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J L Dubbeldam

Publications and source records attributed to J L Dubbeldam.

47 records · Page 3Linked to original sources
PubMed1981

Studies on the somatotopy of the trigeminal system in the mallard, Anas platyrhynchos L. III. Afferents and organization of the nucleus basalis.

The ascending projections from the principal sensory nucleus V (PrV) have been studied by tracing degeneration after lesions in the PrV and by injections of HRP into the projection zone of PrV. The quintofrontal tract arises from PrV, ascends into the forebrain, and terminates in the ipsilateral and the contralateral nucleus basalis (NB). The contralateral fibers decussate in the tegmentum at the level of the trochlear-oculomotor nuclei. NB is a laminar nucleus lying over the rostral part of the paleostriatal complex. Dorsally NB is bounded by the neostriatum. NB consists of small neurons. In the dorsal part of NB, these neurons are arranged in vertical columns; the afferents ascend through these columns, and clusters of degenerated boutons are found around the cells. It is possible to distinguish regions in NB receiving ophthalmic, maxillary, mandibular, or glossopharyngeal afferents. The rostral part of NB receives an exclusive ipsilateral projection; the intermediate part, a bilateral projection; and the caudal part, a contralateral projection, with the exception of the most caudal area, which also receives a bilateral projection. It is not clear whether NB should be considered a thalamic, a telencephalic, or even a pallial structure. The hypothesis that the columnar organization of the NB is a prerequisite to preserve a precise somatotopy of the tactile system of the oral region is discussed. In this respect the organization of NB can be compared to that of layer IV of the somatosensory (SI) cortex of mammals. Knowledge of the structure and functions of the peripheral tactile sense system opens the possibility of subdividing the NB into functional units.

Afferent Pathways↗
PubMed1981

Studies on the somatotopy of the trigeminal system in the mallard, Anas platyrhynchos L. IV. Tactile representation in the nucleus basalis.

This electrophysiological study complements neuroanatomical work from our department on the somatotopy of the trigeminal system of the mallard. Peripheral areas of mechanoreceptors in bills and tongue were mapped in the telencephalic nucleus basalis, a second-order relay nucleus in the ascending trigeminal pathway. The multi-unit responses recorded under Equithesin anaesthesia did not show spontaneous activity and all animals adapted rapidly after mechanical stimulation. They showed well-circumscribed receptive fields whose peripheral position did not change when the electrode was lowered in the vertical stereotaxic plane, but changes immediately when its position was changed in the horizontal XZ-plane. The somatotopic picture presented here corresponds in many details to that obtained with combined neuroanatomical techniques (Dubbeldam et al., '81). In the discussion the structural point-to-point relationship between the peripheral mechanoreceptive areas and the nucleus basalis is tentatively changed to a division into areas related to the functional units involved in the subsequent sensory events during feeding. The somatotopy provides a basis for future chronic experiments to investigate this postulated role of the various areas in the nucleus basalis.

Afferent Pathways↗
PubMed1980

Studies on the somatotopy of the trigeminal system in the mallard, Anas platyrhynchos L. II. Morphology of the principal sensory nucleus.

The projections from the ophthalmic, maxillary, and mandibular parts of the trigeminal ganglion upon the principal sensory trigeminal nucleus (PrV) in the mallard have been studied with the Fink-Heimer I method. PrV is a large nucleus subdivided in cell groups by layers of fibers. The orientation of the dentritic arborizations differs in the different parts of the nucleus. A dorso-caudal cell group sIX is an exclusive glossopharyngeal terminal field. A second, caudo-ventral projections area of NIX also receives trigeminal afferents. A small n. supratrigeminalis lies medial to PrV in the pathway of the mesencephalic trigeminal root. This nucleus seems to be part of the proprioceptive trigeminal system. The rostralmost part of PrV receives ophthalmic projections, the caudalmost part receives mandibular projections, the maxillary area being intermediate. Taking the stereotaxic plane of the mallard atlas (Zweers, '71) into account, it can be concluded that the situation is essentially not different from that in the pigeon and from the situation described for mammals.

Animals↗
PubMed1979

The central projections of the glossopharyngeal and vagus ganglia in the mallard, Anas platyrhynchos L.

The central projections of the glossopharyngeal and vagus nerves in the mallard have been studied with the Fink-Heimer I method and are compared to those of the trigeminal and facial nerves. The N. vagus projects ipsilaterally and contralaterally upon the central nuclei of the solitary complex, except the most rostral part of it, upon the n. sulcalis dorsalis, the parasolitary nuclei and the n. commissuralis. The glossopharyngeal nerve contributes to the rostral pole of the n. centralis anterior and to the n. ventrolateralis anterior of the solitary complex, but it has also terminal fields in a cellgroup sIX of the principal sensory trigeminal nucleus, in a small cellgroup sIXd on the dorsum of the descending trigeminal tract, in the n. interpolaris of this tract and in nuclei of the cuneate complex. There is hardly any overlap of the respective terminal fields. The convergence of projections from N VII and N IX can be connected with the presence of tastebuds in upper and lower bill and in the soft palate. The converging projections from N V and N IX in "trigeminal" nuclei may reflect the functional coherence of the mechanoreceptors in bill and tongue. It is suggested that these nuclei play a role in the feeding behavior.

Animals↗
PubMed1978

The trigeminal system in the pigeon (Columba livia). I. Projections of the gasserian ganglion.

The central projections of the Gasserian ganglion were investigated in the pigeon, Columba livia. Lesions were placed in the ganglion either by direct surgical exposure or stereotaxically, and following survival times of one to four days, the brains stained with the Fink-Heimer method. The main group of central axons bifurcate to form distinct ascending and descending branches, the tractus trigemini ascendens (TTA) and the tractus trigemini descendens (TTD). A smaller tract also courses caudally (ITTD) separate of TTD proper to terminate in the nucleus cuneatus externus. The TTA projects topographically upon the principal sensory nucleus of the trigeminus, ending in both the pars dorsalis and a smaller pars ventralis. The neurons at the point of bifurcation of the entering radix have been designated as the pars oralis of nTTD. The TTD distributes caudally to several distinct subnuclei at each level, and extends into the cervical spinal cord. Relatively discrete regions corresponding to the pars interpolaris and caudalis were recognized. The projections to the cervical cord terminate in laminae I-IV. There was no evidence of projections to the cerebellum, or contralateral PrV or TTD. There was a small projection to the contralateral cervical spinal cord. No clear evidence of a projection to the nucleus solitarius was found. The distribution of primary trigeminal axons is compared to that described in other vertebrates.

Animals↗
PubMed1976

Central projections of the chorda tympani nerve in the mallard, Anas platyrhynchos L.

The central projections of the chorda tympani nerve in the duck were studied by means of the Fink-Heimer technique. Following section of the VIIth nerve proximal to the geniculate ganglion terminal projections of the CT are found in the sensory nucleus N VII (sVIId) on the dorsum of the descending trigeminal root, the n. presulcalis anterior solitarii, the n. sulcalis anterior solitarii p. dorsalis and p. ventralis, and the n. ventrolateralis anterior solitarii (Vla). Small quantities of terminal degeneration are also found in the n. intermedius anterior and the lateral substantia gelatinosa of the solitary complex. A number of fibers decussate to terminate contralaterally in corresponding portions of the opposite solitary complex. Comparison with data of the pigeon reveals a limited overlap of projections of the chorda tympani nerve and of the nodose ganglion, respectively, in the dorsal and ventral parts of the n. sulcalis anterior. We suggest that the regions sVIId and Vla alone may convey gustatory information.

Afferent Pathways↗
PubMedDate not supplied

The central mesencephalic grey in birds: nucleus intercollicularis and substantia grisea centralis.

The question discussed in this paper is, whether the dorsomedial part of the intercollicular nucleus and central mesencephalic grey of birds are comparable to (parts of) the periaqueductal grey in mammals. The mammalian periaqueductal grey, and the avian dorsomedial part of the intercollicular nucleus + central mesencephalic grey are each part of pathways in control of functions such as vocalization and sexual behavior. The connectivity and histochemical features of the dorsomedial intercollicular nucleus and central mesencephalic grey are partly different and also differ partly from those of the mammalian periaqueductal grey. It is suggested that these areas in mammals and birds form comparable links in the emotional motor pathway that has been defined before in mammals.

Animals↗