Predictive grid coding in the medial entorhinal cortex.

The entorhinal cortex represents allocentric spatial geometry and egocentric speed and heading information required for spatial navigation. However, it remains unclear whether it contributes to the prediction of an animal's future location. We discovered grid cells in the medial entorhinal cortex (MEC) that have grid fields representing future locations during goal-directed behavior.

Replays of socially acquired information in the hippocampus.

Replays of place cell sequences in the hippocampus are thought to underlie memory consolidation for spatial learning. In this issue of Neuron, Mou et al. show that not only self-running but also social observation experiences promote awake remote replays for planning future journeys.

Quick visualization of neurons in brain tissues using an optical clearing technique.

Neurons are classified into several morphological types according to the locations of their somata and the branching patterns of their axons and dendrites. Recent studies suggest that these morphological features are related to their physiological properties, including firing characteristics, responses to neuromodulators, and wiring patterns. Therefore, rapid morphological identification of electrophysiologically recorded neurons promises to advance our understanding of neuronal circuits.

GABAergic inhibition reduces the impact of synaptic excitation on somatic excitation.

The effect of excitatory synaptic input on the excitation of the cell body is believed to vary depending on where and when the synaptic activation occurs in dendritic trees and the spatiotemporal modulation by inhibitory synaptic input. However, few studies have examined how individual synaptic inputs influence the excitability of the cell body in spontaneously active neuronal networks mainly because of the lack of an appropriate method. We developed a calcium imaging technique that monitors synaptic inputs to hundreds of spines from a single neuron with millisecond resolution in combination with whole-cell patch-clamp recordings of somatic excitation.