Histochemical changes in cytochrome oxidase of cortical barrels after vibrissal removal in neonatal and adult mice.

What is it about?

This was the first time that the rodent barrel cortex was studied with cytochrome oxidase histochemistry. There were three major findings: (1) The labeling does not highlight the cell bodies, which form the rims of barrels, but rather, mainly neuronal dendrites that receive input from thalamic afferents within the centers of barrels, i.e., where synapses occur. (2) After neonatal whisker removal, the corresponding row of barrels shrink in size, in agreement with previous studies using other techniques. Moreover, neighboring rows of barrels expand in size in compensation for the loss of space. (3) If whiskers are removed in the adult, no changes could be observed in cortical barrels with a cell body (Nissl) stain. However, the relative activity of cytochrome oxidase is clearly reduced.

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Why is it important?

This was one of the earliest studies to indicate that cytochrome oxidase is a sensitive marker of neuronal activity, that the labeling is mainly postsynaptic in dendrites, which require energy for repolarization after depolarization for reactivation, and that metabolic plasticity, which reflect changes in neuronal activity, occurs after functional changes even in the adult.

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