Interneuronal gap junctional coupling is a hallmark of neural development whose functional significance is poorly understood. We have characterized the extent of electrical coupling and dye coupling and patterns of gap junction protein expression in lumbar spinal motor neurons of neonatal rats. Intracellular recordings showed that neonatal motor neurons are transiently electrically coupled and ...

Motor function deteriorates with advancing age, increasing the risk of adverse health outcomes. While it is well established that skeletal muscles and neuromuscular junctions (NMJs) degenerate with increasing age, the effect of aging on α-motor neurons and their innervating synaptic inputs remains largely unknown. In this study, we examined the soma of α-motor neurons and innervating synaptic i...

Intersegmental interneurons in a mesothoracic population that receive inputs from extero- and proprioceptors on a middle leg of a locust (Laurent, 1987a) make direct synaptic connections with nonspiking local interneurons and motor neurons controlling the movements of the ipsilateral hindleg. Of 25 direct connections that were established, 80% are excitatory, and 60% are made with nonspiking in...

BACKGROUND Dopamine (DA) has long been known to have modulatory effects on vertebrate motor circuits. However, the types of information encoded by supraspinal DAergic neurons and their relationship to motor behavior remain unknown. RESULTS By conducting electrophysiological recordings from awake, paralyzed zebrafish larvae that can produce behaviorally relevant activity patterns, we show that...

Van Damme, P., L. Van Den Bosch, E. Van Houtte, G. Callewaert, and W. Robberecht. GluR2-dependent properties of AMPA receptors determine the selective vulnerability of motor neurons to excitotoxicity. J Neurophysiol 88: 1279–1287, 2002; 10.1152/jn.00163.2002. AMPA receptor-mediated excitotoxicity has been implicated in the selective motor neuron loss in amyotrophic lateral sclerosis. In some cu...

Sensory processing in the local bending reflex of the leech (Hirudo medicinalis) was studied by examining the input-output relations of the reflex. Sensory cells (P cells) were stimulated singly and in pairs and the responses of the longitudinal muscle motor neurons were recorded. Each pattern of single and paired P cell stimulation produced a unique pattern of motor neuron response. In general...

Neurofilaments (NFs) are the major intermediate filaments in most mature neurons. Genetic approaches have now proven that NFs are an essential determinant for radial growth of axons. NF phosphorylation most probably plays an important role in this function. Further, forced over-expression of NF subunits in transgenic mice yields NF misaccumulation in motor neurons and, subsequently, causes moto...

Motor cortex output is capable of considerable reorganization, which involves modulation of excitability within the cortex. Does such reorganization also involve changes beyond the cortex, at the level of throughput from single motor cortex neurons to muscle activity? We examined such throughput during a paradigm that provided incentive for enhancing functional connectivity from motor cortex ne...

We developed an isolation technique for motor neurons from adult rat spinal cord. Spinal cord enlargements were discretely microdissected into ventral horn tissue columns that were trypsin-digested and subjected to differential low-speed centrifugation to fractionate ventral horn cell types. A fraction enriched in alpha-motor neurons was isolated. Motor neuron enrichment was verified by immunof...

The motor pattern that drives each crayfish swimmeret consists of alternating bursts of impulses in power-stroke (PS) and return-stroke (RS) motor neurons. A model of the neural circuit that generates this pattern focused on connections between motor neurons themselves (Heitler, 1978, 1981). The model predicts that synergist motor neurons are electrically coupled, whereas antagonists make mostl...