The Miller Lab

In this paper, Miller Lab alumnus Andreas Nieder tested neurons in the prefrontal cortex while animals switched between performing “greater than” vs “less than” rules on either spatial or numerical values.  A majority of the engaged neurons were selective for either the spatial or numerical judgments.  However, a significant proportion of neurons were “generalists” in the sense that they coded both types magnitude judgments.
Eiselt and Nieder (2013) Journal of Neuroscience

This supports a growing body of evidence that many neurons in higher-level cortex  can participate in different functions.  Like LIP neurons that categorize both motion and objects (Fitzgerald et al, Nature Neurosciene, 2011), these neurons were cognitive generalists that can participate in different  magnitude judgments. We have shown that the proportion of specialists vs generalists neurons in the PFC depends on task demands.  If the two category problems are disssimilar (cats vs dog and sport cars vs sedans) and can’t be confused, the majority of PFC neurons were generalists..  If instead, the category problems are similar and can easily be confused (categorizing the same set of animals in two different ways), the modal group of PFC neurons were specialists.  It is as if the PFC was orthogonalizing the two potentially confusable categories to reduce errors.  This shows that the PFC is highly sensitive to top-down demands, more so than bottom-up information, and can adapt the way it represents information to meet current cognitive demands.

For further reading, see:
Cromer, J.A., Roy, J.E., and Miller, E.K. (2010) Representation of multiple, independent categories in the primate prefrontal cortex. Neuron, 66: 796-807. View PDF »
Roy, J.E., Riesenhuber, M., Poggio, T., and Miller, E.K. (2010) Prefrontal cortex activity during flexible categorization. Journal of Neuroscience, 30:8519-8528. View PDF »