Inference, neural replay and cognitive maps

Neural activity decoupled from current sensory input is thought to underpin memory, imagination, and planning. Such decoupled neuronal activity often takes the form of internally generated sequences, encoding trajectories through past or possible future states. This phenomenon has been most widely studied in rodent hippocampus, where place cells that normally encode an organism’s current position in space can spontaneously play out, in a fast time-compressed manner, sequences of other positions, referred to as neural replay. Using magnetoencephalography (MEG) it is now possible to non-invasively measure a similar phenomenon in the human brain, providing for the first time an index of human neural replay. My talk will outline this approach and then focus on how it has been informative with respect to understanding human cognitive function. This has enabled testing of sophisticated hypotheses regarding the precise contribution of replay to higher order human cognition, including its role in inference, planning and compositionality. Finally, in light of the latter, I will consider its likely contribution to psychopathology, focusing on findings from patients with schizophrenia.