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.

Public Health Relevance

Epilepsy affects about 50 million people worldwide, 3 million in the US alone. Current pharmacological and surgical approaches to treatment are inadequate and risky for a substantial number of patients. This project will use novel recording technologies that will provide an unprecedented level of detail into the microphysiology and mechanisms underlying intractable epilepsy. The long-term goals of this research are to provide a basis for new therapies and approaches to seizure prevention, in the hopes of restoring the quality of life and autonomy of people suffering from intractable epilepsy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS079533-01
Application #
8342922
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
2012-07-01
Budget End
2013-06-30
Support Year
1
Fiscal Year
2012
Total Cost
$335,708
Indirect Cost
$104,824
Name
Brown University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
001785542
City
Providence
State
RI
Country
United States
Zip Code
02912
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
Wagner, Fabien B; Eskandar, Emad N; Cosgrove, G Rees et al. (2015) Microscale spatiotemporal dynamics during neocortical propagation of human focal seizures. Neuroimage 122:114-30
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
Wagner, Fabien B; Truccolo, Wilson; Wang, Jing et al. (2015) Spatiotemporal dynamics of optogenetically induced and spontaneous seizure transitions in primary generalized epilepsy. J Neurophysiol 113:2321-41
Harrison, Matthew T; Amarasingham, Asohan; Truccolo, Wilson (2015) Spatiotemporal conditional inference and hypothesis tests for neural ensemble spiking precision. Neural Comput 27:104-50
Park, Yun S; Hochberg, Leigh R; Eskandar, Emad N et al. (2014) Early detection of human focal seizures based on cortical multiunit activity. Conf Proc IEEE Eng Med Biol Soc 2014:5796-9
Aghagolzadeh, Mehdi; Truccolo, Wilson (2014) Latent state-space models for neural decoding. Conf Proc IEEE Eng Med Biol Soc 2014:3033-6
Truccolo, Wilson; Ahmed, Omar J; Harrison, Matthew T et al. (2014) Neuronal ensemble synchrony during human focal seizures. J Neurosci 34:9927-44
Park, Yun S; Hochberg, Leigh R; Eskandar, Emad N et al. (2013) Early Detection of Human Epileptic Seizures Based on Intracortical Local Field Potentials. Int IEEE EMBS Conf Neural Eng :323-326
Park, Yun S; Hochberg, Leigh R; Eskandar, Emad N et al. (2013) Adaptive Parametric Spectral Estimation with Kalman Smoothing for Online Early Seizure Detection. Int IEEE EMBS Conf Neural Eng :1410-1413

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