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Intrinsic noise at synapses between a wing hinge stretch receptor and flight motor neurons in the locust

Lookup NU author(s): Dr Peter Simmons


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Variability in postsynaptic potential (PSP) amplitude due to intrinsic noise limits the reliability of communication between neurons. I measured PSP variability at synapses between a forewing stretch receptor and wing depressor motor neurons in locusts, a pathway that is important in the control of flying. The intrinsic noise in the stretch receptor output synapse was measured by subtracting the background noise, originating in other synaptic pathways onto the motor neuron, from the variability in the amplitudes of PSPs evoked by the stretch receptor. Intrinsic synaptic noise caused successive PSPs to vary by 4-10 % in basalar and subalar flight motor neurons. Recordings from pairs of these wing depressor motor neurons showed that the amount of transmitter released varied independently between different output sites from the stretch receptor. Histograms of excitatory postsynaptic potential amplitude were normal distributions that lacked separate peaks. I estimate that quantal amplitude is significantly less than 0.1 mV and that several hundred quanta are released for each presynaptic spike. This accords well with a previous estimate of the number of discrete anatomical synapses and would facilitate modulation of output from the stretch receptor.

Publication metadata

Author(s): Simmons PJ

Publication type: Article

Publication status: Published

Journal: Journal of Experimental Biology

Year: 2001

Volume: 204

Issue: 1

Pages: 127-138

ISSN (print): 0022-0949

ISSN (electronic): 1477-9145

Publisher: The Company of Biologists Ltd

PubMed id: 11104716


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