Peters et al used functional imaging in humans to examine the effects of the contents of working memory on extrastriate visual cortex. Subjects performed a visual search task. The target item in working memory enhanced processing of a matching visual input whereas other “accessory” items held in working memory suppressed extrastriate activity. These dual effects may help focus on relevant tasks while avoiding distractions.
-
Everybody knows that we can only hold a limited number of things in mind simultaneously. Is this capacity limit due to a limited number of “slots” in working memory or due a limited resource pool that is divided among the items held in mind? We found evidence for both (Buschman et al, 2011). Now, Roggeman et al use computational modeling to provide further evidence for a hybrid model for capacity limits of working memory.
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 » -
An article in MIT’s Technology Review magazine about our work on how multitasking “mixed selectivity” neurons may be key for cognition.
Do-It-All Neurons – A key to cognitive flexibility by Anne Trafton -
A review of the groundbreaking work of Patricia Goldman-Rakic by Amy Arnsten
-
Lopour et al report evidence for phase coding in the human temporal lobe. They recorded local field potentials (LFPs) in patients during performance of a card matching task. Classification of correct/incorrect responses was better when LFP phase was taken into account. The phases aligned just before the the two cards were compared and then diverged to code the response.
-
Dipoppa and Gutkin propose a model of working memory in which gamma-beta oscillations gates access, theta oscillations protects working memory from distractions, and alpha oscillations clears out old memories.
This is consistent with our observations that beta helps from ensembles for rules held in working memory while alpha clears out a dominant ensemble so that a weaker one can be used:
Buschman, T.J., Denovellis, E.L., Diogo, C., Bullock, D. and Miller, E.K. (2012) Synchronous oscillatory neural ensembles for rules in the prefrontal cortex. Neuron, 76: 838-846. View PDF