During insect metamorphosis the nervous system is reorganized to accommodate changes in behavior. In the hawkmoth, Manduca sexta, many identified larval motoneurons persist to innervate new adult muscles, while undergoing changes in dendritic morphology and synaptic connections. The thoracic leg motoneurons, for example, innervate different sets of muscles in the larva and adult and participate...

An assemblage of 110 individual tricipital motoneurons has been examined with the aim of determining those factors that predispose certain motoneurons to heteronymous response in post-tetanic potentiation. Motoneurons that respond most readily to homonymous volleys are not those that respond most readily to post-tetanically potentiated heteronymous volleys. Hence differences in presynaptic orga...

Synaptic connections between medullary expiratory neurons and phrenic motoneurons were studied in anesthetized cats using spike-triggered averaging of synaptic noise in phrenic motoneurons. Monosynaptic inhibition of phrenic motoneurons originating from the rostral medullary expiratory neurons of the Bötzinger complex was revealed. Neither mono- nor disynaptic inhibition from expiratory neurons...

The effects of stimulation of low-threshold proprioceptive afferents in the tibial nerve on two types of excitatory inputs to α-motoneurons were tested. The first input is formed by glutamatergic Ia sensory afferents contacting monosynaptically α-motoneurons. The second one is the cholinergic input originating from V0c-interneurons, located in lamina X of the spinal cord, modulating activity of...

Delaying clinical disease onset would greatly reduce neurodegenerative disease burden, but the mechanisms influencing early preclinical progression are poorly understood. Here, we show that in mouse models of familial motoneuron (MN) disease, SOD1 mutants specifically render vulnerable MNs dependent on endogenous neuroprotection signaling involving excitability and mammalian target of rapamycin...

In an attempt to integrate biological components with silicon-based devices and systems, artificial silane surfaces have been successfully used to grow motoneurons in a defined environment. In this study we characterized the morphology and electrophysiology of purified rat embryonic (E14) motoneurons grown on a self-assembled monolayer (SAM) of N-1[3-(trimethoxysilyl)propyl]diethylenetriamine (...

Reinnervation is needed to rescue muscle when motoneurons die in disease or injury. Embryonic ventral spinal cord cells transplanted into peripheral nerve reinnervate muscle and reduce atrophy, but low motoneuron survival may limit motor unit formation. We tested whether transplantation of a purified population of embryonic motoneurons into peripheral nerve (mean ± SE, 146,458 ± 4,011 motoneuro...

Monosynaptic connections to dorsal neck motoneurons of the cat from single afferents supplying primary endings of neck muscle spindles were studied using spike-triggered averaging techniques. Single-fiber EPSPs were detected in only 11 of the 112 afferent-motoneuron pairs examined. The average amplitude of single-fiber EPSPs recorded in motoneurons with a membrane potential of greater than -40 ...

Motoneurons seem to require contact with their target muscle even after embryogenesis is complete, but the consequences of target-deprivation during postnatal development are poorly understood. To examine the fate of motoneurons separated from their targets postnatally, we labeled the motoneurons that innervate the biceps brachii muscle with the retrograde tracer Fluorogold and then separated t...

Approximately half of the motoneurons generated during normal embryonic development undergo programmed cell death. Most of this death occurs during the time when synaptic connections are being formed between motoneurons and their target, skeletal muscle. Subsequent muscle activity stemming from this connection helps determine the final number of surviving motoneurons. These observations have gi...