Amygdaloid nucleus: new afferent input from the vomeronasal organ.

Terminal degeneration stained by the Fink-Heimer technique was found in the medial and cortical amygdaloid nuclei in a discrete zone after lesions were inflicted in the accessory olfactory bulb but not after lesions were made in the main olfactory bulb in the rabbit. Since the accessory olfactory bulb receives the endings of the vomeronasal nerve, the mediocortical complex of the amygdala is the central projection area for the vomeronasal sensory organ. The vomeronasal organ is seen as having new potential significance in sexual and feeding behavior because the cortical amygdaloid nucleus projects to the anterior, medial hypothalamus and the ventromedial nucleus.

Distribution of primary afferent fibers within the sacrococcygeal dorsal horn: an autoradiographic study.

The spinal segmental distribution and intersegmental course of primary afferent fibers were studied by injecting (by pressure or iontophoresis) tritiated amino acids (L-proline or L-leucine) into spinal ganglia of coccygeal and sacral segments and autoradiographically analyzing histological sections of the spinal cord, particularly those regions lying dorsal to the central canal. The results from eight cats and three monkeys are described. A heavy projection of primary afferent fibers to the marginal zone (lamina I), the substantia gelatinosa Rolandi (lamina II), and throughout the nucleus proprius (laminae III-IV) was demonstrated. The projections to these three areas appeared to be substantially independent. Primary afferent fibers were found to course rostrally and caudally within the marginal zone, in the midline dorsal to the central canal, in Lissauer's tract, and in the dorsal columns. A crossed projection passed by way of the dorsal commissure to the contralateral marginal zone and to a region ventrolateral to the contralateral nucleus proprius. There was a distinct medial-to-lateral shift in the termination of primary afferent fibers in the substantia gelatinosa and in the dorsal portion of the nucleus proprius. The most medial distribution occurred immediately caudal to the entry zone of the primary afferent fibers, and the most lateral at the cephalad end of the segment immediately rostral to the entry level. Small (iontophoretic) injections revealed circumscribed fields of termination, approximately 40 micrometers by 70 micrometers (dorsoventrally) by 400 micrometers or more (rostrocaudally) in the substantia gelatinosa.

The projection of the lateral geniculate nucleus to area 18.

The present study is concerned with the projection of the lateral geniculate nucleus onto cortical area 18. Horseradish peroxidase (HRP) was injected into area 18 of 15 cats. Drawings were made to determine the location of the injection site and the distribution of labeled neurons in the lateral geniculate nuclei of each cat. The local retinotopic maps constructed prior to the injections and the reconstructions of the lateral geniculate nucleus were used to determine the location and the extent of each of the HRP injections. In 15 of the 25 hemispheres studied, the ratio of the number of HRP-labeled neurons in lamina A relative to the number of labeled neurons in lamina A1 was calculated. This ratio varied from 1.06 to 0.28, indicating that at least some regions of area 18 are dominated by inputs from lamina A1. However, if the HRP-labeled neurons in lamina C are included in the counts for lamina A, then the ratio A+C/A1 has a mean of 1.11, suggesting that area 18 receives a balanced input, with inputs from the contralateral eye being relayed through laminae A and C, and inputs from the ipsilateral eye being relayed through lamina A1. When the distribution of HRP-labeled neurons in lamina A was plotted onto a dorsal view of the lateral geniculate nucleus, the labeled neurons formed an ellipse with the long axis of the ellipse oriented parallel to the isoelevation lines. The representation of azimuth is compressed in area 18 relative to the lateral geniculate nucleus. In six hemispheres the injections were restricted to a few layers of the area 18. Following small injections into layer IV of area 18, the HRP-labeled neurons occupied an extensive region of the lateral geniculate nucleus, indicating a considerable amount of convergence of the inputs to area 18. In hemispheres where the injections were restricted to layers I and II, labeled neurons were only seen in the medial interlaminar nucleus and the C laminae.

Mystacial vibrissae representation within the trigeminal sensory nuclei of the cat.

Somatotopic arrangements of axon terminals of primary afferent fibers innervating follicles of the mystacial vibrissae were examined in the cat by the transganglionic horseradish peroxidase (HRP) method. Forty to 60 hours after injecting HRP into a single or a group of vibrissal follicles, transported HRP was visualized by the tetramethylbenzidine technique. HRP-labeled axon terminals were distributed in the ventral subnucleus of the principal sensory trigeminal nucleus (ventral Vp), in the oral and interpolar spinal trigeminal nuclei (Vo and Vi), and in the caudal spinal trigeminal nucleus (Vc) (layer I, deep part of layer II, layers III-V) with its spinal extension into the dorsal horn of the first cervical cord segment (rostral C1). In cross sections through the caudal parts of the ventral Vp, Vi, and layer IV of the Vc and rostral C1, a single mystacial vibrissa was represented in a one-to-one fashion by a patch of dense terminal arbors of primary afferent fibers. The more dorsally a horizontal row of the mystacial vibrissae was located, the more ventrally was it represented in the ventral Vp, the more ventrolaterally in the Vi, and the more ventrally in layer IV of the Vc and the rostral C1. In addition, the more anteriorly a vibrissa was located in a horizontal row of the mystacial vibrissae, the more medially was it represented in the ventral Vp, the more ventromedially in the Vi, and the more laterally in layer IV of the Vc and rostral C1; the most posteriorly located vibrissae in the horizontal rows of the mystacial vibrissae were represented along the lateral border of the ventral Vp and Vi, and most medially in layer IV of the Vc and rostral C1. Thus, the representation pattern in the ventral Vp was rotated clockwise at about 45 degrees angle in the Vi, and projected as a mirror image in layer IV of the Vc and rostral C1. It was also indicated that the anterior-posterior arrangement of the mystacial vibrissae was represented in a rostral-caudal organization within layer IV of the Vc and rostral C1. It was also indicated that the anterior-posterior arrangement of the mystacial vibrissae was represented in a rostral-caudal organization within layer IV of the Vc and rostral C1. Patchy patterns probably replicating the distribution of the vibrissae on the face of the cat were also revealed by the cytochrome oxidase histochemical staining in cross sections through the caudal parts of the ventral Vp, Vi, and layer IV of the Vc and rostral C1.

The sympathetic and sensory components of the caudal lumbar sympathetic trunk in the cat.

The cell bodies of the lumbar sensory and sympathetic pre- and postganglionic neurons that project in the caudal lumbar sympathetic trunk of the cat have been labeled retrogradely with horseradish peroxidase applied to the central end of their cut axons. The application was made just proximal to the segmental ganglion that sends its gray rami to the L7 spinal nerve, and so identified the sympathetic outflow concerned primarily with the vasculature of the hindlimb and tail. The numbers, segmental distribution, location, and size of the labeled somata have been determined quantitatively. Labeled cell bodies were found ipsilaterally, but the segmental distributions of the different cell types were not matched. Afferent cell bodies lay in dorsal root ganglia L1-L5 (maximum L4), preganglionic cell bodies in spinal segments T10-L5 (maximum L2/3), and postganglionic cell bodies in ganglia L2-L5 (maximum L5). Both numbers and dimensions of labeled dorsal root ganglion cells were variable between experiments (maximum about 1,000); the majority were small relative to the entire population of sensory neurons. Labeled preganglionic cell bodies were located right across the intermediate region of the spinal cord, extending from the lateral part of the dorsolateral funiculus to the central canal. The highest density of labeled neurons lay at the border between the white and gray matter (corresponding to the intermediolateral cell column) with smaller proportions medially in L1-L2, and laterally in caudal L4-L5. Medial preganglionic neurons were generally larger than those lying in lateral positions. From the data, it is estimated that about 650 afferent, about 4,500 preganglionic, and some 2,500 postganglionic neurons project in each lumbar sympathetic trunk distal to the ganglion L5 in the cat.

Responses of bulbospinal and laryngeal respiratory neurons to hypercapnia and hypoxia.

The purpose was to evaluate activities of medullary respiratory neurons during equivalent changes in phrenic discharge resulting from hypercapnia and hypoxia. Decerebrate, cerebellectomized, paralyzed, and ventilated cats were used. Vagi were sectioned at left midcervical and right intrathoracic levels caudal to the origin of right recurrent laryngeal nerve. Activities of phrenic nerve and single respiratory neurons were monitored. Neurons exhibiting antidromic action potentials following stimulations of the spinal cord and recurrent laryngeal nerve were designated, respectively, bulbospinal or laryngeal. The remaining neurons were not antidromically activated. Hypercapnia caused significant augmentations of discharge frequencies for all neuronal groups. Many of these neurons had no change or declines of activity in hypoxia. We conclude that central chemoreceptor afferent influences are ubiquitous, but excitatory influences from carotid chemoreceptors are more limited in distribution among medullary respiratory neurons. Hypoxia will increase activities of neurons that receive sufficient excitatory peripheral chemoreceptor afferents to overcome direct depression by brain stem hypoxia. The possibility that responses of respiratory muscles to hypoxia are programmed within the medulla is discussed.

Carbonic anhydrase and horseradish peroxidase: double labelling of rat dorsal root ganglion neurons innervating motor and sensory peripheral nerves.

Dorsal root ganglion neurons supplying peroneus longus, soleus and gastrocnemius medius muscles and the sural nerve of the rat were labelled with horseradish peroxidase and analysed for their carbonic anhydrase content. Staining of the sections was done either on the same or on alternate slides. Both methods led to the same results, despite a slight fading of the carbonic anhydrase reaction in double-stained sections. The data indicated that the muscles under study were supplied by approximately the same number of horseradish peroxidase-labelled cells, irrespective of their differences in size. 74.9% of these labelled neurons had diameters exceeding 30 microns and 52.4% of them also stained for carbonic anhydrase. The double-labelled cells represented 66.9% of the population of large neurons (greater than 30 microns) and comprised most of those measuring over 47.5 microns. Richness in carbonic anhydrase of the large muscle afferent neurons may be linked to their innervation of the stretch receptors, as components of an active apparatus which includes the gamma motor axons which also stain positively for carbonic anhydrase. In contrast, the ganglion cells supplying the sural nerve were almost totally devoid of carbonic anhydrase, as only 6.4% showed double labelling. This contingent possibly represents the muscle afferents of the small motoneural population which supplies, through this nerve, part of the foot musculature of the rat.

1,25(OH)2 vitamin D3 sites of action in spinal cord and sensory ganglion.

Autoradiographic studies revealed concentration of 3H 1,25(OH)2 vitamin D3 in nuclei of certain neurons in the spinal cord of adult and neonatal mice, fed a normal or a vitamin D deficient diet. Nuclear uptake and retention was strongest in motor neurons in lamina IX. Nuclear concentration also existed in neurons of lamina II, lamina VIII, lamina X and intermediate nucleus of the lateral column. The results indicate that these neurons are target neurons which contain nuclear receptors for 1,25(OH)2 vitamin D3. This suggests that 1,25(OH)2 vitamin D3 has direct genomic actions on the innervation of skeletal muscle by exerting related trophic, secretory, and electrophysiological effects. In addition, these data point to direct genomic actions of 1,25(OH)2 vitamin D3 on spinal sensory perception, and on certain autonomic functions. Nuclear binding in certain neurons in the peripheral ganglion of the trigeminal nerve further suggests that sensory perception is influenced by 1,25(OH)2 vitamin D3 not only at the level of the substantia gelatinosa, but also at the level of spinal ganglia.

Nerve supply of the human knee and its functional importance.

This investigation utilized gross dissections, histological preparations, and neurophysiologic experiments to gain an improved understanding of the innervation of the human knee. Anatomical illustrations represent the findings of dissections of 15 fresh amputation specimens. Neurohistologic preparations using silver staining techniques demonstrate the rich innervation of the soft tissues of the knee, and a variety of specialized receptors are identified. In 10 subjects with normal knees, and experimentally produced knee effusion of 60 cc was found to result in profound inhibition of reflexly evoked quadriceps contraction. Clinical implications of the anatomical and physiologic data are discussed.

Pain: its physiology and rationale for management. Part I. Neuroanatomical substrate of pain.

Pain, one of man's most worrisome afflictions, is also one of neurobiology's most challenging problems. Even its definition is beset with controversy. The origin and current resolution of this controversy are presented in this paper, but the major purpose of Part I is to review the anatomical substrate of the peripheral and central nervous systems involved in pain. Structural and functional characteristics of pain receptors and their afferent fibers are described, with emphasis upon current hypotheses regarding putative neural transmitters and possible mechanisms for signal transduction. Hitherto unrecognized details of the cytoarchitecture, anatomical organization, and circuitry of the dorsal horns are reviewed. The paper concludes with a consideration of the major components of the ascending and descending systems of subserving pain.

Spinal nerve root origins of the cutaneous nerves arising from the canine brachial plexus.

The spinal nerve root origins of the cutaneous nerves arising from the brachial plexus were investigated in 10 babiturate-anesthetized dogs by stimulating dorsal roots C5 to T2 and recording from each cutaneous nerve. Upon completion of the experiment, the contributions of the spinal nerve ventral branches to the brachial plexus were verified by anatomic dissection. The brachial plexus was formed by the ventral branches of C6 to T2 in 8 dogs, C6 to T1 in 1 dog, and C5 to T1 in 1 dog. The cutaneous branch of brachiocephalicus nerve was formed primarily by contributions from the C6 dorsal root. The cranial lateral cutaneous brachial nerve, a branch of the axillary nerve, was formed predominantly from C6 to C7. The median nerve received contributions primarily from C7, C8, and T1, and the communicating branch from the musculocutaneous to the median nerve contained fibers primarily from C7 and C8. The medial and lateral branches of the superficial branch of the radial nerve arose from C6, C7, C8, and T1, with the medial branch generally arising 1 segment craniad to the lateral. The palmar and dorsal branches of the ulnar nerve arose predominately from C8 and T1, and the caudal cutaneous antebrachial nerve of the ulnar arose predominately from T1 and T2.

["Functional and anatomical organization of associative" cortical areas 7, 21 and 22 in monkeys. A study of the cortical projections from the pulvinar by means of HRP tracing technique (author's transl)]. / Organisation anatomique et fonctionnelle des aires corticales "associatives" 7, 21, et 22 chez le singe. A propos de la mise en evidence par la technique de marquage par la peroxydase de projections corticales du pulvinar.

The thalamic projections to the parietal and temporal associative areas (Brodmann's areas 7, 21 and 22) have been revealed by means of the retrograde axonal transport of horseradish peroxidase (HRP). The medial pulvinar (PM) was found to send afferents to the three studied areas. Labelled neurones of the PM appeared to be grouped in terms of their cortical target; indeed, neurones of origin of projection fibres to areas 7, 21 and 22 were respectively localized in the dorso-lateral, ventro-lateral and ventro-medial part of the PM. Although the multimodal sensory nature of the PM has been demonstrated by electrophysiological works, the function of PM neurones and the significance of their topographical repartition remain unknown. However PM could be involved in the transmission of specific sensory informations to the three associative areas 7, 21 and 22. Such an hypothesis is discussed according to the hitherto available data.