Divergent recruitment of developmentally defined neuronal ensembles supports memory dynamics.

Memories are dynamic constructs whose properties change with time and experience. The biological mechanisms underpinning these dynamics remain elusive, particularly concerning how shifts in the composition of memory-encoding neuronal ensembles influence the evolution of a memory over time. By targeting developmentally distinct subpopulations of principal neurons, we discovered that memory encoding resulted in the concurrent establishment of multiple memory traces in the mouse hippocampus.

Distinct Mechanisms for Visual and Motor-Related Astrocyte Responses in Mouse Visual Cortex.

Astrocytes are a major cell type in the mammalian nervous system, are in close proximity to neurons, and show rich Ca activity thought to mediate cellular outputs. Astrocytes show activity linked to sensory [1, 2] and motor [3, 4] events, reflecting local neural activity and brain-wide neuromodulatory inputs. Sensory responses are highly variable [5-10], which may reflect interactions between distinct input types [6, 7, 9].

Sparse orthogonal population representation of spatial context in the retrosplenial cortex.

Sparse orthogonal coding is a key feature of hippocampal neural activity, which is believed to increase episodic memory capacity and to assist in navigation. Some retrosplenial cortex (RSC) neurons convey distributed spatial and navigational signals, but place-field representations such as observed in the hippocampus have not been reported. Combining cellular Ca imaging in RSC of mice with a head-fixed locomotion assay, we identified a population of RSC neurons, located predominantly in superficial layers, whose ensemble activity closely resembles that of hippocampal CA1 place cells during the same task.

Mesoscale Architecture Shapes Initiation and Richness of Spontaneous Network Activity.

Spontaneous activity in the absence of external input, including propagating waves of activity, is a robust feature of neuronal networks and The neurophysiological and anatomical requirements for initiation and persistence of such activity, however, are poorly understood, as is their role in the function of neuronal networks. Computational network studies indicate that clustered connectivity may foster the generation, maintenance, and richness of spontaneous activity. Since this mesoscale architecture cannot be systematically modified in intact tissue, testing these predictions is impracticable Here, we investigate how the mesoscale structure shapes spontaneous activity in generic networks of rat cortical neurons In these networks, neurons spontaneously arrange into local clusters with high neurite density and form fasciculating long-range axons.