摘要:

AbstractThe structure and connectivity of the basal nucleus of Meynert, the substantia innominata in which it lies, and certain related areas have been examined in New World and Old World Monkeys, using retrograde and anterograde axonal transport methods.Experiments using the retrograde, horseradish peroxidase method confirm the observations of Kievet and Kuypers ('75) that the basal nucleus and substantia innominata project directly, heavily and with a somewhat crude topography upon the neocortex.Experiments involving the anterograde, autoradiographic method show that the basal nucleus and substantia innominata form part of a complex pathway that links them together with the lateral hypothalamus, certain parts of the amygdala and the peripeduncular nucleus of the midbrain. The peripeduncular nucleus is often regarded as a part of the central auditory pathway; it gives rise to a fiber bundle of considerable size that ascends on the dorsal surface of the ipsilateral optic tract and terminates ultimately in the lateral hypothalamic area of both sides. As well as distributing fibers to the basal nucleus, substantia innominata and lateral hypothalamus, this pathway provides a heavy projection to a cytoarchitectonically distinct posterior part of the lateral nucleus of the amygdala, the medial and intercalated nuclei of the amygdala and a less dense projection to the bed nucleus of the stria terminalis.Certain parts of the hypothalamus and possibly the preoptic areas give rise to a complementary descending pathway that distributes fibers to the ipsilateral basal nucleus, substantia innominata and amygdala, and ends in the peripeduncular nuclei of both sides. Decussating fibers in both the ascending and descending pathways cross in the ventral supraoptic commissure.It is concluded that the basal nucleus should include most of the aggregated and unaggregated large cells that lie in the substantia innominata and which in places intrude upon the preoptic regions and the nucleus of the diagonal band of Broca. Together, these may form a complex that receives inputs from a variety of brainstem sources, and projects widely and diffusely upon all cortical structures of the telencephalon.

ISSN:0092-7317    

DOI:10.1002/cne.901670402

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractIn the present study the origin of the pathways descending from the brain stem to the spinal cord has been investigated in the reptilesTestudo hermanni, Pseudemys scripta elegans, Tupinambis nigropunctatusandPython reticulatus.These reptiles, using highly different types of progression, have been selected, because fundamental variations in the organization of the central motor apparatus are to be expected.The origin of the descending pathways has been demonstrated by recording the occurrence of retrograde cell changes following hemicordotomies and by searching for labeled cells following injection into the spinal cord of the enzyme horseradish peroxidase.In the reptiles studied the presence of interstitiospinal, vestibulospinal and reticulospinal pathways could be demonstrated. A crossed rubrospinal tract has been shown in the turtles and in the lizard, but could not be demonstrated in the Python. The presence of a direct tectospinal pathway could not be shown.

ISSN:0092-7317    

DOI:10.1002/cne.901670403

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe course and termination of the pathways descending from the brain stem to the spinal cord have been studied by tracing the ensuing antero grade fiber degeneration, following appropriate lesions in the reptilesTestudo hermanni, Tupinambis nigropunctatusandPython reticulatus.In these reptiles the presence of interstitiospinal, vestibulospinal and reticulospinal pathways has been demonstrated. A crossed rubrospinal tract has been shown in the turtle and lizard, but could not be demonstrated in the Python. The presence of a tectospinal pathway of any importance could not be shown. However, the tectum mesencephali has been found to project profusely to the brain stem reticular formation.The interstitiospinal tract projects predominantly to the ipsilateral side of the spinal cord. The vestibulospinal projection, arising from the large‐celled nucleus vestibularis ventrolateralis, comprises a large uncrossed and a small decussating component.The rubrospinal pathway terminates in a particular area of the spinal gray, i.e., the intermediate zone, whereas the interstitiospinal, reticulospinal and vestibulospinal tracts all terminate in the medial part of the ventral horn.It appeared that the classification of descending pathways as advocated in mammals by Kuypers ('64) into lateral and medial systems can be readily applied to reptiles. The lateral system terminates in the dorsal and lateral parts of the intermediate zone, the medial system predominantly in the dorsomedial part of the ventral horn. This classification renders it likely that the absence of a lateral focus of termination as well as the absence of a rubrospinal tract in the Python, is correlated to the absence of limbs.A comparison of experimental data concerning the systems descending from the brain stem to the spinal cord in amphibians, reptiles, birds and mammals suggests that these systems with regard to origin, course and termination have a basic pattern in commo

ISSN:0092-7317    

DOI:10.1002/cne.901670404

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractHypothalamic involvement in visually conditioned heart rate change (established by pairing light and foot‐shock) was studied in 128 pigeons by evaluating conditioning performance following lesions of various hypothalamic areas. Extensive destruction of the posterior hypothalamus severely impaired development of conditioned heart rate change. Anterior hypothalamic lesions also produced serious deficits, though not as severe as following posterior hypothalamic damage. Partial posterior hypothalamic, unilateral and tuberal lesions produced only minor to moderate deficits. The critical locus for profound impairment of conditioned response development appeared to be the medial hypothalamus, and it is suggested that more specifically it is the terminal field of the archistriatal projection upon the medial hypothalamus. It is concluded that the medial hypothalamus is essential for the development of defensively conditioned heart rate change, and based on previous findings it is suggested that the critical descending pathway for expression of this conditioned response involves the archistriatal projection upon the medial hypothalamus and subsequently a polysynaptic pathway through the ventral brainste

ISSN:0092-7317    

DOI:10.1002/cne.901670405

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractThe response of non‐neuronal cells in the brain to monosodium glutamate (MSG) was studied in the neonatal mouse brain. Neurons rapidly degenerate in this chemically‐induced lesion, and the glia reflect and respond to their early pyknosis and death. Astrocytic glia exhibit the most profound responses in the form of degenerative nuclear and cytoplasmic changes within 15 to 20 minutes after ingestion of MSG. After 6 to 12 hours, a large glial cell population, containing neuronal and synaptic debris, can be seen. Recovery of severely damaged astrocytes is unlikely. Further, evidence of multiplication of uninjured cells to supply this observed repopulation was found.Microglia start to engulf debris at 6 to 12 hours and continue this process through at least 48 hours. From 3 to 48 hours, a third cell type, tentatively identified as a Gitter cell, is prominently involved in phagocytosis of neuronal elements. Nuclei of these cells enlarge and their perikarya become vastly expanded in a fashion typical of Gitter cells. These cells appear to represent the transformed microglia.Phagocytosis following a chemical lesion induced by glutamic acid, a neurotransmitter substance, is exceedingly rapid in comparison to that elicited by other types of lesions. Further, endogenous glial cells cope with the cellular debris; no participation in this process by hematogenous cells was obser

ISSN:0092-7317    

DOI:10.1002/cne.901670406

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

摘要:

AbstractIn birds, superficial laminae of the optic tectum receive a massive retinal input; the tectum in turn projects upon the nucleus rotundus thalami, which then sends its efferents to the ectostriatal core of the telencephalon. To examine the detailed organization of this principal ascending visual pathway, small injections of the marker horseradish peroxidase (HRP) were placed in various sites throughout the ectostriatum (E) or nucleus rotundus (Rt) in pigeons. Analysis of the resulting patterns of retrograde labeling indicates the tectofugal pathway to be comprised of at least five different channels. Cells which lie at various depths in the stratum griseum centrale (SGC) of the tectum project upon distinct subdivisions of nucleus rotundus. Anterior portions of Rt receive input from superficial most cells in the SGC, while medial and more caudal portions of Rt are projected upon by deeper SGC neurons. A ventral subdivision of Rt was found to receive its primary input from two pretectal nuclei. Additional inputs to all portions of Rt arise from nucleus reticularis superior thalami.The various subdivisions of rotundus in turn project upon distinct portions of the ectostriatum. Thus, the segregation between the different input classes into Rt is largely retained at the telencephalic level. In contrast, the nucleus triangularis, a dorso‐medial extension of Rt which receives its input from the deepest of all SGC neurons, sends its efferents to all parts of the ectostriatu

ISSN:0092-7317    

DOI:10.1002/cne.901670407

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901670401

出版商:The Wistar Institute of Anatomy and Biology    

年代:1976

数据来源: WILEY