There is currently no unique catalogue of cortical GABAergic interneuron types, and building one is a major goal in neuroscience. In 2013, we asked 48 prominent neuroscientists to classify 320 interneurons by inspecting images of their morphology (see the paper here). That study was the first to quantify the degree of agreement among neuroscientists in morphology-based interneuron classification.

In our paper, out today in Scientific Data, we present the data set containing the classification choices provided by the 48 neuroscientists. These data can be used as training labels for learning supervised machine learning classifiers of interneurons, or pinpoint anatomical characteristics that make an interneuron especially difficult or especially easy to classify.

The idea of seeking a consensus on interneuron classification came following the meeting of the Petilla interneuron nomenclature Group, held in in 2005 in Petilla de Aragón, a small village in Navarra (Northern Spain), where Santiago Ramón y Cajal was born (see figure). We gathered a set of interneurons, built a web application for classification, and asked 48 neuroscientists, many of them members of the Petilla group, to classify the interneurons according to a proposed taxonomy. The data gathered is available here while an R package to simplify analysis is available here.

High-throughput generation of data is expected to enable learning a systematic taxonomy within a decade from data, by considering molecular, morphological, and electro-physiological features. Hopefully, our data can contribute towards that goal by allowing researchers to leverage the knowledge of leading neuroscientists.

Petilla de Aragón (Navarra), birthplace of Cajal. A, photograph of Main Street. The church of San Millán (XII-XIII century) can be seen in the background. B, the house where Cajal was born, located on Main Street. C, image taken from inside the Church of San Millán during one of the scientific sessions of the international meeting on classification of cortical neurons “Petilla terminology” (Ascoli et al., 2006). First row: Bernardo Rudy, György Buzsáki and Giorgio Ascoli. Second row: Carl Petersen, Andreas Burkhalter, Tamás Freund and Gábor Tamás. Third row: Ruth Benavides-Piccione and Lidia Alonso-Nanclares. Taken from DeFelipe, 2018 (Cajal's Neuronal Forest: Science and Art, Oxford University Press, New York).

References:

Mihaljević, B. et al. Classification of GABAergic interneurons by leading neuroscientists, Scientific Data 6, Article number: 221 (2019)

DeFelipe, J. et al. New insights into the classification and nomenclature of cortical GABAergic interneurons. Nature Reviews Neuroscience 14, 202–216 (2013)

Ascoli, G. A. et al. Petilla Terminology: Nomenclature of features of GABAergic interneurons of the cerebral cortex. Nature Reviews Neuroscience 9, 557-568 (2008).