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Orthogonal wave propagation of epileptiform activity in the planar mouse hippocampus in vitro.

ABSTRACT: In vitro brain preparations have been used extensively to study the generation and propagation of epileptiform activity. Transverse and longitudinal slices of the rodent hippocampus have revealed various patterns of propagation. Yet intact connections between the transverse and longitudinal pathways should generate orthogonal (both transverse and longitudinal) propagation of seizures involving the entire hippocampus. This study utilizes the planar unfolded mouse hippocampus preparation to reveal simultaneous orthogonal epileptiform propagation and to test a method of arresting propagation.This study utilized an unfolded mouse hippocampus preparation. It was chosen due to its preservation of longitudinal neuronal processes, which are thought to play an important role in epileptiform hyperexcitability. 4-Aminopyridine (4-AP), microelectrodes, and voltage-sensitive dye imaging were employed to investigate tissue excitability.In 50-?m 4-AP, stimulation of the stratum radiatum induced transverse activation of CA3 cells but also induced a longitudinal wave of activity propagating along the CA3 region at a speed of 0.09 m/s. Without stimulation, a wave originated at the temporal CA3 and propagated in a temporal-septal direction could be suppressed with glutamatergic receptor antagonists. Orthogonal propagation traveled longitudinally along the CA3 pathway, secondarily invading the CA1 region at a velocity of 0.22 ± 0.024 m/s. Moreover, a local lesion restricted to the CA3 region could arrest wave propagation.These results reveal a complex two-dimensional epileptiform wave propagation pattern in the hippocampus that is generated by a combination of synaptic transmission and axonal propagation in the CA3 recurrent network. Epileptiform propagation block via a transverse selective CA3 lesion suggests a potential surgical technique for the treatment of temporal lobe epilepsy.

SUBMITTER: Kibler AB

PROVIDER: S-EPMC3169769 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

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Orthogonal wave propagation of epileptiform activity in the planar mouse hippocampus in vitro.

Kibler Andrew B AB Durand Dominique M DM

Epilepsia 20110610 9

<h4>Purpose</h4>In vitro brain preparations have been used extensively to study the generation and propagation of epileptiform activity. Transverse and longitudinal slices of the rodent hippocampus have revealed various patterns of propagation. Yet intact connections between the transverse and longitudinal pathways should generate orthogonal (both transverse and longitudinal) propagation of seizures involving the entire hippocampus. This study utilizes the planar unfolded mouse hippocampus prepa ...[more]

PMID: 21668440

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Project description:ObjectiveIntracranial electroencephalography (ICEEG) recordings are performed for seizure localization in medically refractory epilepsy. Signal quantifications such as frequency power can be projected as heatmaps on personalized three-dimensional (3D) reconstructed cortical surfaces to distill these complex recordings into intuitive cinematic visualizations. However, simultaneously reconciling deep recording locations and reliably tracking evolving ictal patterns remain significant challenges.MethodsWe fused oblique magnetic resonance imaging (MRI) slices along depth probe trajectories with cortical surface reconstructions and projected dynamic heatmaps using a simple mathematical metric of epileptiform activity (line-length). This omni-planar and surface casting of epileptiform activity approach (OPSCEA) thus illustrated seizure onset and spread among both deep and superficial locations simultaneously with minimal need for signal processing supervision. We utilized the approach on 41 patients at our center implanted with grid, strip, and/or depth electrodes for localizing medically refractory seizures. Peri-ictal data were converted into OPSCEA videos with multiple 3D brain views illustrating all electrode locations. Five people of varying expertise in epilepsy (medical student through epilepsy attending level) attempted to localize the seizure-onset zones.ResultsWe retrospectively compared this approach with the original ICEEG study reports for validation. Accuracy ranged from 73.2% to 97.6% for complete or overlapping onset lobe(s), respectively, and ~56.1% to 95.1% for the specific focus (or foci). Higher answer certainty for a given case predicted better accuracy, and scorers had similar accuracy across different training levels.SignificanceIn an era of increasing stereo-EEG use, cinematic visualizations fusing omni-planar and surface functional projections appear to provide a useful adjunct for interpreting complex intracranial recordings and subsequent surgery planning.

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Orthogonal wave propagation of epileptiform activity in the planar mouse hippocampus in vitro.

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Orthogonal wave propagation of epileptiform activity in the planar mouse hippocampus in vitro.

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