Marked bias towards spontaneous synaptic inhibition distinguishes non-adapting from adapting layer 5 pyramidal neurons in the barrel cortex.
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2017
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Nature Scientific Reports
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Abstract
Pyramidal neuron subtypes differ in intrinsic electrophysiology properties and dendritic morphology.
However, do different pyramidal neuron subtypes also receive synaptic inputs that are dissimilar in frequency
and in excitation/inhibition balance? Unsupervised clustering of three intrinsic parameters that vary by
cell subtype – the slow afterhyperpolarization, the sag, and the spike frequency adaptation – split layer
5 barrel cortex pyramidal neurons into two clusters: one of adapting cells and one of non-adapting cells,
corresponding to previously described thin- and thick-tufted pyramidal neurons, respectively. Non-adapting
neurons presented frequencies of spontaneous inhibitory postsynaptic currents (sIPSCs) and spontaneous
excitatory postsynaptic currents (sEPSCs) three- and two-fold higher, respectively, than those of adapting
neurons. The IPSC difference between pyramidal subtypes was activity independent. A subset of neurons
were thy1-GFP positive, presented characteristics of non-adapting pyramidal neurons, and also had higher
IPSC and EPSC frequencies than adapting neurons. The sEPSC/sIPSC frequency ratio was higher in adapting
than in non-adapting cells, suggesting a higher excitatory drive in adapting neurons. Therefore, our study on
spontaneous synaptic inputs suggests a different extent of synaptic information processing in adapting and
non-adapting barrel cortex neurons, and that eventual deficits in inhibition may have differential effects on
the excitation/inhibition balance in adapting and non-adapting neurons.