Conference on Cognitive Computational Neuroscience

It has recently been reported that representations of task goals in spatial navigation tasks are separated in time by locking to the theta rhythm. Here, we explore whether task demand influences the representation of non-spatial dimensions as well. We record spiking activity in the hippocampus of epilepsy patients, while they perform an associative memory task, and analyze whether representations of perceptual and semantic object dimensions in the spike trains are locked to the theta rhythm of the local field potential. We show that opposing non-spatial task dimensions are temporally separated in human hippocampus, by representing opposing goals at different theta phases, suggesting an important role of phase coding in associative memory.