4 research outputs found
Cellular Mechanisms Underlying State-Dependent Neural Inhibition with Magnetic Stimulation
Novel stimulation protocols for neuromodulation with magnetic fields are explored in clinical and laboratory settings. Recent evidence suggests that the activation state of the nervous system plays a significant role in the outcome of magnetic stimulation, but the underlying cellular and molecular mechanisms of state-dependency have not been completely investigated. We recently reported that high frequency magnetic stimulation could inhibit neural activity when the neuron was in a low active state. In this paper, we investigate state-dependent neural modulation by applying a magnetic field to single neurons, using the novel micro-coil technology. High frequency magnetic stimulation suppressed single neuron activity in a state-dependent manner. It inhibited neurons in slow-firing states, but spared neurons from fast-firing states, when the same magnetic stimuli were applied. Using a multi-compartment NEURON model, we found that dynamics of voltage-dependent sodium and potassium channels were significantly altered by the magnetic stimulation in the slow-firing neurons, but not in the fast-firing neurons. Variability in neural activity should be monitored and explored to optimize the outcome of magnetic stimulation in basic laboratory research and clinical practice. If selective stimulation can be programmed to match the appropriate neural state, prosthetic implants and brain-machine interfaces can be designed based on these concepts to achieve optimal results
Activity-Dependent Neuronal Cell Migration Induced by Electrical Stimulation
Recently, we found that electrical stimulation
can induce neuronal migration in neural networks cultured
for more than 3 weeks on microelectrode arrays. Immunocytochemistry
data showed that the aggregation of neurons
was related to the emergence of astrocytes in culture. In this
study, when neurons were cocultured with astrocytes, electrical
stimulation could induce the migration of neuronal cell
bodies after only 1 week in culture, while the same stimulation
paradigm caused neural necrosis in neuron-only
cultures. In addition, the stimulation-induced migration was
inhibited by blocking action potentials in neural networks
using the voltage-gated sodium channel blocker, tetrodotoxin.
Immunocytochemistry was performed to monitor
precisely the neuronal migration and count the number of
neurons. These results indicate that neuronal migration of
cell bodies is dependent on neuronal activity evoked by
electrical stimulation and can be enhanced by coculturing with astrocytes. We believe this method can be employed as
a means for modifying neural networks and improving the
interface between electrodes and neurons.This work was supported by the Korea Science
and Engineering Foundation (KOSEF) through the Nano Bioelectronics
and Systems Research Center [Grant No. R11-2000-075-
00002-0 for domestic research and R11- 330 2000-075-01001-0 for
international collaboration (June)]