Recent findings published in Nature Neuroscience highlight the discovery of a brand new human neuronal cell type not yet described in any animal. The work, which identifies new "rosehip neurons,” comes from a collaboration led by Allen Institute for Brain Science, J. Craig Venter Institute, and the University of Szeged in Hungary.
The researchers used cortex tissue samples from postmortem brains of two men in their 50s who had died and donated their bodies to research. Transcriptomic and morphological analyses of the outermost layer of the brain led to the identification of ‘rosehip’-like cells with a unique genetic profile.
“Using unbiased single-nucleus RNA sequencing, we identify ten GABAergic interneuron subtypes with combinatorial gene signatures in human cortical layer 1 and characterize a group of human interneurons with anatomical features never described in rodents, having large ‘rosehip’-like axonal boutons and compact arborization,” the team reported.
“These rosehip cells show an immunohistochemical profile (GAD1+CCK+, CNR1–SST–CALB2–PVALB–) matching a single transcriptomically defined cell type whose specific molecular marker signature is not seen in mouse cortex.”
In addition to turning on unique gene signatures, the rosehip neurons appear to also form preferential synapses with another type of neuron in a different part of the human cortex, known as pyramidal neurons. This selectivity for a cellular partner may indicate that the new neurons may be involved with specialized control of the flow of information.
"We really don't understand what makes the human brain special," said study senior co-author Ed Lein. "Studying the differences at the level of cells and circuits is a good place to start, and now we have new tools to do just that."