TY - JOUR AU - Ivet Rafegas AU - Maria Vanrell AU - Luis A Alexandre AU - G. Arias PY - 2020// TI - Understanding trained CNNs by indexing neuron selectivity T2 - PRL JO - Pattern Recognition Letters SP - 318 EP - 325 VL - 136 N2 - The impressive performance of Convolutional Neural Networks (CNNs) when solving different vision problems is shadowed by their black-box nature and our consequent lack of understanding of the representations they build and how these representations are organized. To help understanding these issues, we propose to describe the activity of individual neurons by their Neuron Feature visualization and quantify their inherent selectivity with two specific properties. We explore selectivity indexes for: an image feature (color); and an image label (class membership). Our contribution is a framework to seek or classify neurons by indexing on these selectivity properties. It helps to find color selective neurons, such as a red-mushroom neuron in layer Conv4 or class selective neurons such as dog-face neurons in layer Conv5 in VGG-M, and establishes a methodology to derive other selectivity properties. Indexing on neuron selectivity can statistically draw how features and classes are represented through layers in a moment when the size of trained nets is growing and automatic tools to index neurons can be helpful. UR - https://doi.org/10.1016/j.patrec.2019.10.013 L1 - http://refbase.cvc.uab.es/files/RVL2019.pdf N1 - CIC; 600.087; 600.140; 600.118 ID - Ivet Rafegas2020 ER -