Endogenous cannabinoids in the piriform cortex tune olfactory perception.

Sensory perception depends on interactions between external inputs transduced by peripheral sensory organs and internal network dynamics generated by central neuronal circuits. In the sensory cortex, desynchronized network states associate with high signal-to-noise ratio stimulus-evoked responses and heightened perception. Cannabinoid-type-1-receptors (CB1Rs) - which influence network coordination in the hippocampus - are present in anterior piriform cortex (aPC), a sensory paleocortex supporting olfactory perception.

Altered neural odometry in the vertical dimension.

Entorhinal grid cells integrate sensory and self-motion inputs to provide a spatial metric of a characteristic scale. One function of this metric may be to help localize the firing fields of hippocampal place cells during formation and use of the hippocampal spatial representation ("cognitive map"). Of theoretical importance is the question of how this metric, and the resulting map, is configured in 3D space.

Entorhinal Neurons Exhibit Cue Locking in Rodent VR.

The regular firing pattern exhibited by medial entorhinal (mEC) grid cells of locomoting rodents is hypothesized to provide spatial metric information relevant for navigation. The development of virtual reality (VR) for head-fixed mice confers a number of experimental advantages and has become increasingly popular as a method for investigating spatially-selective cells. Recent experiments using 1D VR linear tracks have shown that some mEC cells have multiple fields in virtual space, analogous to grid cells on real linear tracks.

An independent, landmark-dominated head-direction signal in dysgranular retrosplenial cortex.

We investigated how landmarks influence the brain's computation of head direction and found that in a bidirectionally symmetrical environment, some neurons in dysgranular retrosplenial cortex showed bidirectional firing patterns. This indicates dominance of neural activity by local environmental cues even when these conflicted with the global head direction signal. It suggests a mechanism for associating landmarks to or dissociating them from the head direction signal, according to their directional stability and/or utility.

Neural encoding of large-scale three-dimensional space-properties and constraints.

How the brain represents represent large-scale, navigable space has been the topic of intensive investigation for several decades, resulting in the discovery that neurons in a complex network of cortical and subcortical brain regions co-operatively encode distance, direction, place, movement etc. using a variety of different sensory inputs. However, such studies have mainly been conducted in simple laboratory settings in which animals explore small, two-dimensional (i.

Grid cells on steeply sloping terrain: evidence for planar rather than volumetric encoding.

Neural encoding of navigable space involves a network of structures centered on the hippocampus, whose neurons -place cells - encode current location. Input to the place cells includes afferents from the entorhinal cortex, which contains grid cells. These are neurons expressing spatially localized activity patches, or firing fields, that are evenly spaced across the floor in a hexagonal close-packed array called a grid.

Hippocampal neurons: simulating the spatial structure of a complex maze.

Hippocampal place neurons not only represent current location, but fire in sequences that appear to simulate past and future spatial trajectories. A recent study has found that the firing sequences match the structure of a complex maze, suggesting that the structure of the environment is encoded by the place system, perhaps to aid navigational planning.