A lot of recent work has advanced the learning of increasingly context-sensitive distributed representations (i.e., so-called ’embeddings’). In particular. DeepMind’s paper on “Contrastive Predictive Coding” (CPC) is particularly interesting and advances on a number of fronts. For example, in wav2vec, Facebook AI Research (FAIR) uses CPC to obtain apparently superior acoustic modeling results to DeepSpeech’s connectionist temporal classification (CTC) approach. In the CPC paper, the following image is particularly striking, harkening back to the early notion of a Grandmother Cell.