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Patch-clamp recordings of rat neurons from acute brain slices of the somatosensory cortex during magnetic stimulation.

Pashut T, Magidov D, Ben-Porat H, Wolfus S, Friedman A, Perel E, Lavidor M, Bar-Gad I, Yeshurun Y, Korngreen A - Front Cell Neurosci (2014)

Bottom Line: Although transcranial magnetic stimulation (TMS) is a popular tool for both basic research and clinical applications, its actions on nerve cells are only partially understood.In agreement with the modeling, our recordings demonstrate the dependence of magnetic stimulation-triggered action potentials on the type and state of the neuron and its orientation within the magnetic field.Our results suggest that the observed effects of TMS are deeply rooted in the biophysical properties of single neurons in the central nervous system and provide a framework both for interpreting existing TMS data and developing new simulation-based tools and therapies.

View Article: PubMed Central - PubMed

Affiliation: The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University Ramat-Gan, Israel.

ABSTRACT
Although transcranial magnetic stimulation (TMS) is a popular tool for both basic research and clinical applications, its actions on nerve cells are only partially understood. We have previously predicted, using compartmental modeling, that magnetic stimulation of central nervous system neurons depolarized the soma followed by initiation of an action potential in the initial segment of the axon. The simulations also predict that neurons with low current threshold are more susceptible to magnetic stimulation. Here we tested these theoretical predictions by combining in vitro patch-clamp recordings from rat brain slices with magnetic stimulation and compartmental modeling. In agreement with the modeling, our recordings demonstrate the dependence of magnetic stimulation-triggered action potentials on the type and state of the neuron and its orientation within the magnetic field. Our results suggest that the observed effects of TMS are deeply rooted in the biophysical properties of single neurons in the central nervous system and provide a framework both for interpreting existing TMS data and developing new simulation-based tools and therapies.

No MeSH data available.


Related in: MedlinePlus

Suprathreshold magnetic stimulation induces a pause in the spontaneous firing of cortical neurons. (A) Ten overlaid sweeps from a low threshold interneuron firing spontaneously. Magnetic stimulation (0.24 T) was applied after 1 s of recording. (B) Raster plot of the neuron's reaction to the magnetic stimulus. (C) PSTH of the neuron's reaction to the magnetic pulse summed over 50 sweeps.
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Figure 7: Suprathreshold magnetic stimulation induces a pause in the spontaneous firing of cortical neurons. (A) Ten overlaid sweeps from a low threshold interneuron firing spontaneously. Magnetic stimulation (0.24 T) was applied after 1 s of recording. (B) Raster plot of the neuron's reaction to the magnetic stimulus. (C) PSTH of the neuron's reaction to the magnetic pulse summed over 50 sweeps.

Mentions: Assuming that magnetic stimulation induces action potential firing in the axon's initial segment, then suprathreshold magnetic stimulation should cause the neuron to enter a refractory period phase-locked with the stimulus. To test this hypothesis the standard ACSF was replaced with ACSF2, inducing an increase in the synaptic activity in the slice that caused spontaneous firing in some neurons (Bar-Yehuda and Korngreen, 2007; Bar-Yehuda et al., 2008). Such spontaneously firing low threshold interneurons were magnetically stimulated 50 times, each time inducing an action potential (Figure 7A). In all sweeps the magnetic stimulation-generated action potential was followed by a short reduction in the firing of the neuron, as shown in the raster plot (Figure 7B) and peristimulus histogram (Figure 7C). In low threshold interneurons recorded in these experiments this reduction in firing induced by the stimulus lasted 156 ± 60 ms (n = 13). Obviously, this pause may be the result of a combination of cellular refractory period and network activity that could not be told apart while recording in the loose-patch configuration. This experiment could not be performed with L5 pyramidal neurons; the residual mechanical vibrations at high magnetic pulse intensities did not allow collecting enough stimulation sweeps to generate a raster plot and PSTH. However, a similar pattern of activity was qualitatively observed in three L5 pyramidal neurons.


Patch-clamp recordings of rat neurons from acute brain slices of the somatosensory cortex during magnetic stimulation.

Pashut T, Magidov D, Ben-Porat H, Wolfus S, Friedman A, Perel E, Lavidor M, Bar-Gad I, Yeshurun Y, Korngreen A - Front Cell Neurosci (2014)

Suprathreshold magnetic stimulation induces a pause in the spontaneous firing of cortical neurons. (A) Ten overlaid sweeps from a low threshold interneuron firing spontaneously. Magnetic stimulation (0.24 T) was applied after 1 s of recording. (B) Raster plot of the neuron's reaction to the magnetic stimulus. (C) PSTH of the neuron's reaction to the magnetic pulse summed over 50 sweeps.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4042461&req=5

Figure 7: Suprathreshold magnetic stimulation induces a pause in the spontaneous firing of cortical neurons. (A) Ten overlaid sweeps from a low threshold interneuron firing spontaneously. Magnetic stimulation (0.24 T) was applied after 1 s of recording. (B) Raster plot of the neuron's reaction to the magnetic stimulus. (C) PSTH of the neuron's reaction to the magnetic pulse summed over 50 sweeps.
Mentions: Assuming that magnetic stimulation induces action potential firing in the axon's initial segment, then suprathreshold magnetic stimulation should cause the neuron to enter a refractory period phase-locked with the stimulus. To test this hypothesis the standard ACSF was replaced with ACSF2, inducing an increase in the synaptic activity in the slice that caused spontaneous firing in some neurons (Bar-Yehuda and Korngreen, 2007; Bar-Yehuda et al., 2008). Such spontaneously firing low threshold interneurons were magnetically stimulated 50 times, each time inducing an action potential (Figure 7A). In all sweeps the magnetic stimulation-generated action potential was followed by a short reduction in the firing of the neuron, as shown in the raster plot (Figure 7B) and peristimulus histogram (Figure 7C). In low threshold interneurons recorded in these experiments this reduction in firing induced by the stimulus lasted 156 ± 60 ms (n = 13). Obviously, this pause may be the result of a combination of cellular refractory period and network activity that could not be told apart while recording in the loose-patch configuration. This experiment could not be performed with L5 pyramidal neurons; the residual mechanical vibrations at high magnetic pulse intensities did not allow collecting enough stimulation sweeps to generate a raster plot and PSTH. However, a similar pattern of activity was qualitatively observed in three L5 pyramidal neurons.

Bottom Line: Although transcranial magnetic stimulation (TMS) is a popular tool for both basic research and clinical applications, its actions on nerve cells are only partially understood.In agreement with the modeling, our recordings demonstrate the dependence of magnetic stimulation-triggered action potentials on the type and state of the neuron and its orientation within the magnetic field.Our results suggest that the observed effects of TMS are deeply rooted in the biophysical properties of single neurons in the central nervous system and provide a framework both for interpreting existing TMS data and developing new simulation-based tools and therapies.

View Article: PubMed Central - PubMed

Affiliation: The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University Ramat-Gan, Israel.

ABSTRACT
Although transcranial magnetic stimulation (TMS) is a popular tool for both basic research and clinical applications, its actions on nerve cells are only partially understood. We have previously predicted, using compartmental modeling, that magnetic stimulation of central nervous system neurons depolarized the soma followed by initiation of an action potential in the initial segment of the axon. The simulations also predict that neurons with low current threshold are more susceptible to magnetic stimulation. Here we tested these theoretical predictions by combining in vitro patch-clamp recordings from rat brain slices with magnetic stimulation and compartmental modeling. In agreement with the modeling, our recordings demonstrate the dependence of magnetic stimulation-triggered action potentials on the type and state of the neuron and its orientation within the magnetic field. Our results suggest that the observed effects of TMS are deeply rooted in the biophysical properties of single neurons in the central nervous system and provide a framework both for interpreting existing TMS data and developing new simulation-based tools and therapies.

No MeSH data available.


Related in: MedlinePlus