Temporal coding and rate remapping: Representation of nonspatial information in the hippocampus

AbstractHippocampal place cells represent nonspatial information through a process called rate remapping, which involves a change in the firing rate of a place cell without changes in its spatial specificity. However, many hippocampal phenomena occur on very short time scales over which long ‐term average firing rates are not an appropriate description of activity. To understand how rate remapping relates to fine‐scale temporal firing phenomena, we asked how rate remapping affected burst firing and trial‐to‐trial spike count variability. In addition, we looked at how rate remapp ing relates to the theta‐frequency oscillations of the hippocampus, which are thought to temporally organize firing on time scales faster than 100 ms. We found that theta phase coding was preserved through changes in firing rate due to rate remapping. Interestingly, rate remapping in CA1 in respon se to task demands preferentially occurred during the first half of the theta cycle. The other half of the theta cycle contained preferential expression of phase precession, a phenomenon associated with place cell sequences, in agreement with previous results. This difference of place cell coding du ring different halves of the theta cycle supports recent theoretical suggestions that different processes occur during the two halves of the theta cycle. The differentiation between the halves of the theta cycle was not clear in recordings from CA3 during rate remapping induced by task‐irrelevant sens...

Source: Hippocampus - November 22, 2018 Category: Neurology Authors: Honi Sanders, Daoyun Ji, Takuya Sasaki, Jill K. Leutgeb, Matthew A. Wilson, John E. Lisman Tags: RESEARCH ARTICLE Source Type: research