Ventromedial thalamic lesions and seizure susceptibility

Structures responsible for the onset, propagation, and cessation of generalized seizures are not known. Lesion and microinfusion studies suggest that the substantia nigra pars reticulata (SNR) seizurecontrolling network could play a key role. However, the expression of neural activity within the SNR and its targets during discrete pre-and postictal periods has not been investigated. In rats, we used flurothyl to induce generalized seizures over a controlled time period and 2-deoxyglucose autoradiography mapping technique. Changes in neural activity within the SNR were region-specific. The SNR posterior was selectively active during the pre-clonic period and may represent an early gateway to seizure propagation. The SNR anterior and superior colliculus changed their activity during progression to tonic-clonic seizure, suggesting the involvement in coordinated regional activity that results in inhibitory effects on seizures. The postictal suppression state was correlated with changes in the SNR projection targets, specifically the pedunculopontine tegmental nucleus and superior colliculus.

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“…However, pharmacological and lesion studies showed no involvement of VM in seizure control (Garant et al, 1993;Moshé et al, 1985).…”

Section: Discussionmentioning

confidence: 96%

Regional neural activity within the substantia nigra during peri-ictal flurothyl generalized seizure stages

Velı́šková

Miller

Nunes

et al. 2005

Neurobiology of Disease

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“…The lesions failed to alter flurothyl seizure thresholds. 54 These data argue against a role of the ventromedial thalamus in seizures of adult rats. 55 Garant and Gale 55 have presented evidence that the nigrotegmental pathway also may not participate.…”

Section: Maturational Changes Of Nigral Gada Receptorsmentioning

confidence: 99%

Experimental epilepsy: developmental aspects

Moshé

Sperber

Brown

et al. 1989

Cleveland Clinic Journal of Medicine

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PIDEMIOLOGIC studies indicate that in humans, seizures occur more frequently early in life. 1 ' 2 During the first few years some of the seizure types are age-specific 3-4 and difficult to control with conventional therapies. 5 The high incidence of seizures cannot be attributed only to the greater number of insults that may occur during the newborn period and early infancy. Experimental evidence suggests that the immature central nervous system (CNS) is more susceptible to seizures than its mature counterpart, 6-14 at least during a specific stage of development. Ontogenetic seizure studies have demonstrated that 15-to-18-day-old rat pups are more prone to the development of bilateral, asynchronous convulsions and status epilepticus than adult rats regardless of the seizure model used to induce the seizures. 6-10 These behavioral observations parallel the human epidemiologic and behavioral data concerning the expression of seizures as a function of age. 3-4 Ongoing studies suggest that some of the age-related differences in seizure susceptibility may be due to a functional immaturity of the substantia nigra (SN). 15-19 ROLE OF THE SN IN SEIZURES OF ADULT ANIMALS The SN is considered to be a critical site involved in the expression of generalized seizures in adult animals. 15 ' 20 ' 21 It has been repeatedly demonstrated From the Departments of Neurology (S.

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Anatomical and Neurochemical Substrates of Clonic and Tonic Seizures

Gale

Browning

1988

Mechanisms of Epileptogenesis

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Ventromedial thalamic lesions and seizure susceptibility

Cited by 21 publications

References 32 publications

Regional neural activity within the substantia nigra during peri-ictal flurothyl generalized seizure stages

Regional neural activity within the substantia nigra during peri-ictal flurothyl generalized seizure stages

Experimental epilepsy: developmental aspects

Anatomical and Neurochemical Substrates of Clonic and Tonic Seizures

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