Morphological plasticity in an infant monkey model of temporal lobe epilepsy.

PURPOSE/METHODS: Seizures in early life are thought to contribute to the development of human temporal lobe epilepsy. To examine the consequences of early seizures, we elicited status epilepticus in immature, 5.5- to 7.0-month-old pigtailed macaques by unilateral microinfusion of bicuculline methiodide into the entorhinal cortex. RESULTS: This report focuses on neuropathological changes in the hippocampus. Bicuculline infusion consistently elicited limbic-like seizures with prolonged, relatively localized electrographic activity. Magnetic resonance imaging revealed enhanced signal intensity in the ipsilateral hippocampus after seizures; in some cases, there was also progressive hippocampal atrophy. Histological changes were variable; in two of five monkeys, there was significant hippocampal neuron loss, gliosis, granule cell dispersion, and mossy fiber reorganization. CONCLUSIONS: The histopathological findings and associated magnetic resonance imaging abnormalities after bicuculline-induced status epilepticus in infant monkeys mimic common aspects of human temporal lobe epilepsy.

Techniques for improving stereotaxic accuracy in Macaca fascicularis.

Sources of stereotaxic variability in long-tailed macaques (Macaca fascicularis) were examined by X-ray techniques. Accuracy in the vertical dimension can be improved significantly by measuring from the top of the brain rather than from the Frankfurt plane established by external bony landmarks. Even greater accuracy in both the vertical and anterior-posterior dimensions can be attained by rotating the cranium in the stereotaxic instrument to bring the intercommissural line, as defined by ventriculography, into a plane parallel to the horizontal stereotaxic plane, thus approximating the orientation of the brain as represented in both of the brain atlases currently available for this species. An adjustable eyebar spacer, which allows the cranium to be rotated in the stereotaxic instrument, is described.

A chronic stereotaxic guide-tube platform for intracranial infections in macaques.

Intracranial injection is a valuable method for testing the effects of pharmacologic agents on the central nervous system or specific areas of the brain with minimal peripheral effects. Improved apparatus and techniques have made it possible to treat the same site repeatedly over extended periods of time in unrestrained subjects. Methods are described for the construction and implantation of a durable platform that assures stereotaxic accuracy of intracranial injections for up to two years. The design and use of two kinds of injection cannula for intracerebroventricular and intracerebral injections of one or a few microliters are described in detail. The apparatus and methods have been used in studies of large number of rhesus, longtailed, and pigtailed macaques over a period of several years. The influence of species characteristics and skull growth on the effectiveness of the techniques is discussed.