TH group: 1--When the cornea on the clinically nonaffected side was stimulated the corneal reflex responses were elicited bilaterally, with normal latency on the clinically normal side and delayed on the affected side. 2--When the cornea on the clinically affected side was stimulated, the corneal responses on both sides were either abnormal or could not be elicited. 3--The ipsilateral R1 and R2 responses recorded by stimulation of the supraorbital nerve on the clinically affected side were abnormal where the contralateral R2 responses were in the normal range. In the normal control and TH groups: 1--No statistical difference could be detected between the responses elicited by air-puff or direct touch to cornea (p > 0.05). 2--CR responses were statistically different from the R2 response of the BR (p < 0.005).

Adult↗

The three responses of the blink reflex in adult and juvenile migraine.

Recent theories about migraine pathogenesis have emphasized the role of the trigeminal system in the pathogenesis of migraine attacks (Moskowitz, 1997). The blink reflex (BR) could be a suitable method to evaluate the trigeminal system in migraine, as it is generally elicited by stimulation of the trigeminal ophthalmic division (Kimura et al., 1967), involved in migraine attacks. Sixty one adult and 15 juvenile migraine without aura subjects were selected, in order to evaluate the BR features, including the subjective perceptive and pain thresholds and the R1, R2 and R3 components intensity thresholds and amplitudes. The electrophysiological procedure was carried out during the pain free phase. The findings were compared with those of 28 healthy controls, 18 adults and 10 children. In both adult and juvenile migraine sufferers an early appearance of the R3 response at almost the R2 threshold was observed in comparison with age-matched controls. Unfortunately, the anatomic and physiologic organization of the R3 component is uncertain: its early onset could suggest a dysfunction of the inhibitory control system on the trigeminal networks, which may predispose to migraine attacks.

Adolescent↗

Nature of codes extracted during the attentional blink.

This set of 6 experiments used a 2-target rapid serial visual presentation paradigm to address 2 main questions: (a) What is the nature of the code retrieved from nontarget (i.e., unselected) items? and (b) How do the processing demands of the target affect the nature of the codes extracted from its proximate distractors? There were 3 main results: First, unless a nontarget receives attentional processing, its codes remain dormant. The type of activated codes depends on the perceptual load imposed by the other items that also underwent processing. Second, the item trailing the target invariably gets processed, but those farther downstream are excluded. If target selection is exacting, the codes of the item leading the target may also be enhanced. Third, the magnitude of the attentional blink increases with target selection difficulty; it is, however, unaffected by the perceptual load imposed by the target.

Attention↗

[Brainstem lesion in multiple sclerosis, blink reflex, and brainstem auditory evoked potentials].

Blink reflex (BR) and brainstem auditory evoked potentials (BAEP) were recorded from 168 patients with several diagnostic categories of multiple sclerosis, from which 98 complained brainstem symptoms (BSS+). From the whole group, the BR showed a higher degree of abnormality (45.75%) than BAEP (27.95). This range increased in the group BSS+ (52.15% for the BR and 34.9% for the BAEP) and even more when sings or symptoms of brainstem were present at the time of exploration (BSS+P) 60.4% for the BR and 41.3% for BAEP. Among patients who never complained brainstem symptoms, the BR disclosed a subclinical lesion in the 33.3% and the BAEP in the 16.9%. The combination of BR and BAEP were more useful than an isolated test. The localization of the lesion both clinically and in the BR were mostly on the pons. Light correlation between the presence of isolated or multiple symptoms and the disorder in the BR were present. Facial myokymia and internuclear ophthalmoplegia were most often associated with disorder in the BR, in both, the commonest localization was on the pons, and in the former about the motor nucleus of the facial nerve.

Adolescent↗

The usefulness of the blink reflex in the early diagnosis of cranial nerve neuropathy associated with diabetes mellitus.

BACKGROUND: Electrophysiological testing can be of value in early diagnosis of diabetic neuropathy. Limited data is available in the use of the blink reflex (BR) in diabetes mellitus (MD). AIM: is to evaluate the efficacy of BR in early diagnosis of cranial nerve neuropathy in DM. MATERIALS AND METHODS: 67 diabetes and 32 healthy controls-age and sex matched- were chosen. The diabetes were of type I and type II and of more than or less than 10 years duration. The BR was elicited by stimulation the supraorbital nerve using the Dantec Neuromatic 2000M machine. The latency of the components response recorded as R1, R2y (ipsilateral) and R2c (contralateral). A direct response was achieved by the stimulation of the facial nerve; a square wave of 200 msec. was used. RESULTS: No differences were noted when the two sides were compared in diabetic patients, while the difference was highly significant in the increased latency of R1, R2y and R2c each type of diabetes as compared to the control. Comparison of the types and duration of diabetes between each other showed no significant difference. Direct measurement of the latency response of the facial nerve gave a response in diabetics of both types and duration. CONCLUSION: the BR can be useful in the early diagnosis of diabetic neuropathy.

Adult↗

Blink reflexes in patients with atypical odontalgia.

AIMS: To use the human blink reflex (BR) to explore possible neuropathic pain mechanisms in patients with atypical odontalgia (AO). METHODS: In 13 AO patients, the BR was elicited using a concentric electrode and recorded bilaterally with surface electromyographic (EMG) electrodes on both orbicularis oculi muscles. Electrical stimuli were applied to the skin above branches of the V1, V2, and V3 nerves and to the V branch contralateral to the painful branch. Sensory and pain thresholds were determined. The BR examination of the painful V branch was repeated during a capsaicin pain-provocation test. The data were analyzed with nonparametric statistics. RESULTS: The BR responses (R2 and R3) evoked by stimulation of V3 were significantly smaller than the BR responses evoked by stimulation of V1 and V2 (P < .004). There were no differences in BR (R2 or R3) between the painful and nonpainful sides (P > .569), and the BR (R2 and R3) was not significantly modulated by experimental pain (P > .080). The sensory thresholds were significantly lower on the painful side compared to the nonpainful side (P = .014). The pain thresholds were not different between sides (P > .910). CONCLUSION: No major differences between the V nociceptive pathways on the right and left sides were found in a relatively small group of AO patients. Future studies that compare BRs in AO patients and healthy volunteers are needed to provide further knowledge on the pain mechanisms in AO.

Adult↗

Role of Blink Reflex in diagnosis of subclinical cranial neuropathy in Diabetic Mellitus type II.

BACKGROUND AND OBJECTIVES: Peripheral Neuropathy (PN) is one of the late complications of Diabetes Mellitus. Cranial nerves III, VII and V are among the most commonly affected in diabetic patients. Traditional Electrodiagnosis (Edx) studies are useful method for diagnosis of PN and symptomatic cranial neuropathy, and may not be useful for detecting subclinical involvement of cranial nerves. The main objective of this study is to evaluate the role of Blink Reflex (BR) for early diagnosis of cranial neuropathy in diabetic patients with PN. DESIGN: A prospective study was performed on NIDDM patients with a PN. 188 subjects were included in our study in which 142 acted as healthy subjects and 46 as diabetic patients. Patients were excluded with prior history of cranial nerve lesions, stroke, and other disease with polyneuropathy or drug-induced neuropathy. Routine nerve conduction studies were performed and only patients with PN were included in this study. RESULTS: Abnormalities were found in 54.4% of patients. R1, IR2 and CR2 were prolonged relative to healthy group. Statistically there was no significant difference in R/D ratio of patients (P = 0.201). Also there was a positive correlation between R1, IR2 and CR2 latencies with duration of diabetes and severity of polyneuropathy, but not for R/D. The greatest correlation was shown in R1 latency (69.9% abnormality). CONCLUSION: BR is a non-invasive and very useful method for evaluation and diagnosis of subclinical cranial nerve involvement in diabetic patients.

Action Potentials↗

[Relationship between electroencephalographic abnormality and late blink reflex responses in infantile spasms and EIEE].

Electrically elicited blink reflex (BR) were analyzed in seven patients with age dependent epileptic encephalopathies (5 patients with infantile spasms and 2 with EIEE). Four patients with infantile spasms showed prolonged latency of the late BR responses (R2). In 2 patients with EIEE showing suppression burst pattern on EEG, R2 was not detectable. R2 abnormality in BR might reflect the dysfunction of the brainstem reticular formation in age dependent epileptic encephalopathies.

Age Factors↗

Effect of occlusal splint therapy on blink reflex time in TMJ dysfunction patients.

This study compares the changes that occur in latency before and after use of splint therapy in patients with TMJ dysfunction. The sensory fibers of the upper branch of the trigeminal nerve were stimulated and the time required for the sensory and motor responses to occur were measured. A reduction in latency occurred in the late component. Also a reduction of the delay occurred between ipsi and contralateral late responses. This finding can be attributed to the lateral reticular formation in the blink reflex arc. This study demonstrates a method for evaluating TMJ dysfunction and a way to monitor clinical response.

Blinking↗

[Study of the blink reflex in spinocerebellar degeneration].

Blink reflex (BR) was composed of R1 and R2. R1 is considered to indicate the brainstem function. The purpose of this study was to evaluate the brainstem function of spinocerebellar degeneration (SCD) by the R1 latency (R1). BR was evoked by the percutaneous stimulation of supraorbital nerve. And R1 was measured by the action potential of orbucularis oculi muscle. Direct response was recorded by the percutaneous stimulation of facial nerve to determine the terminal latency of facial nerve (D). By these methods R1, D, R1/D and difference between at right and left side of these data (delta R1, delta D, delta R1/D) were measured in 21 normal subjects (57.7 +/- 10.1 ys.) and 28 cases of SCD (56.6 +/- 8.2 ys.), including 12 cases of sporadic type olivopontocerebellar atrophy (SOPCA), 4 of Menzel type olivopontocerebellar atrophy (MOPCA), 6 of late cortical cerebellar atrophy (LCCA) and 6 of Holmes type cortical cerebellar atrophy (HCCA). There was no difference between all types of SCD and normal subject at D, but significant difference of R1 and R1/d was observed between at MOPCA and normal subject. Concerning the difference between right and left side delta R1 and delta R1/D showed the significant difference with MOCA and SOPCA, but delta D showed no difference. Elongation of R1 and R1/D without the delay of facial nerve and the significant difference of R1 and R1/d between at right and left side suggested the synaptic transmission disorder form trigeminal nerve to facial nerve at brainstem of MOCA.

Adult↗

[Developmental changes in electrically elicited blink reflex in infancy and childhood].

Developmental changes in electrically elicited blink reflex (BR) in 118 normal subjects, aged from 32 weeks of conceptional age to 14 years of age. During the waking state, R1 and bilateral R2 responses were always elicited. The latency of R1 shortened rapidly during the neonatal period, reaching the adult value at 3 months of age. The latency of R2 and contralateral R2 (CR2), which were elicited synchronously after 3 years of age, shortened slowly during childhood and reached the adult value at 6 years of age. The conduction indexes of R1, R2 and CR2, which were calculated as head circumference/latency (m/sec), increased rapidly during the neonatal period and reached the adult values at 6 years of age. The influence of NREM sleep on BR in neonates was different from those in infants and children. While BR of neonates in NREM sleep showed similar to that seen in wakefulness, BR of infants and children after one month of age was suppressed during NREM sleep. BR pattern in NREM sleep in infants and children after 6 months of age was similar to that seen in adults.

Adult↗

Comparative study of pain perception and polysynaptic blink reflex responses in man.

Stimulation of the first trigeminal branch using a 10 ms train of 5 pulses of 0.1 ms duration is performed on 17 healthy subjects (19-65 years of age) in order to assess the relationship between polysynaptic components of the blink reflex and perceptive and pain thresholds (ths). The mean value of tactile ths (Pth) is 2.22 +/- 0.86 mA; while R2, R3 and pain threshold values are 1.25 +/- 0.34, 3.52 +/- 1.94 and 4.78 +/- 2.77 times the Pth respectively. The pain ths average is 1.47 +/- 0.92 with regard to the R3 threshold. The R2 ths are very close to those of tactile perception, while those of R3 appear significantly related to the pain ths.

Adolescent↗