It remains unclear why regional diversity is so important in neurons, and to some extent, astrocytes, but not in oligodendrocytes. Among CNS neurons, we found that four main categories of genes drive neuronal diversity: those involved in cellular identity (transcription factors), connectivity (synaptic proteins, junction proteins), neurotransmission (neurotransmitters, neuropeptides), and membrane conductance (ion channels, calcium-binding proteins, solute carriers). But synaptic connectivity, neurotransmission, and membrane conductance are uniquely neuronal properties, and their diversity between regions is consistent with the diverse computational roles of each neuronal circuit. Conversely, the relative homogeneity of oligodendrocytes points to a common function, myelination, across all regions. The intermediate behavior of astrocytes is therefore consistent with the emerging view that they are not simply support cells, but they play an active role in computational processing (Henneberger et al., 2010).
