Biomaterial Database

Contribution of intralaminar thalamic nuclei to spike-and-wave-discharges during spontaneous seizures in a genetic rat model of absence epilepsy. 2001

T Seidenbecher, and H C Pape

Otto-von-Guericke Universität, Medizinische Fakultät, Institut für Physiologie, Leipziger Str. 44, D-39120 Magdeburg, Germany.

In an epileptic rat model of generalized absence epilepsies, the genetic absence epilepsy rats from Strasbourg (GAERS), simultaneous recordings of bilateral epidural electroencephalogram (EEG) of the prefrontal cortex and unit activity of neurons in the intralaminar centrolateral (CL) and paracentral thalamic nucleus (PC) were performed under neurolept-anaesthesia (fentanyl-dehydrobenzperidol analgesia). Spike-and-wave (SW) seizures in these rats are characterized by generalized 7-10 Hz spike-and-wave discharges (SWDs) on the EEG. All neurons recorded in intralaminar thalamic nuclei during spontaneous SWDs showed high-frequency (average 368 Hz, range 200-500 Hz), burst-like activity, which occurred in a highly synchronized fashion with every SWD or with alternating SWD-complexes. Burst discharges in intralaminar neurons were delayed by 13.1 ms (CL) and 12.7 ms (PC), with respect to the spike component of a given SWD on the EEG, whereas burst discharges in the ventrobasal thalamus (VB) and in the rostral nucleus reticularis thalami (rRT) preceded the spike component by 17.8 ms and 8.3 ms, respectively. The onset of SWDs on the EEG was preceded by a tonic firing pattern (20-50 Hz) in about one third of CL and PC neurons. Microiontophoretic application of the gamma-aminobutyric acid (GABA)A receptor antagonist bicuculline aggravated, whereas, the glutamate receptor antagonists DNQX and APV dampened, SWD-related discharges in PC and CL; the GABAB receptor antagonist CGP 35347 had no measurable effect. These data indicate that intrathalamic nuclei are recruited rhythmically during SWDs, through mechanisms that seem to rely on a delayed glutamatergic excitation modulated by GABAergic influences, rather than a GABA-mediated rebound burst activity typical of relay cells. The finding of a temporal delay of SWD-related activity in intrathalamic, compared with "specific" thalamic relay nuclei, does not support the notion of a leading or pacemaker role in SWD generation. It is, however, rather suggestive of a function of intrathalamic neurons during synchronization and maintenance of neuronal oscillations, and these intrathalamic neurons may be recruited through glutamatergic corticofugal inputs.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D011922	Rats, Mutant Strains	Rats bearing mutant genes which are phenotypically expressed in the animals.	Mutant Strains Rat,Mutant Strains Rats,Rat, Mutant Strains,Strains Rat, Mutant,Strains Rats, Mutant
D011930	Reaction Time	The time from the onset of a stimulus until a response is observed.	Response Latency,Response Speed,Response Time,Latency, Response,Reaction Times,Response Latencies,Response Times,Speed, Response,Speeds, Response
D011999	Recruitment, Neurophysiological	The spread of response if stimulation is prolonged. (Campbell's Psychiatric Dictionary, 8th ed.)	Recruitment, Motor Unit,Motor Unit Recruitment,Neurophysiological Recruitment
D004569	Electroencephalography	Recording of electric currents developed in the brain by means of electrodes applied to the scalp, to the surface of the brain, or placed within the substance of the brain.	EEG,Electroencephalogram,Electroencephalograms
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D004832	Epilepsy, Absence	A seizure disorder usually occurring in childhood characterized by rhythmic electrical brain discharges of generalized onset. Clinical features include a sudden cessation of ongoing activity usually without loss of postural tone. Rhythmic blinking of the eyelids or lip smacking frequently accompanies the SEIZURES. The usual duration is 5-10 seconds, and multiple episodes may occur daily. Juvenile absence epilepsy is characterized by the juvenile onset of absence seizures and an increased incidence of myoclonus and tonic-clonic seizures. (Menkes, Textbook of Child Neurology, 5th ed, p736)	Akinetic Petit Mal,Epilepsy, Minor,Petit Mal Epilepsy,Pyknolepsy,Absence Seizure Disorder,Childhood Absence Epilepsy,Epilepsy Juvenile Absence,Epilepsy, Absence, Atypical,Epilepsy, Petit Mal,Juvenile Absence Epilepsy,Pykno-Epilepsy,Seizure Disorder, Absence,Absence Epilepsy,Absence Epilepsy, Childhood,Absence Epilepsy, Juvenile,Absence Seizure Disorders,Epilepsy, Childhood Absence,Epilepsy, Juvenile Absence,Minor Epilepsy,Petit Mal, Akinetic,Pykno Epilepsy,Pyknolepsies,Seizure Disorders, Absence
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia