A study of the transition from spindles to spike and wave discharge in feline generalized penicillin epilepsy: Microphysiological features

Kostopoulos, George; Gloor, P.; Pellegrini, A; Gotman, Jean

doi:10.1016/0014-4886(81)90045-5

Cited by 128 publications

(61 citation statements)

References 42 publications

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“…This finding is in agreement with the frequent midfrontal amplitude predominance in the EEG of these discharges. It is also in midfrontal regions that another thalamocortical phenomenon, the sleep spindle, is most prominent, and the link between the two has been established (11,12).…”

Section: Discussionmentioning

confidence: 99%

Generalized epileptic discharges show thalamocortical activation and suspension of the default state of the brain

Gotman

Grova

Bagshaw

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

538

491

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Our objective was to evaluate the brain regions showing increased and decreased metabolism in patients at the time of generalized bursts of epileptic discharges in order to understand their mechanism of generation and effect on brain function. By recording the electroencephalogram during the functional MRI, changes in the blood oxygenation level-dependent signal were obtained in response to epileptic discharges observed in the electroencephalogram of 15 patients with idiopathic generalized epilepsy. A group analysis was performed to determine the regions of positive (activation) and negative (deactivation) blood oxygenation leveldependent responses that were common to the patients. Activations were found bilaterally and symmetrically in the thalamus, mesial midfrontal region, insulae, and midline and bilateral cerebellum and on the borders of the lateral ventricles. Deactivations were bilateral and symmetrical in the anterior frontal and parietal regions and in the posterior cingulate gyri and were seen in the left posterior temporal region. Activations in thalamus and midfrontal regions confirm known involvement of these regions in the generation or spread of generalized epileptic discharges. Involvement of the insulae in generalized discharges had not previously been described. Cerebellar activation is not believed to reflect the generation of discharges. Deactivations in frontal and parietal regions remarkably followed the pattern of the default state of brain function. Thalamocortical activation and suspension of the default state may combine to cause the actual state of reduced responsiveness observed in patients during spike-and-wave discharges. This brief lapse of responsiveness may therefore not result only from the epileptic discharge but also from its effect on normal brain function.absence ͉ epilepsy ͉ thalamus T he electroencephalogram (EEG) of patients with epilepsy presents paroxysmal discharges that depend on the type of epilepsy. In epilepsy that has been termed ''idiopathic generalized'' according to the Commission on Classification and Terminology of the International League Against Epilepsy (1), the most common type of discharge is the 2-to 3-Hz spike-and-wave burst, which occurs simultaneously over wide cortical regions, most often with an anterior predominance. The origin of this discharge and of the absence seizures that often accompany spike-and-wave bursts when they last several seconds has been a subject of investigation and controversy for many years (see ref.2 for a review), particularly with respect to the involvement of subcortical structures. The recently developed method of combined EEG and functional magnetic resonance imaging (fMRI) (EEG͞fMRI) allows the investigation of the brain regions, cortical and subcortical, that are involved in metabolic changes as a result of epileptic discharges seen in the scalp EEG. In our recent publication (3), we described for each individual the patterns of increases and decreases in blood oxygenation leveldependent (BOLD) signal resulting from bu...

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Section: Discussionmentioning

confidence: 99%

Generalized epileptic discharges show thalamocortical activation and suspension of the default state of the brain

Gotman

Grova

Bagshaw

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

538

491

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“…During epileptic seizures, high-frequency neuronal firing in the cerebral cortex causes massive synchronized presynaptic and postsynaptic activity in local microcircuits (Avoli et al, 1990;Kostopoulos et al, 1981). Thus, during seizures, local recordings of spiking rate and field potentials are closely related.…”

Section: Methodsmentioning

confidence: 99%

“…Although this debate is likely to continue, what is clear is that during epileptic seizures there is high frequency neuronal firing in the cerebral cortex causing massive synchronized activity in both presynaptic and postsynaptic local microcircuits (Avoli et al, 1990;Kostopoulos et al, 1981). Thus, during seizures, local recordings of spiking rate and field potentials are closely related, regardless of their relative contributions to neuroimaging signals.…”

Section: Figmentioning

confidence: 99%

“…One important aspect of SWD that may lead to variability is the fact that the local neuronal firing rate increases sharply during the spike component of SWD, but during the wave component firing decreases and may even enter a brief silent period with each cycle of the SWD (Avoli et al, 1990;Kostopoulos et al, 1981). Because cerebral metabolic energy requirements and CBF vary on the timescale of seconds, their changes may depend on the mean neuronal activity level averaged over several cycles of SWD.…”

Section: Figmentioning

confidence: 99%

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Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

Nersesyan

Hermán

Erdogan³

et al. 2004

J Cereb Blood Flow Metab

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Summary:There is broad agreement that generalized tonicclonic seizures (GTCS) and normal somatosensory stimulation are associated with increases in regional CBF. However, the data regarding CBF changes during absence seizures are controversial. Electrophysiologic studies in WAG/Rij rats, an established animal model of absence seizures, have shown spikewave discharges (SWD) that are largest in the perioral somatosensory cortex while sparing the visual cortex. Recent functional magnetic resonance imaging (fMRI) studies in the same model have also shown localized increases in fMRI signals in the perioral somatosensory cortex during SWD. Because fMRI signals are only indirectly related to neuronal activity, the authors directly measured CBF and neuronal activity from specific microdomains of the WAG/Rij cortex using a specially designed probe combining laser-Doppler flowmetry and extracellular microelectrode recordings under fentanyl/haloperidol anesthesia. Using this approach, parallel increases in neuronal activity and CBF were observed during SWD in the whisker somatosensory (barrel) cortex, whereas the visual cortex showed no significant changes. For comparison, these measurements were repeated during somatosensory (whisker) stimulation, and bicuculline-induced GTCS in the same animals. Interestingly, whisker stimulation increased neuronal activity and CBF in the barrel cortex more than during SWD. During GTCS, much larger increases that included both the somatosensory and visual cortex were observed. Thus, SWD in this model produce parallel localized increases in neuronal activity and CBF with similar distribution to somatosensory stimulation, whereas GTCS produce larger and more widespread changes. The normal response to somatosensory stimulation appears to be poised between two abnormal responses produced by two physiologically different types of seizures.

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“…From this we can expect development of therapeutic agents that will modify sleep as well as some forms of epilepsy that appear to be an aberrant form of sleep oscillation (Kellaway 1985;Kostopoulos et al 1981a;Kostopoulos et al 1981b).…”

Section: Introductionmentioning

confidence: 99%

Anatomical and physiological considerations in thalamic rhythm generation

Huguenard

1998

Journal of Sleep Research

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SUMMARYThe thalamus, known as the pacemaker for spindle rhythms in sleep, has several enabling features that promote such pacemaking. These include a circuitry that interconnects large groups of excitatory and inhibitory neurons, all of which are essentially capable of firing high-frequency`bursts' of discharges. Bursts in thalamic reticular neurons produce powerful inhibition in thalamic relay neurons, which leads to rebound excitation. The timing properties of the inhibition regulate the network activity by controlling rebound burst latency. Anatomical features within thalamus such as convergence and divergence determine the spread and synchronization of pacemaking activity. The anatomical basis of divergence, i.e. the degree of axonal arborization of elements within the thalamic circuit, can be functionally modified in a dynamic fashion by biochemical pathways that regulate the properties of synaptic release. These data suggest that it will be possible to therapeutically regulate the thalamus to modify not only the propensity to sleep but also forms of epilepsy that rely on similar thalamic circuitry.

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A study of the transition from spindles to spike and wave discharge in feline generalized penicillin epilepsy: Microphysiological features

Cited by 128 publications

References 42 publications

Generalized epileptic discharges show thalamocortical activation and suspension of the default state of the brain

Generalized epileptic discharges show thalamocortical activation and suspension of the default state of the brain

Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

Anatomical and physiological considerations in thalamic rhythm generation

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