Action potentials reliably invade axonal arbors of rat neocortical neurons

Cox, C. L., Denk, W., Tank, D. W., Svoboda, K. (August 2000) Action potentials reliably invade axonal arbors of rat neocortical neurons. Proceedings of the National Academy of Sciences of the United States of America, 97 (17). pp. 9724-9728. ISSN 0027-8424

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Abstract

Neocortical pyramidal neurons have extensive axonal arborizations that make thousands of synapses. Action potentials can invade these arbors and cause calcium influx that is required for neurotransmitter release and excitation of postsynaptic targets. Thus, the regulation of action potential invasion in axonal branches might shape the spread of excitation in cortical neural networks. To measure the reliability and extent of action potential invasion into axonal arbors, we have used two-photon excitation laser scanning microscopy to directly image action-potential-mediated calcium influx in single varicosities of layer 2/3 pyramidal neurons in acute brain slices. Our data show that single action potentials or bursts of action potentials reliably invade axonal arbors over a range of developmental ages (postnatal 10-24 days) and temperatures (24 degrees C-30 degrees C). Hyperpolarizing current steps preceding action potential initiation, protocols that had previously been observed to produce failures of action potential propagation in cultured preparations, were ineffective in modulating the spread of action potentials in acute slices. Our data shaw that action potentials reliably invade the axonal arbors of neocortical pyramidal neurons. Failures in synaptic transmission must therefore originate downstream of action potential invasion. We also explored the function of modulators that inhibit presynaptic calcium influx. Consistent with previous studies, we find that adenosine reduces action-potential-mediated calcium influx in presynaptic terminals. This reduction was observed in all terminals tested, suggesting that some modulatory systems are expressed homogeneously in most terminals of the same neuron.

Item Type:	Paper
Uncontrolled Keywords:	CENTRAL-NERVOUS-SYSTEM SHORT-TERM ENHANCEMENT ROOT GANGLION-CELLS PRESYNAPTIC INHIBITION CALCIUM TRANSIENTS CORTICAL-NEURONS K+ CHANNELS PROPAGATION HIPPOCAMPUS CULTURE
Subjects:	organs, tissues, organelles, cell types and functions > tissues types and functions > axon > axon arbors organs, tissues, organelles, cell types and functions > tissues types and functions > neural networks organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons > pyramidal neurons organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons > pyramidal neurons organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons > pyramidal neurons
CSHL Authors:	Svoboda, Karel
Communities:	CSHL labs > Svoboda lab
Depositing User:	Matt Covey
Date:	August 2000
Date Deposited:	31 Jan 2014 20:26
Last Modified:	10 Sep 2019 19:17
PMCID:	PMC16932
Related URLs:	Publisher
URI:	https://repository.cshl.edu/id/eprint/29345

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