The Miller Lab

Matsushima and Tanaka compared neural correlates of spatial working memory for locations within the same hemifield or across hemifields.  When the two remembered locations were in the same hemifield (right or left side of vision), the neural response in the prefrontal cortex was intermediate to the two cues presented alone.  When the cues were across hemifields, the neural response was the same as the preferred cue presented alone.  In other words, remembered locations within a hemifield seemed to be in competition with each other whereas locations across the hemifields seemed to be have no interaction at all.  In yet other words, it was as if the (intact) monkeys had their brains split down the middle. The authors concluded local inhibitory interactions between cues within, but not across, hemifields.

This confirms Buschman et al (2011) who found that independent capacities for visual working memory in the right and left hemifields.

Further reading:
Buschman,T.J., Siegel, M., Roy, J.E. and Miller, E.K. (2011) Neural substrates of cognitive capacity limitations. Proceedings of the National Academy of Sciences. 108(27):11252-5. View PDF »