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Evoked transmitter release depends upon calcium influx into synaptic boutons, but mechanisms regulating bouton calcium levels and spontaneous transmitter release are obscure. To understand these processes better, we monitored calcium transients in axons and presynaptic terminals of pyramidal neurons in hippocampal slice cultures. Action potentials reliably(More)
We have used confocal microscopy to monitor synaptically evoked Ca2+ transients in the dendritic spines of hippocampal pyramidal cells. Individual spines respond to single afferent stimuli (<0.1 Hz) with Ca2+ transients or failures, reflecting the probability of transmitter release at the activated synapse. Both AMPA and NMDA glutamate receptor antagonists(More)
The mechanisms by which long-term potentiation (LTP) is expressed are controversial, with evidence for both presynaptic and postsynaptic involvement. We have used confocal microscopy and Ca(2+)-sensitive dyes to study LTP at individual visualized synapses. Synaptically evoked Ca(2+) transients were imaged in distal dendritic spines of pyramidal cells in(More)
Under some conditions, synaptically released glutamate can exert long-range actions in the cortical microcircuitry. To what extent glutamate spillover leads to direct cross talk among individual synapses remains unclear. We recorded NMDAR-mediated EPSCs in acute hippocampal slices at 35 degrees C by stimulating two independent pathways that converge on the(More)
Synaptic activation is associated with rapid changes in intracellular Ca(2+), while the extracellular Ca(2+) level is generally assumed to be constant. Here, using a novel optical method to measure changes in extracellular Ca(2+) at high spatial and temporal resolution, we find that brief trains of synaptic transmission in hippocampal area CA1 induce(More)
Odor molecules are transduced by thousands of olfactory sensory neurons (OSNs) located in the nasal cavity. Each OSN expresses a single functional odorant receptor protein and projects an axon from the sensory epithelia to an olfactory bulb glomerulus, which is selectively innervated by only one or a few OSN types. We used whole-mount immunocytochemistry to(More)
Key aspects of the expression of long-term potentiation (LTP) and long-term depression (LTD) remain unresolved despite decades of investigation. Alterations in postsynaptic glutamate receptors are believed to contribute to the expression of various forms of LTP and LTD, but the relative importance of presynaptic mechanisms is controversial. In addition,(More)
During development, most neurons become polarized when one neurite, generally the longest, becomes the axon and the other neurites become dendrites. The physical mechanism responsible for such length-related differentiation has not been established. Here, we present a model of neuronal polarization based upon the existence of a "determinant chemical' whose(More)
Highly branched dendritic shapes are distinguishing characteristics of neurons and certain other cell types, but the physical mechanisms responsible for their formation are not well understood. Here, we model the growth of cells under the control of diffusible growth-regulating factors (morphogens such as calcium ion) whose local internal concentration(More)
The zebrafish olfactory system is an attractive model for studying neural processing of chemosensory information. Here we characterize zebrafish olfactory behaviors and their modification through learning, using an apparatus consisting of a circular flow-through tank that allows controlled administration of odorants. When exposed to the amino acids(More)