Abstract
Transmission at individual synaptic contacts on CA1 hippocampal pyramidal neurons has been found to be very unreliable, with greater than half of the arriving presynaptic nerve impulses failing to evoke a postsynaptic response. This conclusion has been reached using the method of minimal stimulation of Schaffer collaterals and whole cell recording in hippocampal slices; with minimal stimulation only one or a few synapses are activated on the target neuron and the behavior of individual synapses can be examined. Four sources for the unreliability of synaptic transmission have been investigated: (i) the fluctuation of axon thresholds at the site of stimulation causing the failure to generate a nerve impulse in the appropriate Schaffer collaterals, (ii) the failure of nerve impulses generated at the site of stimulation to arrive at the synapse because of conduction failures at axon branch points, (iii) an artifactual synaptic unreliability due to performing experiments in vitro at temperatures well below the normal mammalian body temperature, and (iv) transmission failures due to probabilistic release mechanisms at synapses with a very low capacity to release transmitter. We eliminate the first three causes as significant contributions and conclude that probabilistic release mechanisms at low capacity synapses are the main cause of unreliability of synaptic transmission.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
