Hippocampal neuron density and seizures in the Mongolian gerbil

Absence of Gliosis in the Brains of Epileptic Fowl

Chickens homozygous for the epi gene (epileptics) suffer from spontaneous seizures throughout their life, whereas heterozygous (carriers) are phenotypically normal. Seizures can also be evoked in epileptics by photic stimulation. In addition, epileptic chickens' brains are 25% heavier than those of carriers. We have investigated whether hyperplasia or hypertrophy of astrocytes or increased numbers of astrocytic processes are involved in the development of seizures and the megalencephaly in this model by quantitative comparison of sections immunocytochemically stained for glial fibrillary acidic protein (GFAP). No statistically significant differences between epileptics and controls were found in any of seven areas selected for comparison. In this model gliosis is not involved in the development of epilepsy, nor does it result from repeated seizures.

Does electroconvulsive therapy cause brain damage?

Although the use of ECT has declined dramatically from its inception, this decrease has recently shown signs of leveling out because of ECT's powerful therapeutic effect in severely ill depressed individuals who either do not respond to pharmacologic alternatives or are too ill to tolerate a relatively lengthy drug trial. Notwithstanding its therapeutic benefits, ECT has also remained a controversial treatment modality, particularly in the eye of the public. Given the unsavory qualities associated with the word “electroconvulsive,” claims of possible, probable, or even certain brain damage with ECT have easily found listeners. A careful, nonselective assessment of data covering the areas of pathology, radiology, electrophysiology, biochemistry, and neuropsychology leads both to certain conclusions and to certain unanswered questions. ECT is not the devastating purveyor of wholesale brain damage that some of its detractors claim. For the typical individual receiving ECT, no detectable correlates of irreversible brain damage appear to occur. Still, there remains the possibility that either subtle, objectively undetectable persistent deficits, particularly in the area of autobiographic memory function, occur, or that a rarely occurring syndrome of more pervasive persistent deficits related to ECT use may be present. Clearly, more research directed toward answering these questions needs to be carried out so that the role of ECT can be more rigorously defined. While such research is pending, however, we cannot expect that the conditions that predispose to clinical referrals for ECT will disappear. Given the misery, anguish, and risk of death by suicide, starvation, or debilitation associated with severe depressive illness, for example, it still appears that ECT, at least for the present, must continue to be available.

Use of short echo time two-dimensional 1H-magnetic resonance spectroscopy in temporal lobe epilepsy with negative magnetic resonance imaging findings

We evaluated short echo time two-dimensional 1H magnetic resonance spectroscopy (2D-1HMRS) with the point-resolved spatial selection (PRESS) protocol in temporal lobe epilepsy (TLE) patients with negative magnetic resonance imaging (MRI) findings and described the characteristics of 2D-(1)HMRS in the epileptic focus. Thirty-eight TLE patients with negative conventional MRI findings and 10 healthy controls were studied by 2D-1HMRS. A 128-channel prolonged video-electroencephalographic (EEG) method was used as the standard for epileptogenic focus localization to evaluate N-acetyl aspartate/(choline + creatine + phosphocreatine) (NAA/[Cho + Cr-PCr]), glutamate + glutamine/creatine (Glx/Cr-PCr) and myo-inositol/Cr-PCr ratios in patients with negative MRI findings. The 2D-1HMRS showed that 32/38 patients and all healthy controls had stable baselines and good signal-to-noise ratios. Compared with the healthy controls, 32 patients showed abnormal NAA/(Cho + Cr-PCr) ratios in the hippocampus and, in 25 of these patients, focus lateralization agreed with the EEG. It is concluded that short echo time 2D-1HMRS with the PRESS protocol can help find abnormalities in lateralization of temporal epilepsy in patients with negative MRI findings.

Epileptic seizure of El mouse initiates at the parietal cortex: depth EEG observation in freely moving condition using buffer amplifier

The initiation site of seizure discharges and the relationship between behavioral manifestations and electroencephalography were investigated in the El mouse, a hereditary epilepsy model. The chronic depth electrodes were implanted stereotaxically into the frontal cortex, parietal cortex, temporal cortex, hippocampus, striatum, amygdaloid complex, non-specific nuclei of thalamus and substantia nigra. Electrical activities were recorded in freely moving condition with use of the buffer amplifier devised in the laboratory and behaviors were monitored simultaneously. Seizure spike discharges started in the parietal cortex and spread out into other brain areas. When the hippocampus was involved, the tonic convulsion occurred behaviorally. The paper describes the first direct evidence of the initiation and propagation of seizure discharges in the brain of El mouse.

Hippocampal interneuron loss and plasticity in human temporal lobe epilepsy

It has been hypothesized on the basis of animal models of epilepsy that abnormal neural activity in epilepsy may be related to reorganized neural circuits that facilitate epileptogenesis. Little evidence of this was available for human epilepsy. This paper provides the first evidence of such reorganization of a hippocampal seizure focus in human temporal lobe epilepsy (TLE). This reorganization involves the selective loss of somatostatin and neuropeptide Y immunoreactive interneurons, and axonal sprouting of other neuropeptide Y neurons and dynorphin-A immunoreactive granule cells. This set of changes is not exactly like those that are reported in animal models.

Benzodiazepine/gamma-aminobutyric acid receptor deficit in the midbrain of the seizure-susceptible gerbil

The density of benzodiazepine/gamma-aminobutyric acid receptor binding sites was lower in the midbrain of seizure-susceptible gerbils compared to control seizure-resistant gerbils. Binding of [3H]diazepam to high-affinity brain-specific sites in membrane homogenates of gerbil brain showed a 20-30% lower binding in midbrain (but not other regions) in adult seizure-susceptible gerbils than in controls. This binding deficit was localized by tissue slice autoradiography with [3H]flunitrazepam to the substantia nigra and mesencephalic periaqueductal gray regions, while higher binding was observed in the interpeduncular nucleus. These differences were also seen in animals sacrificed immediately after a seizure. A parallel deficit of [3H]bicuculline methochloride binding to low-affinity gamma-aminobutyric acid receptors also was seen in the same midbrain regions. Scatchard plot analysis showed that the benzodiazepine binding deficit in the nigra was due to a lower number of binding sites with not significant difference in affinity. Lower [3H]flunitrazepam binding was likewise seen in younger animals (29% lower at 30 days of age, 38% at 60 days, and 21% at 90 days), indicating that the midbrain receptor deficit is present in the seizure-susceptible gerbil prior to the age of onset of seizures at 50-100 days. Therefore, these changes are not likely to result from seizures but reflect genetically determined biochemical differences that could play a role in the expression of seizure susceptibility. The deficit in midbrain benzodiazepine/gamma-aminobutyric acid receptors in the seizure-susceptible gerbil would be consistent with the hypothesis that a deficit of gamma-aminobutyric acid-mediated inhibition might contribute to some kinds of epilepsy.