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Stimulus-induced Epileptic Spike-Wave Discharges in Thalamocortical Model with Disinhibition

View Article: PubMed Central - PubMed

ABSTRACT

Epileptic absence seizure characterized by the typical 2–4 Hz spike-wave discharges (SWD) are known to arise due to the physiologically abnormal interactions within the thalamocortical network. By introducing a second inhibitory neuronal population in the cortical system, here we propose a modified thalamocortical field model to mathematically describe the occurrences and transitions of SWD under the mutual functions between cortex and thalamus, as well as the disinhibitory modulations of SWD mediated by the two different inhibitory interneuronal populations. We first show that stimulation can induce the recurrent seizures of SWD in the modified model. Also, we demonstrate the existence of various types of firing states including the SWD. Moreover, we can identify the bistable parametric regions where the SWD can be both induced and terminated by stimulation perturbations applied in the background resting state. Interestingly, in the absence of stimulation disinhibitory functions between the two different interneuronal populations can also both initiate and abate the SWD, which suggests that the mechanism of disinhibition is comparable to the effect of stimulation in initiating and terminating the epileptic SWD. Hopefully, the obtained results can provide theoretical evidences in exploring dynamical mechanism of epileptic seizures.

No MeSH data available.


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The stimulus-induced seizures of the periodical spike and wave discharge (SWD).Time series of the mean of the excitatory and inhibitory neuronal populations, PY and IN1: (a) the initial background state of the system, i.e., low-amplitude and high frequency oscillations, (b) SWD can be induced by the weak stimulation, −0.3, indicated by the green bar performed on the background state (a), (c) SWD can also be terminated by another successively performed weaker stimulation, −0.2, indicated by the red bar. Particularly, periodical successive stimulations can induce the recurrent seizures of SWD (d), (e,f) are the enlarged versions of one periodical stimulation in (d) describing the seizure (f) and seizure abatement (e) of SWD, respectively.
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f2: The stimulus-induced seizures of the periodical spike and wave discharge (SWD).Time series of the mean of the excitatory and inhibitory neuronal populations, PY and IN1: (a) the initial background state of the system, i.e., low-amplitude and high frequency oscillations, (b) SWD can be induced by the weak stimulation, −0.3, indicated by the green bar performed on the background state (a), (c) SWD can also be terminated by another successively performed weaker stimulation, −0.2, indicated by the red bar. Particularly, periodical successive stimulations can induce the recurrent seizures of SWD (d), (e,f) are the enlarged versions of one periodical stimulation in (d) describing the seizure (f) and seizure abatement (e) of SWD, respectively.

Mentions: During the seizures of spike-wave discharge (SWD) the coexistence of seizure and background states has been found20. Also, single-pulse stimulations have been suggested to prematurely terminate the seizure (Taylor et al.)20. However, single-point stimulations or perturbations can also induce the occurrence of the SWD. As shown in the Fig. 2(a), before seizure the system shows the stable background state. From the inset of Fig. 2(a), we can see that the system can display small-amplitude and high-frequency tonic oscillations. However, as a single-point stimulation of −0.3 indicated by the green bar (Fig. 2(b)) is performed around t = 20 s, the SWD (see the inset of Fig. 2(b)) discharges can be induced from the background state. Here, the single-point stimulation can be considered as the little perturbation for the system on the background state. Interestingly, the SWD discharges can also be terminated and return to the background state when another smaller stimulation or perturbation of −0.2 (see Fig. 2(c)), indicated by the red bar, is given around t = 35 s. Hence, the SWD discharges can be induced, and also can be terminated by the single-point stimulations or perturbations, respectively.


Stimulus-induced Epileptic Spike-Wave Discharges in Thalamocortical Model with Disinhibition
The stimulus-induced seizures of the periodical spike and wave discharge (SWD).Time series of the mean of the excitatory and inhibitory neuronal populations, PY and IN1: (a) the initial background state of the system, i.e., low-amplitude and high frequency oscillations, (b) SWD can be induced by the weak stimulation, −0.3, indicated by the green bar performed on the background state (a), (c) SWD can also be terminated by another successively performed weaker stimulation, −0.2, indicated by the red bar. Particularly, periodical successive stimulations can induce the recurrent seizures of SWD (d), (e,f) are the enlarged versions of one periodical stimulation in (d) describing the seizure (f) and seizure abatement (e) of SWD, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120301&req=5

f2: The stimulus-induced seizures of the periodical spike and wave discharge (SWD).Time series of the mean of the excitatory and inhibitory neuronal populations, PY and IN1: (a) the initial background state of the system, i.e., low-amplitude and high frequency oscillations, (b) SWD can be induced by the weak stimulation, −0.3, indicated by the green bar performed on the background state (a), (c) SWD can also be terminated by another successively performed weaker stimulation, −0.2, indicated by the red bar. Particularly, periodical successive stimulations can induce the recurrent seizures of SWD (d), (e,f) are the enlarged versions of one periodical stimulation in (d) describing the seizure (f) and seizure abatement (e) of SWD, respectively.
Mentions: During the seizures of spike-wave discharge (SWD) the coexistence of seizure and background states has been found20. Also, single-pulse stimulations have been suggested to prematurely terminate the seizure (Taylor et al.)20. However, single-point stimulations or perturbations can also induce the occurrence of the SWD. As shown in the Fig. 2(a), before seizure the system shows the stable background state. From the inset of Fig. 2(a), we can see that the system can display small-amplitude and high-frequency tonic oscillations. However, as a single-point stimulation of −0.3 indicated by the green bar (Fig. 2(b)) is performed around t = 20 s, the SWD (see the inset of Fig. 2(b)) discharges can be induced from the background state. Here, the single-point stimulation can be considered as the little perturbation for the system on the background state. Interestingly, the SWD discharges can also be terminated and return to the background state when another smaller stimulation or perturbation of −0.2 (see Fig. 2(c)), indicated by the red bar, is given around t = 35 s. Hence, the SWD discharges can be induced, and also can be terminated by the single-point stimulations or perturbations, respectively.

View Article: PubMed Central - PubMed

ABSTRACT

Epileptic absence seizure characterized by the typical 2–4 Hz spike-wave discharges (SWD) are known to arise due to the physiologically abnormal interactions within the thalamocortical network. By introducing a second inhibitory neuronal population in the cortical system, here we propose a modified thalamocortical field model to mathematically describe the occurrences and transitions of SWD under the mutual functions between cortex and thalamus, as well as the disinhibitory modulations of SWD mediated by the two different inhibitory interneuronal populations. We first show that stimulation can induce the recurrent seizures of SWD in the modified model. Also, we demonstrate the existence of various types of firing states including the SWD. Moreover, we can identify the bistable parametric regions where the SWD can be both induced and terminated by stimulation perturbations applied in the background resting state. Interestingly, in the absence of stimulation disinhibitory functions between the two different interneuronal populations can also both initiate and abate the SWD, which suggests that the mechanism of disinhibition is comparable to the effect of stimulation in initiating and terminating the epileptic SWD. Hopefully, the obtained results can provide theoretical evidences in exploring dynamical mechanism of epileptic seizures.

No MeSH data available.


Related in: MedlinePlus