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B G Klein

Publications and source records attributed to B G Klein.

At least 19 recordsLinked to original sources
PubMed2001

Pharmacological properties of the MPTP analog trans-1-methyl-4-[4-dimethylaminophenylethenyl]-1,2,3,6-tetrahydropyridine and its pyridinium metabolite in mouse brain synaptosomes: a potential visual marker for substrates of MPTP-induced neurotoxicity.

1. The tetrahydropyridine trans-1-methyl-4-[4-dimethylaminophenylethenyl]-1,2,3,6-tetrahydropyridine (t-THP), like MPTP, can undergo monoamine oxidase (MAO)-mediated conversion to a dihydropyridinium intermediate and subsequent metabolism to a pyridinium species. t-THP is also a better substrate for MAO B than MAO A. In contrast to the metabolism of MPTP, the pyridinium ion derived from t-THP is highly fluorescent. This endows t-THP with potential as an in vivo visual probe for localizing the substrates of MPTP-like neurotoxicity. As a prelude to in vivo labeling studies, we examined the metabolism and uptake kinetics of t-THP and its metabolites in mouse striatal and cortical synaptosomes. 2. T-THP was found to induce a concentration-dependent and saturable fluorescence within striatal and cortical synaptosomes that was also MAO-dependent. Like MPP+, the fluorescent pyridinium ion t-P+, derived from t-THP, inhibited the uptake and facilitated the release of monoamines from synaptosomes in a concentration-dependent fashion. The ion did not rely on sodium-dependent membrane transporters for its concentration-dependent uptake into synaptosomes, although it may have an irreversible affinity for the dopamine transporter. 3. These data suggest that t-THP could be appropriate for use as a visual marker for microenvironments where MPTP-like compounds are taken up and converted to potentially neurotoxic pyridinium species. Such a marker could be employed to address some of the issues regarding the selectivity of MPTP-induced neurotoxicity.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2001

The 2001 Carl J. Norden Distinguished Teacher Award. Teaching the basic sciences to veterinary students: science or art or both? One teacher's journey into self-examination.

Veterinary faculty do not often get the chance to reflect on their own teaching practices. Recent circumstances dictated that the author perform such a self-analysis. This article represents the fruits of that reflection process. A personal philosophy of teaching is presented, along with impressions of the student experience. Using these as a guide, ideas are presented about the package of material that should be delivered to the students, how that package should be delivered, and some special tools to aid delivery. A personal wish list of items that might lead to a better teaching experience is also included. Although the teaching game plan presented here is unlikely to be the best strategy, it is hoped that it may provide some helpful hints for other instructors of veterinary medicine or, at least, stimulate further thinking about how the teaching and learning experience can be improved for both teacher and student.

Awards and Prizes↗
PubMed1998

Rapid shifts in receptive fields of cells in trigeminal subnucleus interpolaris following infraorbital nerve transection in adult rats.

Transection of the infraorbital nerve in adult rats results in an array of chronic functional anomalies in trigeminal brainstem subnucleus interpolaris, including changes in normal receptive field organization. This work examined whether long-term maintenance of acute modifications, such as unmasking or strengthening of normally ineffective inputs to interpolaris cells, might contribute to the previously described chronic abnormalities. Using glass micropipettes, extracellular isolation of 37 interpolaris cells, with infraorbital receptive fields, was maintained following intraorbital transection of the infraorbital nerve. Receptive fields and dynamic response properties were characterized immediately before and after the cut and throughout the post-transection isolation period. Orthodromic latencies to trigeminal ganglion shocks and antidromic activation from thalamus or cerebellum were also examined. Of the 37 cells, 21.6% exhibited receptive field shifts to non-infraorbital regions after cutting the infraorbital nerve. Using the normal probability of observing an interpolaris cell with more than one trigeminal division in its receptive field, the probability of observing this shift by chance was 0.0013. No such changes were observed for 12 control cells, recorded for durations equal to or greater than total recording times for the shifting cells, with the nerve intact. The representation of local circuit, thalamic-projecting and cerebellar-projecting cells was similar in the total sample; however, all neurons exhibiting transection-induced receptive field shifts were projection neurons. In comparing the sample of cells that exhibited receptive field shifts with those that did not, prior to infraorbital nerve cut, there was no difference in mean latencies and thresholds for activation from the stimulating electrodes or in mean depth at which the cells were isolated. In addition, no difference was evident in receptive field size, effective receptor surface, dynamic response characteristics or spontaneous activity. These data suggest that maintenance of acute receptive field changes, following infraorbital nerve cut, may contribute to some types of chronic functional alterations observed after such damage.

Animals↗
PubMed1995

Structure-function relationships in rat brainstem subnucleus interpolaris. XI. Effects of chronic whisker trimming from birth.

Whisker trimming from birth reduces activity and alters receptive fields (RFs) in the barrel cortex and thalamus. To assess whether or not this reflects deprivation effects on trigeminal (V) first- and second-order neurons, 59 primary afferents and 343 cells in V brainstem subnucleus interpolaris (SpVi) were studied in rats whose whiskers were trimmed daily for 6-9 weeks from birth. Deprivation did not effect brainstem somatotopy or primary afferent RFs. However, many SpVi cells had abnormal RFs and higher-order inputs, resembling the changes caused by infraorbital nerve injury. For example, in controls, only 3% of whisker-sensitive local circuit neurons responded to more than one whisker, whereas 35% of the deprived and 41% of the infraorbital nerve cut samples had multiwhisker. RFs. Deprived rats also had higher than normal incidences of cells with split or absent RFs, RFs spanning more than one V division, intermodality convergence, and directional or high-velocity sensitivity. Because these changes mimic those caused by nerve section, deprivation may underlie some nerve injury effects on V brainstem RF size and character. Insofar as cytochrome oxidase, anterograde labeling, and unit recordings revealed normal topography in deprived primary afferents and SpVi cells, RF changes in SpVi cells may reflect altered SpVi circuitry. To test this hypothesis, we assessed the morphology of 32 similarly deprived V primary afferents. In SpVi, deprived fibers had normal numbers of collaterals with normal shapes, transverse arbor areas, and topography. However, the total number of boutons per collateral was significantly reduced. Thus, deprivation effects on V higher-order RFs reflect quantitative changes in V afferent terminals.

Afferent Pathways↗
PubMed1995

Functional properties of cells in rat trigeminal subnucleus interpolaris following local serotonergic deafferentation.

We have previously demonstrated increases in serotonin (5-HT) content and immunoreactivity within spinal trigeminal subnucleus interpolaris (SpVi) that are correlated with the functional changes observed in this subnucleus following adult infraorbital nerve (ION) transection. To assess the possible functional significance of this change, we have examined the influence of 5-HT afference upon the normal response properties of cells in SpVi. We employed local depletion of the transmitter, using 5,7-dihydroxtryptamine (5,7-DHT), in combination with extracellular single-cell recording. Chromatographic methods revealed a 97.6% depletion of 5-HT 24 hr after neurotoxin injection. Immunocytochemical procedures revealed depletion of 5-HT throughout SpVi. Physiological recordings were made from 403 SpVi cells in 5,7-DHT-injected rats and 387 cells in vehicle-injected rats. All recordings were made 19-27 hr after injection. Horseradish peroxidase (HRP) deposits from the recording electrode were used to mark recording tracks. 5-HT depletion did not influence receptive field (RF) location, size, or continuity, or the dynamic response characteristics of SpVi cells. It did, however, (1) alter the probability that certain types of somatosensory receptor surfaces would activate local-circuit neurons, and (2) influence the rate of firing of spontaneously active SpVi cells. There was a significant increase in the proportion of vibrissa-sensitive cells with infraorbital RF components, and a concurrent decrease in the proportion of guard-hair-sensitive cells. It therefore appears that 5-HT input to SpVi is necessary for some mechanoreceptive features of the normal functional organization of this area. These functional changes were interesting in that they were opposite to those found following adult ION transection, which increases 5-HT within SpVi. Thus, changes in 5-HT central afference to SpVi that follow ION damage may be responsible for at least one type of functional change observed following this peripheral lesion.

Afferent Pathways↗
PubMed1994

Neonatal infraorbital nerve damage and the development of eating behavior in the rat.

It has been previously shown that bilateral infraorbital nerve (ION) transection in adult rats has little effect upon body weight regulation or eating behavior. However, in neonatal mouse, unilateral ION cut produces a profound decrease in body weight, beginning around the time of weaning. To help clarify the role of the ION in the development and sensorimotor control of eating solid food in rodents, the present experiment examined the effects of unilateral, neonatal ION transection in rats, upon body weight regulation and post-weaning eating behaviors. Comparison of normal and lesioned groups of rats, up to postnatal day (PND) 61, revealed no significant difference in mean adjusted (for sex) body weight. In addition, no significant differences were detected between the groups on post-weaning (PND 26 to PND 61) measures of mean adjusted (for weight) food intake, responsiveness to food, biting ability or inefficiency of mandibulation. At the end of the experiment, the effectiveness of the lesion was histologically evaluated. A significant 48.5% mean reduction in the cross-sectional area of the ophthalmic-maxillary portion of the trigeminal ganglion was observed on the lesioned side, relative to the intact side. There appears to be a differential influence of unilateral, neonatal ION cut upon eating in rat and mouse.

Afferent Pathways↗
PubMed1993

Structure-function relationships in rat brainstem subnucleus interpolaris. X. Mechanisms underlying enlarged spared whisker projections after infraorbital nerve injury at birth.

Prior studies indicate that the central projections of noninfraorbital vibrissae occupy greater than normal transverse areas in the rat trigeminal brainstem complex after infraorbital nerve section at birth. Here, we assessed the development of this phenomenon and possible underlying mechanisms. Cytochrome oxidase patches representing spared supraorbital (SO) or posteroorbital (PO) whiskers in the trigeminal subnucleus interpolaris (SpVi) were not reliably larger than those on the control side 24 hr after the infraorbital lesion. By 72 hr, SO and PO patches were 91% and 28% larger than those on the control side. Reliable increases were also observed on postnatal day 5 (PND5), PND7, and PND10 for the SO (59%, 65%, 66%) and PO (23%, 44%, 51%) patches. To test the hypothesis that central reorganization reflects the maintenance of peripheral supernumerary axons, myelinated and unmyelinated axons in SO vibrissa follicles were counted at PND0, PND7, PND17, and PND60. A corollary hypothesis, that peripheral regeneration errors result in both SO and surviving infraorbital axons, contributing to central SO patches, was tested with retrograde double-labeling methods. Both hypotheses were rejected. Thus, enlargement of SO patches is not due to either the maintenance of an immature peripheral innervation pattern, or regeneration of infraorbital axons into SO follicles. To determine if the enlargement of SO and PO patches produced by infraorbital nerve section is due to an activity-dependent competitive disadvantage imposed upon infraorbital afferents, TTX or bupivicaine was applied to the intact infraorbital nerve over the first 5-9 postnatal days. Brainstem maps developed normally and SO and PO patch areas were unaffected. Thus, impulse activity-based mechanisms do not appear to contribute to injury-induced patch enlargement. To test the hypothesis that patch enlargement is due to central collateral reorganization, intra-axonal recording and staining methods were applied to control and spared-whisker primary afferents in adult rats. Total bouton or collateral numbers did not differ in SpVi; however, arbor areas were reliably larger in experimental (14,879 +/- 350 microns 2) versus control (5527 +/- 1811 microns 2) fibers.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1992

Time course of serotonergic afferent plasticity within rat spinal trigeminal nucleus following infraorbital nerve transection.

High-performance liquid chromatography with electrochemical detection (HPLC-ED) and immunocytochemistry were used to examine the time course of serotonergic afferent plasticity within trigeminal subnucleus interpolaris (SpVi) following infraorbital nerve (ION) transection in adult rats. Biochemical analysis was also performed in trigeminal subnucleus caudalis (SpVc) to examine the possibility of transient lesion-induced changes in this region. No significant changes in serotonin (5-HT) or 5-hydroxyindoleacetic acid (5-HIAA) concentration, or in density of 5-HT-immunoreactive (5-HTIR) axonal varicosities were observed in either subnucleus on the lesioned side, up to 51 days following ION cut. However, at 76-79 days post-lesion, a significant increase in 5-HT concentration was again demonstrated within SpVi.

Animals↗
PubMed1991

Orofacial pain sensitivity in adult rats following neonatal infraorbital nerve transection.

A modification of the formalin test was used to assess orofacial pain sensitivity in adult rats that received infraorbital nerve transection at birth. Normal and neonatally lesioned adult animals received an injection of either 5% formalin or saline vehicle into the whiskerpad and the duration of whiskerpad rubbing was observed for 45 min. Normal rats given formalin exhibited the previously reported biphasic pattern of rubbing. Neonatally lesioned rats given formalin did not exhibit this pattern, and were indistinguishable from either of the saline control groups.

Afferent Pathways↗
PubMed1991

Numbers of axons innervating mystacial vibrissa follicles in newborn and adult rats.

Electron-microscopic techniques were used to determine the numbers of axons in the deep vibrissal nerves innervating the C1 and C4 follicles in newborn and adult rats. All counts were made from thin sections taken after the nerve had entered the follicle capsule (FC). In newborn animals, the nerves supplying the C1 (n = 10) and C4 (n = 10) follicles contained an average (means +/- standard deviation) of 355.0 +/- 40.0 and 233.9 +/- 19.2 axons, respectively. In the adult animals (n = 10 for C1 and n = 9 for C4), the respective values were 314.4 +/- 26.2 and 233.3 +/- 34.4 axons. There were no significant differences between the values for the counts from the neonates and adults for either follicle (p greater than 0.01, independent t tests). In the vibrissal nerves of neonates, both degenerating axons and occasional growth cones were visible. Such profiles were not observed in the nerves taken from adults.

Aging↗
PubMed1991

Trigeminal projections to contralateral dorsal horn originate in midline hairy skin.

The present study tested the hypothesis that the trigeminal (V) primary afferent projection to the contralateral dorsal horn originates in midline hairy skin. A prior study (Jacquin et al., 1990) showed that this crossed projection is heaviest to ophthalmic regions of medullary and cervical dorsal horns, and that it does not arise from V ganglion cells that innervate cornea, nasal mucosa, or cerebral dura mater. Here, retrograde double-labeling methods were used to show that many ophthalmic ganglion cells that innervate midline hairy skin via the supraorbital nerve project to the contralateral medullary and upper cervical dorsal horns. Diamidino yellow injections into the right dorsal horn labeled an average of 104 cells in the left V ganglion. Of these contralaterally projecting ganglion cells, an average of 45% were also labeled by horseradish peroxidase (HRP) injections into the left supraorbital nerve, and 25% were also labeled by HRP injections into the midline opthalmic hairy skin. However, only 2% were labeled by HRP injections restricted to left supraorbital vibrissae follicle nerves. Almost all of the double-labeled cells were located in the dorsal one-half of the V ganglion, and they did not differ in size from single-labeled cells. On the basis of these and prior data, we conclude that a high percentage of contralaterally projecting V ganglion cells originate in midline hairy skin. It is also likely that the contralaterally projecting V ganglion cells serve a low-threshold mechanoreceptive function, given the relatively large ganglion cells and axons giving rise to this pathway and their central terminations in dorsal horn laminae III-V.

Afferent Pathways↗
PubMed1991

Chronic functional consequences of adult infraorbital nerve transection for rat trigeminal subnucleus interpolaris.

In adult rats, transection of the infraorbital nerve and subsequent regeneration have been shown to result in altered somatotopic organization and changes in response properties of primary afferents within the trigeminal ganglion. The present study examined how these changes affect the postsynaptic targets of these neurons within subnucleus interpolaris of the trigeminal brainstem. Extracellular recordings were made from 330 cells in normal rats and 424 cells in rats surviving 57-290 days after transection of the infraorbital nerve in adulthood. Adult infraorbital nerve transection resulted in significant functional reorganization within subnucleus interpolaris. Relative to normal rats, the major changes can be summarized as follows: (1) a decrease in the dorsoventral extent of infraorbital representation; (2) a disruption of inter- and intradivisional somatotopic organization; (3) an increase in the proportion of cells with no discernible receptive field; (4) an increase in receptive field size for cells with infraorbital receptive field components; (5) the appearance of a significant proportion of cells with discontinuous receptive fields; (6) an increase in the proportion of cells exhibiting interdivisional convergence; (7) significant changes in the types of receptor surfaces activating local-circuit neurons with infraorbital receptive field components; (8) the appearance of a significant proportion of cells exhibiting convergence of different receptor surfaces; (9) significant changes in the dynamic response characteristics of cells with infraorbital receptive field components; and (10) an increase in the proportion of spontaneously active infraorbital-responsive cells. The changes observed were quite similar to those reported in adult subnucleus interpolaris following neonatal infraorbital nerve transection. The majority of changes observed in both studies can be most parsimoniously explained by alterations of primary afferents. However, central mechanisms may be more likely substrates for others. Regardless of the mechanism, the mature rodent trigeminal system appears capable of considerable functional reorganization following peripheral nerve damage.

Afferent Pathways↗
PubMed1990

Biochemical and anatomical consequences of adult infraorbital nerve transection for serotonergic afferents within rat trigeminal subnuclei interpolaris and caudalis.

Immunocytochemistry and high-performance liquid chromatography with electrochemical detection (HPLC-ED) were used, more than 76 days after infraorbital nerve (ION) transection, to examine the distribution and density of serotonin-immunoreactive (5-HTIR) axons, as well as serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content, within the infraorbital (IO) regions of subnuclei caudalis (SpVc) and interpolaris (SpVi). In SpVi, increases in 5-HT concentration and in density of 5-HTIR axonal varicosities were observed on the lesioned side. No changes were seen in SpVc.

Afferent Pathways↗
PubMed1990

Topography of the facial musculature within the facial (VII) motor nucleus of the neonatal rat.

WGA-HRP, HRP and fluorescent tracers were used to determine the representation of the facial muscles in the facial motor nuclear complex (FMNC) of the newborn rat. Tracer injections of the superficial cervical and anterior mandibular portions of platysma, the orbicularis oculi muscle, the nasolabial musculature and the posterior auricular musculature revealed an adult-like topographic organization across FMNC subnuclei. Tracer delivery to individual vibrissa follicle loci of the whiskerpad also demonstrated an adult-like musculotopic organization within the lateral subnucleus.

Animals↗
PubMed1989

Structure-function relationships in the rat brainstem subnucleus interpolaris: VI. Cervical convergence in cells deafferented at birth and a potential primary afferent substrate.

Possible substrates for peripheral injury-induced receptive field (RF) changes were assessed in the trigeminal (V) subnucleus interpolaris (SpVi). In adult rats with infraorbital nerve section at birth, 449 cells were studied ipsilateral to the lesion by using electrophysiological methods. Of these, 33 (7.4%) had RFs that included facial vibrissae, guard hairs, and skin, as well as ipsilateral regions normally innervated by cervical primary afferents (ear, neck, shoulder, arm, forepaw). Such non-V convergence was never seen in 373 normal SpVi cells or in 641 V ganglion cells ipsilateral to the lesion. SpVi cells with cervical RFs discharged to V ganglion shocks and their latencies (1.6 +/- 0.7 ms, mean +/- s.d.) did not differ from normal (1.4 +/- 0.5). Most (71%) projected to the thalamus. None were nociceptive-biased, and many had unusually discontinuous RFs (48%). Possible pathways by which cervical inputs might reach SpVi neurons were investigated in additional anatomical and electrophysiological experiments. Eight SpVi cells with cervical RFs were intracellularly labeled with HRP. Although all had dendrites that were polarized toward SpVi regions containing spared mandibular and/or ophthalmic primary afferents, none had dendrites which extended out of SpVi. In other neonatally nerve-damaged adults, WGA-HRP was injected bilaterally into forepaw, arm, and shoulder regions. Transganglionic transport was restricted to normal targets. However, WGA-HRP injections into SpVi retrogradely labeled a total of 46 +/- 20 (mean +/- s.d.) cells in ipsilateral C1-3 dorsal root ganglia, and 24 +/- 8 cells in C4-8 ganglia. In controls, labeled cells were seen only in C1-3 ganglia (32 +/- 9). The distribution and number of labeled cells in the somatosensory cortex did not differ in experimental and control cases. No labeled cells were visible in the dorsal column nuclei of either the normal or experimental rats. Thus, retrograde labeling studies suggest that a cervical primary afferent projection to SpVi is a potential substrate for cervical convergence expressed in neonatally deafferented SpVi cells.

Action Potentials↗
PubMed1989

Physiological and anatomical consequences of infraorbital nerve transection in the trigeminal ganglion and trigeminal spinal tract of the adult rat.

Single-unit recording and retrograde tracing techniques were used to assess the receptive field properties, topography, and projections of rat trigeminal primary afferent neurons subsequent to transection of the infraorbital (IO) nerve in adulthood. Four hundred and fifty-eight units were recorded in the trigeminal ganglion ipsilateral to nerve section. Of these, 66.6% had IO receptive fields. Thirty percent responded to innocuous stimulation of vibrissae, 39.1% to guard hair deflection, 8.2% to gentle indentation or stretch of the skin, and 22.3% to noxious stimuli (compared to 77.2% vibrissa, 12.0% guard hair, 4.5% skin, and 6.3% noxious in normal animals). An additional 15 units were driven by a stimulating electrode placed on the IO nerve proximal to the site of the lesion but had no receptive field. Of the cells with vibrissa receptive fields, 33.3% were slowly adapting type I (SAI), 6.6% were slowly adapting type II (SAII), 32.2% were low velocity rapidly adapting (RA-LV), 20.0% were high velocity rapidly adapting (RA-HV), and 7.7% were nociceptive (NX, in normal animals 43.8% were SAI, 10.3% SAII, 27.6% RA-LV, 16.8% RA-HV, and 1.5% NX). A number of cells had receptive field properties not seen in normal animals. The single-unit recordings indicated that the topography of mandibular and ophthalmic representations in the ganglion were essentially normal, while the organization of the maxillary region of the ganglion was slightly abnormal. The ganglion physiology experiments were augmented by records from primary afferents in the trigeminal spinal tract (TrV). Eighty-one (72.2%) of the 112 fibers recorded in the TrV of normal rats had IO receptive fields. Of these, 73.2% responded to innocuous vibrissal stimulation, 14.6% to guard hair deflection, 8.5% to gentle indentation of the skin, and 2.5% to noxious stimuli. Of the 61 vibrissa units, 37.8% were SAI, 19.7% SAII, 37.8% RA-LV, 3.3% RA-HV, and 1.6% NX. In adult-lesioned animals, 81 (61.3%) of the recorded fibers had IO receptive fields. Of this number, 38.2% responded to vibrissae, 29.6% to guard hairs, 16.0% to skin, and 19.7% to noxious simuli. Of the vibrissa-sensitive units, 16.1% were SAI, 3.2% were SAII, 45.2% were RA-LV, 35.5% were RA-HV, and 3.2% NX. As in the ganglion recording studies, a number of abnormal receptive fields were documented.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Anatomical consequences of neonatal infraorbital nerve transection upon the trigeminal ganglion and vibrissa follicle nerves in the adult rat.

A large body of experimental literature has demonstrated that neonatal infraorbital nerve damage in rodents produces anatomical and/or functional alterations of the normal whisker representation in central trigeminal structures. Less is known about the organization of primary afferent components of the trigeminal system following this manipulation. Such information provides an important basis for interpreting the central changes observed following damage of infraorbital nerve fibers at birth. We have therefore examined the composition and order of peripheral innervation in the pathway from the trigeminal ganglion to the vibrissa follicles in adult rats subjected to unilateral neonatal infraorbital nerve transection. Electron microscopy was used to determine the number and diameter of myelinated and unmyelinated fibers in vibrissa follicle nerves of these animals. Wheat germ agglutinin-horseradish peroxidase and fluorescent retrograde tracers were employed to examine the number and diameter, as well as the topographic organization and branching, of ganglion cells innervating the vibrissae in these rats. The data presented below indicate that neonatal infraorbital nerve transection has the following consequences within the adult trigeminal nerve and ganglion: 1) an alteration of the gross morphology of vibrissal nerves, 2) a significant reduction in the average number (85.4%) and diameter (32.6%) of myelinated, but not unmyelinated, follicle nerve axons, 3) a significant decrease in the average number (36.8%) of trigeminal ganglion cells innervating vibrissa follicles, 4) no significant change in the distribution of ganglion cell diameters, 5) an increase in peripheral branching (1.8-fold) of these ganglion cell axons, and 6) an alteration of somatotopic order within the trigeminal ganglion. Taken together, these data indicate that neonatal infraorbital nerve transection produces a profound reorganization of the primary afferent component of the trigeminal neuraxis.

Animals↗