CLOSED-LOOP SEIZURE CONTROL WITH VERY HIGH FREQUENCY ELECTRICAL STIMULATION AT SEIZURE ONSET IN THE GAERS MODEL OF ABSENCE EPILEPSY

2011 ◽  
Vol 21 (02) ◽  
pp. 163-173 ◽  
Author(s):  
TIMOTHY S. NELSON ◽  
COURTNEY L. SUHR ◽  
DEAN R. FREESTONE ◽  
ALAN LAI ◽  
AMY J. HALLIDAY ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Closed Loop ◽  
Absence Epilepsy ◽  
High Frequency Stimulation ◽  
Very High Frequency ◽  
Ultra High Frequency ◽  
Epileptiform Discharges ◽  
Frequency Stimulation ◽  
Very High

A closed-loop system for the automated detection and control of epileptic seizures was created and tested in three Genetic Absence Epilepsy Rats from Strasbourg (GAERS) rats. In this preliminary study, a set of four EEG features were used to detect seizures and three different electrical stimulation strategies (standard (130 Hz), very high (500 Hz) and ultra high (1000 Hz)) were delivered to terminate seizures. Seizure durations were significantly shorter with all three stimulation strategies when compared to non-stimulated (control) seizures. We used mean seizure duration of epileptiform discharges persisting beyond the end of electrical stimulation as a measure of stimulus efficacy. When compared to the duration of seizures stimulated in the standard approach (7.0 s ± 10.1), both very high and ultra high frequency stimulation strategies were more effective at shortening seizure durations (1.3 ± 2.2 s and 3.5 ± 6.4 s respectively). Further studies are warranted to further understand the mechanisms by which this therapeutic effect may be conveyed, and which of the novel aspects of the very high and ultra high frequency stimulation strategies may have contributed to the improvement in seizure abatement performance when compared to standard electrical stimulation approaches.

Cellular Mechanisms Underlying Antiepileptic Effects of Low- and High-Frequency Electrical Stimulation in Acute Epilepsy in Neocortical Brain Slices In Vitro

2007 ◽  
Vol 97 (3) ◽  
pp. 1887-1902 ◽  
Author(s):  
Yitzhak Schiller ◽  
Yael Bankirer
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Brain Slices ◽  
Low Frequency ◽  
High Frequency Stimulation ◽  
Dependent Manner ◽  
Cellular Mechanisms ◽  
Epileptiform Discharges ◽  
Frequency Stimulation

Approximately 30% of epilepsy patients suffer from drug-resistant epilepsy. Direct electrical stimulation of the epileptogenic zone is a potential new treatment modality for this devastating disease. In this study, we investigated the effect of two electrical stimulation paradigms, sustained low-frequency stimulation and short trains of high-frequency stimulation, on epileptiform discharges in neocortical brain slices treated with either bicuculline or magnesium-free extracellular solution. Sustained low-frequency stimulation (5–30 min of 0.1- to 5-Hz stimulation) prevented both interictal-like discharges and seizure-like events in an intensity-, frequency-, and distance-dependent manner. Short trains of high-frequency stimulation (1–5 s of 25- to 200-Hz stimulation) prematurely terminated seizure-like events in a frequency-, intensity-, and duration-dependent manner. Roughly one half the seizures terminated within the 100-Hz stimulation train ( P < 0.01 compared with control), whereas the remaining seizures were significantly shortened by 53 ± 21% ( P < 0.01). Regarding the cellular mechanisms underlying the antiepileptic effects of electrical stimulation, both low- and high-frequency stimulation markedly depressed excitatory postsynaptic potentials (EPSPs). The EPSP amplitude decreased by 75 ± 3% after 10-min, 1-Hz stimulation and by 86 ± 6% after 1-s, 100-Hz stimulation. Moreover, partial pharmacological blockade of ionotropic glutamate receptors was sufficient to suppress epileptiform discharges and enhance the antiepileptic effects of stimulation. In conclusion, this study showed that both low- and high-frequency electrical stimulation possessed antiepileptic effects in the neocortex in vitro, established the parameters determining the antiepileptic efficacy of both stimulation paradigms, and suggested that the antiepileptic effects of stimulation were mediated mostly by short-term synaptic depression of excitatory neurotransmission.

Thunderstorm Signals at Very-high Frequency and Ultra-high Frequency

Nature ◽  
1955 ◽  
Vol 175 (4465) ◽  
pp. 949-950 ◽  
Author(s):  
D. R. HAY ◽  
T. R. HARTZ
Keyword(s):  
High Frequency ◽  
Very High Frequency ◽  
Ultra High Frequency ◽  
Very High

Street‐Scale Mapping of Urban Radio Frequency Noise at Very High Frequency and Ultra High Frequency

Radio Science ◽  
2019 ◽  
Vol 54 (11) ◽  
pp. 934-948
Author(s):  
Daniel J. Breton ◽  
Caitlin E. Haedrich ◽  
Matthew J. Kamrath ◽  
D. Keith Wilson
Keyword(s):  
Radio Frequency ◽  
High Frequency ◽  
Frequency Noise ◽  
Very High Frequency ◽  
Ultra High Frequency ◽  
Very High

The regulation of adult rodent hippocampal neurogenesis by deep brain stimulation

2008 ◽  
Vol 108 (1) ◽  
pp. 132-138 ◽  
Author(s):  
Hiroki Toda ◽  
Clement Hamani ◽  
Adrian P. Fawcett ◽  
William D. Hutchison ◽  
Andres M. Lozano
Keyword(s):  
Electrical Stimulation ◽  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
High Frequency ◽  
Hippocampal Neurogenesis ◽  
High Frequency Stimulation ◽  
Sham Surgery ◽  
Frequency Stimulation ◽  
Deep Brain ◽  
Stimulation Of

Object To examine the influence of deep brain stimulation on hippocampal neurogenesis in an adult rodent model. Methods Rats were anesthetized and treated for 1 hour with electrical stimulation of the anterior nucleus of the thalamus (AN) or sham surgery. The animals were injected with 5′-bromo-2′-deoxyuridine (BrdU) 1–7 days after surgery and killed 24 hours or 28 days later. The authors counted the BrdU-positive cells in the dentate gyrus (DG) of the hippocampus. To investigate the fate of these cells, they also stained sections for doublecortin, NeuN, and GFAP and analyzed the results with confocal microscopy. In a second set of experiments they assessed the number of DG BrdU-positive cells in animals treated with corticosterone (a known suppressor of hippocampal neurogenesis) and sham surgery, corticosterone and AN stimulation, or vehicle and sham surgery. Results Animals receiving AN high-frequency stimulation (2.5 V, 90 μsec, 130 Hz) had a 2- to 3-fold increase in the number of DG BrdU-positive cells compared with nonstimulated controls. This increase was not seen with stimulation at 10 Hz. Most BrdU-positive cells assumed a neuronal cell fate. As expected, treatment with corticosterone significantly reduced the number of DG BrdU-positive cells. This steroid-induced reduction of neurogenesis was reversed by AN stimulation. Conclusions High-frequency stimulation of the AN increases the hippocampal neurogenesis and restores experimentally suppressed neurogenesis. Interventions that increase hippocampal neurogenesis have been associated with enhanced behavioral performance. In this context, it may be possible to use electrical stimulation to treat conditions associated with impairment of hippocampal function.

Turning on the central contribution to contractions evoked by neuromuscular electrical stimulation

2007 ◽  
Vol 103 (1) ◽  
pp. 170-176 ◽  
Author(s):  
J. C. Dean ◽  
L. M. Yates ◽  
D. F. Collins
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Muscle Fibers ◽  
Neuromuscular Electrical Stimulation ◽  
Motor Units ◽  
Stimulation Frequency ◽  
Central Mechanism ◽  
Triceps Surae ◽  
High Frequency Stimulation ◽  
Frequency Stimulation

Neuromuscular electrical stimulation can generate contractions through peripheral and central mechanisms. Direct activation of motor axons (peripheral mechanism) recruits motor units in an unnatural order, with fatigable muscle fibers often activated early in contractions. The activation of sensory axons can produce contractions through a central mechanism, providing excitatory synaptic input to spinal neurons that recruit motor units in the natural order. Presently, we quantified the effect of stimulation frequency (10–100 Hz), duration (0.25–2 s of high-frequency bursts, or 20 s of constant-frequency stimulation), and intensity [1–5% maximal voluntary contraction (MVC) torque generated by a brief 100-Hz train] on the torque generated centrally. Electrical stimulation (1-ms pulses) was delivered over the triceps surae in eight subjects, and plantar flexion torque was recorded. Stimulation frequency, duration, and intensity all influenced the magnitude of the central contribution to torque. Central torque did not develop at frequencies ≤20 Hz, and it was maximal at frequencies ≥80 Hz. Increasing the duration of high-frequency stimulation increased the central contribution to torque, as central torque developed over 11 s. Central torque was greatest at a relatively low contraction intensity. The largest amount of central torque was produced by a 20-s, 100-Hz train (10.7 ± 5.5 %MVC) and by repeated 2-s bursts of 80- or 100-Hz stimulation (9.2 ± 4.8 and 10.2 ± 8.1% MVC, respectively). Therefore, central torque was maximized by applying high-frequency, long-duration stimulation while avoiding antidromic block by stimulating at a relatively low intensity. If, as hypothesized, the central mechanism primarily activates fatigue-resistant muscle fibers, generating muscle contractions through this pathway may improve rehabilitation applications.

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