The initiation of bursts in thalamic neurons and the cortical control of
thalamic sensitivity
Alain Destexhe and Terrence J. Sejnowski
Phil. Trans. Roy. Soc. Lond. Series B. 357: 1649-1657 (2002).
Abstract
Thalamic neurons generate high-frequency bursts of action potentials when a
low-threshold (T-type) calcium current, located in soma and dendrites, becomes
activated. Computational models were used to investigate the bursting properties
of thalamic relay and reticular neurons. These two types of thalamic cells
differ fundamentally in their ability to generate bursts following either
excitatory or inhibitory events. Bursts generated with excitatory inputs in
relay cells required a high degree of convergence from excitatory inputs, whereas
moderate excitation drove burst discharges in reticular neurons from
hyperpolarized levels. The opposite holds for inhibitory rebound bursts, which
are more difficult to evoke in reticular neurons than in relay cells. The
differences between the reticular neurons and thalamocortical neurons were due to
different kinetics of the T-current, different electrotonic properties, and
different distribution patterns of the T-current in the two cell types. These
properties enable the cortex to control the sensitivity of the thalamus to inputs
and also participate in pathological states such as absence seizures.
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