Parietal and premotor cortices of the macaque monkey contain distinct populations of neurons which, in addition to their motor discharge, are also activated by visual stimulation. Among these visuomotor neurons, a population of grasping neurons located in the anterior intraparietal area (AIP) shows discharge modulation when the own hand is visible during object grasping. Given the dense connect...

The precision with which motor neurons innervate target muscles depends on a regulatory network of Hox transcription factors that translates neuronal identity into patterns of connectivity. We show that a single transcription factor, FoxP1, coordinates motor neuron subtype identity and connectivity through its activity as a Hox accessory factor. FoxP1 is expressed in Hox-sensitive motor columns...

The motor innervation of the major flight muscles powering the fore- and hindwings of the cricket Teleogryllus oceanicus was investigated. The morphology of the motor neurons was determined by filling them via their axons in the periphery with either Lucifer Yellow or cobalt chloride followed by silver intensification. Details of the location of branches of motor neurons within the ganglion wer...

1. Command neurons for the pedal wave motor program (PWMP) that drives locomotion in Aplysia were examined electrophysiologically in the isolated nervous system. The cerebral ganglion contained a minimum of four command (type I) neurons that were excited by stimuli known to trigger locomotion in vivo and evoke its neural correlates in vitro. 2. Type I neurons fired during both spontaneous and s...

Locomotion in adult Drosophila depends on motor neurons that target a set of multifibered muscles in the appendages. Here, we describe the development of motor neurons in adult Drosophila, focusing on those that target the legs. Leg motor neurons are born from at least 11 neuroblast lineages, but two lineages generate the majority of these cells. Using genetic single-cell labeling methods, we a...

The original motivation for this study was the observation in previous human experiments that the motor neuron firing frequency (recorded from the motor units in the EMG) was lower at derecruitment than that at recruitment, with slow linearly varying voluntary contractions. Are the lower firing rates at derecruitment correlated with a change in the postspike afterhyperpolarization (AHP) after p...

REASONS FOR PERFORMING STUDY Equine motor neuron disease (EMND) was diagnosed in 3 horses maintained on lush, grass-based pasture. This contrasted with North American studies which identified limited or no access to green herbage as an important risk factor for EMND. HYPOTHESIS Grazing horses that have an apparently adequate intake of pasture herbage to meet normal equine vitamin E requiremen...

The purpose of this review was to examine three issues that limit our understanding of motor unit physiology: (1) the range and distribution of the innervation ratios in a muscle; (2) the association between discharge rate and force; and (3) the variation in motor unit activity across contractions that differ in speed and type. We suggest that if more data were available on these issues, the un...

Sensory-motor circuits in the spinal cord are constructed with a fine specificity that coordinates motor behavior, but the mechanisms that direct sensory connections with their motor neuron partners remain unclear. The dorsoventral settling position of motor pools in the spinal cord is known to match the distal-to-proximal position of their muscle targets in the limb, but the significance of in...

The axonal conduction velocity and the axonal refractory period were determined using electromyographic techniques for 60 single motor units in 11 patients with antecedent poliomyelitis. The results were compared with previous observations in healthy subjects as well as subjects with motor neuron disease. In antecedent poliomyelitis there was a reduced proportion of nerve fibres with low conduc...