Visual Stimuli in Daily Life

Identifying individual's distractor suppression using functional connectivity between anatomical large-scale brain regions

Distractor suppression (DS) is crucial in goal-oriented behaviors, referring to the ability to suppress irrelevant information. Current evidence points to the prefrontal cortex as an origin region of DS, while subcortical, occipital, and temporal regions are also implicated. The present study aimed to examine the contribution of communications between these brain regions to visual DS. To do it, we recruited two independent cohorts of participants for the study. One cohort participated in a visual search experiment where a salient distractor triggering distractor suppression to measure their DS and the other cohort filled out a Cognitive Failure Questionnaire to assess distractibility in daily life. Both cohorts collected resting-state functional magnetic resonance imaging (rs-fMRI) data to investigate function connectivity (FC) underlying DS. First, we generated predictive models of the DS measured in visual search task using resting-state functional connectivity between large anatomical regions. It turned out that the models could successfully predict individual's DS, indicated by a significant correlation between the actual and predicted DS (r = 0.32, p < 0.01). Importantly, Prefrontal-Temporal, Insula-Limbic and Parietal-Occipital connections contributed to the prediction model. Furthermore, the model could also predict individual's daily distractibility in the other independent cohort (r = -0.34, p < 0.05). Our findings showed the efficiency of the predictive models of distractor suppression encompassing connections between large anatomical regions and highlighted the importance of the communications between attention-related and visual information processing regions in distractor suppression. Current findings may potentially provide neurobiological markers of visual distractor suppression.

Efficacy of color lenses in abolishing photosensitivity: Beyond the one-type-fits-all approach?

OBJECTIVE

Red-light filtering lenses represent an additional option to medication in photosensitive epilepsy. Blue lenses (Clarlet Z1 F133) can dramatically reduce seizure frequency, with a substantial restriction in luminance that can limit their applicability in daily life. We investigated the efficacy of 4 blue lenses with higher transmittance and reduced chromatic distortion in abolishing the photoparoxysmal EEG response (PPR) compared to the gold-standard Z1 lenses.

METHODS

We reviewed EEG data during photic-and pattern stimulation in 19 consecutive patients (6-39 years) with photosensitivity (PS). Stimulation was performed at baseline and while wearing Z1 and the four new lenses. Lenses were tested in the same session by asking the patient to wear them in a sequentially randomized fashion while stimulating again with the most provocative photic/pattern stimuli. The primary outcome was the change in the initial PPR observed for each lens, categorized as no change, reduction, and abolition.

RESULTS

Photosensitivity was detected in 17 subjects (89.5%); pattern sensitivity (PtS) was identified in 14 patients (73.7%). The highest percentages of PPR abolition/reduction were observed with Z1, for both PS and PtS. Regarding the new lenses, B1 + G1 offered the best rates, followed by B1 + G2. B1 + G3 and B1 showed lower efficacy rates, particularly for PtS. In the comparative analysis, no significant differences in PPR suppression were detected between the five lenses for PS. For PtS, the capacity of Z1 for PPR abolition was significantly higher compared with B1 + G3 and B1.

CONCLUSIONS

This preliminary study suggests efficacy of the new group of blue lenses with potentially greater tolerability, particularly in regions with fewer sunlight hours during winter. In line with the current trend for personalized approach to treatment, this study suggests that in some patients there might be scope in extending the testing to offer the lens with the higher transmittance effective in abolishing the PPR.

Visual-Sensitive Epilepsies: Classification and Review

Photosensitivity, photosensitive seizures, and photosensitive epilepsy are discussed. The International League against Epilepsy has suggested the term “visual-sensitive” replace “photosensitive”. Visual-sensitive seizures may be more common than is realized. A classification for visual-sensitive epilepsies is presented. Chromosomal and DNA testing may help to refine the classification further. A standardized approach for neurophysiologic testing, such as that proposed by European experts, is recommended. These steps should promote evidenced-based management for this group of disorders.

Management of juvenile myoclonic epilepsy

Juvenile myoclonic epilepsy (JME) is a common form of epilepsy and a fairly lifelong disorder that may significantly lower a patient's expectations and potential for a full life. Luckily, it is also a highly treatable disorder, and up to 85% of patients with JME will enjoy satisfactory seizure control. Among anticonvulsants, valproate still stands out as the most efficacious drug, but may be poorly tolerated by some, and is considered unsafe for the fetuses of pregnant women. Alternatives have emerged in recent years, especially levetiracetam, but also topiramate, zonisamide or lamotrigine. In some cases, combination therapy may be useful or even required. One should not forget the potential aggravation induced not only by some commonly used anticonvulsants, especially carbamazepine and oxcarbazepine, but also, in some patients, by lamotrigine. In special settings, older drugs like benzodiazepines and barbiturates may be useful. But the management of JME should also include intervention in lifestyle, with strict avoidance of sleep deprivation and the management of copathologies, including the cognitive and psychiatric problems that are often encountered. With adequate management, there will only remain a small proportion of patients with uncontrolled epilepsy and all of its related problems. Juvenile myoclonic epilepsy is a condition in which the clinician has a fair chance of significantly helping the patient with medication and counseling.

Does photoparoxysmal response in children represent provoked seizure? Evidence from simultaneous motor task during EEG

OBJECTIVES

Acute cognitive changes during epileptiform discharges have been studied using computer assisted cognitive tasks. We aimed to demonstrate acute behavioral change (using a simple motor response task MRT) during photoparoxysmal response (PPR) in children below 18 years.

METHODS

Children performed a simple repetitive motor task during intermittent photic stimulation (IPS). All episodes of PPR not associated with obvious clinical change (as observed by the technologist or reported by the patient) were analyzed for this study. The average time interval between two successive motor responses across a PPR (test time) was compared to the average time interval between two successive motor responses during IPS not associated with PPR (control time) using Wilcoxon signed ranks test.

RESULTS

21 children who had PPR successfully completed the MRT. The difference between the mean durations was 0.894 s (p=0.002). More than 50% increase compared to the control time was considered a delay in MRT during PPR. 10 children showed slowing of MRT during PPR.

CONCLUSION

By definition, acute behavioral change during generalized epileptiform discharges represent provoked seizures. Detecting subclinical seizures can have important safety implications in children (skiing, skating and driving) with PPR on EEG, but no clinical seizures. We recommend MRT during IPS.

Treatment of photosensitivity

Not all visually sensitive patients need antiepileptic drug treatment, and even those who do can benefit from additional preventive measures. Visually provoked seizures, in particular, can be prevented or treated by avoiding or altering the triggering stimulus. Apart from individual preventive measures (use of specific television or video screens, colored glasses, etc.), prevention and warning on a larger scale are helpful. The choice for drug treatment will depend on the type of stimulus, the environment in which the person has to live and work, the frequency and severity of seizures, and the type of epileptic syndrome. A review is given of all treatment options with focus on the specific nonpharmacologic and pharmacologic tools used in clinical practice.

Suppressive Efficacy by a Commercially Available Blue Lens on PPR in 610 Photosensitive Epilepsy Patients

PURPOSE

Photosensitivity can represent a serious problem in epilepsy patients, also because pharmacologic treatment is often ineffective. Nonpharmacologic treatment using blue sunglasses is effective and safe in controlling photosensitivity, but large series of patients have never been studied.

METHODS

This multicenter study was conducted in 12 epilepsy centers in northern, central, southern, and insular Italy. A commercially available lens, named Z1, obtained in a previous trial, was used to test consecutively enrolled pediatric and adult epilepsy patients with photosensitivity. Only type 4 photosensitivity (photoparoxysmal response, PPR) was considered in the study. A standardized method was used for photostimulation.

RESULTS

Six hundred ten epilepsy patients were tested. Four hundred (66%) were female patients; 396 (65%) were younger than 14 years. Three hundred eighty-one (62%) subjects were pharmacologically treated at the time of investigation. Z1 lenses made PPR disappear in 463 (75.9%) patients, and PPR was considerably reduced in an additional 109 (17.9%) of them. PPR remained unchanged only in the remaining 38 (6.2%) patients. The response of PPR to Z1 lenses was not significantly influenced by the patients' age, sex, or type of epilepsy. No difference was found between pharmacologically treated and untreated patients.

CONCLUSIONS

The Z1 lens is highly effective in controlling PPR in a very large number of photosensitive epilepsy patients irrespective of their epilepsy or antiepileptic drug treatment. The lens might become a valid resource in the daily activity of any clinician who cares for patients with epilepsy.

Human photosensitivity: from pathophysiology to treatment

Photosensitivity is a condition detected on the electroencephalography (EEG) as a paroxysmal reaction to Intermittent Photic Stimulation (IPS). This EEG response, elicited by IPS or by other visual stimuli of daily life, is called Photo Paroxysmal Response (PPR). PPRs are well documented in epileptic and non-epileptic subjects. Photosensitivity rarely in normal individuals evolves into epilepsy. Photosensitive epilepsy is a rare refex epilepsy characterized by seizures in photosensitive individuals. The development of modern technology has increased the exposition to potential seizure precipitants in people of all ages, but especially in children and adolescents. Actually, videogames, computers and televisions are the most common triggers in daily life of susceptible persons. The mechanisms of generation of PPR are poorly understood, but genetic factors play an important rule. The control of visually induced seizures has, generally a good prognosis. In patients known to be visually sensitive, avoidance of obvious source and stimulus modifications are very important and useful to seizure prevention, but in the large majority of patients with epilepsy and photosensitivity antiepileptic drugs are needed.

Photosensitivity and visually induced seizures

PURPOSE OF REVIEW

Interest in visually induced seizures has increased in recent years as a result of the increasing number of precipitants in our modern environment. This review addresses new developments in this field with special attention given to the emergence of new diagnostic, therapeutic and preventive approaches; it also emphasizes the importance of this condition as a public health issue.

RECENT FINDINGS

Current evidence indicates the presence of two different mechanisms of photosensitivity, one dependent on luminance changes and the other on wavelength. Both mechanisms may be active in the same patient, although one may be dominant. Magnetoencephalography studies revealed an enhancement in gamma frequency preceding the development of a paroxysmal response as well as underlying uncomfortable visual illusions, suggesting that a loss of control over high-frequency oscillatory processes may be involved in the genesis of both types of phenomenon. The genetics underlying this trait remain to be determined. More precise definition of different phenotypes should help in this search. Recognition of the risks posed by the audiovisual environment for induction of seizures in photosensitive individuals, who may not even be aware of their condition, will prompt further development of guidelines and devices designed to prevent the occurrence of seizures triggered by dangerous video sequences.

SUMMARY

Photosensitive epilepsy constitutes a unique benchmark model in which to address important issues in human epileptogenesis. The scope of the health risks posed by the modern audiovisual environment is increasingly being recognized, and further development of guidelines and regulations to control exposure to provocative materials are warranted.

Intermittent photic stimulation as an activation method for electroencephalographic screening of aircrew applicants

Disqualifying criteria for aircrew in Europe (JAR-FCL 3) are, besides a diagnosis of epilepsy after the age of 5 and a history of episode(s) of disturbance of consciousness, epileptiform paroxysmal electroencephalographic abnormalities and focal slow waves. Intermittent photic stimulation (IPS) provokes in about 0.5% of healthy subjects (range 0-2%) a photoparoxysmal response and is most often the only abnormality (70-90%). The literature is scarce and shows great diversity in methodology. Standardized IPS with simultaneous video will not only allow collection of sufficient data for proper epidemiological studies, but can also reveal clinical and often unnoticed or misinterpreted signs and symptoms like myoclonia, loss of consciousness, and occipital seizures with visual auras. The pilot (sleep deprivation, strong sunlight) and the traffic controller (stress, monitors) are more prone to visually induced seizures. Furthermore, the increasing exposure to potentially seizure-triggering visual stimuli might have its impact in a more indirect or cumulative way.