Working memory, the ability to keep recently accessed information available for immediate manipulation, has been proposed to rely on two mechanisms that appear difficult to reconcile: self-sustained neural firing, or the opposite — activity-silent synaptic traces.
I will attempt to show that both phenomena can co-exist within a unified system in which neurons hold information in both activity and synapses.
One memory item is held by persistent activity in an attended or “focused” state, and is thus remembered better than other items.
Other, previously attended items can remain in memory but in the background, encoded in activity-silent synaptic traces.
The plastic attractors in the model provide a common mechanism accounting for a diversity of working memory phenomena that have been hitherto difficult to explain in a single theoretical framework.
I will review some of our previous behavioural and TMS studies demonstrating the predicted attentional effects in working memory, then I will present new data that tests some of the model's predictions.
Finally I will suggest an extension of the model to store and implement task rules, and formulate some strong neural predictions.