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We describe a method for determining intracellular free calcium concentration ([Ca(2+)]) from single-wavelength fluorescence signals. In contrast to previous single-wavelength calibration methods, the proposed method does not require independent estimates of resting [Ca(2+)] but relies on the measurement of fluorescence close to indicator saturation during(More)
Cortical synaptic circuitry develops rapidly in the second postnatal week, simultaneous with experience-dependent turnover of dendritic spines. To relate the emergence of sensory maps to synaptogenesis, we recorded synaptic potentials evoked by whisker deflection in layer 2/3 neurons from postnatal day (P) 12 to 20. At P12, synaptic responses were(More)
Neuronal responses to ongoing stimulation in many systems change over time, or "adapt." Despite the ubiquity of adaptation, its effects on the stimulus information carried by neurons are often unknown. Here we examine how adaptation affects sensory coding in barrel cortex. We used spike-triggered covariance analysis of single-neuron responses to continuous,(More)
The thalamo-cortical pathway is the crucial sensory gateway into the cerebral cortex. We aimed to determine the nature of the tactile information encoded by neurons in the whisker somatosensory relay nucleus (VPm). We wanted to distinguish whether VPm neurons encode similar stimulus features, acting as a single information channel, or encode diverse(More)
Rats discriminate texture by whisking their vibrissae across the surfaces of objects. This process induces corresponding vibrissa vibrations, which must be accurately represented by neurons in the somatosensory pathway. In this study, we investigated the neural code for vibrissa motion in the ventroposterior medial (VPm) nucleus of the thalamus by(More)
In the cerebral cortex, pyramidal cells and interneurons are generated in distant germinal zones, and so the mechanisms that control their precise assembly into specific microcircuits remain an enigma. Here we report that cortical interneurons labeled at the clonal level do not distribute randomly but rather have a strong tendency to cluster in the mouse(More)
In rat barrel cortex, development of layer 2/3 receptive fields can be disrupted by sensory deprivation, with a critical period ending around postnatal day (PND) 14. To determine if experience-dependent plasticity of dendritic morphology could contribute to the reorganization of synaptic inputs, we analyzed dendritic structure in acute brain slices using(More)
The development of layer 2/3 sensory maps in rat barrel cortex (BC) is experience dependent with a critical period around postnatal days (PND) 10-14. The role of intrinsic response properties of neurons in this plasticity has not been investigated. Here we characterize the development of BC layer 2/3 intrinsic responses to identify possible sites of(More)
A fundamental problem in neuroscience, to which Prof. Segundo has made seminal contributions, is to understand how action potentials represent events in the external world. The aim of this paper is to review the issue of neural coding in the context of the rodent whiskers, an increasingly popular model system. Key issues we consider are: the role of spike(More)
Adaptive processes over many timescales endow neurons with sensitivity to stimulus changes over a similarly wide range of scales. Although spike timing of single neurons can precisely signal rapid fluctuations in their inputs, the mean firing rate can convey information about slower-varying properties of the stimulus. Here, we investigate the firing rate(More)