| 1. |
- Froriep, Ulrich P, et al.
(författare)
-
Altered theta coupling between medial entorhinal cortex and dentate gyrus in temporal lobe epilepsy
- 2012
-
Ingår i: Epilepsia. - : Wiley. - 0013-9580 .- 1528-1167. ; 53:11, s. 1937-1947
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Temporal lobe epilepsy is often accompanied by neuron loss and rewiring in the hippocampus. We hypothesized that the interaction of subnetworks of the entorhinalhippocampal loop between epileptic events should show significant signatures of these pathologic changes.Methods: We combined simultaneous recording of local field potentials in entorhinal cortex (EC) and dentate gyrus (DG) in freely behaving kainate-injected mice with histologic analyses and computational modeling.Key Findings: In healthy mice, theta band activity was synchronized between EC and DG. In contrast, in epileptic mice, theta activity in the EC was delayed with respect to the DG. A computational neural mass model suggests that hippocampal cell loss imbalances the coupling of subnetworks, introducing the shift.Significance: We show that pathologic dynamics in epilepsy encompass ongoing activity in the entorhinal-hippocampal loop beyond acute epileptiform activity. This predominantly affects theta band activity, which links this shift in entorhinal-hippocampal interaction to behavioral aspects in epilepsy.
|
|
| 2. |
- Heining, Katharina, et al.
(författare)
-
Bursts with High and Low Load of Epileptiform Spikes Show Contex-Dependent Correlations in Epileptic Mice
- 2019
-
Ingår i: eNeuro. - : SOC NEUROSCIENCE. - 2373-2822. ; 6:5
-
Tidskriftsartikel (refereegranskat)abstract
- Hypersynchronous network activity is the defining hallmark of epilepsy and manifests in a wide spectrum of phenomena, of which electrographic activity during seizures is only one extreme. The aim of this study was to differentiate between different types of epileptiform activity (EA) patterns and investigate their temporal succession and interactions. We analyzed local field potentials (LFPs) from freely behaving male mice that had received an intrahippocampal kainate injection to model mesial temporal lobe epilepsy (MTLE). Epileptiform spikes occurred in distinct bursts. Using machine learning, we derived a scale reflecting the spike load of bursts and three main burst categories that we labeled high-load, medium-load, and low-load bursts. We found that bursts of these categories were non-randomly distributed in time. High-load bursts formed clusters and were typically surrounded by transition phases with increased rates of medium-load and low-load bursts. In apparent contradiction to this, increased rates of low-load bursts were also associated with longer background phases, i.e., periods lacking high-load bursting. Furthermore, the rate of low-load bursts was more strongly correlated with the duration of background phases than the overall rate of epileptiform spikes. Our findings are consistent with the hypothesis that low-level EA could promote network stability but could also participate in transitions towards major epileptiform events, depending on the current state of the network.
|
|
| 3. |
- Kim, Christopher M., et al.
(författare)
-
Dynamics of multiple interacting excitatory and inhibitory populations with delays
- 2020
-
Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : AMER PHYSICAL SOC. - 1539-3755 .- 1550-2376. ; 102:2
-
Tidskriftsartikel (refereegranskat)abstract
- A network consisting of excitatory and inhibitory (EI) neurons is a canonical model for understanding local cortical network activity. In this study, we extended the local circuit model and investigated how its dynamical landscape can be enriched when it interacts with another excitatory (E) population with long transmission delays. Through analysis of a rate model and numerical simulations of a corresponding network of spiking neurons, we studied the transition from stationary to oscillatory states by analyzing the Hopf bifurcation structure in terms of two network parameters: (1) transmission delay between the EI subnetwork and the E population and (2) inhibitory couplings that induced oscillatory activity in the EI subnetwork. We found that the critical coupling strength can strongly modulate as a function of transmission delay, and consequently the stationary state can be interwoven intricately with the oscillatory state. Such a dynamical landscape gave rise to an isolated stationary state surrounded by multiple oscillatory states that generated different frequency modes, and cross-frequency coupling developed naturally at the bifurcation points. We identified the network motifs with short-and long-range inhibitory connections that underlie the emergence of oscillatory states with multiple frequencies. Thus, we provided a mechanistic explanation of how the transmission delay to and from the additional E population altered the dynamical landscape. In summary, our results demonstrated the potential role of long-range connections in shaping the network activity of local cortical circuits.
|
|
