... We show that a transient
potassium (KA) current allows the Fast Spiking (FS) interneuron to strike a balance
between sensitivity to correlated input and robustness to noise,
thereby increasing its signal-to-noise ratio (SNR). First, a compartmental
FS neuron model was created to match experimental data from
striatal FS interneurons in cortex–striatum–substantia nigra organotypic
cultures. Densities of sodium, delayed rectifier, and KA channels
were optimized to replicate responses to somatic current injection.
Spontaneous AMPA and GABA synaptic currents were
adjusted to the experimentally measured amplitude, rise time, and
interevent interval histograms. Second, two additional adjustments
were required to emulate the remaining experimental observations.
GABA channels were localized closer to the soma than AMPA
channels to match the synaptic population reversal potential. Correlation
among inputs was required to produce the observed firing rate
during up-states. In this final model, KA channels were essential for
suppressing down-state spikes while allowing reliable spike generation
during up-states. ... Our results suggest that KA
channels allow FS interneurons to operate without a decrease in SNR
during conditions of increased dopamine, as occurs in response to
reward or anticipated reward. See paper for more and details.
Reference:
1 .
Kotaleski JH, Plenz D, Blackwell KT (2006) Using potassium currents to solve signal-to-noise problems in inhibitory feedforward networks of the striatum. J Neurophysiol 95:331-41 [PubMed]
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