Figure 1.

Basic spindle properties and model topology. A, Field potential and simultaneous recordings from cortical and thalamocortical neurons. A recording from reticular thalamic neuron was obtained in a different experiment [modified from Timofeev and Bazhenov (2005)]. B(1), [Ca²⁺]_i-dependent shift in the activation curve of the hyperpolarization-activated h-type current, I_h. T-type current, I_T, allows Ca²⁺ ions to enter the cell, bind to the mixed Na⁺/K⁺ channel I_h, and modify its voltage-dependent properties. B(2), Binding of Ca²⁺ ions to I_h channels shifts the voltage dependence of the current toward positive membrane potentials. C, Model topology and structure of the thalamocortical network distributed into four different layers. The TC (thalamocortical relay) neurons and the thalamic RE (reticular) neurons formed two of the layers, strongly interacting with each other. The two cortical layers contained PY (pyramidal excitatory) neurons and IN (inhibitory) neurons. Connections between layers were stochastically distributed. Heterogeneity in the same layer was achieved through a random distribution of parameters for intrinsic properties (see Materials and Methods for details).