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Do new synapses form in the adult cortex to support experience-dependent plasticity? To address this question, we repeatedly imaged individual pyramidal neurons in the mouse barrel cortex over periods of weeks. We found that, although dendritic structure is stable, some spines appear and disappear. Spine lifetimes vary greatly: stable spines, about 50% of(More)
Dendritic spines were imaged over days to months in the apical tufts of neocortical pyramidal neurons (layers 5 and 2/3) in vivo. A fraction of thin spines appeared and disappeared over a few days, while most thick spines persisted for months. In the somatosensory cortex, from postnatal day (PND) 16 to PND 25 spine retractions exceeded additions, resulting(More)
Although many genes predisposing to autism spectrum disorders (ASD) have been identified, the biological mechanism(s) remain unclear. Mouse models based on human disease-causing mutations provide the potential for understanding gene function and novel treatment development. Here, we characterize a mouse knockout of the Cntnap2 gene, which is strongly(More)
To understand the cellular and circuit mechanisms of experience-dependent plasticity, neurons and their synapses need to be studied in the intact brain over extended periods of time. Two-photon excitation laser scanning microscopy (2PLSM), together with expression of fluorescent proteins, enables high-resolution imaging of neuronal structure in vivo. In(More)
Monocular deprivation during early postnatal development remodels the circuitry of the primary visual cortex so that most neurons respond poorly to stimuli presented to the deprived eye. This rapid physiological change is ultimately accompanied by a matching anatomical loss of input from the deprived eye. This remodeling is thought to be initiated at the(More)
Early sensory experience instructs the maturation of neural circuitry in the cortex. This has been studied extensively in the primary visual cortex, in which loss of vision to one eye permanently degrades cortical responsiveness to that eye, a phenomenon known as ocular dominance plasticity (ODP). Cortical inhibition mediates this process, but the precise(More)
Microelectrode recordings and optical imaging of intrinsic signals were used to define the critical period for susceptibility to monocular deprivation (MD) in the primary visual cortex of the ferret. Ferrets were monocularly deprived for 2, 7 or >14 d, beginning between postnatal day 19 (P19) and P110. The responses of visual cortical neurons to stimulation(More)
Schwann cells (SCs) that cap neuromuscular junctions (nmjs) play roles in guiding nerve terminal growth in paralyzed and partially denervated muscles; however, the role of these cells in the day-to-day maintenance of this synapse is obscure. Neuregulins, alternatively spliced ligands for several erbB receptor tyrosine kinases, are thought to play important(More)
Visual experience begins at eye opening, but current models consider cortical circuitry to be resistant to experience-dependent competitive modification until the activation of a later critical period. Here we examine this idea using optical imaging to map the time course of receptive field refinement in normal mice, mice in which the contralateral eye(More)
We found that in mice, following eye opening, fast-spiking, parvalbumin-positive GABAergic interneurons had well-defined orientation tuning preferences and that subsequent visual experience broadened this tuning. Broad inhibitory tuning was not required for the developmental sharpening of excitatory tuning but did precede binocular matching of excitatory(More)