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Corticothalamic inputs control the pattern of activity generated in thalamocortical networks
1Section of Neurobiology and Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520, USA. hal.blumenfeld@yale.edu
Summary
The corticothalamic network can switch between generating sleep spindles (6-10 Hz) and absence seizures (3-4 Hz). Differential activation of GABA receptors by varying cortical input patterns controls this oscillation frequency.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Systems Neuroscience
Background:
- Absence seizures and sleep spindles share the corticothalamic network.
- The mechanism for switching between these brain oscillations is unclear.
Purpose of the Study:
- Investigate how the corticothalamic network transitions between absence seizure and sleep spindle activity.
- Determine the role of GABAergic signaling in regulating oscillation frequency.
Main Methods:
- Used ferret lateral geniculate nucleus slices.
- Stimulated the corticothalamic tract with single shocks or high-frequency bursts.
- Recorded thalamic and thalamocortical neuron activity.
- Utilized GABA(A) and GABA(B) receptor antagonists.
Main Results:
- High-frequency cortical stimulation transformed 6-10 Hz spindle waves into 3-4 Hz paroxysmal oscillations.
- This transition correlated with increased GABAergic perigeniculate neuron firing and slower IPSPs.
- GABA(B) receptor blockade prevented the shift to 3-4 Hz oscillations.
- GABA(A) receptor blockade blocked spindle oscillations, resulting in 3-4 Hz activity.
Conclusions:
- Differential activation of thalamic GABA(A) and GABA(B) receptors by varying corticothalamic input patterns is critical for setting oscillation frequency.
- This mechanism may explain the network's ability to generate both sleep spindles and absence seizures.