Epilepsy caused by an abnormal alternative splicing with dosage effect of the SV2A gene in a chicken model.

Photosensitive reflex epilepsy is caused by the combination of an individual's enhanced sensitivity with relevant light stimuli, such as stroboscopic lights or video games. This is the most common reflex epilepsy in humans; it is characterized by the photoparoxysmal response, which is an abnormal electroencephalographic reaction, and seizures triggered by intermittent light stimulation. Here, by using genetic mapping, sequencing and functional analyses, we report that a mutation in the acceptor site of the second intron of SV2A (the gene encoding synaptic vesicle glycoprotein 2A) is causing photosensitive reflex epilepsy in a unique vertebrate model, the Fepi chicken strain, a spontaneous model where the neurological disorder is inherited as an autosomal recessive mutation.

Transfer of an avian genetic reflex epilepsy by embryonic brain graft: a tissue autonomous process?

Electroencephalographic characteristics and clinical symptoms of an avian genetic reflex epilepsy have been transferred from Fayoumi epileptic (Fepi) chickens to non-epileptic chickens by embryonic homotopic grafts of brain neuroepithelium. Transplanted tissues belonging to the prosencephalic vesicle transferred epileptic electrical features while tissues from the mesencephalic vesicle were responsible for seizure motor manifestations of the disease. Thus each of these tissues can express their own specificity when grafted separately in a normal host, but they co-operate to produce the complete epileptic phenotype when grafted together.

An avian model of genetic reflex epilepsy.

The Fayoumi strain of chickens (Fepi) carries a recessive autosomal gene mutation in which homozygotes are afflicted with a photogenic and audiogenic reflex epilepsy. Seizures consist of stimulus-locked motor symptoms followed by generalized self sustained convulsions. EEG recordings show spikes and spike and waves patterns at rest which are suppressed during seizures and replaced by a desynchronized pattern of activity.

Medical technology assessment photic stimulation--standardization of screening methods.

Rationale: In many EEG laboratories in Europe, intermittent photic stimulation (IPS) is not performed routinely, and consequently, great variation exists in the type of photo stimulator used, the methodology employed, and the interpretation of the EEG curves, thus leading to different outcomes.

Methodology: It was decided to hold a consensus meeting with experts in the field of photic stimulation from various European countries. This meeting was held at the Stichting Epilepsie Instellingen Nederland, Heemstede, the Netherlands.

Epilepsies and video games: results of a multicentric study.

Objectives: The purpose of this study was to research whether or not video games may induce paroxysmal discharges (PD) in different groups of patients.

Methods: One hundred and fifteen subjects from 5 different French laboratories were studied: 33 had seizures exclusively under visual stimuli, 42 had both photogenic seizures and spontaneous seizures occuring independently, and 40 had non-photogenic seizures. The same protocol which included one TV sequence, 3 sequences of video games selected on particular criteria (pattern, luminosity and nature of the scene), were presented at different distances from the TV screen at 50 and 100 Hz.

EEG and sleep disturbances during dives at 450 msw in helium-nitrogen-oxygen mixture.

To study the effects of nitrogen addition to the breathing mixture on sleep disturbances at pressure, two dives were performed in which helium-nitrogen-oxygen mixture was used up to 450 m sea water (msw). In total, sleep of 12 professional divers was analyzed (i.e.

Brain chimeras in birds: application to the study of a genetic form of reflex epilepsy.

A strain of chicken, called here FEpi (for Fayoumi epileptic), bearing an autosomal recessive mutation, exhibits a form of reflex epilepsy with EEG interictal paroxysmal manifestations and generalized seizures in response to either light or sound stimulations. By using the brain chimera technology, we demonstrate here that the epileptic phenotype can be partially or totally transferred from an FEpi to a normal chick by grafting specific regions of the embryonic brain. The mesencephalon contains the generator of all epileptic manifestations whether they involve visual or auditory neuronal circuits, with the exception of the abnormal EEG which is transmitted exclusively by telencephalic grafts.

Electrographic studies of the effects of RP 60180, a novel kappa agonist, on the photosensitive baboon Papio papio.

1. The authors describe here the effects of intravenous administration of RP 60180, a novel kappa agonist, on conscious baboons of the species Papio papio, which spontaneously present photically induced epileptic responses. 2.

Brain chimeras for the study of an avian model of genetic epilepsy: structures involved in sound and light-induced seizures.

The epileptic homozygotes of the Fayoumi strain of chickens (Fepi) are affected by photogenic reflex epilepsy with complete penetrance. Here we demonstrate that they are equally affected by audiogenic reflex epilepsy induced by intense sound stimulation. All the Fepi display sound-induced seizures from hatching to adulthood consisting of initial 'ictal arousal' and running fits usually followed by generalized clonico-tonic convulsions.

Reflex epilepsy of the fowl and its transfer to normal chickens by brain embryonic grafts.

The genetic photosensitive epilepsy of the Fayoumi chicken was transferred to normal chickens by in situ grafts at 2 days of incubation, of both the prosencephalic and mesencephalic brain vesicles taken from epileptic embryos. However, mesencephalic graft is sufficient to allow convulsions under sound stimulation. Typical EEG patterns are recorded in chimeras having the prosencephalon plus or not the mesencephalon.

Reflex epilepsy in the Papio-papio baboon, particularly photosensitive epilepsy.

Papio-papio baboons may present two types of reflex paroxysmal manifestations: --Myoclonia and generalized seizures are induced by intermittent light stimulation in predisposed animals; this photosensitive epilepsy resembles that observed in some human patients; it involves mainly the cerebral cortex during myoclonia which are accompanied by EEG paroxysmal discharges, and the mesencephalic reticular formation during seizures; --Myoclonia of a different type, never accompanied by EEG paroxysmal discharged and never evolving into seizures, may occur during movement or agitation of predisposed animals; these myoclonia are considered "non-epileptic" since they do not involve the cerebral cortex but probably the lower brain stem; they resemble that observed in startle disease or in some human degenerative disorders. The paper demonstrates that these manifestations constitute two different entities with clinical and electrophysiological characteristics as well as pharmacological reactivities completely different one from the other. Their "epileptic" or "non-epileptic" nature is discussed.

Development of epileptic activity in embryos and newly hatched chicks of the Fayoumi mutant chicken.

The homozygous Fayoumi strain of epileptic chickens (Fepi) is affected by generalized convulsions consistently induced by intermittent light stimulation (ILS) and by intense sound. Although interictal EEG recordings show continuous spikes and spike and wave activity, desynchronization and flattening (DF) of the EEG are observed during seizures. We have studied development of the epileptic phenotype in embryonic (E) and posthatching (P) Fepi.

High expression of noradrenaline, choline acetyltransferase and glial fibrillary acidic protein in the epileptic focus consecutive to GABA withdrawal. An immunocytochemical study.

Interruption of a chronic GABA infusion into the rat somatosensory cortex induces the appearance of focal epileptic manifestations, known as the 'GABA withdrawal syndrome' (GWS). The aim of the present study was to determine, by immunocytochemistry, if neurotransmitters other than GABA are involved in GWS, namely: noradrenaline (NA), serotonin, choline acetyltransferase (CAT), cholecystokinin, neuropeptide Y, somatostatin and glial fibrillary acid protein (GFAP). Immunocytochemical data were compared in three animal groups: GABA-, saline- and L-aspartate (L-Asp)-infused rats.

Transfer of a genetic form of epilepsy in the chicken by embryonic brain grafts.

The genetic photosensitive epilepsy of the Fayoumi chickens was transferred to normal chickens by grafting, in situ, on the 2nd day of incubation, the prosencephalic and mesencephalic vesicles from epileptic embryos. Such chimeras displayed typical interictal EEG and developed intermittent light stimulation-induced seizures phenotypically and electrically similar to the epileptic strain seizures.

Avian photogenic epilepsy and embryonic brain chimeras: neuronal activity of the adult prosencephalon and mesencephalon.

Photogenic genetic epilepsy was studied in an avian model, using either the Fayoumi epileptic chicken (Fepi) or neural chimeras obtained by replacement of embryonic brain vesicles in normal chickens with those of Fepi embryos. In these two kinds of animals motor seizures accompanied by electroencephalographic (EEG) desynchronization and flattening (DF) were evoked by intermittent light stimulation (ILS). In chimeras with only the prosencephalon grafted, motor seizures were less severe but DF remained.