Chapter 5 - Organization and control of epileptic circuits in temporal lobe epilepsy
Section snippets
Organization and Reorganization of Microcircuits: Anatomical Changes in Temporal Lobe Epilepsy
Temporal lobe epilepsy (TLE) is the most common subtype of epilepsy in human patients (Wiebe, 2000). Unlike many other forms of human epilepsies, TLE results in stereotyped pathological changes that can be examined not only in human tissue but in an array of animal models of this disease (Kandratavicius et al., 2014, Levesque et al., 2015). To understand a network pathology such as epilepsy, a good starting point is to attempt to understand any anatomical microcircuit alterations that may occur
From Organization to Control of Neuronal Circuits: Introduction to Graph Theory
Before we discuss how the above anatomical changes might lead to hyperexcitability or seizures, we pause for a brief background on graph theory. Pioneered by Euler in the 18th century, it has gained a recent resurgence in popularity, in large part due to the important work of Watts and Strogatz who demonstrated its usefulness in describing systems as diverse as neural networks of Caenorhabditis elegans, power grids, and the interconnectedness of film actors (Watts and Strogatz, 1998).
Graph
Beginning to Control Microcircuits: Using Graph Theory to Control Circuits In Silico
We will now focus our attention on studies that use computational techniques to apply graph theory as a technique in understanding how experimentally demonstrated changes in microcircuitry contribute to network hyperexcitability. TLE development is most often characterized by three different stages: (1) an initial precipitating event, (2) a period of epileptogenesis, and (3) recurrent spontaneous seizures. Most of the anatomical and physiological changes occur during the period of
Further Control of Microcircuits: Can We Learn to Control a Pathological Circuit in Order to Treat Epilepsy?
Ultimately, the goal of all research into epileptic circuits is to understand this pathology in order to develop better treatments for patients with TLE. Once details of epileptic circuits are known at small and large scales, controlling the circuit may become possible. There are a wide variety of techniques other than anatomy or electrophysiology which may be useful for continuing to helping to map out these circuits including an innovative type of high-resolution microscopy called STORM (Dani
Network Organization at the Macrocircuit Level: Applications of Graph Theory at a Larger Scale
Although most of the pathological changes in TLE occur in the hippocampus and adjacent structures, this disease affects extratemporal structures as well, as evidenced by the facts that many patients with TLE do not have a complete remission of their seizures after TLE and also that many patients with TLE suffer from psychiatric comorbidities (Kandratavicius et al., 2014, Wiebe and England, 2001). Therefore, graph theory analysis has been proposed as a way to understand the changing circuitry of
Conclusions
In summary, computational science and experimental techniques offer complementary techniques to allow researchers to understand brain dynamics in normal and pathological conditions. Many anatomical details about circuit reorganization in epilepsy have already been demonstrated, and these predictions can offer the possibility of expanding this knowledge further. As computational models grow in size, accuracy, and complexity, they will produce more reliable predictions as to what variables are
Acknowledgments
The work was funded by the US National Institutes of Health grants NS35915 and NS94668 (to I.S.), R25NS065741-04S1 (to A.A.), and the National Aeronautics and Space Administration grant NSCOR NNX10AD59G (to I.S.).
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2022, Experimental NeurologyCitation Excerpt :But the extent of resection is still a concern for neurosurgeons around the world (Wang et al., 2017; Al-Otaibi et al., 2012). Recognition of the epileptiform activity in the regions other than the hippocampus in TLE will be beneficial in understanding epileptiform network hubs (Alexander et al., 2016). As for the ethical reasons, the region-specific analysis of glutamatergic activity is not possible in TLE patients, findings from the animal models of TLE will help pinpoint the mechanism of the enhanced excitatory activity in various temporal lobe structure (Lippmann et al., 2017; Reyes-Garcia et al., 2018).
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2021, Revue NeurologiqueCitation Excerpt :Because GABAergic interneurons are less numerous than excitatory neurons and because they are subdivided into numerous heterogeneous populations [102,103], the exhaustive characterization of each inhibitory neuron subtype property in TLE conditions appears to be a dauntingly long task. However, numerous alterations concerning GABAergic neurons have been documented [104]. For excitatory neurons, some specific interneuron subpopulations are vulnerable to neuronal death in the hippocampus [105,106] but also in other temporal lobe structures [107].