Cortical up state activity is enhanced after seizures: a quantitative analysis

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Neurons in the neocortex exhibit Up states, periods of high activity, during various brain states.
• Understanding Up state regulation is crucial for assessing neural network connectivity and excitability.
• Accurate detection of Up states is essential for analyzing neuronal firing patterns across conditions.

Purpose of the Study:

• To develop a robust, automated method for detecting neuronal Up states.
• To quantify changes in Up state characteristics after seizures.
• To investigate the role of BK channels in post-seizure neuronal hyperexcitability.

Main Methods:

• Developed a quantitative, automated method using membrane potential mean and variance from whole-cell recordings.
• Applied the method to neurons from control and postseizure (chemoconvulsant-induced) tissue.
• Assessed the effects of BK-channel antagonists on Up state properties.

Main Results:

• The new method accurately detects Up states, independent of cell-specific variability.
• Up state frequency and firing rates were significantly increased in layer 2/3 neocortical neurons 24 hours post-seizure.
• Post-seizure Down states exhibited increased membrane potential variance and synaptic activity.
• BK-channel antagonists reduced abnormal Up state firing in post-seizure neurons.

Conclusions:

• Established a robust algorithm for Up state detection and analysis.
• Demonstrated that prior seizures increase spontaneous firing activity in cortical networks.
• Showed that BK-channel antagonists can mitigate seizure-induced hyperexcitability and normalize Up state activity.