Adult-born neurons facilitate olfactory bulb pattern separation during task engagement.

The rodent olfactory bulb incorporates thousands of newly generated inhibitory neurons daily throughout adulthood, but the role of adult neurogenesis in olfactory processing is not fully understood. Here we adopted a genetic method to inducibly suppress adult neurogenesis and investigated its effect on behavior and bulbar activity. Mice without young adult-born neurons (ABNs) showed normal ability in discriminating very different odorants but were impaired in fine discrimination.

Lack of Pattern Separation in Sensory Inputs to the Olfactory Bulb during Perceptual Learning.

Recent studies revealed changes in odor representations in the olfactory bulb during active olfactory learning (Chu et al., 2016; Yamada et al., 2017).

Balancing the Robustness and Efficiency of Odor Representations during Learning.

For reliable stimulus identification, sensory codes have to be robust by including redundancy to combat noise, but redundancy sacrifices coding efficiency. To address how experience affects the balance between the robustness and efficiency of sensory codes, we probed odor representations in the mouse olfactory bulb during learning over a week, using longitudinal two-photon calcium imaging. When mice learned to discriminate between two dissimilar odorants, responses of mitral cell ensembles to the two odorants gradually became less discrete, increasing the efficiency.

Dynamic sensory representations in the olfactory bulb: modulation by wakefulness and experience.

How are sensory representations in the brain influenced by the state of an animal? Here we use chronic two-photon calcium imaging to explore how wakefulness and experience shape odor representations in the mouse olfactory bulb. Comparing the awake and anesthetized state, we show that wakefulness greatly enhances the activity of inhibitory granule cells and makes principal mitral cell odor responses more sparse and temporally dynamic. In awake mice, brief repeated odor experience leads to a gradual and long-lasting (months) weakening of mitral cell odor representations.

MEGF10 and MEGF11 mediate homotypic interactions required for mosaic spacing of retinal neurons.

In many parts of the nervous system, neuronal somata display orderly spatial arrangements. In the retina, neurons of numerous individual subtypes form regular arrays called mosaics: they are less likely to be near neighbours of the same subtype than would occur by chance, resulting in 'exclusion zones' that separate them. Mosaic arrangements provide a mechanism to distribute each cell type evenly across the retina, ensuring that all parts of the visual field have access to a full set of processing elements.

Neurod6 expression defines new retinal amacrine cell subtypes and regulates their fate.

Most regions of the CNS contain many subtypes of inhibitory interneurons with specialized roles in circuit function. In the mammalian retina, the ∼30 subtypes of inhibitory interneurons called amacrine cells (ACs) are generally divided into two groups: wide/medium-field GABAergic ACs and narrow-field glycinergic ACs, which mediate lateral and vertical interactions, respectively, within the inner plexiform layer. We used expression profiling and mouse transgenic lines to identify and characterize two closely related narrow-field AC subtypes.

Retinal ganglion cells with distinct directional preferences differ in molecular identity, structure, and central projections.

The retina contains ganglion cells (RGCs) that respond selectively to objects moving in particular directions. Individual members of a group of ON-OFF direction-selective RGCs (ooDSGCs) detect stimuli moving in one of four directions: ventral, dorsal, nasal, or temporal. Despite this physiological diversity, little is known about subtype-specific differences in structure, molecular identity, and projections.