Receptive fields of motor neurons underlying local tactile reflexes in the locust.

The receptive fields of motor neurons to a hind leg were mapped by recording intracellularly from their cell bodies or from the muscle fibers they innervate while stimulating mechanoreceptors on the surface of that leg. Each motor neuron is affected by a specific array of receptors that make up its receptive field. Boundaries along the anteroposterior or dorsoventral axes of the leg divide the receptive fields into excitatory and inhibitory regions.

The structure of locust nonspiking interneurones in relation to the anatomy of their segmental ganglion.

The morphology of eight nonspiking local interneurones in the metathoracic ganglion of the locust is described in relation to known tracts, commissures, regions of neuropile, and identified motor neurones. They are compared with the spiking local interneurones in the same ganglion. Each nonspiking local interneurone was injected intracellularly with cobalt, following characterization of its physiological effects on identified leg motor neurones.

Organization of receptive fields of spiking local interneurons in the locust with inputs from hair afferents.

The receptive fields of spiking local interneurons in the locust were defined by making intracellular recordings from them while stimulating mechanoreceptors on the surface of a hindleg. All the interneurons tested have their cell bodies near the ventral midline, in the so-called "midline" group. Those described here receive inputs only from external mechanoreceptors; others receive inputs from internal proprioceptors alone or from receptors of both kinds.

The morphological diversity and receptive fields of spiking local interneurons in the locust metathoracic ganglion.

Twenty-one types of spiking local interneurons are described in a segmental ganglion of the locust. All have their cell bodies in a group at the ventral midline of the metathoracic ganglion. The interneurons are characterized by their shape as revealed by intracellular injection of dye, and by their physiology as revealed by intracellular recording.

The morphology of two groups of spiking local interneurons in the metathoracic ganglion of the locust.

Two bilaterally symmetrical groups of spiking local interneurons are described in a segmental ganglion of the locust. Interneurons in both groups are excited by specific sets of sensory receptors on one leg. The cell bodies of the anterior-lateral group lie amongst approximately 40 small cell bodies at the anterior of the ganglion, close to the lateral edge of an anterior connective.

Spiking local interneurons as primary integrators of mechanosensory information in the locust.

A population of spiking local interneurons in the metathoracic ganglion of the locust is vigorously excited by particular sensory stimuli from the hindlegs and participates in local postural reflexes. We examined the inputs from singly innervated mechanoreceptors (hairs and campaniform sensilla) to these spiking local interneurons, to nonspiking local interneurons, and to motor neurons that are also elements of local reflex pathways. Recordings were made intracellularly from the interneurons and motor neurons and extracellularly from afferent fibers.