Epilepsy is one of the most common neurological disorders. Yet, very little is known about how seizures start, spread and terminate. Progress thus far has been hampered by the challenge of monitoring the activity of ensembles of single neurons in humans. Most studies have been limited to intracranial electroencephalograms (iEEGs). Animal models have been used as an alternative approach, but it remains an open question how well these animal models capture mechanisms underlying human epilepsy. Recent technological advances will allow the present proposal to meet this challenge, through the simultaneous recording of large ensembles of single neurons in humans with focal epilepsy, during interictal, preictal, ictal and postictal periods (Truccolo et al., 2011). Patients with pharmacologically intractable focal epilepsy will be recorded during pre-resection surgery monitoring. This will be accomplished using intracortical 96-microelectrode arrays (96-MEA, 4 mm X 4 mm), in addition to subdural iEEGs. The activity of large neocortical ensembles of single units (SUs), multiunits (MUs) and high-spatial resolution local field potentials (LFPs) will be recorded continuously (24hr/day over a period of ~1-2 weeks).
Three specific AIMs will address three main fundamental and inter-related problems in the neurophysiology of human focal epilepsy.
AIM 1 will determine the role of interictal discharges (IIDs) in seizure facilitation/inhibition and relate the activation patterns of neuronal ensembles during IIDs and ictal periods. Some previous studies propose that IIDs initiate a condition that preludes the onset of an ictal event. By contrast, other work hypothesizes that IID events actually inhibit the occurrence of seizures.
AIM 2 will determine the microphysiology of high frequency oscillations (HFOs) and their role in seizure initiation. Recent studies propose that HFOs (~ 80-250 Hz and >250 Hz) in local field potentials are a hallmark of seizure initiation and might play a causal role. Yet, the relationship between these HFOs and single neuron activity in human epilepsy is unknown. Importantly, it is also unclear whether these HFOs are specific to epileptogenic neocortex or might have similar incidence rates even in healthy neocortex. We will thus compare the incidence and spatiotemporal properties of HFOs in epileptic neocortex in humans with focal epilepsy and in nonepileptic neocortex in human and nonhuman primates during sleep, rest and wake states. Finally, AIM 3 will determine the temporal evolution of neural synchrony at the level of single neurons during the preictal-to-ictal transition and during the seizure. Contrary to mainstream thought, recent animal models suggest that hyposynchrony, not hypersynchrony, initiates seizures.

Public Health Relevance

The long term aim of this research is the restoration of quality of life and autonomy in people with intractable epileps. Advances in understanding the 3 fundamental problems outlined above could have an important impact on diagnosis and early treatment, the development of new therapies, the localization of epileptogenic areas for surgical procedures, and seizure prediction and early detection for closed-loop seizure control systems.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS079533-03
Application #
8686976
Study Section
Acute Neural Injury and Epilepsy Study Section (ANIE)
Program Officer
Fureman, Brandy E
Project Start
2012-07-01
Project End
2017-06-30
Budget Start
2014-07-01
Budget End
2015-06-30
Support Year
3
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Brown University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
City
Providence
State
RI
Country
United States
Zip Code
02912
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Martinet, L-E; Fiddyment, G; Madsen, J R et al. (2017) Human seizures couple across spatial scales through travelling wave dynamics. Nat Commun 8:14896
Gerhard, Felipe; Deger, Moritz; Truccolo, Wilson (2017) On the stability and dynamics of stochastic spiking neuron models: Nonlinear Hawkes process and point process GLMs. PLoS Comput Biol 13:e1005390
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Aghagolzadeh, Mehdi; Hochberg, Leigh R; Cash, Sydney S et al. (2016) Predicting seizures from local field potentials recorded via intracortical microelectrode arrays. Conf Proc IEEE Eng Med Biol Soc 2016:6353-6356
Y Ho, E C; Truccolo, Wilson (2016) Interaction between synaptic inhibition and glial-potassium dynamics leads to diverse seizure transition modes in biophysical models of human focal seizures. J Comput Neurosci 41:225-44
Lu, Yao; Truccolo, Wilson; Wagner, Fabien B et al. (2015) Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex. J Neurophysiol 113:3574-87

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