Lateral horn

The cell bodies of visceral motor neurons are found in the lateral horn. The axons of these neurons form efferent nerve fibers of the autonomic nervous system (ANS). The ANS innervates cardiac muscle, smooth muscle and glands (see Chapter 9). The axons of these neurons exit the spinal cord by way of the ventral root. 

Cell bodies in brainstem, lateral horn of spinal cord... 

The efferent pathways of the ANS consist of two neurons that transmit impulses from the CNS to the effector tissue. The preganglionic neuron originates in the CNS with its cell body in the lateral horn of the gray matter of the spinal cord or in the brainstem. The axon of this neuron travels to an autonomic ganglion located outside the CNS, where it synapses with a postganglionic neuron. This neuron innervates the effector tissue. 

The detection of serotonin in nervous and non-nervous tissue was aided by the development of the Falck-Hillarp histochemical technique, a method whereby freeze-dried sections of tissue, when exposed to formaldehyde vapour cause indoleamines to emit a yellow fluorescence. Dahlstrom and Fuxe used this technique to show that the highest concentration of serotonin in the brain is located in the raphe nuclei, projections from these cell bodies ascending to the forebrain via the medial forebrain bundle. Descending fibres were also shown to project to the dorsal and lateral horns and the intermediolateral column of the spinal cord. Detailed observation of the distribution of the serotonergic system in the brain became possible with... 

If a spinal cord is cross-sectioned, the gray matter appears as a roughly H-shaped area in its middle which is, divided into dorsal (posterior), lateral, and ventral (anterior) horns. The horns are interconnected by a crossbar, the gray commissure. The rest of the spinal cord is the white matter, made up largely of tracts of myelinated nerve fibers (axons). Ascending tracts carry afferent sensory impulses towards the brain, descending tracts transmit motor impulses from the brain to the motor neurons in the ventral or lateral horns of the gray matter. 

The axon wiring in the insect antennal lobe is anatomically and physiologically similar to that in the mammalian olfactory bulb. Insect ORNs target and synapse with two neurons projection neurons and GABA-mediated local intemeurons. Projection neurons are second-order olfactory intemeurons that transmit the information of odorants into the mushroom body calyx and lateral horn, which is the center for olfactory-related memory formation (Heisenberg... 

As detailed already, the olfactory system conveys odour information initially to the antennal lobe and then further via the projection neurons to the lateral horn and the mushroom bodies. From both these centres, premotor commands are thought to originate. The gustatory system, in contrast, carries sugar information to the suboesophageal ganglion, from where premotor commands likely can be triggered... 

Figure 2. Overall system context of the pheromone detection system in moths (shown in centre). AL is the antennal lobe, MB the mushroom bodies and, LH the lateral horn. This schematic shows the animal in an input/output diagram with respect to its environment.

To test this idea of symmetry breaking with lateral excitation, we have built a full size model of the locust olfactory system using Hodgkin-Huxley type model neurons for PNs, leaky integrate-and-fire neurons for KCs and a single Hodgkin-Huxley neuron to represent the global inhibition from lateral horn interneurons onto the KCs. The KCs... 

Kusunoki, S., Chiba, A., Hirabayashi, Y., Irie, F., Kotani, M., Kawashima, I., Tai, T, and Nagai, Y, 1993, Generation of a monoclonal antibody specific for a new class of minor ganglioside antigens, GQlba and GTlaa its binding to dorsal and lateral horn of human thoracic cord. Brain Research 623 83-88. 

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