This study examined how incorporation of synthetic hippocampal signals is constrained by pre-existing circuit dynamics. For this study, they optogenetically stimulated small groups of CA1 neurons as mice traversed a chosen segment of a linear track, which mimicked the emergence of place fields. Mice were trained to run laps on a linear track to retrieve water reward at each end. Before implantation,...

Medial septum (MS) is important for theta generation by either a unitary pacemaker timing signal imposed on the hippocampal system or assisting in organizing target subcircuits within the phase space of theta oscillations. Therefore, this study used temperature manipulation of the MS to test these models. Long Evens rats were water restricted for 22 hours and trained to perform the behavioral task...

Several spatial coding mechanisms are known to coexist in the hippocampus. However, how are they influenced by various environmental features is still unclear. This study investigated the spatial coding characteristics of hippocampal neurons in mice and rats navigating in different environments. C57BL/6 mice and Long-Evans rats were used in this study. For both mice and rats, most CA1 cells were recorded...

Hippocampus plays a key role in navigation guided by environmental inputs. However, a critical aspect of navigation is a sequence of planned and coordinated actions. This study investigated the role of action in the neuronal organization of the hippocampus by training rats to jump a gap on a linear track. For this study, Long-Evans rats were used for recording local field potentials and ensembles of...

Place cells receive a disparate collection of excitatory and inhibitory currents that provide them with spatially selective discharges and rhythmic activity. This study combined intracellular and extracellular recordings with computational modeling and optogenetic or chemogenetic manipulations to examine the influence of inhibitory and excitatory inputs on CA1 pyramidal cell responses. For this study,...

Hippocampal activity supports internal representation of learned experiences and contexts, which allows individuals to form long-term memories. This study investigated hippocampal maps formed under structured attention with learning rules stabilize and maintain task-selectivity during memory recall. They used longitudinal two-photon imaging of hundreds of hippocampal CA1 pyramidal neurons while mice...

This study investigated the subthreshold dynamics using optogenetic depolarizing pulses in hippocampal neuronal assemblies in freely moving mice to understand how excitatory and inhibitory inputs are integrated by neurons. For the study, they recorded and examined large numbers of CA1 pyramidal neurons simultaneously in freely moving CamKIIα-Cre::Ai32 mice. This dataset contains electrophysiology and...

Previous studies indicated that the fraction of splitter fields is affected by the delay between responses in a spatial alternation task. This study demonstrated that memory and place field features of both pyramidal cells and interneurons in the hippocampus are interchangeable. They trained two groups of mice with and without delays in one or two environments and examined firing characteristics of...