Epilepsy: Ever-changing states of cortical excitability.
Summary of "Epilepsy: Ever-changing states of cortical excitability."
It has been proposed that the underlying epileptic process is mediated by changes in both excitatory and inhibitory circuits leading to the formation of hyper-excitable seizure networks. In this review we aim to shed light on the many physiological factors that modulate excitability within these networks. These factors have been discussed extensively in many reviews each as a separate entity and cannot be extensively covered in a single manuscript. Thus for the purpose of this work in which we aim to bring those factors together to explain how they interact with epilepsy, we only provide brief descriptions. We present reported evidence supporting the existence of the epileptic brain in several states; interictal, peri-ictal and ictal, each with distinct excitability features. We then provide an overview of how many physiological factors influence the excitatory/inhibitory balance within the interictal state, where the networks are presumed to be functioning normally. We conclude that these changes result in constantly changing states of cortical excitability in patients with epilepsy.
Department of Clinical Neurosciences, St Vincent's Hospital, Fitzroy, Australia; Department of Medicine, The University of Melbourne, Parkville, Australia; Department of Electrical and Electronic Engineering, The University of Melbourne, Parkville, Austra
This article was published in the following journal.
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/22813999
- DOI: http://dx.doi.org/10.1016/j.neuroscience.2012.07.015
Public misconception of epilepsy may lead to significant stigma to the disease itself, thereby causing impaired quality of life in people with epilepsy. Traditionally, epilepsy has been considered to...
SCN1A encodes the alpha subunit of the voltage-gated sodium channel and plays a crucial role in several epilepsy syndromes. The common SCN1A splice-site polymorphism rs3812718 (IVS5N+5 G>A) might cont...
Despite optimal medical treatment, including epilepsy surgery, many epilepsy patients have uncontrolled seizures. In the last decades, interest has grown in invasive intracranial neurostimulation as a...
Up-/down-state transitions are a form of network activity observed when sensory input into the cortex is diminished such as during non-REM sleep. Up-states emerge from coordinated signaling between gl...
Previous studies have investigated how tDCS over the primary motor cortex modulates excitability in the intrinsic hand muscles. Here, we tested if tDCS changes corticomotor excitability and/or cortica...
Epileptic disease is characterised by enhanced brain excitability. Low frequency repetitive transcranial magnetic stimulation (rTMS) can be an effective treatment for refractory frontal ep...
The aim of the study is to evaluate the cortical excitability in the severe brain injured patients. We hypothesize that: 1. There is a continuous decrease in intracortical inhibition fr...
The purpose of this research is to determine whether athletes with concussion have changes in cortical excitability. Single and paired transcranial magnetic stimulation (TMS) can be used...
Focal cortical dysplasia (FCD) is a common finding in epilepsy surgery in pediatric patients. Children with intractable epilepsy would have extensive tests to identify the cause of epilep...
The purpose of this study is to determine whether patients with neuropathic pain has abnormal excitability in somatosensory cortex and abnormal sensory-motor connections.
Medical and Biotech [MESH] Definitions
A neurosurgical procedure that removes or disconnects the epileptogenic CEREBRAL CORTEX of a hemisphere. Hemispherectomy is usually performed for patients with intractable unilateral EPILEPSY due to malformations of cortical development or brain lesions. Depending on the epileptogenic area in the hemisphere, cortical removal can be total or partial.
A disorder characterized by recurrent partial seizures marked by impairment of cognition. During the seizure the individual may experience a wide variety of psychic phenomenon including formed hallucinations, illusions, deja vu, intense emotional feelings, confusion, and spatial disorientation. Focal motor activity, sensory alterations and AUTOMATISM may also occur. Complex partial seizures often originate from foci in one or both temporal lobes. The etiology may be idiopathic (cryptogenic partial complex epilepsy) or occur as a secondary manifestation of a focal cortical lesion (symptomatic partial complex epilepsy). (From Adams et al., Principles of Neurology, 6th ed, pp317-8)
A localization-related (focal) form of epilepsy characterized by recurrent seizures that arise from foci within the temporal lobe, most commonly from its mesial aspect. A wide variety of psychic phenomena may be associated, including illusions, hallucinations, dyscognitive states, and affective experiences. The majority of complex partial seizures (see EPILEPSY, COMPLEX PARTIAL) originate from the temporal lobes. Temporal lobe seizures may be classified by etiology as cryptogenic, familial, or symptomatic (i.e., related to an identified disease process or lesion). (From Adams et al., Principles of Neurology, 6th ed, p321)
Abnormalities in the development of the CEREBRAL CORTEX. These include malformations arising from abnormal neuronal CELL PROLIFERATION or APOPTOSIS; abnormal neuronal migration; and abnormal establishment of cortical organization via neurite extension, synaptogenesis, or neuronal maturation. As well as mutations effecting these developmental processes directly, there are a variety of inborn metabolic errors, such as PEROXISOMAL DISORDERS and mitochondrial and pyruvate metabolic disorders which effect them secondarily and also exhibit these malformations. They are common causes of EPILEPSY and developmental delay and are often a component of multiple congenital anomalies.
A technique that involves the use of electrical coils on the head to generate a brief magnetic field which reaches the CEREBRAL CORTEX. It is coupled with ELECTROMYOGRAPHY response detection to assess cortical excitability by the threshold required to induce MOTOR EVOKED POTENTIALS. This method is also used for BRAIN MAPPING, to study NEUROPHYSIOLOGY, and as a substitute for ELECTROCONVULSIVE THERAPY for treating DEPRESSION. Induction of SEIZURES limits its clinical usage.