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Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. An epileptic seizure is the clinical manifestation of an abnormal, excessive, and synchronized electrical discharge in the neurons. The occurrence of two or more unprovoked seizures defines epilepsy. The occurrence of just one seizure may warrant the definition in a more clinical usage where recurrence may be able to be prejudged. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical activity in the brain. These episodes can result in physical injuries, either directly such as broken bones or through causing accidents. In epilepsy, seizures tend to recur and may have no detectable underlying cause. Isolated seizures that are provoked by a specific cause such as poisoning are not deemed to represent epilepsy. People with epilepsy may be treated differently in various areas of the world and experience varying degrees of social stigma due to the alarming nature of their symptoms.
A seizure is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with loss of consciousness, to shaking movements involving only part of the body with variable levels of consciousness, to a subtle momentary loss of awareness. These episodes usually last less than two minutes and it takes some time to return to normal. Loss of bladder control may occur.
The hippocampus is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation. The hippocampus is located in the allocortex, with neural projections into the neocortex, in humans as well as other primates. The hippocampus, as the medial pallium, is a structure found in all vertebrates. In humans, it contains two main interlocking parts: the hippocampus proper, and the dentate gyrus.
The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.
Neurotoxins are toxins that are destructive to nerve tissue. Neurotoxins are an extensive class of exogenous chemical neurological insults that can adversely affect function in both developing and mature nervous tissue. The term can also be used to classify endogenous compounds, which, when abnormally contacted, can prove neurologically toxic. Though neurotoxins are often neurologically destructive, their ability to specifically target neural components is important in the study of nervous systems. Common examples of neurotoxins include lead, ethanol, glutamate, nitric oxide, botulinum toxin, tetanus toxin, and tetrodotoxin. Some substances such as nitric oxide and glutamate are in fact essential for proper function of the body and only exert neurotoxic effects at excessive concentrations.
An apical dendrite is a dendrite that emerges from the apex of a pyramidal cell. Apical dendrites are one of two primary categories of dendrites, and they distinguish the pyramidal cells from spiny stellate cells in the cortices. Pyramidal cells are found in the prefrontal cortex, the hippocampus, the entorhinal cortex, the olfactory cortex, and other areas. Dendrite arbors formed by apical dendrites are the means by which synaptic inputs into a cell are integrated. The apical dendrites in these regions contribute significantly to memory, learning, and sensory associations by modulating the excitatory and inhibitory signals received by the pyramidal cells.
Kainic acid, or kainate, is an acid that naturally occurs in some seaweed. Kainic acid is a potent neuroexcitatory amino acid agonist that acts by activating receptors for glutamate, the principal excitatory neurotransmitter in the central nervous system. Glutamate is produced by the cell's metabolic processes and there are four major classifications of glutamate receptors: NMDA receptors, AMPA receptors, kainate receptors, and the metabotropic glutamate receptors. Kainic acid is an agonist for kainate receptors, a type of ionotropic glutamate receptor. Kainate receptors likely control a sodium channel that produces excitatory postsynaptic potentials (EPSPs) when glutamate binds.
The postictal state is the altered state of consciousness after an epileptic seizure. It usually lasts between 5 and 30 minutes, but sometimes longer in the case of larger or more severe seizures, and is characterized by drowsiness, confusion, nausea, hypertension, headache or migraine, and other disorienting symptoms.
Brian R. Christie is a Professor of Medicine and Neuroscience at The University of Victoria. He helped found the Neuroscience Graduate Program at the University of Victoria and served as its director from 2010–2017. He is a Michael Smith Senior Scholar Award winner. Christie received his PhD in 1992 from the University of Otago before doing postdoctoral work with Daniel Johnston at Baylor College of Medicine and Terrence Sejnowski at the Salk Institute for Biological Studies, and then became Assistant Professor at the University of British Columbia. Promoted to Associate Professor in 2007. Full Professor in 2013.
Racine stages are a categorization of epileptic seizures proposed by Ronald J. Racine in 1972. Prior to Racine's research in epilepsy, a quantifiable means to describe seizure intensities and their causes was not readily available. Racine's work allowed for epilepsy to be understood on a level previously thought impossible.
Epileptogenesis is the gradual process by which a typical brain develops epilepsy. Epilepsy is a chronic condition in which seizures occur. These changes to the brain occasionally cause neurons to fire in an abnormal, hypersynchronous manner, known as a seizure.
Kindling is a commonly used model for the development of seizures and epilepsy in which the duration and behavioral involvement of induced seizures increases after seizures are induced repeatedly. Kindling is also referred as an animal visual model of epilepsy that can be produced by focal electrical stimulation in the brain. This is mainly used in visualising epilepsy in humans. The kindling model was first proposed in the late 1960s by Graham V. Goddard and colleagues. Although kindling is a widely used model, its applicability to human epilepsy is controversial.
An autapse is a chemical or electrical synapse from a neuron onto itself. It can also be described as a synapse formed by the axon of a neuron on its own dendrites, in vivo or in vitro.
Sharp waves and ripples (SWRs) are oscillatory patterns produced by extremely synchronised activity of neurons in the mammalian hippocampus and neighbouring regions which occur spontaneously in idle waking states or during NREM sleep. They can be observed with a variety of imaging methods, such as EEG. They are composed of large amplitude sharp waves in local field potential and produced by tens of thousands of neurons firing together within 30–100 ms window. They are some of the most synchronous oscillations patterns in the brain, making them susceptible to pathological patterns such as epilepsy.They have been extensively characterised and described by György Buzsáki and have been shown to be involved in memory consolidation in NREM sleep and the replay of memories acquired during wakefulness.
Lori L. Isom is an American pharmacologist, an elected Fellow of the American Association for the Advancement of Science, and a member of the National Academy of Medicine.
Fiona Jean McDonald is a New Zealand physiologist, professor and head of the McDonald Lab and the Department of Physiology at the University of Otago.
Dianne Sika-Paotonu is a New Zealand immunologist, biomedical scientist and academic in the Department of Pathology and Molecular Medicine and Associate Dean (Pacific) at the University of Otago Wellington. She is of Tongan descent and is the first Pasifika biomedical scientist to receive the Cranwell Medal for science communication in 2020 and the 2022 Prime Minister's Science Communicator of the Year prize.
Eva King Killam was a research pharmacologist who studied the activity of drugs on the brain and behavior, developing animal models for epilepsy and opiate dependence.
Natalie June Hughes, also known as Natalie Medlicott and Natalie Hughes-Medlicott, is a New Zealand pharmaceutical scientist, and is a full professor at the University of Otago.
Stephanie Margaret Hughes is a New Zealand molecular neurobiologist, and is a full professor at the University of Otago, specialising in gene therapy for the fatal childhood disorders known as Batten disease.
References
- 1 2 Physiology, Department of. "Profile". www.otago.ac.nz.
- ↑ Robson, Zoe. "Researcher Profile: Ruth Empson | Otago Medical Research Foundation".
- ↑ "Ruth Empson – Fulbright New Zealand Scholar Award". www.fulbright.org.nz.
- ↑ Board, Otago Bulletin. "Otago Fulbright recipients excited by opportunity". University of Otago.
- ↑ "Ruth Mary Empson | Fulbright Scholar Program". www.cies.org.
