Topic: distributed cortical representations

Reinstating details of previously seen stimuli given a recall cue is a common cognitive function. Studies suggest that such recollection involves hippocampus-mediated top-down reactivation of neural ensembles active during encoding, yet the neural mechanisms of such generative retrieval remain unknown. We formulate a biologically plausible hypothesis where transient cholinergic modulation, known to enhance backpropagated action potentials and trigger recall, initiates backward signals from sparse neurons discriminatively representing the cue to cortical areas encoding the trace. These signals