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T E Finger

Publications and source records attributed to T E Finger.

At least 73 records · Page 4Linked to original sources
PubMed1986

The ultrastructure of enkephalin-immunoreactive neurons in the interpeduncular nucleus of the rat.

The interpeduncular nucleus of the rat is a complex structure, displaying diverse immunocytochemical and ultrastructural features. This nucleus contains opiate receptors, enkephalin-positive cell bodies and enkephalin-positive fibers. The ultrastructure of rat interpeduncular enkephalinergic neurons has not been described, nor has the role that these neurons play in the internal organization of the interpeduncular nucleus been established. The purpose of the present study was to describe the ultrastructure of enkephalinlike-immunoreactive (ELI) cells with particular emphasis on the subnuclear organization of their dendritic and terminal fields. Enkephalinlike-immunoreactive (ELI) cell bodies are present in the rostral and apical subnuclei of the interpeduncular nucleus (IPN), but are absent from the other subnuclei of the IPN. The rostral subnucleus also contains immunoreactive dendrites that are postsynaptic to nonreactive terminal boutons. Numerous ELI axon terminals were observed in the central and intermediate subnuclei. The results of our study suggest that enkephalinergic interneurons link the rostral IPN with more caudal regions of this nucleus.

Animals↗
PubMed1986

Immunohistochemical localization of GRF-containing neurons in rat brain.

Brains from 4 normal and 4 colchicine-treated rats were studied for the presence of growth hormone-releasing factor (GRF) using an antibody directed against rat hypothalamic GRF (rGRF). Noncolchicine-treated animals showed intense staining in the external layer of the median eminence. Rats pretreated with intraventricular colchicine for 48 h showed localization of GRF-containing cell bodies in the arcuate nucleus, the perifornical area, the lateral basal hypothalamic region and lateral to the ventromedial nucleus and the premammillary nucleus. This pattern of distribution is consistent with the postulated role of GRF in hypothalamic regulation of growth hormone secretion. Our results confirm the predominant localization of GRF perikarya in the arcuate nucleus of the rat which has been noted in studies using antibodies directed against both human pancreas GRF (hpGRF) and rGRF, and demonstrate a unique pattern of rGRF-positive cell bodies elsewhere in the hypothalamus. No rGRF perikarya or processes were seen outside the hypothalamus.

Animals↗
PubMed1985

Substantia nigra transplants into denervated striatum of the rat: ultrastructure of graft and host interconnections.

A number of recent experiments suggest that grafted dopaminergic neurons provide functional input to a host caudoputamen which previously had been deprived of its dopaminergic input. The purpose of the present study was to determine whether tyrosine hydroxylase immunoreactive processes which originate in the graft participate in morphologically identifiable synapses in the host neuropil. Prior to transplantation, adult Sprague-Dawley rats received unilateral injections of 6-hydroxydopamine into the medial forebrain bundle. Animals were screened for the success of striatal denervation by a test of apomorphine-induced rotation. Transplants of fetal substantia nigra then were placed into cavities in the caudoputamen. After a 6-8 month survival period, animals were perfused and prepared for tyrosine hydroxylase immunocytochemistry. No evidence of sprouting of the host catecholoaminergic system was observed, even after long survival times. Both pre- and postsynaptic immunoreactive elements were clearly present in the host caudoputamen. Immunoreactive axons made synaptic contact with unlabeled dendrites; immunoreactive dendrites were postsynaptic to unlabeled axon terminals. The present results suggest that both host-to-graft and graft-to-host synapses are present in the host caudoputamen.

Animals↗
PubMed1985

Organization of motoneuronal pools in the rostral spinal cord of the sea robin, Prionotus carolinus.

The functional organization of the motoneurons in the spinal cord of the sea robin, Prionotus carolinus, was studied by means of retrograde transport of horseradish peroxidase (HRP). This species has a complex pectoral apparatus which includes not only a webbed fin, but also three independently mobile fin rays. The motoneurons in the rostral spinal cord fall into two longitudinal columns: dorsal and ventral. The motoneurons of the ventral column innervate the appendicular musculature of the pectoral apparatus. Within the ventral motor column of the rostral spinal cord, four distinct motoneuronal pools were found. The largest pool is situated at the rostral-most end of the spinal cord and contains the motoneurons that innervate the musculature of the webbed pectoral fin. The motoneurons that innervate the fin rays are located in sequentially more posterior pools so that the anteroventral fin ray is controlled by motoneurons situated farthest caudally. The somatotopic arrangement exactly corresponds to the sensory somatotopy determined previously. Furthermore, each fin ray has its sensory representation in a unique accessory spinal lobe which is connected in a reflex fashion to the motoneuronal pool that provides motor output to the same fin ray.

Animals↗
PubMed1985

Topographic and laminar organization of the vagal gustatory system in the goldfish, Carassius auratus.

The large majority of intraoral taste buds in goldfish are located on the gill arches and on the palatal organ, a muscular organ situated on the roof of the mouth. These taste buds are innervated by branches of the vagus nerve which terminate in a laminated vagal lobe, itself being an enlargement of the special visceral sensory column of the medulla. The tracer horseradish peroxidase (HRP) was used to determine the connectivity of the various branches of the vagus nerve that innervate the oropharyngeal gustatory surfaces. The entire oral cavity is mapped onto the vagal lobe so that the anterior end of the palatal organ and the most anterior gill arch are represented anteriorly in the vagal lobe; progressively more posterior oral structures are represented progressively more posteriorly in the lobe. The medial part of the palatal organ and the opposing gill arch surface, i.e., the ventromedial portion, are represented ventrally in the vagal lobe. The dorsolateral portions of the palatal organ and gill arches are represented dorsomedially in the vagal lobe. The topographic representation of the oral structures is similar for both the motor and sensory systems. In addition to this overall topographic organization, the different oropharyngeal structures are represented differentially in the layers of the vagal lobe. Palatal organ inputs reach layers VI and IX while gill arch inputs terminate in layers II, IV, and IX. The overall organization of the vagal lobe suggests a highly organized reflex system which is involved in the separation of food from substrate, especially during bottom feeding.

Animals↗
PubMed1985

Two gustatory systems: facial and vagal gustatory nuclei have different brainstem connections.

The gustatory sense in catfish consists of two dissociable components, a facial nerve system used for food selection and a vagal nerve system involved in swallowing. Neural tracing experiments demonstrate that the primary sensory nucleus for the facial gustatory system is connected to the reticular formation and trigeminal nuclei. In contrast, the primary sensory nucleus for the vagal gustatory system is connected to the motoneurons that mediate swallowing. These results provide anatomical evidence for parallel gustatory systems within the vertebrate central nervous system.

Afferent Pathways↗
PubMed1985

Reflex connections of the facial and vagal gustatory systems in the brainstem of the bullhead catfish, Ictalurus nebulosus.

The primary gustatory sensory nuclei in catfish are grossly divisible into a vagal lobe and a facial lobe. In this study, the reflex connections of each gustatory lobe were determined with horseradish peroxidase (HRP) tracing methods. In addition, in order to determine the loci and morphology of the other brainstem cranial nerve nuclei, HRP was applied to the trigeminal, facial, glossopharyngeal, or vagus nerve. The sensory fibers of the facial nerve terminate in the facial lobe. The facial lobe projects bilaterally to the posterior thalamic nucleus, superior secondary gustatory nucleus, and medial reticular formation of the rostral medulla. The facial lobe has reciprocal connections with the n. lobobulbaris, medial reticular formation of the rostral medulla, descending trigeminal nucleus, medial and lateral funicular nuclei, and the vagal lobe, ipsilaterally; and with the facial lobe contralaterally. In addition, the facial lobe receives inputs from the raphe nuclei, from a pretectal nucleus, and from perilemniscal neurons located immediately adjacent to the ascending gustatory lemniscal tract at the level of the trigeminal motor nucleus. The gustatory fibers of the vagus nerve terminate in the vagal lobe, while the general visceral sensory fibers terminate in a distinct general visceral nucleus. The vagal lobe projects ipsilaterally to the superior secondary gustatory nucleus, lateral reticular formation, and n. ambiguus; and bilaterally to the commissural nucleus of Cajal. The vagal lobe has reciprocal connections with the ipsilateral lobobulbar nucleus and facial lobe. In addition, the vagal lobe receives input from neurons of the medullary reticular formation and perilemniscal neurons of the pontine tegmentum. In summary, the facial gustatory system has connections consonant with its role as an exteroceptive system which works in correlation with trigeminal and spinal afferent systems. In contrast, the vagal gustatory system has connections (e.g., with the n. ambiguus) more appropriate to a system involved in control of swallowing. These differences in central connectivity mirror the reports on behavioral dissociation of the facial and vagal gustatory systems.

Animals↗
PubMed1984

Central organization of eighth nerve and mechanosensory lateral line systems in the brainstem of ictalurid catfish.

The octavolateral sensory systems in teleost fish comprise at least four distinct hair-cell sensory modalities which are processed separately within the CNS. Two of these modalities, the mechanosensory lateral line system and the eighth nerve auditory system, have been implicated in the animal's ability to detect and localize underwater vibrations. Distinct mechanosensory lateral line and auditory nuclei are present within the torus semicircularis, the midbrain homologue of the inferior colliculus. The present study utilized horseradish peroxidase tracing techniques to delineate those areas of the lower brainstem which are involved in auditory as opposed to mechanosensory lateral line processes. The primary mechanosensory nucleus of the medulla, n. medialis, projects directly to the optic tectum and to the mechanosensory nucleus of the torus semicircularis. Nucleus medialis receives input from primary lateral line nerve fibers as well as from a number of sites within the CNS: n. praeeminentialis pars ventralis, and the eminentia granularis and lobus caudalis of the cerebellum. The n. praeeminentialis itself receives a descending input from the mechanosensory nucleus of the torus semicircularis. These mechanosensory lateral line pathways are parallel to, but distinct from, those of the electrosensory lateral line system. Auditory signals reach the midbrain via an entirely separate route. The octaval nerve terminates in a column of five medullary nuclei. Of these, only the anterior and descending octaval nuclei maintain a direct but sparse projection to the auditory nucleus of the midbrain. The bulk of the auditory input to the midbrain involves a newly described medullary nucleus, the medial auditory nucleus of the medulla. This nucleus receives input from the descending octaval nucleus and projects bilaterally to the auditory nucleus of the torus semicircularis. It is suggested that the medial auditory nucleus of the medulla is homologous to portions of the superior olivary complex of other vertebrates.

Afferent Pathways↗
PubMed1984

Asymmetry of the olfactory system in the brain of the winter flounder, Pseudopleuronectes americanus.

Adult flatfishes exhibit grossly asymmetric external morphology. Even the olfactory apparatus is asymmetric, being larger on the upward-facing side. We undertook the present study on the winter flounder, Pseudopleuronectes americanus, to examine whether the asymmetry of the peripheral olfactory system is maintained in its central organization. In winter flounder, the right olfactory organ, nerve, and bulb are larger than the contralateral counterparts. In addition, the right telencephalon is about 8% larger than the left. Horseradish peroxidase (HRP) and degeneration techniques were used to trace the central connections of the olfactory bulbs. Neurons afferent to the olfactory bulb occur bilaterally in the telencephalon and mesencephalic tegmentum. Afferent neurons are also present at the junction between the posterodorsal bulb and telencephalon, in the basal preoptic region, nucleus of the posterior tuber, locus coeruleus, raphe nucleus, and the contralateral bulb. Each olfactory bulb projects bilaterally to several restricted areas of the telencephalon, the posterodorsal neurons of the nucleus preopticus and the tuberal region, with ipsilateral connections being heavier in all areas. Corresponding to the differences in the peripheral olfactory apparatus, the central olfactory projections were also asymmetric. The right olfactory bulb projects to 2.6% of the ipsilateral telencephalon and 1.99% of the contralateral telencephalon. The left bulb projects to 1.8% of the ipsilateral and 0.6% of the contralateral telencephalic hemisphere. Thus the left telencephalon receives roughly equal olfactory input from the two sides, while the right telencephalon receives vastly more input from the right olfactory system. The asymmetry in the projections of the right and left bulbs may be due to differential postmetamorphic growth of the olfactory system on the two sides.

Animals↗
PubMed1984

Immunohistochemical localization of enkephalin- and ACTH-related substances in the pituitary of the lamprey.

The distributions of ACTH-, alpha MSH-, beta LPH-, and enkephalin-related substances were determined immunohistochemically in the pituitary of the brook lamprey, Lampetra lamotenii. an antiserum directed against the middle region of ACTH reacted chiefly with cells in the pro-adenohypophysis. An antiserum specific for alpha MSH reacted with all of the cells of the meta-adenohypophysis, but did not react with any of the middle ACTH-positive cells in the pro-adenohypophysis. Several antisera which crossreact with both beta LPH and beta-endorphin did not react with any region of the lamprey pituitary. However, an antiserum directed against gamma LPH did react with a small population of cells in the meso-adenohypophysis. This reactivity could be blocked following pre-absorption with mouse beta LPH but was not blocked by synthetic beta-endorphin (1-31). Antisera directed against either met-enkephalin or leuenkephalin reacted with fibers in the anterior neurohypophysis, cells in the pro-adenohypophysis, and all the cells of the meta-adenohypophysis. This crossreactivity could be blocked following pre-absorption with the appropriate enkephalin, but not by pre-absorption with synthetic beta-endorphin (1-31) or dynorphin (1-13). In addition, the enkephalin-like reactivity in the adenohypophysis of the lamprey was coincident with middle ACTH-like immunoreactivity in the pro-adenohypophysis and with alpha MSH-like immunoreactivity in the meta-adenohypophysis. The absence of beta LPH/beta-endorphin immunoreactivity coincident with ACTH immunoreactivity, and the presence of enkephalin-like material in the adenohypophysis are unique to the lamprey.

Adrenocorticotropic Hormone↗
PubMed1984

Vagotomy induced changes in acetyl cholinesterase staining and substance P-like immunoreactivity in the gustatory lobes of goldfish.

In teleost fish, the visceral sensory nuclei of the medulla are clearly separated into gustatory lobes and a general visceral sensory nucleus. Those branches of the vagus nerve which innervate the orobranchial cavity terminate in the vagal gustatory lobe, while the general visceral component of the vagus nerve terminates in the separate general visceral nucleus. In goldfish, the vagal lobe is a complex, laminated structure containing both motor and sensory elements. Transection of the vagus nerve results in distinct changes in the pattern of acetylcholinesterase staining and substance-P-like (SPL) immunoreactivity in the vagal lobe of goldfish. Following vagotomy, cholinesterase activity is eliminated from layers 4 and 6, both being layers in which primary gustatory afferent fibers terminate. In addition, SPL immunoreactive fibers disappear from the capsular root of the vagus nerve. These results indicate that the primary afferent input to the gustatory lobe involves at least two cytochemically distinct fiber types, one containing substance-P-immunoreactive material and the other containing or inducing acetylcholinesterase activity. Vagotomy also affects immunostaining and cholinesterase activity of the motoneurons deep in the vagal lobe. Following nerve transection, acetylcholinesterase activity is diminished, and SPL-immunoreactivity increased in the affected motoneurons. Similar changes were observed in axotomized motoneurons of other cranial nerve nuclei.

Acetylcholinesterase↗
PubMed1983

Accuracy of regeneration of vagal parasympathetic axons.

The degree of accuracy with which regenerating preganglionic parasympathetic fibers can restore their original connections was examined in the frog, Rana pipiens. The normal motor pool of the vagus nerve was determined by labeling the vagal cardiac branch fibers with horseradish peroxidase (HRP). Cardiac neurons form a relatively compact subgroup within the rostral half of the vagal motor column and represent less than 5% of the total vagal motor pool. Five to 14 weeks after crushing the vagus nerve, HRP labeling revealed that a more extensive population of vagal motor neurons has reinnervated the cardiac branch. The regenerated cardiac motor neuron pool is about twice as numerous as normal but is still centered in the rostral half of the vagal motor column. These experiments show that regeneration of the cardiac branch of the vagus nerve is neither a random process nor one which is completely accurate. Some degree of accuracy is maintained during regeneration following a crush lesion. Neurons nearer the original cardiac motor pool are more likely to reinnervate the cardiac branch than are vagal motor neurons located at some distance from the original cardiac pool.

Animals↗
PubMed1983

Central organization of the electrosensory lateral line system in bullhead catfish Ictalurus nebulosus.

The connections of the electrosensory lateral line lobe (ELL) of ictalurid catfish were examined by means of horseradish peroxidase tracing methods. The ELL receives direct input from the anterior and posterior lateral line nerves. Some of these nerve fibers continue through the ELL to end as mossy fibers in the lateral portion of the eminentia granularis. Granule cells in this area as well as those in lobus caudalis of the cerebellum project back to the ELL as parallel fibers in the upper molecular layer. The lower molecular layer of the ELL receives its input from the n. praeeminentialis. The ELL projects via the lateral lemniscus to the n. praeeminentialis and torus semicircularis bilaterally, but more heavily on the contralateral side. In addition, the n. praeeminentialis receives the bulk of its input from the ipsilateral torus semicircularis. The caudal lobe of the cerebellum both projects to the electrosensory portion of the torus semicircularis and receives indirect input from the torus semicircularis via the anterior olivary nucleus. In summary, the central organization of this ampullary receptor electrosensory system in catfish is similar to that of the ampullary-tuberous receptor electrosense of mormyrids and gymnotids.

Animals↗
PubMed1982

Spinal and medullary dorsal cell axons in the trigeminal nerve in lampreys.

The ophthalmic branch of the trigeminal nerve was labeled with horseradish peroxidase (HRP) in 3 species of adult lampreys. In each species, some medullary and spinal dorsal cells were retrogradely labeled by HRP. Approximately 30% of spinal dorsal cells were labeled ipsilateral to the injection; an occasional contralateral spinal dorsal cell was also labeled. Intracellular recordings confirmed the anatomical findings.

Afferent Pathways↗
PubMed1982

Thalamic center for the lateral line system in the catfish Ictalurus nebulosus: evoked potential evidence.

By means of evoked potential methods, a lateral line center in the thalamus of the bullhead catfish is here identified. The locus of this lateral line center corresponds to the mechanoreceptive thalamic zone and/or torothalamic tract identified by anatomical means. The thalamic lateral line area responds to acoustic stimuli as well as lateral line nerve shock but fails to respond to electroreceptor inputs that do cause responses in their special part of the midbrain torus semicircularis. The latency of the first peak of response to lateral line nerve shock, which is also the main response peak, is 30 ms for the thalamic zone compared to 15 ms for the earliest peak response in the mechanoreceptive part of the torus semicircularis. The thalamic response fatigues much more quickly than the toral response and has different dynamic properties to closely spaced stimulus pairs as well.

Animals↗
PubMed1981

Central connections of the posterior lateral line lobe in mormyrid fish.

Primary electroreceptor afferents terminate in the posterior lateral line lobe (PLLL) in electroreceptive teleosts. This paper examines the central connections of PLLL in fish of the family Mormyridae using horseradish peroxidase and tritiated amino acid tracing techniques. Some connections of the closely related lobus caudalis of the cerebellum are also examined. There are three zones on each side of the mormyrid PLLL cortex. Two receive input from mormyromast receptors, and one from ampullary receptors. An intrazonal projection system, intrinsic to PLLL, connects neighboring points within each zone. It also joins corresponding zones on the two sides of the body via commissural fibers. An interzonal system connects the two mormyromast zones on the same side of the midline. Central structures which project to PLLL include lobus caudalis, nucleus paratrigeminalis lateralis, and nucleus praeeminentialis. Nucleus praeeminentialis projects bilaterally and somatotopically to the lower molecular layer of PLLL. PLLL cortex projects bilaterally and somatotopically to two major mesencephalic sites: n. praeeminentialis, and n. lateralis. Somatotopically corresponding points in each zone of PLLL cortex project to the same small region of n. lateralis. Nucleus lateralis has a large and somatotopically organized projection to n. praeeminentialis. The afferent and efferent connections of lobus caudalis are similar to those of PLLL, indicating its close association with the electrosensory system. The anatomical results show that there is ample opportunity for electrosensory information arising on left and right sides of the body to interact centrally. One can suggest that comparison of afferent input from the two sides would reduce the non-significant variability which affects both of them equally. The results also show the presence of several somatotopically organized feedback lops which return the results of higher order processing of electrosensory information to earlier stages.

Afferent Pathways↗
PubMed1981

Electrosensory pathways to the valvula cerebelli in mormyrid fish.

The valvula cerebelli of mormyrid fish has been implicated in the electroreceptive capabilities of these animals. This study uses peroxidase and tritiated amino acid tracing techniques to examine the pathways by which electroreceptive information gains access to the valvula. Ampullary and mormyromast receptor information reaches the medial and ventrolateral portions of the valvula by means of a large, direct projection from n. lateralis, part of the midbrain electrosensory area. In addition, smaller indirect n. lateralis-valvular projections travel via a pretectal nucleus and the so-called postventral thalamic nucleus, Knollenorgan receptor information ends in the dorsolateral portion of the valvula. A small, relatively direct pathway runs via n. medialis ventralis, but most Knollenorgan information appears to travel via an indirect system involving n. extrolateralis pars posterior and n. isthmi. The lateral line processing areas of the valvula project back onto many of the midbrain electrosensory nuclei. These results indicate that much of the cerebellum of this family is devoted to sensory processing rather than motor functions.

Afferent Pathways↗