Cellular and network models for intrathalamic augmenting responses during 10-Hz stimulation

Area of Science:

• Neuroscience
• Computational Neuroscience

Background:

• Repetitive stimulation of the thalamus at 7-14 Hz leads to augmenting responses in the thalamus and neocortex.
• The underlying mechanisms of these thalamic augmenting responses are not fully understood.

Purpose of the Study:

• To investigate the mechanisms of thalamic augmenting responses using computer models.
• To compare model simulations with in vivo thalamic recordings.

Main Methods:

• Computer modeling of interacting thalamocortical (TC) and thalamic reticular (RE) cells using Hodgkin-Huxley kinetics.
• Simulations of single RE-TC cell pairs and reciprocally interacting RE-TC cell chains.
• Comparison of model results with in vivo thalamic recordings from decorticated cats.

Main Results:

• A single RE-TC cell pair model demonstrated augmenting responses due to RE-induced IPSPs in TC cells, leading to deinactivation of a low-threshold Ca2+ current.
• Augmenting responses in reciprocal RE-TC chains also involved gamma-aminobutyric acid-B (GABAB) IPSPs.
• Lateral GABAA inhibition between RE cells diminished GABAB IPSPs and delayed augmenting responses in TC cells.

Conclusions:

• The interplay between existing mechanisms within the thalamus, including inhibitory postsynaptic potentials (IPSPs) and specific ionic currents, sufficiently explains intrathalamic augmenting responses.
• Computational models provide valuable insights into the complex dynamics of thalamocortical circuitry.