Still challenging the pattern separation dogma: ‘quiero retruco’

Published on September 29, 2021

In a famous Argentinean card game, a player with a good hand may call ‘truco’, to which his/her opponent may pass or raise the bet with ‘quiero retruco’. Rolls makes interesting arguments [1] in response to my claim of no pattern separation in the human hippocampus [2]. However, these arguments reflect long-standing misconceptions about the coding of human hippocampal memories and some misunderstandings about the human experiments and data. To his criticisms, I say ‘quiero retruco’, and highlight here that (i) there is currently no single solid evidence of pattern separation, that is, conjunctive coding at the single neuron level, in the human hippocampus (see [2] and Box 1 in [3]); (ii) on the contrary, evidence so far points to a lack of conjunctive hippocampal coding in humans, distinct to what has been described in the rat and monkey hippocampus [2–4]; and (iii) given the richness of human memory, the core notion of storing our experiences in separate, largely orthogonal (pattern-separated) hippocampal assemblies does not make sense.

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