The discovery of grid cells in the medial entorhinal cortex (mEC) encouraged investigation of the effect of the mEC on the hippocampus. Large lesions of the entorhinal cortex reduced theta oscillations, decreased the fraction of hippocampal CA1 place cells, and affected various features of place field properties. This study performed combined optogenetic and pharmacogenetic local and upstream inactivation...

This study described robust oxytocinergic modulation of intrinsic properties and circuit operations in hippocampal area CA2. For this study, male mice were used for all experiments to avoid variation in oxytocin receptor (OXTR) expression throughout the estrous cycle of female mice. C57BL/6 mice were used in wild-type experiments, while homozygous Oxt-IRES-Cre and hemizygote Amigo2-Cre mice were used...

The medial septum is critical in theta generation by two possible mechanisms: a unitary ‘pacemaker’ timing signal is imposed on the hippocampal system or it may assist in organizing target subcircuits within the phase space of theta oscillations. Therefore, this study used temperature manipulation of the medial septum to test these models. Long Evans rats were implanted with silicon probes and tungsten...

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...

Polycomb repressive complexes (PRCs) are known for repressing transcription through histone modifications and chromatin compaction. The PRCs consist of two central protein complexes, PRC1 and PRC2, which are important for normal gene regulation and development. This study found that PRC1 is essential for the specification of segmentally restricted spinal motor neuron subtypes, while PRC2 activity is...

This study compared the interictal epileptiform discharges (IEDs) of human epilepsy patients from microwire hippocampal recording with those of Alzheimer’s disease (AD) transgenic mice with implanted multilayer hippocampal silicon probes. They investigated the local field potential properties of human IEDs recorded from mesial temporal lobe structures of patients with drug-resistant frontal and temporal...

GABAergic interneurons (INs) typically project their axons locally to regulate the excitability of nearby pyramidal cells and other INs. Recent studies on INs focused on subtypes distinguished by expression of Parvalbumin, Somatostatin, or Vasoactive Intestinal Peptide. However, a fourth group that includes neurogliaform cells (NGFCs) has been less well characterized due to a lack of genetic tools....

Alzheimer’s disease (AD) is characterized by abnormal aggregation of the proteins amyloid-β (Aβ). Recent studies showed that 40-Hz sensory stimulation is a potential treatment in AD. This study examined whether 40-Hz flickering light entrains gamma oscillations and suppresses Aβ in the brains of APP/PS1 and 5xFAD mouse models. For the study, they investigated the effect of 40-Hz light stimulation on...

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...

This study developed a ThermoMaze to understand neuronal mechanisms supporting exploratory and consummatory states. ThermoMaze is a behavioral paradigm that allows for the collection of large amounts of physiological data while the animal rests at distinct experimenter-controlled locations. For the study, mice were implanted with a thermistor in the hippocampus. After 5 days of postsurgical recovery,...