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To explore the anatomical substrates for network hyperexcitability in adult rats that become chronically epileptic after recurrent seizures in infancy, the dendritic and axonal arbors of biocytin-filled hippocampal pyramidal cells were reconstructed. On postnatal day 10, tetanus toxin was unilaterally injected into the hippocampus and produced brief but(More)
Studies of neurons from human epilepsy tissue and comparable animal models of focal epilepsy have consistently reported a marked decrease in dendritic spine density on hippocampal and neocortical pyramidal cells. Spine loss is often accompanied by focal varicose swellings or beading of dendritic segments. An ongoing excitotoxic injury of dendrites(More)
Both clinical and experimental studies suggest that the immature nervous system is unusually susceptible to seizures during critical periods in postnatal life. A late onset of gamma-aminobutyric acid (GABA)-mediated synaptic inhibition could conceivably play a contributing role in this phenomenon. Numerous studies have shown that neural systems that use(More)
PURPOSE Infantile spasms is one of the most severe epileptic syndromes of infancy and early childhood. Progress toward understanding the pathophysiology of this disorder and the development of effective therapies has been hindered by the lack of a relevant animal model. We report here the creation of such a model. METHODS The sodium channel blocker,(More)
C-fos is a proto-oncogene that is expressed within some neurons following depolarization. The protein product, fos, has been proposed as an anatomical marker for neuronal activity following noxious peripheral stimulation. However, the literature on noxious-stimulus induced fos expression contains several puzzling observations on the time course and laminar(More)
Neurons surrounding the central canal in sacral spinal segments were functionally characterized on the basis of somatic and/or visceral afferent input, then intracellularly marked with horseradish peroxidase (HRP). Tissue sections containing portions of HRP-stained neurons were subsequently immunohistochemically examined for the presence of contacts made by(More)
Studies were undertaken to examine the effects recurrent early-life seizures have on the ability of rats to acquire spatial memories in adulthood. A minute quantity of tetanus toxin was injected unilaterally into the hippocampus on postnatal day 10. Within 48 h, rats developed recurrent seizures that persisted for 1 week. Between postnatal days 57 and 61,(More)
The ventrobasal complex (VB) of the rat thalamus contains neurons responding to non-noxious somatic stimuli as well as neurons driven exclusively by noxious stimuli. This study presents a comparison of morphological features of these two kinds of neurons. Thirteen neurons electrophysiologically characterized were impaled with the micropipette used for the(More)
Recurrent seizures in animal models of early-onset epilepsy have been shown to produce deficits in spatial learning and memory. While neuronal loss does not appear to underlie these effects, dendritic spine loss has been shown to occur. In experiments reported here, seizures induced either by tetanus toxin or flurothyl during the second postnatal week were(More)
The question we attempted to address in this chapter is: Do brief but recurrent seizures in early life alter the ontogeny of hippocampal networks in ways that produce epileptic circuits? Results from the tetanus toxin model suggest that this is likely the case. Following seizures in Postnatal Weeks 2 and 3, most adult rats have a focal epilepsy that arises(More)