Biomaterial Database

Inhibitory interactions between spiking and nonspiking local interneurons in the locust. 1987

M Burrows

Department of Zoology, University of Cambridge, England.

Simultaneous intracellular recordings were made from pairs of spiking and nonspiking local interneurons in the metathoracic ganglion of the locust to search for interactions that might underlie tactile and proprioceptive reflexes of a leg. A spike in a spiking local interneuron is followed after a consistent latency (0.6 +/- 0.12 msec, mean +/- SD) by an IPSP in a particular nonspiking interneuron. The connection appears to be direct and chemically mediated. By contrast, manipulating the membrane potential of a nonspiking interneuron by injecting current through the recording electrode has no direct effect on a spiking local interneuron. The direct interactions between pairs of these local interneurons are thus one-way. If, however, the current injected into a nonspiking interneuron is sufficient to evoke a movement by exciting motor neurons, then the spiking interneuron can be excited or inhibited by the resulting reafference. The spiking local interneurons have excitatory regions in their receptive fields formed by arrays of exteroreceptors or by proprioceptors at specific joints. The inhibitory connections mean that the postsynaptic nonspiking interneurons have corresponding inhibitory regions to their receptive fields. Several spiking local interneurons with similar receptive fields may converge onto one nonspiking interneuron. Some nonspiking interneurons, however, have larger receptive fields than an individual spiking interneuron, again indicating convergence of inputs. The specificity of the inhibitory connections preserves the spatial representation of sensory information for use in particular reflexes. For example, touching hairs on the ventral femur evokes a reflex extension of the tibia. Spiking interneurons excited by these receptors inhibit a nonspiking interneuron that would cause the opposing and therefore unwanted flexion movement. Viewed in this behavioral context, the pattern of connections between the local interneurons forms the basis of the circuitry for the local reflex adjustments of posture and locomotion.

UI	MeSH Term	Description	Entries
D007395	Interneurons	Most generally any NEURONS which are not motor or sensory. Interneurons may also refer to neurons whose AXONS remain within a particular brain region in contrast to projection neurons, which have axons projecting to other brain regions.	Intercalated Neurons,Intercalated Neuron,Interneuron,Neuron, Intercalated,Neurons, Intercalated
D008297	Male		Males
D009433	Neural Inhibition	The function of opposing or restraining the excitation of neurons or their target excitable cells.	Inhibition, Neural
D009434	Neural Pathways	Neural tracts connecting one part of the nervous system with another.	Neural Interconnections,Interconnection, Neural,Interconnections, Neural,Neural Interconnection,Neural Pathway,Pathway, Neural,Pathways, Neural
D005260	Female		Females
D006110	Grasshoppers	Plant-eating orthopterans having hindlegs adapted for jumping. There are two main families: Acrididae and Romaleidae. Some of the more common genera are: Melanoplus, the most common grasshopper; Conocephalus, the eastern meadow grasshopper; and Pterophylla, the true katydid.	Acrididae,Locusts,Romaleidae,Grasshopper,Locust
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia