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R B Hamilton

Publications and source records attributed to R B Hamilton.

At least 19 recordsLinked to original sources
PubMed2000

Projections of the parabrachial nucleus in the old world monkey.

The efferent projections of the pontine parabrachial nucleus (PBN) were examined in the Old World monkey (Macaca fascicularis) using tritiated amino acid autoradiography and horseradish peroxidase histochemistry. Parabrachiofugal fibers ascended to the forebrain along three pathways: the central tegmental tract, the ventral ascending catecholaminergic pathway, and a pathway located on the midline between the medial longitudinal fasciculi. The PBN projected heavily to the central nucleus of the amygdala and the lateral division of the bed nucleus of the stria terminalis and moderately to the ventral tegmental area and the substantia nigra. Light terminal label also was present within the dorsomedial, ventromedial, lateral, supramammillary, and infundibular nuclei of the hypothalamus and the annular nucleus and the dorsal raphe nucleus within the brain stem. The overall pattern of terminal label was similar to that previously reported for nonprimate species, but several differences were notable. In monkey the projection to the ventrobasal thalamus did not coincide with the region that contains gustatory-responsive neurons. In rats, these parabrachiothalamic fibers convey gustatory activity but in the monkey these fibers may carry visceral afferent information. The projections from the PBN to the hypothalamus in the monkey were neither as widespread nor as intense as in the rat, and the monkey lacks a projection from the PBN to the frontal and insular cortices.

Afferent Pathways↗
PubMed1994

Taste preference of Old World monkeys: I. A single-bottle preference test.

There have been relatively few published reports of the taste preferences of nonhuman primates due, in part, to the expense and relative difficulty associated with maintaining a large group of these animals. The present report describes a version of the single-bottle preference test that can be used effectively with small groups of macaque monkeys. Experiment 1 determined the optimal durations for the pretest water deprivation period, the test trial itself, and the posttest rehydration period. Experiment 2 used this procedure to examine intake of the four prototypical gustatory stimuli. The results showed that cynomolgus monkeys, like other species, accept solutions containing sucrose and isotomic saline and reject those containing quinine hydrochloride. Unlike most other species, however, these monkeys do not find moderate concentrations of hydrochloric acid aversive.

Animals↗
PubMed1990

Gustatory rhinorrhea after radical parotidectomy.

A man of 63 developed unilateral gustatory rhinorrhea shortly after radical parotidectomy for infiltrating squamous cell carcinoma that had metastasised to the parotid lymph nodes. There is a similarity between this condition and the gustatory vasodilatation and sweating of Frey's syndrome, but despite circumstantial evidence that misdirected nerve regeneration causes these symptoms, their exact aetiology is still unknown.

Eating↗
PubMed1989

Neural coding of gustatory information in the thalamus of Macaca mulatta.

1. Extracellular action potentials were recorded from single neurons in the parvicellular division of the ventroposteromedial (VPMpc) nucleus of the thalamus of restrained, but alert, Old World monkeys during gustatory, tactile, and thermal stimulation of the oral cavity. In contrast to previous reports in anesthetized or paralyzed rats, the spontaneous activity of these neurons was brisk and their evoked responses robust. 2. Each of 50 taste-responsive neurons was tested with 1.0 M sucrose, 0.1 M NaCl, 0.003 M HCl, and 0.001 M QHCl before other concentrations of the same stimuli were used. Sucrose, which was effective in 80% of the neurons tested, evoked the largest responses of the 4 standard gustatory stimuli (16.1 spikes/s). The average response to NaCl, an effective stimulus for 44% of the neurons in the sample, was 7.5 spikes/s. HCl and QHCl, which few neurons responded to, typically evoked smaller responses. 3. Most of the neurons tested showed monotonic intensity-response (I-R) functions. The power functions showed about the same degree of compression (range = 0.39-0.53), which has been described previously for brain stem neurons in anesthetized rodents. Only 9.1% of the responses were inhibitory, and there was no tendency for these responses to be associated with either specific neurons or stimuli. These data suggest that quality coding of gustatory information in the thalamus is not radically different from that seen among lower-order neurons in other species. 4. Through the use of hierarchical cluster analysis, it was possible to divide the neuron sample into 2 groups, one of which consisted of sucrose-best neurons that had an average entropy value of 0.56. The neurons in the other group, though more heterogeneous, showed either primary or side-band sensitivity to NaCl. The average breadth of responsiveness of the 50 thalamic neurons as described by the entropy coefficient was 0.73. 5. In addition to gustatory neurons, tactile (n = 15), thermal (n = 1), and nonresponsive (n = 25) neurons also were located within VPMpc. An additional 48 neurons that could not be classified as either sensory or motor in nature, inhibited their bursting spontaneous discharge just prior to the onset of fluid stimulation. Only 2 of these neurons demonstrated differential chemical sensitivity. The presence of these nongustatory neurons within the thalamic taste area suggests that the traditional characterization of VPMpc as a gustatory relay may understate its role in ingestive behavior and ignore other noningestive functions of the area.

Animals↗
PubMed1987

Central distribution of the cervical vagus nerve in Old and New World primates.

The central distribution of the cervical vagus nerve was examined in Old and New World primates using anterograde transganglionic and retrograde horseradish peroxide (HRP) histochemistry. Crystals of HRP were applied to the cut central end of the cervical vagus nerve in two Old World (one bonnet, one cynomolgus) and two New World (squirrel) monkeys. Bright- and darkfield examination of coronal sections from the pons, medulla, and upper cervical spinal cord revealed two major concentrations of retrogradely labeled cells in the ipsilateral dorsal motor nucleus (DMX) and nucleus ambiguous (NA). DMX was heavily labeled, containing about 5 times as many labeled cells as NA. The anterograde distribution of reaction product did not extend as far in the rostrocaudal plane as did the retrograde distribution. Labeled afferent fibers entered the medulla at the level of the caudal dorsal cochlear nucleus, joined the solitary tract, and descended to the obex. Ipsilateral terminal label first appeared at the level where the nucleus of the solitary tract (NST) abuts the IVth ventricle. The terminal field grew in extent and density, until at the level of the area postrema (AP), the distribution extended throughout the medial NST, ventrolateral NST, and AP. Contralateral terminal label was sparse and restricted to the medial NST. In the commissural division of the solitary nucleus, sparse reaction product was present bilaterally, with the denser concentration ipsilateral to the treated nerve. Examination of peripheral ganglia revealed labeled somata in the nodose, jugular, and superior cervical ganglia.

Animals↗
PubMed1986

Projections of thalamic gustatory and lingual areas in the monkey, Macaca fascicularis.

The efferent projections of the parvicellular division of the ventroposteromedial nucleus of the thalamus (VMPpc; thalamic taste area) were traced to cortex in Macaca fascicularis by using tritiated amino acid autoradiography. Labeled fascicles could be traced from VPMpc to two discrete regions of cortex. The primary efferent projection was located on ipsilateral insular-opercular cortex adjacent to the superior limiting sulcus and extended as far rostrally as the posterior lateral orbitofrontal cortex. An additional projection was located within primary somatosensory (SI) cortex subjacent to the anterior subcentral sulcus. Following autoradiographic injections in VPM, the trigeminal somatosensory relay, a dense terminal plexus was labeled on SI cortex of both pre- and postcentral gyri, but not within insular-opercular cortex. The autoradiographic data were verified by injecting each cortical projection area with horseradish peroxidase (HRP) and observing the pattern of retrogradely labeled somata within the thalamus. Injections in the precentral gyrus near the anterior subcentral sulcus retrogradely labeled neurons within VPMpc, whereas injections further caudally near the floor of the central sulcus labeled neurons within VPM. Injections of HRP within opercular, insular, or posterior lateral orbitofrontal cortex retrogradely labeled neurons within VPMpc.

Animals↗
PubMed1985

A modified halo frame to assist omentum transfer to the scalp.

A modification of the halo frame to facilitate management of major scalp wounds is described. It has been used successfully in the management of a major scalp defect covered by a microvascular omental free flap. It has potential application in managing a replanted scalp.

Basal Cell Carcinoma↗
PubMed1984

Central projections of gustatory nerves in the rat.

The central distributions of gustatory and non-gustatory branches of cranial nerves V, VII, IX, and X were examined after application of horseradish peroxidase to the cut nerve. The nerves conveying gustatory information, chorda tympani (CT), greater superficial petrosal (GSP), lingual-tonsilar branch of IX (LT-IX), superior laryngeal branch of X (SL), distributed primarily to the lateral division of the nucleus of the solitary tract (NST) from its rostral pole to the obex. The CT and GSP distributions were coextensive and terminated most densely in the rostral pole of NST. The LT-IX distribution concentrated between this major CT/GSP distribution and the area postrema with a caudal extension into the interstitial nucleus of NST. This nerve also had a substantial projection, not found in other gustatory nerves, into the dorsolateral aspect of the medial NST. The SL distribution overlapped LT-IX in the caudal medulla. The lingual and inferior alveolar nerves, two oral trigeminal branches, projected to regions of NST innervated by the gustatory nerves. The cervical vagus nerve distributed primarily to the medial NST in the caudal half of the nucleus and exhibited only minimal overlap with gustatory nerve distributions. The nucleus of the solitary tract appears to have two major functional divisions--an anterior-lateral oral-gustatory half, and a posterior-medial visceral afferent half.

Afferent Pathways↗
PubMed1984

Survival factors in replantation and revascularization of the amputated thumb--10 years experience.

An unabridged series of 73 thumb amputations subjected to replantation or revascularization surgery in the years 1971 to 1980 has been examined in detail as a combined prospective and retrospective study to determine the factors playing a role in survival and failure. The causes of failure and complications are demonstrated. The overall failure rate was 27%. The factors influencing the outcome were: the injury--mechanical type and degree of amputation; the patient--age and amputation level; and the surgeon--frequency of utilization of vein grafts. The highest failure was seen in the complete amputation with avulsion/diffuse crush injury group (63%). Incomplete amputations had the lowest failure rate, particularly if the injury type was guillotine/local crush and at a level proximal to the metacarpophalangeal joint. Patients aged 11 to 20 years had a low failure rate (18%) whereas children under 5 years had a high failure rate (40%). Arterial thrombosis was the most frequent complication and cause of failure. The surgeon could modify the result by frequent use of vein grafts for arterial reconstruction and by reoperation for thrombotic complication. Five thumbs failed to revascularize at the primary operation and were removed at this primary operation.

Adolescent↗
PubMed1981

Parabrachial area as mediator of bradycardia in rabbits.

This study examined the role of the parabrachial nucleus (PBN) in the mediation of bradycardia and in the reception of barosensory information. The 82 rabbits in the investigation were anesthetized with ethyl carbamate. Train stimulation of medial or lateral PBN produced primary bradycardia (mean peak change: -74 beats/min) associated with a pressor response (average peak mean change: +10 mm Hg) of longer latency. Section of the cervical vagus nerves indicated that the bradycardia was mediated primarily by the parasympathetic nervous system. Heart rate and blood pressure responses to train stimulation did not vary systematically as a function of respiratory pattern; paralyzing animals with decamethonium hydrochloride and artificially ventilating them also did not influence the cardiovascular responses to stimulation. Single-pulse stimulation of PBN in conjunction with extracellular single neuron recording established that neurons originating in or projecting through PBN project to the commissural region of nucleus tractus solitarius (NTS) where synapse is made neurons receiving barosensory input. In addition to establishing the existence of descending functional projections passing from PBN to NTS, injections of HRP into PBN revealed direct descending anatomical projections to PBN from regions of the forebrain previously implicated in the mediation of bradycardia. These included central nucleus of amygdala, lateral preoptic region, medial, forebrain bundle, bed nucleus of stria terminalis, anterior and lateral hypothalamus and zona incerta. The present investigation also indicated that PBN receives barosensory information. Single-pulse electrical stimulation of the aortic nerve (AN) activated neurons in NTS at an average latency of 7.5 ms and in PBN at a mean latency of 12.1 ms. Mean latency of 9 neurons in NTS activated antidromically by PBN stimulation was 3.4 ms. Conduction velocity of the monosynaptic fibers projecting from NTS to PBN was approximately 3.5 m/s, which would be characteristic of finely myelinated fibers. Injection of HRP into PBN confirmed the existence of direct ascending projections to PBN from regions of NTS (e.g. lateral commissural area) previously shown to receive primary barosensory input. However, the finding that only 1 of 9 NTS neurons antidromically activated by PBN stimulation also received barosensory stimulation, indicates that additional study is needed of the mono- and oligosynaptic functional projections from NTS to PBN. The present study did provide evidence that PBN both receives barosensory information at short latency over a direct route, and serves as a relay for descending projections mediating bradycardia.

Amygdala↗
PubMed1980

Microvascular segmental thumb reconstruction: a case report.

The great toe provides an ideal source of tissue for both functional and aesthetic reconstruction of segmental defects in the thumb and can be used without mutilation of the foot. A successful case is presented of a I-stage primary reconstruction of a segmental defect of the thumb using a composite free flap transfer from the great toe containing pulp, tissue, nail and bone, with neurovascular anastomosis. The donor defect on the great toe was repaired at the same time.

Adult↗
PubMed1980

Replantation and revascularization of digits.

Between 1970 and 1978, 160 digits in 120 patients were replanted or revascularized. One hundred and nineteen digits survived, and these patients were assessed objectively and subjectively for functional results and their ability to return to work. Providing that strict indications are observed, long term objective and subjective results of digital replantation have proved most valuable from the point of view of the examiner and the patient. The best results were obtained with replantation of the thumb.

Adolescent↗
PubMed1978

Neurovascular free foot flaps in reconstruction of the mutilated hand.

The neurovascular free flap from the first web region of the foot affords unrivalled potential for refurbishing sensibility to the denervated hand. Its greatest application is when no conventional island flap tissue remains for transfer. Its two-point discrimination is only moderate, but when used for thumb reconstruction, its sensibility is adequate because no functional substitute exists. Functionally and cosmetically it is superior to other methods of thumb reconstruction because of its pulp, size, and nail availability. There are no finger identification problems and secondary donor defects are minimal.

Adult↗