Grandmother cells: much ado about nothing

We do not dispute the possibility of the existence in the brain of grandmother cells, which are very finely tuned neurons that fire only in the presence of specific objects or categories. However, we question the causal efficacy of such neurons at the functional or behaviour level. We claim that, even though very familiar items, such as my grandmother, may well have associated grandmother neurons, these neurons have very little, or no impact on the actual recognition of my grandmother. A study by Thomas, Van Hulle, and Vogels [(2002). Encoding of categories by noncategory-specific neurons in the inferior temporal cortex. Journal of Cognitive Neuroscience, 13, 190-200. doi:10.1162/089892901564252] found finely tuned, category-specific neurons in the inferior temporal cortex of monkeys, but also found that when these neurons were removed from their analysis, this had no effect on categorisation performance. Further, we have found no reported cases of the loss of recognition of single, highly familiar objects, which also argues for a lack of causal efficacy of grandmother-cell neurons.